Tue·May 12, 2026Tuesday·May 12, 2026

1. 01*

   Electroweak Restoration: SMEFT and HEFT

   Ian M. Lewis🇺🇸 · Zhen Liu🇺🇸 · Ishmam Mahbub🇺🇸

   Colliders continue to push our understanding of electroweak (EW) interactions to ever higher energies. At high energies, many observables in the broken EW theory are expected to approach the unbroken theory. This is the electroweak restoration regime, where longitudinal gauge boson production corresponds to Goldstone boson production. As such, in this paper we investigate electroweak restoration in the context of linear and non-linear realizations of the EW symmetry in longitudinal di-boson production: $f{\bar{f}}^{\prime }\to V_L{V}_L^{\prime }$ and $f{\bar{f}}^{\prime }\to V_{L}h$, where $V_L,V_L^{\prime }$ are longitudinal gauge bosons, $h$ is the Higgs boson, and $f,f^{\prime }$ are SM fermions. For the linear beyond the SM (BSM) theory, we use the Standard Model Effective Theory (SMEFT), and for the non-linear BSM theory, we use Higgs Effective Field Theory (HEFT). We give a general discussion of these amplitudes and cross sections in the SM, SMEFT, and HEFT. Using the Goldstone boson equivalence theorem, we derive a set of ratios among high energy $V_L{V}_L^{\prime }$ and $V_{L}h$ amplitudes that are expected to approach one in the SM and SMEFT. Through our explicit calculations, we show that these ratios do indeed approach one in the SM and dimension-6 SMEFT, but not necessarily HEFT. Beyond the amplitudes, both theoretically and experimentally, we identify the cross section ratio of $W_L^{\pm }{Z}_L$ and $W_L^{\pm }h$ as a particularly promising observable to probe EW restoration and distinguish HEFT and SMEFT. Using current LHC measurements as well as projections for $W_L^{\pm }h$ measurements, we project HL-LHC sensitivities to probing the linear vs. non-linear realizations of the EW symmetry.

   hep-ph1 citation
2. 02*

   Lepton Flavor Violating Higgs decays at the Compact Linear Collider

   Francisca Garay🇨🇱 · Gabriel Vega🇨🇱 · Philipp Roloff🇨🇭

   Lepton flavor violating Higgs decays could appear in scenarios beyond the Standard Model of particle physics. In this article, we study the sensitivity of a future Compact Linear Collider (CLIC) to such processes, namely, $h\to e\mu$, $h\to \tau \mu$, and $h\to e\tau$. In the absence of any observation, 95\% CL\ upper limits in the region of $10^{-4}$ to $10^{-5}$ could be placed on the branching fractions of these processes, assuming integrated luminosities of $4$\,ab${}^{-1}$ at $\sqrt{s}=1.4$ TeV and $5$\,ab${}^{-1}$ at $\sqrt{s}=3$ TeV.

   hep-phhep-ex0 citations
3. 03*

   Scaling properties of net-baryon number fluctuations at the deconfinement critical point

   Michał Szymański🇵🇱 · Pok Man Lo🇵🇱 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱

   We investigate the critical behavior of the first four cumulants of the net-baryon number near the deconfinement critical point in QCD in the limit of heavy quarks. By connecting baryon-number fluctuations to Polyakov loop susceptibilities, we analyze their mean-field scaling properties at zero and non-zero baryon chemical potentials. In the mean-field approximation we derive critical exponents via the Landau theory and validate them through explicit numerical calculations in an effective Polyakov loop model. Using a Ginzburg-Landau criterion as a diagnostic of beyond-mean-field effects, we estimate the size of the critical region and find that it shrinks with increasing baryon density. By utilizing the exact scaling function in the 3D Ising model, we estimate critical exponents beyond the mean-field approximation.

   hep-ph1 citation
4. 04*

   Higher-order local constraints from reciprocal symmetry and entanglement entropy of charged-particle multiplicity distributions in $pp$ collisions

   Mustapha Ouchen🇮🇱 · Alex Prygarin🇮🇱 · Claudelle Capasia Madjuogang Sandeu🇮🇱

   The KNO-violating term $f_s$ of the charged-particle multiplicity distribution in $pp$ collisions measures the relative deviation of $⟨n⟩P_n$ from $e^{-z}$, with $z=n/⟨n⟩$, and is reported to obey the reciprocal symmetry $f_s(z)=f_s(1/z)$, taken here as input. Being an evenness condition in $\ln z$, it generates a tower of local constraints on the derivatives of $P_n$ at the mean. The lowest member holds for the ATLAS data at $7$, $8$ and $13$~TeV at the few-per-cent level, while the third-derivative residual testing the next member is not determined with a controlled uncertainty by the present binning and stays inconclusive. The global test is consistent at $7$ and $8$~TeV, while at $13$~TeV a residual deviation remains, which a closure test shows is not a binning artefact. Multiplicative noise in the Mueller colour-dipole cascade, the negative binomial and the dipole cascades with recombination each give an $f_s$ that is not invariant under $z\to 1/z$, so none of them carries the symmetry. We further obtain a dynamics-independent entropy in the KNO continuum, $S=\ln ⟨n⟩+I_0-\frac{1}{2}\int e^{-z}{f}_s^{2}dz$, with $I_0$ a support factor tending to unity in the continuum limit. The linear term cancels by normalisation and unit mean, independently of the symmetry, and the remaining correction is quadratic and negative. It reproduces the Shannon entropy of the ATLAS data at the $10^{-3}$ level.

   hep-phEPJC(2026)·1 citation
5. 05*

   $B$ anomalies and the tauphilic leptoquark model

   Jong-Phil Lee🇰🇷

   We suggest three scalar leptoquarks, $S_1$, ${\tilde{R}}_2$, and $S_3$ which couple exclusively to the 3rd generation of leptons to explain the $B$ anomalies. The scalar singlet $S_1$ can explain $R(D^{(\ast )})$, while the doublet ${\tilde{R}}_2$ is needed to fit the branching ratio $\mathrm{Br}(B\to K^{(\ast )}\nu \bar{\nu })$ via the right-handed Wilson coefficients $C_R^{\nu }$. A strong constraint from $\Delta m_{B_s}$ requires triplet $S_3$ where the mixing term between $S_1$ and $S_3$ is important. Our analysis suggests subdominant $C_{V_L}<0$ and dominant $C_{S_L}>0$ and lepton-flavor universality violating $C_9^{\mathrm{LQ}}\approx +1$. The masses are expected to be $M_{S_1}\sim M_{{\tilde{R}}_2}<M_{S_3}\lesssim 3$ TeV, which can be probed in future colliders.

   hep-ph0 citations
6. 06*

   F-Term Hybrid Inflation with T-Model Kähler Geometry and Beyond

   Waqas Ahmed🇨🇳 · Constantinos Pallis🇬🇷 · Mansoor Ur Rehman🇸🇦

   We analyze F-term hybrid inflation (FHI) within various grand unified theories (GUTs) in the presence of a Kähler potential for the inflaton field which parameterizes the Kähler manifolds $SU(1,1)/U(1)$ or $SU(2)/U(1)$. We take into account supergravity, radiative, and soft supersymmetry-breaking corrections to the tree-level potential and find that viable FHI can be realized without extrema along the inflationary trajectory for a broad region of the parameter space. For selected superpotential parameters the models' predictions are largely influenced by the curvature of the internal space and the magnitude of the tadpole parameter which are constrained so as to achieve compatibility with the current ACT and SPT data. We also discuss the formation of cosmic strings and their associated gravitational wave signals, potentially detectable by current and upcoming experiments.

   hep-phgr-qchep-thPRD(2026)·2 citations
7. 07*

   Direct determination of the structure functions $F_L$, $F_S$ and $G$ from $F_2$ and $d{F}_2/d{Q}^2$ to $O({\alpha }_s^2)$

   G.R. Boroun🇮🇷 · Loyal Durand🇺🇸 · Phuoc Ha🇺🇸

   We extend the results of Lappi {\em et al.}, Eur.~Phys.~J.~C {\bf 84}, 84 (2024), to show that it is possible to obtain expressions for the longitudinal, singlet and gluon structure functions $F_L$, $F_S$ and $G$ in deep inelastic scattering directly in terms of the measured functions $F_2$ and $d{F}_2/\ln (Q^2)$ {\em modulo} non-singlet corrections expected to be small at very small $x$. The latter can be treated at low $x$ using existing quark distributions. Our results are presented consistently to $O({\alpha }_s^2)$, correcting and extending the mixed-order results of Lappi {\em et al.}.

   hep-phPRD(2026)·0 citations
8. 08*

   Optimizing Yukawa couplings to suppress Dimension-five Proton Decay in $SU(5)$ GUT

   Naoyuki Haba🇯🇵 · Junpei Ikemoto🇯🇵 · Yasuhiro Shimizu🇯🇵 · Toshifumi Yamada🇯🇵

   The minimal supersymmetric $SU(5)$ grand unified theory (GUT) provides a highly compelling framework for physics beyond the Standard Model (SM). However, it suffers from a severe phenomenological challenge: rapid proton decay mediated by colored-Higgsino exchange via dimension-five operators. Resolving this issue often requires adjustments to the Yukawa couplings and the potential sectors, generating a vast and complex parameter space where traditional brute-force numerical scans are rendered computationally intractable due to the curse of dimensionality. In this paper, we overcome this limitation by applying machine learning optimization techniques. We investigate a supersymmetric $SU(5)$ model extended with $45$ and $\overline{45}$ Higgs representations, defining a loss function based on the partial decay width of $p\to K^{+}\bar{\nu }$. Utilizing the Adam optimizer, we systematically explore the 33-dimensional parameter space to identify regions that suppress proton decay. Furthermore, we vary $\tan \beta$ to thoroughly investigate whether the optimized proton lifetime can consistently exceed the stringent experimental lower bound of $5.9\times 10^{33}$ years established by the Super-Kamiokande collaboration.

   hep-ph1 citation
9. 09*

   Inferring identified hadron production in $pp$ collisions with physics-informed machine learning at the LHC

   Rishabh Gupta🇮🇳 · Kangkan Goswami🇮🇳 · Suraj Prasad🇮🇳 · Raghunath Sahoo🇮🇳

   Machine learning has become a powerful tool in high-energy collider experiments, which enables the studies based on data-driven approaches to complex reconstruction and regression tasks. The study of identified hadron spectra in pseudorapidity regions beyond detector acceptance, which is limited to mid-rapidity regions, carries important information about particle production, yet remains unmeasured. In this work, we develop a physics-informed neural network, trained on PYTHIA8 $pp$ collisions at $\sqrt{s}=13.6$ TeV, to infer $p_{\mathrm{T}}$ spectra of ${\pi }^{\pm }$, $K^{\pm }$, $p/\bar{p}$, $\Lambda /\bar{\Lambda }$, and $K_{\mathrm{s}}^0$ in different rapidity regions. Physics-motivated constraints, including particle yield ratios, spectral shape, and smoothness, are incorporated into the loss function. A staged hyperparameter optimization strategy is used to ensure stability. The model achieves yield uncertainties of $\sim 1.5\%$, $1.8\%$, and $5.83\%$ in the training, interpolation, and extrapolation regimes, respectively, outperforming XGBoost and LightGBM. It further reproduces key observables such as particle yield ratios, the multiplicity dependence of $⟨p_{\mathrm{T}}⟩$, and kinetic freeze-out parameters, indicating that the model captures the underlying physics and provides reliable predictions beyond the measured phase space.

   hep-phhep-exhep-thnucl-ex+11 citation
10. 10*

    Can a Nonstandard Invisible Pair Mimic the Michel Distribution?

    Pablo Roig🇲🇽

    We ask whether a measured Michel distribution, apparently in excellent agreement with the Standard Model interpretation of the ${\ell }_i\to {\ell }_j\nu \bar{\nu }$ decay, could instead arise from a different invisible sector. Within a general low-energy effective field theory, we analyze lepton decays ${\ell }_i\to {\ell }_j+X\bar{X}$ for electrically neutral, color-singlet, mutually conjugate invisible pairs $X\bar{X}$ of spin up to $2$, allowing (pseudo)scalar, (axial)vector, and antisymmetric tensor interactions in the lepton current, focusing on the massless limit relevant for exact degeneracies. We formulate a criterion for indistinguishability based on the full set of measurable differential distributions. Under these assumptions, besides the obvious spin $1/2$ case, there is a unique nontrivial solution: a massless complex scalar pair coupled through a purely left-handed vector current exactly reproduces the standard Michel pattern, including its extensions to daughter-lepton polarization and radiative channels. All other cases studied here are distinguishable, in particular because higher-spin invisible pairs produce additional kinematic prefactors. These results isolate the only nonstandard and nontrivial invisible sector that can remain hidden in Michel-type lepton decay measurements. Phenomenologically, a subpercent branching fraction into this channel could bias the conventional muon-lifetime extraction of $G_F$ upward by enough for the corrected value to agree with the CKM-unitarity determination, while increasing the discrepancy with the electroweak fit.

    hep-phhep-exSciPost Phys.(2026)·1 citation
11. 11*

    Ortho-Positronium Three-Photon Decays: Physics Constraints and a Closed-Form Energy Method for Annihilation Vertex Reconstruction

    L. Raczyński🇵🇱 · W. Krzemień🇵🇱 · A. Coussat🇵🇱 · M. Bała · B.C. Hiesmayr🇦🇹 · K. Klimaszewski🇵🇱 · M. Obara · R. Y. Shopa🇵🇱

    We examine the physical foundations of orthopositronium three-photon decay in the context of annihilation vertex reconstruction, focusing on how energy-momentum conservation constrains the space of physically admissible solutions. Finally, we provide a closed-form analytical derivation of an energy-based vertex reconstruction algorithm.

    hep-phphysics.ins-detphysics.med-ph0 citations
12. 12*

    Probing the nature of $D_{1}K$ and $D_{2}K$ molecules through $D_s^{(\ast )}\pi \pi$ and $D_{s0(s1)}\pi$ decays

    Xing-Meng Zhao🇨🇳 · Liu-Lin Wang🇨🇳 · Ying-Bo He🇨🇳 · Xiao-Yun Wang🇨🇳 · Xiao-Hai Liu🇨🇳

    We study the two- and three-body decays of the $I=0$ $D_{1}K$ and $D_{2}K$ molecular states $T_{c\bar{s}1}^{\ast }$ and $T_{c\bar{s}2}^{\ast }$ into $D_s^{(\ast )}$ mesons and pions. Triangle singularities produce narrow peaks in the $D_s^{\ast }\pi$ and $D_s\pi$ invariant mass spectra near the $D^{\ast }K$ and $DK$ thresholds. The isospin-violating two-body decays $T_{c\bar{s}1}^{\ast }\to D_{s1}(2460){\pi }^0$, $T_{c\bar{s}2}^{\ast }\to D_{s1}(2460){\pi }^0$, and $T_{c\bar{s}2}^{\ast }\to D_{s0}^{\ast }(2317){\pi }^0$ exhibit large partial widths, reflecting the strong couplings inherent to molecular states. These predictions, obtained within heavy hadron chiral perturbation theory and the chiral unitary approach, provide complementary signatures for identifying $D_{1}K$ and $D_{2}K$ molecules at experiments.

    hep-phhep-exEPJC(2026)·1 citation
13. 13*

    Non-factorisable electroweak virtual corrections to single-resonant processes

    Fazila Ahmadova🇨🇭 · Luca Buonocore🇨🇭 · Massimiliano Grazzini🇨🇭 · Chiara Savoini🇩🇪

    We consider electroweak (EW) virtual corrections to $2\to 2$ fermion scattering processes mediated by a vector boson $V$ ($V=W^{\pm },Z$) in the pole approximation. As is well known, the computation can be organised into factorisable and non-factorisable contributions. The factorisable corrections can be computed by evaluating the (polarised) EW form factor of the vector boson at the relevant perturbative order. The non-factorisable corrections are instead driven by soft-photon exchanges between the initial- and final-state fermions and/or the resonance. We perform an explicit two-loop computation to show that, once the heavy degrees of freedom are properly decoupled, such non-factorisable corrections can be expressed as an iteration of the one-loop result, plus a new contribution due to (light) fermion loops. The final two-loop result, which can be expected on general grounds from soft-photon factorisation, is shown to hold exactly in dimensional regularisation and is peculiar to the exchange of a single resonance. We discuss its extension to all perturbative orders.

    hep-phJHEP(2026)·0 citations
14. 14*

    An Algorithm for the Symbolic Reduction of Multi-loop Feynman Integrals via Generating Functions

    Bo Feng🇨🇳 · Xiang Li🇨🇳 · Yuanche Liu🇨🇳 · Yanqing Ma🇨🇳 · Yang Zhang🇨🇳

    We develop a generating-function formulation for the symbolic reduction of multi-loop Feynman integrals. In this framework, integration-by-parts identities are rewritten as differential equations for sector-wise generating functions, so the reduction problem can be studied in a non-commutative algebra of differential operators rather than only through relations among individual integrals. This viewpoint leads to an iterative algorithm that generates candidate equations, extracts symbolic reduction rules, updates the active rule set, and tests completeness on the lattice of integral indices. We illustrate the method with the sunset topology, planar and non-planar massless double-box topologies, representative subsectors, and a degenerate example in which the top sector contains no master integral. Together, these examples show how symbolic reduction rules, descendant equations, and completeness criteria can be organized within a single algebraic framework.

    hep-phhep-th3 citations
15. 15*

    A minimization theorem for the Koide ratio and its Standard Model calibration

    K. Hübner

    The charged-lepton Koide relation remains a striking empirical regularity in Standard-Model flavor data. We prove that for any positive mass set with Koide ratio $Q_0$, the one-particle extension $Q(m_1,\dots ,m_N,x)$ has a unique global minimum $Q_{\text{min}}=Q_0/(1+Q_0)$ at $m^{\ast }=[({\sum }_i{m}_i)/({\sum }_i\sqrt{m_i}){]}^2$. This exact kinematic result defines a unique extension benchmark. For the measured charged leptons it gives $m_{\ast }^{\ell }=1.25534(16)\text{GeV}$ and $Q_{4,\min }^{\exp }=0.3999978(43)$; in the ideal Koide limit $Q_{\ell }^{\mathrm{K}}=2/3$, the corresponding minimum is exactly $2/5$. In the effective-participant language $N_{\mathrm{eff}}\equiv 1/Q$, the optimal one-particle extension increases $N_{\mathrm{eff}}$ by one, while the equal-$k$ multiplet extension increases it by $k$. The one-particle $N_{\mathrm{eff}}$ profile is exactly Lorentzian in a dimensionless share-mismatch coordinate $u$, which we interpret kinematically rather than dynamically. Using charged-lepton pole masses with the PDG~2024 own-scale $\overline{\text{MS}}$ charm mass gives $Q(e,\mu ,\tau ,c)=0.4000025(64)$, i.e. $11.7\text{ppm}$ above the measured-input benchmark and $6.2\text{ppm}$ above $2/5$. This intentionally mixed-definition comparison is treated only as a phenomenological coincidence. To calibrate it within a stated benchmark class, we perform an exhaustive common-scale scan over non-neutrino Standard Model 2-body and 3-body seeds with one added mass. The charged-lepton-plus-charm continuation ranks $33/12,720$ in the raw trial set, $24/2,640$ after collapsing repeated scale realizations, and $6/756$ within the fermion-only collapsed subset. We present the charm case as an empirically calibrated example of the theorem, not as a dynamical flavor model.

    hep-ph0 citations
16. 16*

    Spin-flavor entanglement in ${\Lambda }_b\to \Lambda D$ and weak phase extraction

    Yong Du🇨🇳 · Chao-Qiang Geng🇨🇳 · Xiao-Gang He🇨🇳 · Chia-Wei Liu🇨🇳 · Sheng-Lin Liu🇨🇳 · Xin-Yi Liu🇨🇳

    We identify a new spin-flavor entanglement structure in ${\Lambda }_b\to \Lambda D$ decays, formed by the correlation between the $\Lambda$ spin and the $D$ flavor states ($D=D^0,{\overline{D}}^0,D_1,D_2$). The entanglement information is encoded in the decay rates and Lee-Yang parameters of the four neutral-$D$ modes. We then show that the same spin-flavor structure provides a new method to determine the weak phase $\gamma$, a key angle of the Cabibbo-Kobayashi-Maskawa unitarity triangle. We find that the experimental uncertainty scales as ${\sigma }_{\gamma }\propto 1/\mathcal{C}$, where $\mathcal{C}$ is the Wootters concurrence, thereby quantitatively relating the precision of the weak-phase extraction to the amount of spin-flavor entanglement.

    hep-phhep-ex1 citation
17. 17*

    Asymmetric Reheating of Dark QED

    Simon Cléry🇩🇪 · Jean Kimus🇧🇪 · Michel H.G. Tytgat🇧🇪

    We study in detail a scenario in which the inflaton scalar field couples to both a visible sector (VS) and a hidden sector (HS). The VS is assumed to contain the Standard Model (SM), while the HS contains a dark matter (DM) candidate. We are in particular interested in a scenario in which the inflaton decays dominantly into the HS degrees of freedom. The DM candidate is taken to be a dark Dirac fermion $\chi$, coupled to a massive dark photon ${\gamma }^{\prime }$, a popular model for a HS also known as Dark QED. The inflaton decays into particles of both sectors generate an initial asymmetry between the SM and HS fermion abundances, which we model as being proportional to the ratio of effective Yukawa couplings, $y$ and $y^{\prime }$. We pay particular attention to the process of thermalisation of the HS, with temperature $T^{\prime }$, as a function of $y^{\prime }$ and ${\alpha }^{\prime }$, the HS fine structure constant. We investigate the several possible ways of producing the observed DM relic abundance, and their interplay with the reheating of the HS and the transfer of energy between the HS and the VS. Key results, beyond the systematic character of our analysis, include: a new mechanism for DM production, which occurs when DM particles annihilate while still being produced by the inflaton decay; a study of the temperature ratio $\xi =T^{\prime }/T$ and its relation with the initial energy asymmetry between the HS and VS, as parameterized by ${\xi }_i=\sqrt{y^{\prime }/y}$; a reassessment of the domain of viable DM candidates, taking into account the constraints set by unitarity and the thermalisation of the HS, accounting for the LPM effect; and, in cases where the HS does not reach thermal equilibrium, an analysis of how non-thermal DM production fits within the domain of thermal DM candidates.

    hep-phastro-ph.CO1 citation
18. 18*

    Chiral Structure and Selection Rules in Light-Front Nucleon-Pentaquark Mixing

    Fangcheng He🇺🇸 · Edward Shuryak🇺🇸 · Wan Wu🇺🇸 · Ismail Zahed🇺🇸

    We present a light-front Hamiltonian analysis of nucleon-pentaquark mixing induced by $\sigma$- and $\pi$-type transition operators in a fully Pauli-consistent five-quark basis. The pentaquark configurations are constructed using a systematic permutation-group classification of orbital, spin-flavor, and color degrees of freedom, and the hyperfine interaction is diagonalized to obtain orthonormal eigenchannels with definite quantum numbers. We compute the mixing coefficients for all 27 positive-parity $P$-wave pentastates and find a highly sparse structure: only 6 channels contribute to the nucleon wave function, while the remaining 21 vanish due to symmetry selection rules. The nonzero contributions are concentrated in a small set of hyperfine eigenchannels, demonstrating a strong dominance pattern. The $\sigma$- and $\pi$-induced amplitudes populate the same subset of states and are related by a fixed phase, reflecting their common chiral structure, which eliminates interference in the normalization. As a result, their contributions add incoherently, yielding a total five-quark probability of about $29\%$, with the remaining $71\%$ residing in the three-quark core. These results show that nucleon-pentaquark mixing is governed primarily by symmetry selection rules and chiral structure, and that the five-quark content is dominated by a small number of dynamically selected channels.

    hep-ph0 citations
19. 19*

    Dissecting Jet-Tagger Through Mechanistic Interpretability

    Saurabh Rai🇮🇳 · Sanmay Ganguly🇮🇳

    Mechanistic interpretability seeks to reverse engineer a trained neural network by identifying the minimal subset of internal components. We perform a mechanistic interpretability analysis of the Particle Transformer architecture, trained on the Top Quark Tagging reference dataset, with the goal of identifying the computational circuit responsible for jet classification and characterizing the physical content of its internal representations. Combining zero ablation, path patching with two complementary on-manifold corruption strategies and linear probing of the residual stream, we identify a sparse six-head circuit that recovers the great majority of the full model performance while admitting a clean source-relay-readout interpretation. In this circuit, a single early layer head serves as the primary causal source, a cluster of middle-layer heads acts as relays selectively attending to hard pairwise substructure and a single late-layer head reads out the aggregated signal. Linear probes show that the residual stream is preferentially aligned with the energy correlator basis over the $N$-subjettiness basis. Within the energy correlator basis, the model preferentially encodes 2-prong substructure observables over the 3-prong observables. A per-layer trained probe further reveals that the apparent single step commitment of the model to a classification decision in the first class attention block is in fact a basis rotation, with the discriminating signal already saturating in the particle attention stack. These results demonstrate that mechanistic interpretability methods developed for natural language models can be used for jet physics classifiers and indicate that gradient descent may rediscover physically meaningful aspects of jet tagging without supervision.

    hep-phcs.LGhep-ex1 citation
20. 20*

    MSSM flavors from 7-brane configurations of magnetized SYM on $R^{1,3}\times (T^2{)}^3/(Z_2\times Z_2^{\prime })$

    Hiroyuki Abe🇯🇵 · Molin Chen🇯🇵 · Itsuki Miyane🇯🇵 · Naoki Shimada🇯🇵

    We show that chiral matters in the minimal supersymmetric standard model (MSSM) with semi-realistic flavor structures can be obtained from 7-brane configurations of magnetized super Yang-Mills (SYM) theory on a toroidal orbifold $R^{1,3}\times (T^2{)}^3/(Z_2\times Z_2^{\prime })$, where background magnetic fluxes and Wilson-lines are turned on preserving four-dimensional $\mathcal{N}=1$ supersymmetry. The zero-mode spectrum of chiral multiplets in total is just MSSM ones, except the existence of those for three generations of right-handed neutrino and extra generations of MSSM Higgs pairs. Hierarchical Yukawa couplings can be obtained from the overlap integrals of wavefunctions localized in extra dimensions, allowing semi-realistic patterns of flavor structures for quarks and charged leptons. We also develop a systematic way to embed additional 7-branes into the configuration, those are sequestered from the visible sector toward a hidden sector model building.

    hep-phhep-thNPB(2026)·0 citations
21. 21*

    Higgs-Portal Spin-1 Dark Matter with Parity-Violating Interaction for a Galactic Halo Gamma Ray Excess

    Kimiko Yamashita🇯🇵

    We study a dark photon dark matter scenario associated with a gauged $U(1{)}_X$ symmetry, stabilized by a dark parity that forbids kinetic mixing with the Standard Model. The leading interactions between the dark photon dark matter and the Standard Model arise from dimension-six Higgs-portal operators. In previous work, we found that for the parity-violating operator, the dark matter annihilation process is $p$-wave suppressed, naturally evading stringent direct-detection constraints while reproducing the observed relic abundance through thermal freeze-out. For a cutoff scale of 1 TeV, a dark matter mass of around 400 GeV is favored to realize the observed relic abundance. This scenario predicts cosmic-ray signals, in particular in the $W^{+}{W}^{-}$ channel, which can be targeted by indirect-detection experiments. Recently, a halo-like gamma-ray excess has been reported by Totani. Assuming a Navarro--Frenk--White $-{\rho }^2$ morphology for the dark matter distribution, a dark matter mass of 420 GeV is favored for the $W^{+}{W}^{-}$ final state. Motivated by this excess, we consider the present dark photon dark matter framework augmented by a CP-even sub-GeV scalar mediator, which couples to the dark photon mass operator in order to enhance the present-day annihilation rate in the Galactic halo without affecting the freeze-out dynamics. The exchange of this scalar induces a long-range attractive force, leading to Sommerfeld enhancement of the annihilation rate. The enhancement is saturating in dwarf spheroidal galaxies and the annihilation rate is dropping as $p$-wave remaining consistent with constraints from dwarf galaxies and cosmology.

    hep-ph2 citations
22. 22*

    Reconstructing rare particle source by femtoscopic correlations

    Liang Zhang🇨🇳 · Song Zhang🇨🇳 · Kai-Jia Sun🇨🇳 · Yu-Gang Ma🇨🇳

    Measurement of particle emission source is a fundamental objective of femtoscopy in high-energy nuclear collisions. Conventional analyses rely on Gaussian parameterizations of pair emission sources, which makes the extraction of single-particle emission sources challenging, particularly for rare particles. Here, we introduce a novel statistical reconstruction method that allows extracting information of the target source relative to a data-constrained reference source instead of the Gaussian assumption. The correlation function is expressed as an ensemble average over the single-particle-conditioned correlation kernel, defined as the particle-by-particle contribution to the correlation function conditioned by the target particles. For particles with rare yields, the particle-by-particle distribution of this kernel can be transformed into event-by-event extraction and becomes experimentally accessible, enabling a direct statistical reconstruction of the emission source of single particles, instead of inferring a pair source. We apply this method to reconstruct $J/\psi$ source via $p$-$J/\psi$ correlations, using HAL QCD-derived $NJ/\psi$ potentials in $\sqrt{s}=13.6$~TeV $pp$ collisions simulated with EPOS4HQ. The reconstructed source reproduces the key characteristics and this new approach achieves a systematic uncertainty of approximately $13\%$ based on EPOS4 simulation.

    hep-phPRC(2026)·0 citations
23. 23*

    Controlled Penumbral Inflation from Monodromic Valleys

    Pirzada🇨🇳 · Tianjun Li🇨🇳

    Realizing controlled, single-clock inflation in string theory is fundamentally obstructed by the backreaction of heavy moduli. We show that in the \emph{penumbra} -- the near-boundary regime of complex-structure moduli space where asymptotic symmetries are partially broken -- this obstruction can be exactly quantified. We derive a covariant control theorem demonstrating that local branch data dictate whether a monodromic valley supports a controlled inflationary plateau, thereby isolating the first controlled penumbral inflationary window. The result turns the penumbra from a geometric regime into a dynamical filter. In the axion-saxion effective theory, a branch-displacing odd term generates a plateau when $\Delta \equiv p+2\nu -q>0$, while covariant single-clock control further requires $p<2$, or $p=2$ with $12A_p{m}^2/(d{V}_0)\gg 1$ over the observational window. This splits penumbral valleys into no plateau, uncontrolled plateau, and controlled plateau before global completion is attempted. We identify a minimal analytic family with a closed-form valley and an invariant attractor equation for the full two-field dynamics, providing the first exactly solvable penumbral realization that remains predictive under the next penumbral order. The controlled corridor targets $r\sim 10^{-3}$ with the correlated running ${\alpha }_s\simeq -r/2$ for the $d=q=1$ benchmark, providing a falsifiable target for LiteBIRD/CMB-S4.

    hep-phastro-ph.COgr-qc7 citations
24. 24*

    Charged-Lepton Koide Geometry from a Green-Dressed Compact Family Cycle

    Kirill Shulga🇯🇵

    Koide's charged-lepton relation suggests that $(\sqrt{m_e},\sqrt{m_{\mu }},\sqrt{m_{\tau }})$ is the natural family vector. We construct an effective compact-cycle model in which this vector is sampled from one real amplitude $Z(\varphi )$ on an internal circle, while the masses are quadratic overlaps, $m_a\propto |Z(2\pi a/3){|}^2$. The amplitude is built from the two lowest antiperiodic modes on the circle; their symmetric square is periodic and gives the minimal three-harmonic family space $e^{i\varphi },1,e^{-i\varphi }$. A reality condition together with the requirement that the amplitude comes from the square of one two-component spinor fixes the relative weights required by Koide's $45^{\circ }$ geometry. The remaining orientation angle is fixed by matching one $C_3$ family shift to transport on the full circle: integrating out the higher Fourier harmonics gives the Berry dressing that enters the determinant term and selects ${\theta }_{\ell }=-2/9$. Using $m_e$ and $m_{\mu }$ as inputs, the model predicts $m_{\tau }=1776.97\mathrm{MeV}$.

    hep-ph0 citations
25. 25*

    Four-loop anomalous dimension of flavor non-singlet quark operator of twist two and Lorentz spin N for general gauge group: transcendental part

    B.A. Kniehl🇩🇪 · V.N. Velizhanin🇩🇪

    Both for quark flavor asymmetry and valence, we consider the anomalous dimension of the non-singlet twist-two quark operator of arbitrary Lorentz spin N at four loops in SU(nc) color gauge theory and present its term proportional to zeta(3) in closed form. These results have been extracted from published Mellin moments, for N=1,...,16 and N=3,...,15, respectively, by analytic reconstruction using advanced methods of number theory. Via Mellin transformation, we obtain the exact functional forms in x of the respective pieces of Dokshitzer-Gribov-Lipatov-Altarelli-Parisi splitting functions. This allows us to reduce the theoretical uncertainties in the approximations of these splitting functions otherwise amenable from the first few low-N values.

    hep-phNPB(2026)·1 citation
26. 26*

    Phenomenology of electroweak spin-1 resonances

    R. Caliri🇩🇪 · J. Hadlik🇩🇪 · M. Kunkel🇩🇪 · W. Porod🇩🇪 · Ch. Verollet🇫🇷

    Composite Higgs models with a fermionic UV completion predict the existence of various bound states. We investigate models containing SU(2)${}_L\times$SU(2)${}_R$ as part of the unbroken global subgroup in the new strong sector. These models predict that there are two neutral and one charged spin-1 resonances mixing seizable with the SM vector bosons. These can be singly produced at the LHC. We explore their LHC phenomenology and demonstrate that there are still viable scenarios consistent with existing LHC data where the masses of these states can be as low as about 1.5 TeV.

    hep-phPoS(2026)·0 citations
27. 27*

    Parity Nonconservation in Hydrogen Induced by Low-Mass Vector-Boson Exchange

    V. A. Dzuba🇦🇺 · V. V. Flambaum🇦🇺 · G. K. Vong🇦🇺

    Parity-nonconserving (PNC) effects in atoms produced by $Z$-boson exchange between the electron and the nucleus grow rapidly with the nuclear charge $Z$. If a hypothetical additional $Z^{\prime }$ boson is light, however, its contribution does not exhibit the same strong enhancement with $Z$. As a result, the ratio of the low-mass $Z^{\prime }$ contribution to the Standard Model $Z$-boson contribution increases rapidly with decreasing $Z$, in fact faster than $1/Z^2$. Hydrogen has a further important advantage: its theoretical description is substantially cleaner than that of heavy atoms, allowing a more accurate interpretation of experimental results. For these two reasons, hydrogen and deuterium PNC experiments may provide an especially favorable setting in which to disentangle a possible $Z^{\prime }$ contribution from the Standard Model background. In this paper we calculate the ratio of the $Z^{\prime }$-boson contribution, for arbitrary $Z^{\prime }$ mass, to the Standard Model $Z$-boson contribution to parity violation in hydrogen and deuterium, including both nuclear-spin-independent (NSI) and nuclear-spin-dependent (NSD) interactions.

    hep-phphysics.atom-phPRA(2026)·1 citation
28. 28*

    Non-equilibrium scaling across first-order transitions with relativistic scalar fields

    Leon J. Sieke🇩🇪 · Jessica Fuchs🇩🇪 · Lorenz von Smekal🇩🇪

    We investigate the out-of-equilibrium dynamics of a relativistic $Z_2$-symmetric scalar field theory with Langevin dynamics in two and three spatial dimensions under linear driving across magnetic first-order phase transitions, close to and far below the critical temperature $T_c$. Using classical-statistical lattice simulations, we find that if the driving timescale is sufficiently fast, the system exhibits finite-time scaling behavior independent of temperature and dimensionality, identical to that observed in mean-field simulations. In slow quenches near $T_c$ this mean-field behavior crosses over to critical Kibble-Zurek scaling behavior, while for temperatures $T\ll T_c$ nucleation and growth dominate the transition dynamics, resulting in corrections to scaling. Near the transition point where the order parameter changes sign, the crossover between mean-field and critical out-of-equilibrium dynamics is found to be well described by the leading algebraic correction to Kibble-Zurek scaling. We find that universal non-equilibrium scaling behavior can be observed for $T\lesssim T_c$, provided the driving is fast enough to avoid nucleation but slow enough for correlations to form, and compute the associated universal scaling functions for the order parameter.

    hep-phcond-mat.stat-mechNPB(2026)·1 citation
29. 29*

    Revival of the Reactor Antineutrino Anomaly

    Carlo Giunti🇮🇹 · Yu-Feng Li🇨🇳 · Rong-ping Zhang🇨🇳

    The Reactor Antineutrino Anomaly (RAA) refers to the deficit observed between the average event rate measured in reactor antineutrino experiments with respect to the theoretical prediction. This anomaly was first identified in 2011 ($2.5\sigma$) as a consequence of the Huber-Muller reactor antineutrino flux calculation. It was thought to be resolved in 2021 as a result of previous reactor antineutrino flux calculations, with a reduction to about $1\sigma$. In this work, we present the RAA obtained with the latest reactor antineutrino flux calculation published in 2023 by a French research group, which was never used before for the calculation of the RAA. It is the first summation flux model which includes a comprehensive uncertainty budget. The result indicates a revival of the RAA at the level of $2.2\sigma$. We also consider the usual simplest explanation of the RAA by active-sterile neutrino oscillations. We present the constraints on the oscillation parameters and we derive a tension of $3.8\sigma$ with the results of gallium source experiments (Gallium Anomaly) taking into account also the solar neutrino and KATRIN bounds, that of the combined short-baseline reactor spectral ratio measurements, and that of the Daya Bay search for a sub-eV sterile neutrino. Since the tension may be due to underestimated systematic uncertainties and the main tension is between the gallium data and the other data, we finally present the results of a global analysis with enlarged gallium uncertainties, which reduce the global tension to $1.3\sigma$.

    hep-phhep-ex4 citations
30. 30*

    Light-front Hamiltonian jet evolution in the Glasma

    Dana Avramescu🇫🇮 · Carlos Lamas🇪🇸 · Tuomas Lappi🇫🇮 · Meijian Li🇪🇸 · Carlos A. Salgado🇪🇸

    We develop a light-front Hamiltonian formalism to study the real-time quantum evolution of a high-energy quark propagating through the Glasma phase of a heavy-ion collision. In this work, the quark Fock space is truncated to the $|q⟩$ sector and the wavefunction is expanded in a discrete basis representation, following the time-dependent Basis Light-Front Quantization (tBLFQ) framework. The classical Glasma background fields enter as a time-dependent external potential, and physical observables are extracted as expectation values of quantum operators over the time-evolved state. We compute the transverse momentum broadening and the jet quenching parameter, finding results consistent with classical estimates, including the expected scaling with respect to the saturation momentum, and use them to perform phenomenological estimations for different collision systems. We also study the color rotation of the quark state induced by the Glasma fields, and examine its dependence on the saturation scale and the gauge choice. This formalism allows systematic improvements to include, in particular, non-eikonal propagation and parton splittings that will be considered in forthcoming publications.

    hep-phnucl-th1 citation
31. 31*

    RG-Consistent (P)NJL Model: Impact of Thermal Cutoff Modifications on Thermodynamics and Net-Baryon Number Fluctuations

    Jie Tang🇺🇸 · Fan Lin🇺🇸 · Xinyang Wang🇺🇸

    In this paper, we investigate the impact of renormalization group (RG) consistency on the chiral phase transition and thermodynamic properties of QCD matter using the RGNJL and RGPNJL models. By implementing a temperature-dependent thermal cutoff ${\Lambda }_T=k{\Lambda }_0$, we ensure that thermodynamic quantities converge toward the Stefan-Boltzmann limit at high temperatures, effectively extending the applicability of these effective theories. Our analysis shows that while the RG-consistency condition ($k\to \infty$) resolves causality violations in the RGNJL model by binding the speed of sound to the conformal limit, the RGPNJL model exhibits a more complex, non-monotonic sensitivity to the parameter $k$. Furthermore, we demonstrate that the RG-improved PNJL framework significantly enhances the description of net-baryon number fluctuations ($\kappa {\sigma }^2$) relative to lattice QCD data at vanishing chemical potential, though the intensification of these fluctuations at high baryon density highlights a critical sensitivity to the model's parametric constraints. This study provides a rigorous evaluation of the RG-consistency framework's predictive power in mapping the QCD phase diagram and interpreting experimental observables.

    hep-phnucl-th0 citations
32. 32*

    EEXICC: An event generator for doubly heavy baryon production at $e^{+}{e}^{-}$ colliders

    Hong-Tai Li🇨🇳 · Xu-Chang Zheng🇨🇳 · Xing-Gang Wu🇨🇳 · Jiang Yan🇨🇳 · Zhi Yang

    We present EEXICC, a Monte Carlo event generator designed to simulate the production of doubly heavy baryons (${\Xi }_{cc}$, ${\Xi }_{bc}$, and ${\Xi }_{bb}$) via $e^{+}{e}^{-}$ annihilation. Based on nonrelativistic QCD effective theory, the generator calculates the process $e^{+}+e^{-}\to {\Xi }_{Q{Q}^{\prime }}+{\bar{Q}}^{\prime }+\bar{Q}$ using an improved trace technique at the amplitude level, which greatly improves numerical efficiency compared with traditional squared-amplitude methods. EEXICC is developed in Fortran with a modular structure and is fully compatible with the PYTHIA framework, enabling convenient integration into complete event simulation workflows. The program supports both weighted and unweighted event generation, and its numerical reliability has been verified against existing theoretical results. EEXICC provides a flexible and robust tool for studying the properties of doubly heavy baryons at future high-luminosity and high-energy $e^{+}{e}^{-}$ colliders such as the CEPC and FCC-ee.

    hep-ph0 citations
33. 33*

    Axial Quasi-normal Modes of Admixed Neutron Stars

    Hamza Boumaza🇩🇿 · Boris Betancourt Kamenetskaia🇰🇷

    We study axial quasi-normal modes of admixed neutron stars composed of ordinary nuclear matter and a self-interacting bosonic dark matter component. The equilibrium configurations are obtained by solving the coupled two-fluid Tolman-Oppenheimer-Volkoff equations, where the neutron sector is modeled with several realistic equations of state and the bosonic sector is described by a repulsively self-interacting complex scalar field in the strong-coupling regime. We analyze linear axial perturbations governed by a Regge-Wheeler type equation whose effective potential reflects the combined matter distribution. Using a continued-fraction method, we compute the complex eigenfrequencies of the fundamental and overtone $w$ modes. We obtain the quasi-normal mode spectrum and investigate its dependence on the dark matter particle mass, self-coupling, and the central densities of both fluids for several realistic neutron star equations of state. We find that increasing the dark matter fraction shifts the oscillation frequencies and damping times. It can also reorder the mode hierarchy through crossings, and it drives a continuous transition from neutron star-like to boson star-like ringdown behavior. Our results demonstrate that the ringdown gravitational-wave signal from post-merger compact objects could encode clear imprints of a dark matter component, offering a new probe of the dark sector with future gravitational-wave observatories.

    hep-phgr-qc1 citation
34. 34*

    Study of ${\eta }^{\prime }\to \eta \pi \pi$ Decays in Large-$N_C$ Chiral Perturbation Theory

    Feng-Zhi Chen🇨🇳 · Xin-Qiang Li🇨🇳 · Ya-Dong Yang🇨🇳 · Yuan-He Zou🇨🇳

    We investigate the ${\eta }^{\prime }\to \eta \pi \pi$ decays within the framework of large-$N_C$ chiral perturbation theory, by calculating the decay amplitudes up to next-to-next-to-leading order in a simultaneous expansion in powers of external momenta, quark masses, and $1/N_C$. Projecting the amplitudes onto partial waves allows us to implement a unitarization procedure to account for the $S$- and $D$-wave $\pi \pi$ final-state interactions. The relevant low-energy constants are determined by fitting our theoretical results to the precise experimental data from the A2 collaboration. A comparison of fits with and without $\pi \pi$ final-state interactions demonstrates that including these effects significantly improves the agreement of our theoretical predictions with the experimental measurements. Consequently, the Dalitz-plot parameters are extracted as $a=-0.085(18{)}_{\mathrm{stat}}(4{)}_{\mathrm{syst}}$, $b=-0.081(10{)}_{\mathrm{stat}}(6{)}_{\mathrm{syst}}$, and $d=-0.045(6{)}_{\mathrm{stat}}(8{)}_{\mathrm{syst}}$. Our results provide therefore a refined theoretical description of the ${\eta }^{\prime }\to \eta \pi \pi$ decay dynamics.

    hep-ph0 citations
35. 35*

    Heavy-Quark Condensate and Vacuum Energy Anomalous Dimension at Five Loops

    Andreas Maier🇪🇸 · Peter Marquard🇩🇪 · York Schröder🇨🇱

    We present the perturbative heavy-quark condensate at five-loop order in QCD. This constitutes the first calculation at this order accounting for non-vanishing quark masses. Our result confirms the computation of the five-loop vacuum anomalous dimension by Baikov and Chetyrkin.

    hep-phJHEP(2026)·0 citations
36. 36*

    The X17 Existence Hinted at by Nuclear Reactor Neutrinos

    Johan Rathsman🇸🇪 · Joakim Cederkäll🇸🇪 · Yasar Hicyilmaz🇹🇷 · Else Lytken🇸🇪 · Stefano Moretti🇬🇧

    We show that by exploiting the process of Coherent Elastic neutrino (v) Nucleus Scattering (CEvNS), neutrino measurements by nuclear reactor experiments appear to corroborate the evidence of the so-called X17 particle, which has been invoked to explain the ATOMKI anomaly. We base our analysis primarily on CONUS+ and Dresden-II data, which, when combined with CEvNS data from COHERENT and neutrino oscillation data from IceCube, single out a unique region of couplings to neutrinos and nuclei.

    hep-ph2 citations
37. 37*

    Distinguishing Higgs portal and neutralino dark matter via vector boson fusion

    Amit Chakraborty🇮🇳 · Tathagata Ghosh🇮🇳 · Rafiqul Rahaman🇧🇷

    Understanding the nature of dark matter (DM) is a fundamental challenge in particle physics. In this paper, we investigate the potential of vector boson fusion (VBF) processes at the Large Hadron Collider (LHC) to demonstrate, as a proof of principle, the feasibility of distinguishing between different dark matter scenarios, focusing on Higgs portal DM (HPDM) and neutralino DM in the $2j+/E_T$ final state and exploiting the distinctive kinematic features of the VBF jets and the missing transverse energy. Our study reveals that the polarization of weak bosons in VBF plays a crucial role in shaping the transverse momentum distributions of the tagged jets, with the jets being less energetic in the transverse direction for the Higgs portal scenario compared to the neutralino scenario. In addition, the kinematic variables $\Delta \eta$ and $\Delta \varphi$ exhibit characteristic differences between the Higgs portal and neutralino DM signals, providing significant discriminating power between these scenarios. We further apply a Kolmogorov--Smirnov test using linear discriminant analysis to quantify the distinguishability of the signals and find that the Higgs portal signals can be differentiated from neutralino DM signals with a C.L. exceeding $5\sigma$, thereby establishing the viability of collider-based discrimination between dark matter models.

    hep-phhep-exhep-th0 citations
38. 38*

    Non-Forward OPE Kernel versus Scalar Form Factor in Near-Threshold $J/\psi$ Photoproduction

    A. I. Syamtomov🇺🇦

    Near-threshold $J/\psi$ photoproduction has been used to infer scalar gluonic structure from integrated cross-section data. We test whether such an inference is stable against the assumed non-forward continuation of the OPE kernel. With an exponential diffractive slope fixed, the threshold fit favors an additional scalar $G_S(t)$-like contribution. However, the residuals show a systematic $W$-dependent trend. When either the effective slope or the kernel shape is replaced by a physically motivated form-factor continuation, the trend disappears and the fitted scalar coefficient is driven to zero. Thus integrated $\sigma (W)$ data cannot determine the non-forward OPE kernel or isolate a scalar $G_S(t)$ contribution. Differential $d\sigma /dt$ data are required.

    hep-ph0 citations
39. 39*

    Nodal mechanism for the suppressed $D\bar{D}$ decay of $\psi (4040)$ in the Bethe--Salpeter framework

    Bing-Dong Wan🇨🇳 · Sheng-Qi Zhang🇨🇳

    The strong decay $\psi (4040)\to D\bar{D}$ is anomalously suppressed despite ample phase space, whereas the $D{\bar{D}}^{\ast }$ and $D_s{\bar{D}}_s$ channels remain sizable. In this work, we study this suppression and the associated open-charm hierarchy in the framework of the instantaneous Bethe--Salpeter equation combined with the relativistic ${}^3{P}_0$ model, with the pair-creation strength fixed independently from $\psi (3770)\to D\bar{D}$. Within this framework, we show that the suppressed $D\bar{D}$ mode can be understood as a consequence of node-induced cancellations in the relativistic decay amplitude. The $D\bar{D}$ amplitude is strongly reduced because the corresponding overlap integral receives comparable positive and negative contributions from different momentum regions, whereas the $D{\bar{D}}^{\ast }$ and $D_s{\bar{D}}_s$ channels do not undergo the same strong cancellation. This interpretation is further supported by the pronounced sensitivity of the $D\bar{D}$ width to the initial mass, the charged-neutral $D$-meson mass splitting, and the dip structure in the mass dependence of the partial width. Our results provide a dynamical explanation of the suppressed $D\bar{D}$ mode and the core open-charm hierarchy of $\psi (4040)$ within a conventional $3{}^3{S}_1$ charmonium picture, while the precise value of the near-vanishing $D\bar{D}$ width remains model dependent.

    hep-phJHEP(2026)·0 citations
40. 40*

    Tripartite Entanglement as a Probe of Neutrino Mass Hierarchy, CP Violation, and Non-Standard Interactions

    Hridya Harish Nambiar🇮🇳 · Bipin Singh Koranga🇮🇳

    We investigate global tripartite quantum entanglement in three-flavor neutrino oscillations as a tool for probing the neutrino mass hierarchy and CP violation. Using the linear entropy formalism, we compute the global entanglement entropy for an initial electron neutrino state as a function of L/E, comparing Normal Ordering (NO) and Inverted Ordering (IO) across CP phases 0, 90, 120 and 180, in vacuum and in constant-density matter rho = 2.8g/cm^3, L = 1300km). We define the hierarchy sensitivity diagnostic dell S and show that MSW matter effects amplify dell S by roughly a factor of two relative to vacuum, with peak sensitivity at L/E approx 655km/GeV (approx 2GeV at the DUNE baseline). For antineutrinos the diagnostic is near-perfectly antisymmetric to the neutrino case at the MSW resonance, with deviations directly encoding dell CP. ANnother diagonostic defined here separates the matter hierarchy signal from the CP asymmetry signal in the tripartite entanglement. For non-standard interactions (NSI) parameterized by epsilon_{ee}, we find Dell S{max} is approx 0.113 + 0.105epsilon_{ee}, a linear and CP-phase-independent relation. The optimal L/E for hierarchy discrimination is stable at approx 655km/GeV for all epsilon_{ee}less than or equal to 0.2, providing a robust, NSI-independent energy recommendation for DUNE.

    hep-ph1 citation
41. 41*

    Neutrino mixing and gravitational production via inflation

    Oleg Lebedev🇫🇮 · Jong-Hyun Yoon🇰🇷

    We develop the Bogolyubov coefficient formalism for gravitational production of fermions with time-dependent mixing, which allows us to study a prototype neutrino system. The neutrino masses and mixings depend on the scalar field values, i.e. the Higgs or singlet scalar expectation values. These are time-dependent in the Early Universe and, due to de Sitter fluctuations, can reach very large values during inflation. As a result, gravitational production of all types of neutrinos can be much enhanced. We obtain an upper bound on the abundance of active and sterile neutrinos produced by classical gravity, $Y\lesssim 10^{-11}$.

    hep-phastro-ph.CO0 citations
42. 42*

    Electronic Direct Detection of Light Dark Matter with Intermediate-Mass Mediators

    Connor Stratman🇺🇸 · Tanner Trickle🇺🇸

    Recent years have seen dramatic improvements in the sensitivity of electron-based direct detection experiments. Typically, the sensitivity to dark matter scattering is determined in the light and heavy mediator mass limits. In this paper we show that the light and heavy mediator mass limits are not separated by a single scale, but instead can be separated by up to three orders of magnitude in mediator mass for sub-GeV mass dark matter. We calculate the background-free sensitivity in Si and Ge targets, and a projected DAMIC-M sensitivity, to sub-GeV mass dark matter models with ``intermediate-mass" mediators between the light and heavy mediator limits. This allows us to determine the precise range of mediator masses that electron-based direct detection experiments are sensitive to when the dark matter relic abundance is generated via freeze-in. We make the calculations presented here publicly available in an updated release of EXCEED-DM (https://github.com/tanner-trickle/EXCEED-DM).

    hep-phhep-exPRD(2026)·3 citations
43. 43*

    Time-dependent signals of new physics at the LHC

    Max H. Fieg🇺🇸 · Patrick J. Fox🇺🇸 · Jinbo Zhang🇺🇸 · Aishik Ghosh🇺🇸 · Virat Varada🇺🇸 · Daniel Whiteson🇺🇸

    The Large Hadron Collider (LHC) is sensitive to signals of beyond the Standard Model physics through a variety of channels including missing energy and resonance searches. In most searches, the new physics and the Standard Model backgrounds are assumed to be invariant in time, up to systematic effects from the experiment. However, new physics with a time variation would provide an additional handle to separate signal from background. Such a time variation may come from ultralight dark matter coupling to an oscillating background field. In this paper, we consider an interaction of dark matter with quarks and an additional heavy particle, and show that the sensitivity of a search that uses timing information at the LHC can be up to a factor of two stronger compared to one that does not use time information.

    hep-phhep-ex2 citations
44. 44*

    An ultra-broadband axion dark matter experiment

    Angelo Esposito🇮🇹 · Kin Chung Fong🇺🇸 · Lam Hui🇺🇸

    We propose a novel broadband strategy to search for axions by leveraging observables controlled by the axion field squared. We present a practical implementation of this concept for probing the axion--photon coupling. This is done by operating a dc SQUID at the flux sweet spot, where the voltage depends quadratically on the magnetic flux, and using lock-in modulation to evade low-frequency noise. The proposed setup is ultra-broadband, spanning over 15 orders of magnitude in axion mass, with further expansion of the mass range possible. The projected sensitivity is $|g_{a\gamma \gamma }|\gtrsim 10^{-16}{\text{ GeV}}^{-1}$, orders of magnitude better than current bounds, and largely independent of axion mass. We discuss the sources of systematic background and a nulling technique to reduce them to an acceptable level. We also discuss how our strategy could be adapted to probe the axion-fermion coupling, as well as to detect other dark matter candidates such as dark photons.

    hep-phastro-ph.COhep-ex1 citation
45. 45*

    Dark Matter as a Source for Lepton Flavor Violation

    Jeremy Echeverria🇨🇱 · Patricio Escalona🇧🇷 · Farinaldo Queiroz🇧🇷 · David Suarez🇧🇷

    We will witness enormous progress in the experimental sensitivity to charged-lepton-violation processes in the near future. New physics signals of charged lepton violation might be around the corner without conflicting with existing astrophysical and accelerator bounds. In this work, we explore the possibility of having a dark matter particle as a source for $\mu \to e\gamma$, $\mu \to 3e$, and $\mu \to e$ conversion in nuclei. After computing the dark matter relic density and dark matter-nucleon scattering cross section, we outline the region of parameter space where one can simultaneously accommodate a dark matter fermion in agreement with existing collider and direct detection bounds, and positive signals in charged lepton violation observables.

    hep-phNPB(2026)·0 citations
46. 46*

    Polydoxon Transformations and Scientific Reward in Physics

    James D. Wells🇺🇸

    We develop a descriptive account of scientific reward in physics based on the concept of the time-dependent Polydoxon, defined as the structured set of empirically viable theories at a given time. We argue that highly rewarded contributions, such as those recognized by major prizes and professional honors, can be systematically understood as those that transform this space. These transformations take the form of expansion (adding viable theories), contraction (eliminating viable theories), reconfiguration (illuminating deeper structures and relations within and between theories), and enabling moves (methodological or technological advances that enable future transformations). The analysis is further refined by emphasizing that reward correlates with the transformation's magnitude, assessed along dimensions of scope, centrality, depth, and future leverage. This framework reframes the analysis of rewarded achievement away from isolated theoretical successes and toward the dynamics of a landscape of viable theories, providing a more unified descriptive interpretation of rewarded scientific activity in physics across its diverse set of theoretical and experimental discoveries.

    ↳ physics.hist-phhep-phhep-th0 citations
47. 47*

    Bogomol'nyi Equations in Mixed Product Chern-Simons Theories Governing Charged Vortices and Antivortices

    Aonan Xu🇨🇳

    We extend product Chern-Simons theory to develop several mixed $U(1)\times U(1)$ models where one gauge field is governed by a Chern-Simons term and the other by a Maxwell or Born-Infeld term. We show that, by choosing suitable potentials, the energy functional admits a topological lower bound saturated by first-order self-dual equations. The resulting dyonic systems can be divided into vortex-vortex and vortex-antivortex configurations, and the coexistence of vortices and antivortices in the latter extends the vortex-only result known in product Chern-Simons model. On a doubly periodic domain, we establish Bradlow-type bounds with distinct physical implications: for vortex-only systems, the vortex numbers stay below this bound and cannot be arbitrarily large; for vortex-antivortex systems, the bound is imposed on the difference between the vortex and antivortex numbers, while the individual numbers are arbitrary. This distinction results in a bounded energy spectrum for the former and an unbounded energy spectrum for the latter.

    ↳ hep-thhep-phmath-phmath.MPJHEP(2026)·0 citations
48. 48*

    Einstein-Cartan pseudoscalaron inflation, reheating and nonthermal leptogenesis

    Carlo Di Benedetto · Alessandro Di Marco · Emanuele Orazi🇧🇷 · Gianfranco Pradisi🇮🇹

    We study the postinflationary dynamics of an Einstein-Cartan-Holst gravity-motivated inflationary scenario, known as Einstein-Cartan pseudoscalaron inflation, coupled to a type-I seesaw extension of the Standard Model with three heavy right-handed Majorana neutrinos. In particular, we show that nonthermal leptogenesis emerges as a necessary and self-consistent mechanism for generating the observed baryon asymmetry of the Universe, mainly because of the universal coupling of the inflaton to the additional heavy Majorana fermions. The resulting framework provides theoretical predictions that are fully compatible with the latest cosmological constraints from the Cosmic Microwave Background, Baryon Acoustic Oscillations, and Big Bang Nucleosynthesis, as well as with neutrino oscillation experiments, for a wide range of the fundamental Barbero-Immirzi model parameter $\gamma$, which controls the inflationary and postinflationary phases. In particular, for $\gamma \sim -1/100$ and a lightest Majorana-neutrino mass of order $10^{13}$ GeV, we find a scalar spectral index $n_s\sim 0.970$, a tensor-to-scalar ratio $r\sim 0.004$, for a number of e-folds before the end of inflation $N_e\lesssim 60$, and a baryon-to-entropy ratio $n_B/s\sim 8.7\times 10^{-11}$.

    ↳ astro-ph.COhep-phhep-th3 citations
49. 49*

    Reionization History and Neutrino Mass

    YiCheng Dai🇨🇳 · Wei Liao🇨🇳

    Recent baryon acoustic oscillation (BAO) distance measurements, when combined with Cosmic Microwave Background (CMB) observations in the $\Lambda$CDM framework, lead to a preference for negative neutrino masses. We investigate whether this neutrino mass anomaly can be alleviated by a class of astrophysically motivated reionization histories. Using a frequentist analysis, we find that some reionization histories can move the best-fit value of $\sum m_{\nu }$ to a positive value and bring $\sum m_{\nu }\simeq 0.06\mathrm{eV}$ into the 95\% confidence interval. To separate the effect of the total optical depth from that of the details of the reionization history, we compare a high-$\tau$ history with a two-step tanh-like reionization history of the same $\tau$. The resulting $\Delta {\chi }^2(\sum m_{\nu })$ profiles are nearly identical. This indicates that the effect is mainly driven by the total optical depth, while the details of the reionization history play only a minor role.

    ↳ astro-ph.COhep-ph2 citations
50. 50*

    Fifth-Force Constraints from UV-Complete Scalar-Tensor Gravity

    Alfio M. Bonanno🇮🇹 · Emiliano M. Glaviano🇮🇹

    We study an $O(N)$ scalar multiplet nonminimally coupled to gravity and follow its renormalization-group (RG) flow in the vicinity of an interacting, nonperturbatively UV-complete scaling regime of scalar-tensor theory. In the broken phase, the radial mode mediates a universal Yukawa correction to Newtonian gravity, parametrized by a strength $\alpha$ and range $\lambda$. Imposing UV completeness -- regular RG trajectories that reach the UV scaling regime -- restricts the infrared data to a finite wedge, which maps to a narrow region in the $(\alpha ,\lambda )$ plane. Its complement is, therefore, ruled out by UV completeness alone. Remarkably, part of this theory-excluded domain lies below current experimental exclusion envelopes, so improved fifth-force searches can directly test and potentially falsify this class of UV-complete scalar-tensor models.

    ↳ gr-qchep-phhep-thPRL(2026)·3 citations
51. 51*

    Uncertainty in Physics and AI: Taxonomy, Quantification, and Validation

    Manuel Haußmann🇩🇰 · Ramon Winterhalder🇮🇹 · Maria Ubiali🇬🇧

    Reliable uncertainty quantification is essential for the use of machine learning in physics, where scientific discoveries depend on validated probabilistic statements. We provide a structured overview of uncertainty quantification in ML for physics, introducing a unified taxonomy of uncertainty and clarifying the interpretation of predictive and inference uncertainties across frequentist and Bayesian frameworks. We discuss principled validation tools, including coverage, calibration, bias tests, and proper scoring rules, and illustrate them with simple regression and classification examples.

    ↳ stat.MLastro-ph.COastro-ph.GAhep-ex+17 citations
52. 52*

    Infrared spectra of some strongly--coupled chiral gauge theories

    Stefano Bolognesi🇮🇹 · Kenichi Konishi🇮🇹 · Matteo Orso🇮🇹

    Several simple asymptotically-free chiral gauge theories are studied. The only ``free parameters'' of our models are the choice of the gauge group and the matter Weyl fermion representations, and the relative magnitudes of the renormalization-group-invariant scales ${\Lambda }_i$ associated with each gauge group. None of our models has nontrivial nonabelian global symmetries (``family''--like fermion representations). We rely on some recent theoretical developments on the dynamics of strongly--coupled chiral gauge theories, based on the generalized symmetries and associated new types of anomaly-matching consideration, but also on the solid knowledge on vectorlike gauge theories such as QCD and supersymmetric Yang-Mills theories. The structures of the infrared effective theories, the RG flows, and the light spectra found in these models are surprisingly rich and intriguing.

    ↳ hep-thhep-lathep-phPRD(2026)·1 citation
53. 53*

    Dynamic Competition of Fast and Collisional Neutrino Flavor Instabilities with Collisional Damping in Spatially Inhomogeneous Systems

    Shota Takahashi🇯🇵 · Hiroki Nagakura🇯🇵 · Masamichi Zaizen🇯🇵 · Chinami Kato🇯🇵 · Jiabao Liu🇯🇵

    Neutrino flavor evolution in dense astrophysical environments such as core-collapse supernova (CCSN) is influenced by collective effects. While the Fast Flavor Instability (FFI) and the Collisional Flavor Instability (CFI) are recognized as key drivers of rapid flavor conversion, their non-linear competition with collisional damping in spatially inhomogeneous systems remains poorly understood. Motivated by recent findings that FFI and resonance-like CFI co-occur in the post-bounce phase in CCSN, we scrutinize their dynamic competitions and asymptotic states. To this end, we perform numerical simulations of the quantum kinetic neutrino transport, incorporating both spatial advection and the collision terms. We demonstrate that the interplay between these coexisting neutrino flavor instabilities and collisions leads to rich dynamics. Rather than merely inducing simple decoherence, collisional damping can substantially alter the overall dynamics of collective flavor oscillations, driving the system through complex evolutionary pathways. In all cases where flavor instability develops, we find that the system converges to the same flavor-equilibrated asymptotic state, despite the diversity of intermediate dynamics. Our results suggest that realistic collisional effects drive the system to an asymptotic state distinct from the one predicted by the collisionless FFI picture. This highlights the importance of incorporating collisional effects when modeling the asymptotic outcome of flavor conversion in CCSN models.

    ↳ astro-ph.HEhep-phPRD(2026)·0 citations
54. 54*

    Astrons: Reissner-Nordström Primordial Naked Singularities

    Claudio Corianò🇮🇹 · Paul H. Frampton🇮🇹 · Leonardo Torcellini🇮🇹

    We summarize a set of constraints on a proposed population of primordial, ultra-massive, electrically charged compact objects, which we call astrons. The analysis combines charge generation, charge saturation, persistence of the charge in an ionized medium, screening by the intergalactic plasma, the Reissner--Nordström geometry of highly charged compact objects, lensing, and the cosmological implications of a sparse charged population. We also discuss the possible relation to the early structures revealed by the James Webb Space Telescope: if astrons are relevant there, they would be primordial dark seeds rather than luminous objects directly observed at high redshift. The resulting scenario is sharply constrained. Ordinary accretion saturation gives charges far below the large-charge phenomenological benchmark, screening is a serious plasma-physics issue, and a large charge can place the exterior geometry deep in the super-extremal regime. As expected at the level of a homogeneous Friedmann--Lema\^ıtre--Robertson--Walker (FLRW) description, the interaction energy of a population of charged objects scales as \(a^{-4}\), so the simplest perfect-fluid reduction does not generate asymptotically late-time acceleration; any acceleration era tied to that homogeneous component can only be transitory. The astron scenario should be regarded as a constrained framework whose viability depends on plasma physics and on a cosmological treatment beyond the homogeneous approximation.

    ↳ astro-ph.HEgr-qchep-ph0 citations
55. 55*

    Multifield stochastic inflation: Relevance of number of fields in statistical moments

    Tomo Takahashi🇯🇵 · Koki Tokeshi🇫🇷

    In multifield inflation driven by $d$ scalar fields, $O(d)$ symmetry renders the number of fields irrelevant at classical level. This ceases to be the case once stochastic effects are accommodated. The statistical quantities such as the mean number and the variance of $e$-folds as well as the primordial power spectrum and its scale dependence are perturbatively calculated in a small-noise regime. In particular, a general formula is derived for arbitrary higher-order statistical moments of the stochastic number of $e$-folds at all perturbative orders, keeping the dependence on the number of fields fully analytical. It is also discussed that the requirement for inflation to be successfully terminated puts a theoretical bound on the number of fields from above. Those general results are demonstrated for several $O(d)$-symmetric models.

    ↳ astro-ph.COgr-qchep-phhep-th2 citations
56. 56*

    CMB Birefringence from Vacuum Interfaces

    Nemanja Kaloper🇺🇸

    Hints of cosmic microwave background polarization rotation ($\Delta \vartheta \sim 10^{-3}$ rad) are commonly attributed to late-time dynamics of ultralight axions. We show that such ultralight degrees of freedom are not required. Polarization rotation naturally arises as a geometric interface phase acquired when photons cross interfaces between topologically distinct dark sector vacua. The effect is a discrete phase shift fixed by the normalization of a wall-supported electromagnetic Chern--Simons interaction and protected by an emergent $1$-form symmetry of the low energy effective theory. This mechanism reproduces the familiar adiabatic rotation induced by light axion domain walls, but persists for arbitrarily thin walls where the axion is heavy or absent. In this regime the rotation manifests as a Pancharatnam phase localized at vacuum interfaces, independent of redshift and photon frequency below a natural ultraviolet cutoff. Cosmic birefringence thus emerges as a probe of vacuum structure in the dark sector, rather than of light-field dynamics.

    ↳ hep-thastro-ph.COgr-qchep-ph+1PRD(2026)·6 citations
57. 57*

    Positivity in Massive Spin-3/2 EFTs and the Planck-Suppressed Neighbourhood of Supergravity

    Jay Desai🇮🇳 · Diptimoy Ghosh🇮🇳 · Saurabh Pant🇨🇳

    It is well known that a strictly massless spin-$3/2$ particle can interact consistently only within supergravity. Recently, positivity arguments have shown that an effective field theory of a massive Majorana spin-$3/2$ particle admits a smooth $m\to 0$ limit only if a graviton is present and the four-fermion contact interactions are tuned to the values dictated by $\mathcal{N}=1$ supergravity. In this work, we investigate how this limit is approached at finite mass. Assuming that the graviton $t$-channel pole can be discarded, we derive non-forward, tree-level dispersive bounds on massive spin-3/2 contact operators and determine the region of effective couplings consistent with unitarity and analyticity. For sufficiently small $m$, we find that the allowed parameter space forms a bounded, Planck-suppressed neighbourhood of the supergravity point, defined by the supergravity values of the four-fermion couplings. The supergravity point lies on the boundary of this region. In the regime $m\ll M_{\mathrm{Pl}}$, the volume of the allowed region scales parametrically as \[ \mathrm{Vol} \sim \frac{m^{6}}{M_{\rm Pl}^{6}} \, , \] and shrinks to zero as $m\to 0$, smoothly reproducing the massless-limit results. The allowed region becomes unbounded when mass approaches the Planck scale. We further analyze the effect of including additional light scalar and pseudo-scalar degrees of freedom, motivated by the Polonyi model, and find that their couplings are also bounded in a way similar to the contact couplings and that it doesn't enlarge the allowed contact coupling space.

    ↳ hep-thhep-ph1 citation
58. 58*

    New Isocurvature Constraints from JWST UV Luminosity Function

    Raymond T. Co🇺🇸 · Sai Chaitanya Tadepalli🇺🇸

    We constrain uncorrelated primordial isocurvature perturbations using a combination of large- and small-scale cosmological probes, with the small-scale data provided by the ultraviolet luminosity function (UVLF) -- a measure of number density of galaxies as a function of UV brightness. We consider several isocurvature modes, including cold dark matter, baryon, neutrino density, neutrino velocity, and dark radiation perturbations. The isocurvature power spectrum is modeled using two independent parameterizations: a broken power law and a running power law, without fixing the spectral index a priori. Our analysis combines large-scale data from the Cosmic Microwave Background (CMB), baryon acoustic oscillations, and Type Ia supernovae with small-scale constraints from UVLF measurements obtained by \textit{HST} and \textit{JWST}. The UVLF probes matter fluctuations over a continuous range of intermediate scales, $k\sim 0.5$--$10{\mathrm{Mpc}}^{-1}$ over a wide range of redshift $4\lesssim z\lesssim 13$, providing a direct handle on structure formation in a regime where constraints on the scale dependence of isocurvature perturbations remain comparatively limited. Our result represents the first UVLF-based constraint on model-agnostic isocurvature perturbations carried by various components. We construct $68\%$ and $95\%$ credible envelopes in $k$-space for the allowed isocurvature power and find good agreement between the envelopes for the $95\%$ envelope across a wide range of scales, indicating that our constraints are mostly insensitive to the assumed power-law form.

    ↳ astro-ph.COhep-ph3 citations
59. 59*

    Compact space catalysis of false vacuum decay and Schwinger effect

    Saquib Hassan🇬🇧 · John March-Russell🇬🇧

    We study zero-temperature false vacuum decay in $D$ compact spatial dimensions and show that for volumes below a critical value a new bounce solution, different from Coleman's celebrated $O(D)$ bubble, mediates the decay process, and typically leads to an exponentially enhanced decay rate. The bounce, when analytically continued to Lorentzian signature, nucleates a homogeneous field configuration for spatial volumes below a critical value, and quasi-homogeneous configurations for slightly larger volumes, and is not of the form of a thin or thick-walled bubble embedded in a false vacuum background. We explicitly show that the new bounce has the necessary features associated with false vacuum decay, following from its eigenvalue spectrum of fluctuations. The cross-over from homogeneous to quasi-homogeneous solutions as the spatial volume is increased is discussed, as is a real-time interpretation of the bounce. We apply this bounce to the study of a scalar field model, as well as a close cousin of the Schwinger effect that applies to $(1+1)d$ axion electrodynamics in compact space.

    ↳ hep-thhep-ph0 citations
60. 60*

    Quantum Field-Theoretic Predictions of {\Psi}-Epistemic Models of Quantum Mechanics

    İnanç Şahin

    {\Psi}-epistemic models of quantum mechanics imply that the quantum state does not correspond to physical reality, but instead reflects the observer's knowledge of the underlying quantum system. The epistemic view of the quantum state has the potential to shed light on several foundational problems of quantum theory and has attracted considerable attention in the literature. On the other hand, the Pusey-Barrett-Rudolph theorem demonstrated that broad classes of {\psi}-epistemic models must lead to predictions that deviate from those of quantum mechanics. Although the original theorem involved entangled joint measurements on composite systems, alternative no-go theorems involving measurements on single quantum systems were developed shortly thereafter. Experimental investigations of the deviations predicted by {\psi}-epistemic models from quantum mechanics are still ongoing. So far, such tests have been performed within the framework of non-relativistic quantum mechanics and predominantly rely on quantum information based measurement procedures. In this work, we show that {\psi}-epistemic models can give rise to deviations from standard quantum field-theoretic predictions through modifications of polarized scattering cross sections and decay widths. Our results do not require a relativistic formulation of ontological models or of the Harrigan-Spekkens criterion; the essential assumption is merely that measurements implemented through relativistic processes can still be represented within the ontological framework by well-defined response functions and probabilities. The present work constitutes a proof-of-principle study demonstrating that particle physics tests of the ontological status of the quantum state are possible and that {\psi}-epistemic models may exhibit experimentally distinguishable signatures in particle phenomenology.

    ↳ quant-phhep-ph0 citations
61. 61*

    Spin dynamics and polarization in relativistic systems: recent developments

    Sourav Dey🇮🇳 · Arpan Das🇮🇳 · Hiranmaya Mishra🇮🇳 · Amaresh Jaiswal🇮🇳

    We review recent theoretical and experimental developments in spin dynamics and polarization phenomena in relativistic systems, with a particular focus on heavy-ion collisions. The large angular momentum and magnetic field generated in non-central collisions induce vorticity in the quark-gluon plasma, leading to observable spin polarization of emitted hadrons. We discuss the theoretical foundations of spin polarization arising from spin-vorticity coupling, including formulations based on relativistic hydrodynamics, kinetic theory, and quantum statistical approaches such as the Zubarev density operator. A central theme of the review is the role of pseudo-gauge freedom and its implications for defining energy-momentum and spin tensors, which can influence theoretical predictions of polarization observables. We further examine different formulations of spin hydrodynamics, emphasizing the impact of gradient expansions, spin chemical potential, and entropy-current analysis on the structure of the theory and associated transport coefficients. In addition, we discuss the recent developments in heavy flavor spin dynamics within the framework of rotational Brownian motion, where spin degrees of freedom undergo stochastic evolution due to interactions with the medium. This framework provides a complementary perspective on spin relaxation and diffusion by incorporating the effects of strong initial magnetic fields and establishes connections between spin polarization and the initial geometry through the definition of polarization harmonics. This review provides a comprehensive overview of relativistic spin hydrodynamics as well as non-equilibrium spin dynamics, and outlines future directions toward a consistent and predictive description of spin phenomena in strongly interacting matter.

    ↳ nucl-thhep-phhep-th2 citations
62. 62*

    Effective Field Theory for a Baryon-Correlated Dark Matter Profile

    Kento Kamada🇯🇵

    While the standard $\Lambda$CDM model succeeds on large cosmological scales, it faces persistent small-scale challenges, including the core-cusp problem, the diversity of galaxy rotation curves, and the tight correlation between dark matter and baryons observed in the Tully-Fisher relation. To address these issues, we recently proposed an empirical law where the effective dark matter energy density is directly correlated with the baryonic gravitational potential, ${\rho }_{\mathrm{DM}}\propto {\Phi }_b^2$, which reproduces observed rotation curves and resolves the core-cusp and diversity problems. To provide a theoretical foundation for this empirical law, we construct an effective field theory (EFT) introducing massive scalar, vector, and tensor mediators between baryons and a dark sector field $\chi$. We demonstrate that aligning the mediator couplings to a specific ratio (4:6:3) with degenerate masses cancels the additional fifth forces acting on baryons up to $\mathcal{O}(v^2)$. We then show that this theoretical framework originates from a 5-dimensional (5D) spacetime. Treating the baryonic source as a 5D null fluid reveals that the three mediators emerge from a single 5D symmetric tensor field. By confining the field $\chi$ to a 4D brane, we show that its interaction with these mediators generates a pressureless energy density (${\rho }_{\mathrm{int}}\propto {\Phi }_b^2$) that yields the empirically required baryon-correlated profile. Consequently, the field $\chi$ exhibits a scale-dependent transition: on cosmological scales, its mass energy acts as standard Cold Dark Matter (CDM), whereas on galactic scales, its interaction energy governs local dynamics. Finally, by evaluating the dynamical boundary of this localized interaction region, we provide a physical interpretation that yields the relation $\mu =K{M}_b^{-3/2}$, offering a theoretical basis for the Tully-Fisher relation.

    ↳ astro-ph.COastro-ph.GAgr-qchep-ph1 citation

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.