Tue·Mar 3, 2026Tuesday·March 3, 2026

1. 01*

   Search for Light Dark Sectors Using Electron-Photon Collisions

   L. Angel🇧🇷 · G. Casse🇬🇧 · G. Gambini🇵🇪 · A. S. de Jesus🇧🇷 · V. Kozhuharov🇧🇬 · A. Machado🇧🇷 · F. S. Queiroz🇧🇷 · E. Segreto🇧🇷 · J. Smirnov🇬🇧

   The dark photon is a new gauge boson that naturally arises in many beyond the Standard Model theoretical models, featuring interactions that resemble quantum electrodynamics. Due to this feature, it is often considered the portal between dark and visible sectors. For this reason, it has become the target of many experimental searches worldwide. In this work, we propose a search for dark photons based on the Inverse Compton scattering, $\gamma e^{-}\to A^{\prime }{e}^{-}$, to be conducted at electron accelerators. In this setup, photons from a laser source would impinge on the accelerated electron beam, producing a dark photon in the final state. We propose an experimental setup to take advantage of the photon counting technique, and we derive the projected sensitivity by considering the energy of the incident photon to be about 1 eV and an electron beam of 3 GeV. We show that this experimental setup could cover an unexplored region of parameter space and constitute a promising probe for dark sectors in the future.

   hep-phhep-exhep-thnucl-ex2 citations
2. 02*

   Machine Learning insights on the Z3 3HDM with Dark Matter

   Fernando Abreu de Souza🇵🇹 · Rafael Boto🇩🇪 · Miguel Crispim Romão🇬🇧 · Pedro N. de Figueiredo🇵🇹 · Jorge C. Romão🇵🇹

   We study a 3-Higgs Doublet Model (3HDM) with an imposed Z3 symmetry, allowing for two Inert scalar doublets and one active Higgs doublet. The WIMP dark matter candidates correspond to two mass-degenerate states, H1 and A1, which possess opposite CP quantum numbers and can reproduce the correct relic density simultaneously with all theoretical and experimental constraints. We use state-of-the-art machine learning algorithms to probe the parameter space of the model by employing an Evolutionary Strategy augmented with Novelty Reward. We consider two situations: a limit for the dark matter mixing angle {\theta} that closes a gauge annihilation channel that would deplete the DM relic density, and the general case without imposing this limit. For both scenarios, we find viable dark matter candidates within two separate mass regimes, ranging from 50 GeV < mDM < mW and 380 < mDM < 1000 GeV. Moreover, we find it is possible to fulfill all the existing constraints while still obtaining values for the dark matter-higgs coupling of order O(0.1). Exploring the model outside the {\theta} = {\pi}/4 limit proved to be an extremely challenging task, as there are regions which seem easy to explore when projected on a 2D plane, yet may be completely disconnected on the hypersurface supporting the valid points, given its non-convex and multi-dimensional nature. We consider new methods of prototype selection to seed new exploration runs, which allow for efficient global scans over the parameter space.

   hep-ph2 citations
3. 03*

   BSM Searches at a Photon Collider with Energy $E_{\gamma \gamma }<12$ GeV

   Marten Berger🇩🇪 · Gudrid Moortgat-Pick🇩🇪

   The possibility of a photon collider extension to the beam dump of the $17.5$ GeV European XFEL has already been discussed before as the first high energy collider of its sort. It would not only be the first proof of concept and test of a photon collider but would also be a collider without competition in the region of $E_{\gamma \gamma }=5-12$ GeV for photon-photon collision. In this range, $b\bar{b}$ and $c\bar{c}$ resonances, tetraquarks and mesonic molecules can be observed. Furthermore, some BSM processes can also be reached in this range. In this paper we want to discuss the possibility of observing ALPs in the process of light-by-light scattering at such a collider. We will use a simplified description of the Compton backscattering process to get a first look at cross sections for the Standard Model light-by-light scattering and the extension including ALPs. Furthermore, we extend this to the full beam dynamics included prediction, discuss all effects that are important when working with a photon collider and show that the photon collider with energy $E_{\gamma \gamma }<12$ GeV would offer an extended physics reach compared to current limits.

   hep-phhep-ex1 citation
4. 04*

   Cosmological and Astrophysical Constraints on Late First-Order Phase Transitions

   Kylar Greene🇰🇷 · Daven Wei Ren Ho🇺🇸 · Soubhik Kumar🇺🇸 · Yuhsin Tsai🇺🇸

   First-order cosmological phase transitions (PT) can take place in a dark sector at relatively late times between the big-bang nucleosynthesis and recombination epochs. Because bubble nucleation is stochastic, the PT completes at different times in different regions of the Universe. This fluctuation sources a curvature perturbation whose (dimensionless) power spectrum ${\mathcal{P}}_{\zeta }(k)$ features a universal infrared tail, independent of the microscopic details of the PT. Even in the absence of any non-gravitational interaction between the dark sector and the Standard Model, these additional curvature perturbations at small scales impact a variety of observables. We derive new constraints on dark sector phase transitions using {\it Planck}, baryon acoustic oscillation (BAO), Lyman-$\alpha$ observations, spectral distortion limits from FIRAS, constraints on early reionization, and the existence of ultra-faint dwarf galaxies.

   hep-phastro-ph.CO8 citations
5. 05*

   Gluon Sivers function in dijet production at the EIC

   Miguel G. Echevarria🇪🇸 · Patricia Andrea Gutierrez García🇪🇸 · Ignazio Scimemi🇪🇸

   The transverse-momentum-dependent (TMD) factorization theorem for dijet production in deep-inelastic scattering is used here to make predictions of the gluon Sivers function. We revise the previously studied unpolarized case and develop the formalism for a transversely polarized target. We study the impact of TMD evolution in two different schemes and we use the current extractions of the evolution kernel at N${}^3$LO to make predictions for the future Electron-Ion Collider (EIC). The results strongly depend on the TMD gluon distributions and their evolution kernel. At the EIC, and for the considered models, large values of the Sivers asymmetry higher than 5$\%$ are predicted.

   hep-phhep-ex4 citations
6. 06*

   A Unified Interpretation of Supernova, GRB, and QSO Time Dilation Signals in a Generalized Cosmological Time Framework

   Seokcheon Lee

   Cosmological time dilation (CTD) serves as a fundamental probe of cosmic expansion, historically verified through the characteristic (1+z) broadening of Type Ia supernova (SNe Ia) light curves. However, significant tensions arise when extending this test to other astrophysical regimes. While discrete, event-based transients such as Gamma-Ray Bursts (GRBs) exhibit large scatter in interred time-dilation signatures, analyses of stochastic variability in persistent sources, specifically Quasars (QSOs), frequently yield null results. I demonstrate that these discrepancies stem from a previously overlooked distinction between discrete geometric clocks and continuous thermal emission, presenting a resolution within the framework of Generalized Cosmological Time (GCT). The central premise relies on strictly distinguishing global coordinate time, characterized by a generalized lapse function, from the local proper time measured within gravitationally bound systems. We propose that the progenitors of transients, specifically SNe Ia and GRB central engines, are effectively shielded from background time evolution due to strong gravitational binding and environmental decoupling. Consequently, they act as standard clocks tracing pure geometric path dilation, obeying \tau_{\rm obs} \propto (1+z)^{1-b/4}. Conversely, the lack of dilation in QSOs is derived as a consequence of observing persistent thermal accretion disks at fixed wavelengths, introducing an intrinsic selection effect (\tau_{\rm intr} \propto (1+z)^{-2}) that masks the cosmological signal. This framework reconciles the diverse behaviors of transient and persistent sources without modifying local physical laws.

   hep-phastro-ph.HEgr-qcEPJC(2026)·2 citations
7. 07*

   Testing light and heavy vector mediators with solar CE$\nu$NS measurements

   Valentina De Romeri🇪🇸 · Dimitrios K. Papoulias🇩🇪 · Federica Pompa🇮🇹 · Gonzalo Sanchez Garcia🇲🇽 · Christoph A. Ternes🇮🇹

   The recent observation of coherent elastic neutrino-nucleus scattering from solar ${}^8$B neutrinos in dark matter direct detection experiments has inaugurated the \emph{neutrino fog} era, highlighting the extended potential of these experiments as precision neutrino observatories. Recent measurements by the XENONnT, PandaX-4T, and LUX-ZEPLIN experiments provide new opportunities to test Standard Model predictions and to probe physics beyond it, in complementarity with dedicated neutrino facilities. We perform a combined analysis of nuclear recoil data from these three facilities to extract information on the solar ${}^8$B neutrino flux normalization and on the weak mixing angle at low-momentum transfer. We further investigate the impact of new vector interactions on the solar neutrino event rate, deriving constraints on nonstandard neutrino interactions and on scenarios with light vector mediators. Our results demonstrate that dark matter detectors are rapidly becoming complementary to terrestrial neutrino experiments in probing neutrino interactions, and already set competitive bounds on both light and heavy vector mediators.

   hep-phhep-ex7 citations
8. 08*

   Impact of flavor changing processes on prospects for majoron discovery at intensity-frontier searches

   Krzysztof Jodłowski🇰🇷 · Chih-Ting Lu🇨🇳

   The singlet majoron $J$ is the pseudo-Nambu-Goldstone boson of a global, anomaly-free $U(1{)}_{B-L}$ symmetry whose spontaneous breaking generates Majorana masses for right-handed neutrinos. At tree level, the only direct coupling of $J$ to Standard Model fields is $J\nu \nu \propto m_{\nu }/f$ (where $m_{\nu }$ denotes the light neutrino mass and $f$ the $B-L$ breaking scale). Couplings to charged fermions and gauge bosons, in contrast, arise only at loop level. Consequently, $J$ can be long-lived over wide regions of parameter space, motivating displaced-decay searches. We study majoron production and displaced decays at proton beam dump experiments, neutrino facilities, and LHC forward detectors (including DUNE, NA62, FASER/FASER2, MATHUSLA, and SHiP), and we quantify the resulting reach in the $(m_J,f)$ plane. We show that, for realistic seesaw-induced coupling textures, lepton-flavor-violating (LFV) $\tau$ decays $\tau \to \ell J$ ($\ell =e,\mu$) dominate majoron production at these facilities and can extend sensitivity into the intermediate-mass window $m_J\simeq 0.2\text{-}1.7\mathrm{GeV}$, complementary to supernova bounds at lower masses and to dedicated LFV searches at higher masses. We also identify physically consistent benchmark textures for the matrix $K=M_D{M}_D^{†}/(vf)$ with $M_D$ denoting the Dirac mass matrix and $v$ the electroweak scale (including positive semidefinite ``anarchical'', single-flavor, and CP-violating cases) and map their impact on experimental reach.

   hep-ph0 citations
9. 09*

   Constraining Neutrino--Nucleon Form Factors with Charged-Current Scattering at the Electron-Ion Collider

   Guang Yang🇺🇸 · Praveen Kumar🇺🇸

   Next-generation neutrino oscillation experiments such as DUNE require percent-level knowledge of neutrino--nucleon interaction cross sections. The nucleon axial form factor $F_A(Q^2)$, parameterized by the axial mass $\text{MA}$, is the dominant source of uncertainty in the quasi-elastic channel, and the parity-violating structure function $x{F}_3$ is poorly constrained on free nucleons. We propose using charged-current (CC) electron--proton scattering at the Electron-Ion Collider (EIC) to address both problems simultaneously. The measurement exploits three key features of the EIC: (1)~helicity-selective electron bunches provide \emph{in situ} electromagnetic background rejection; (2)~a longitudinally polarized proton target enables extraction of $F_A(Q^2)$ through the target-spin asymmetry $A_{UL}$; and (3)~the $y$-distribution leverage in CC deep inelastic scattering separates $F_2$ and $x{F}_3$ on a \emph{free proton}, without nuclear corrections. Using a Fisher-information analysis at $\sqrt{s}=141\text{GeV}$ with $500{\text{fb}}^{-1}$ of integrated luminosity, we project the Cramér--Rao statistical floor of $\delta \text{MA}\approx 0.03\text{GeV}$ (3\%). Incorporating first-order realistic detector effects: ZDC acceptance, $Q^2$ smearing (5\%), and background noise from helicity subtraction, the projected sensitivity is severely background-limited due to the small signal-to-background ratio ($S/B\approx 3\times 10^{-4}$) in the elastic channel. Achieving competitive sensitivity ($\delta \text{MA}\approx 0.14\text{GeV}$) would require $\sim 10^{-7}$ background suppression, three orders of magnitude beyond current projections. The CC DIS $y$-distribution provides sub-percent extraction of $x{F}_3^{\text{Wminus}}$ over $0.05<x<0.5$, representing the most robust electroweak measurement in the near term.

   hep-phPRD(2026)·4 citations
10. 10*

    Getting a handle on correlation functions

    Gernot Eichmann🇦🇹

    The central objects in a quantum field theory are its n-point correlation functions and matrix elements. Their structure is determined by Lorentz invariance and leads to tensor decompositions whose Lorentz-invariant coefficient functions encode the physics of the process. For growing n, the complexity of these objects may increase considerably and make it challenging to deal with them. Here we give a pedagogical introduction to the topic and provide some tools to manage this complexity, and we will show how symmetries can be used as organizing principles.

    hep-phParticles(2026)·4 citations
11. 11*

    Quark Mixing from a Lattice Flavon Model: A Four-Magnitude Parameterization

    Vernon Barger🇺🇸

    We show that quark weak mixing follows from the same one-flavon, three-messenger Froggatt-Nielsen construction, with a single hierarchy parameter $B$ ($ϵ\equiv 1/B$) and a rational-exponent "$B$-lattice", that organizes the fermion mass spectrum in companion work. The lattice exponents, together with a four-phase messenger coefficient model, account for the four measured CKM magnitudes and, through the Fritzsch-Xing reconstruction, the full $3\times 3$ CKM matrix and the Jarlskog invariant $J$, providing a consistency test of the single-$B$ hypothesis. A benchmark Yukawa pair on the lattice reproduces, under direct diagonalization, the light-quark masses to better than 5%, all nine CKM magnitudes to better than 1.2%, and $J$ within $0.3\sigma$ of the PDG global fit, with order-unity coefficients; a $10^7$-configuration phase scan shows the CKM hierarchy to be generic once the quark masses are fit, while percent-level agreement across all four magnitudes is not. The near-maximal CP phase admits a geometric interpretation: equal-weight messenger interference fixes the phase at exactly $\pi /2$ for any individual phase values, and the fitted ${\varphi }_{\mathrm{FX}}\simeq 93^{\circ }$ measures the departure from this limit. The same lattice parameter fixes the charged-lepton mass ratio $m_{\mu }/m_{\tau }=c_{\mu }{ϵ}^{5/3}$, whose exponent is the second-generation lepton charge sum; this yields $|V_{ub}|\simeq (m_{\mu }/m_{\tau }{)}^2$, agreeing with the measured value at about the 6% level, and the equivalent form $|V_{ub}|\simeq {\sin }^3{\theta }_{13}$ ties the smallest CKM magnitude to the smallest PMNS magnitude, the two routes furnishing complementary determinations of the same ninths-lattice quantity from the quark and lepton sectors.

    hep-ph4 citations
12. 12*

    Non-Minimal Dilaton Inflation from the Effective Gluodynamics

    Pirzada🇨🇳 · Imtiaz Khan🇨🇳 · Mussawair Khan🇨🇳 · Tianjun Li🇨🇳 · Ali Muhammad🇨🇳

    We develop a nonminimal dilaton-inflation model in which the inflaton is the lightest scalar excitation of a hidden confining gauge theory. The Migdal--Shifman anomaly-matching action fixes a logarithmic contribution to the scalar potential, $V_{\mathrm{MS}}=A{\phi }^4[\ln (\phi /\mu )-1/4]$, with $(A,\mu )$ mapped to the scalar mass and vacuum condensate. Embedding this sector in the leading curved-space EFT introduces the independent Wilson coefficients $\lambda$ and $\xi$, and the resulting Einstein-frame dynamics yields a plateau with a calculable anomaly-induced deformation. We analyze the pure MS limit as a baseline, derive the $\mu$--$\lambda$ reparametrization, state finite-window RG-control conditions, and impose both the nonminimal-gravity cutoff and the intrinsic confining-sector gap. Exact slow-roll scans show that the viable regime combines the usual large-$\xi$ attractor behavior with a logarithmic imprint tied directly to nonperturbative trace-anomaly matching.

    hep-phastro-ph.COgr-qc11 citations
13. 13*

    Covariant diffusion tensor for jet momentum broadening out of equilibrium

    Isabella Danhoni🇺🇸 · Nicki Mullins🇺🇸 · Jorge Noronha🇺🇸

    Jets are produced in the earliest stages of heavy-ion collisions, where they can interact with a medium that is not yet close to local equilibrium. Motivated by this, we generalize the usual jet transport coefficient $\hat{q}$ to a Lorentz-covariant diffusion tensor ${\hat{q}}^{\mu \nu }$ within a leading-order elastic (Boltzmann/Fokker--Planck) description of jet--medium interactions. The tensor formulation organizes medium effects in a frame-covariant way and reveals additional information beyond the standard scalar definition, including energy diffusion and off-diagonal components that encode correlations between energy and momentum exchange which are absent (or redundant) in equilibrium. We illustrate the formalism in (tree-level) massless $\lambda {\phi }^4$ theory for isotropic but out-of-equilibrium states. For sufficiently large jet momentum, quantum statistical effects become subleading, so that the non-equilibrium evolution can be studied reliably in the classical (Boltzmann) limit. This allows us to solve the corresponding Boltzmann equation for the medium and determine the time dependence of ${\hat{q}}^{\mu \nu }$ as the system approaches equilibrium. We find that out-of-equilibrium corrections can either enhance or reduce jet momentum broadening, depending on the initial distribution function.

    hep-phhep-thnucl-th3 citations
14. 14*

    Comments on "Unified neutrino mixing and approximate $\mu -\tau$ reflection symmetry" (Mod. Phys. Lett. A, 40 (2025) 26, 2550097 [arXiv:2502.18029 [hep-ph]])

    Chao-Shang Huang · Wen-Jun Li

    Resolving mass ordering is an important issue in the neutrino physics. In Ref.\cite{yt} the authors investigate the phenomenology of a unified neutrino mixing framework and reveal that the predicted sum of neutrino masses derived from an approximate $\mu -\tau$ reflection symmetric flavor neutrino mass matrix based on the unified neutrino mixing with an inverted mass ordering, is excluded from DESI2024 and Supernova Ia luminosity distance data. We note that in Ref.\cite{yt} an error is present in Eq.(20), {\it i.e.}, the expression for $M_{23}^{\mu -\tau }$, a similar error also appears in Eq.(26) for $M_{13}^{\mu -\tau }$. That is, the condition that $M_{ee}$ and $M_{\mu \tau }$ are real is omitted. We impose this condition and analyze its consequences. Using the newest data\cite{azz}, it is obtained that the predicted sm derived from the approximate $\mu -\tau$ reflection symmetric neutrino mass matrices $M_{23}$ for both NO and IO are allowed. We note also that their conclusion is invalid, as it is based on outdated data.

    hep-phMod.Phys.Lett.A(2026)·1 citation
15. 15*

    Anisotropic flows of light-flavor and charmed hadrons in Pb+Pb collisions at LHC energy

    Yan-ting Feng🇨🇳 · Rui-qin Wang🇨🇳 · Feng-lan Shao🇨🇳 · Jun Song🇨🇳

    We apply a constituent quark equal-velocity combination (EVC) model to study the elliptic flow ($v_2$) and triangular flow ($v_3$) of light-flavor and single-charmed hadrons in Pb+Pb collisions at $\sqrt{s_{NN}}=$ 2.76 and 5.02 TeV. $v_{2,3}$ of hadrons in the EVC model can be expressed as a linear superposition of the $v_{2,3}$ of quarks at the same velocity as that of the hadrons. We find that available experimental data for $v_2$ and $v_3$ of $p$, $\Lambda$, $\Xi$, and $\Omega$ as the function of transverse momentum ($p_T$) can be consistently explained by the EVC formula using a $v_2$ of up/down quarks and a $v_2$ of strange quarks. In comparison with $v_2$ data of $\varphi$ at $\sqrt{s_{NN}}=$2.76 TeV which can be naturally explained by $v_2$ of strange quarks, explanation of data of $\varphi$ mesons at $\sqrt{s_{NN}}=$5.02 TeV requires an additional contribution of two-kaon coalescence, which indicates approximately 20% influence of final-state hadronic rescattering on $v_2$ of $\varphi$ at $\sqrt{s_{NN}}=$5.02 TeV. Using $v_2$ and $v_3$ of light-flavor quarks obtained in studying light-flavor hadrons and $v_2$ and $v_3$ of charm quarks determined from $D^0$ meson data, we apply the EVC model to predict the anisotropic flows of $D_s^{+}$, ${\Lambda }_c^{+}$, ${\Xi }_c^0$, and ${\Omega }_c^0$ and compare them with the available experimental data. The preliminary data for $v_2$ of $D^0$, $D_s^{+}$, and ${\Lambda }_c^{+}$ at $\sqrt{s_{NN}}=$ 5.36 TeV are found to be naturally described by the EVC model.

    hep-ph0 citations
16. 16*

    Probing non-unitarity of the PMNS matrix in P2SO and comparison with DUNE

    Sambit Kumar Pusty🇮🇳 · Samiran Roy🇮🇳 · Monojit Ghosh🇭🇷 · Rukmani Mohanta🇮🇳

    We compare the sensitivity of the upcoming long-baseline neutrino experiments Protvino to Super-ORCA (P2SO) and the Deep Underground Neutrino Experiment (DUNE) to non-unitarity (NU) of the leptonic mixing matrix in a model-independent framework. NU can arise in theories beyond the Standard Model that include heavy neutral leptons. These effects can modify neutrino oscillation probabilities and introduce new sources of CP violation, which may affect precision measurements of neutrino parameters. We find that DUNE provides stronger bounds on ${\alpha }_{11}$ and $|{\alpha }_{21}|$, while P2SO shows better sensitivity to ${\alpha }_{22}$ and ${\alpha }_{33}$, mainly due to its longer baseline and stronger matter effects. Our results show that DUNE (P2SO) will be able to improve the current bounds of ${\alpha }_{11}$ (${\alpha }_{33}$). We further examine correlations with standard oscillation parameters and quantify the impact of NU on mass hierarchy, octant, and CP-violation sensitivities. Our results show that these sensitivities depend upon NU in a non-trivial way interconnecting the parameter degeneracies and matter effects. Our results demonstrate the complementarity of P2SO and DUNE in probing NU and show that NU can significantly influence next-generation precision oscillation studies.

    hep-phJHEP(2026)·1 citation
17. 17*

    Quark-diquark effective mass formalism for heavy baryon spectroscopy

    Binesh Mohan🇮🇳 · Rohit Dhir🇮🇳

    We develop a quark-diquark effective mass formalism for heavy-flavor baryon spectroscopy and apply it to the $J^P={\frac{1}{2}}^{+}$ and $J^P={\frac{3}{2}}^{+}$ spectra across the singly, doubly, and triply heavy sectors. The analysis is carried out in two complementary scenarios: Scenario I treats all quark-quark diquark channels dynamically, while Scenario II restricts the dynamics to scalar and axial-vector diquarks, providing a more selective and physically transparent description. Constituent quark masses, effective diquark masses, and chromomagnetic couplings are extracted from known heavy-baryon masses, with the couplings determined solely by the quark content of each state and no sector-dependent adjustment introduced. A mass-dependent binding term is implemented to account for spin-independent chromoelectric effects and to describe the transition from chromomagnetic to color-Coulomb dominance across the light-to-heavy quark regime, ensuring consistency with heavy-quark spin symmetry in the heavy-quark limit. The resulting predictions are in good agreement with available experimental measurements and lattice QCD results across both charm and bottom sectors. The extracted diquark parameters remain stable across all heavy-flavor sectors, establishing the present framework as a symmetry-constrained spectroscopic baseline for heavy-baryon structure.

    hep-phhep-ex2 citations
18. 18*

    Multi-channel phase space with Feynman-diagram-gauge amplitudes

    Kaoru Hagiwara🇯🇵 · Junichi Kanzaki🇯🇵 · Fabio Maltoni🇧🇪 · Kentarou Mawatari🇯🇵 · Ya-Juan Zheng🇯🇵

    Multi-channel phase space with a single Feynman diagram enhancement is a powerful tool for high-energy physics event generation if a diagram with a singular propagator dominates the total scattering amplitude at the corresponding singular kinematical region, and when the interference among amplitudes is not larger than the square of each amplitude. These conditions are satisfied in the Feynman-diagram-gauge amplitudes for both unbroken (QED and QCD) and broken (EW) gauge theories. We illustrate the usefulness of this method in lepton collider processes that are challenging to accurately simulate at very high energies, i.e., $l\bar{l}\to {\nu }_l{\bar{\nu }}_{l}t\bar{t}H$, $l{\bar{\nu }}_{l}t\bar{b}H$, and $l\bar{l}t\bar{t}H$, in the SMEFT with a complex top-Yukawa coupling. The total cross sections of the latter two processes contain lepton-mass singularities arising from $t$-channel photon-exchange diagrams. To address this issue, we develop a phase-space parametrization that accurately generates the distributions of forward-emitted charged leptons. We modify the \HELAS\ library to evaluate helicity amplitudes in the singular region so that vertices at very small invariant momentum square of order $m_e^2$ can be accurately evaluated even at multi-TeV energies.

    hep-phphysics.comp-phPRD(2026)·1 citation
19. 19*

    Elastic Hadron Scattering at High Energies

    O.V. Selyugin🇷🇺

    A brief historical overview of various modern approaches to the problem under consideration is given. It includes existing models based on a sum of different terms of the scattering amplitude with different signs and Regge-eikonal models based on the Born terms of the scattering amplitudes. An example of such a model is a new Regge-eikonal model is given, taking into account the generalized structure of nucleons (the HEGS model), which is based on the analyticity of the scattering amplitude. A unified quantitative description of various hadron reactions and a description of differential cross sections and the spin-correlation parameter for interactions were obtained. In the framework of the model, the existence of experimental data of elastic hadron scattering in the energy range of LHC and in a wide energy region $\sqrt{s}=3.6-13000$ GeV was describe a quantitatively from a unified point of view. The predictions for ${\sigma }_{tot}(s)$ at superhigh energies are presented. The possible thin structure of differential cross sections at small angles of elastic nucleon-nucleon scattering at high energies is discussed.

    hep-ph0 citations
20. 20*

    LHEReader: Simplified Conversion from Les Houches Event Files to ROOT Format

    Aman Desai🇦🇺

    We present the \textsc{LHEReader} program that converts a Les Houches Event file into a \Root file, allowing one to subsequently analyse the file using \Root. We evaluate the performance of this conversion by simulating $pp\to jj$ and $e^{+}{e}^{-}\to ZH$. The application of this program is illustrated through the simulation of $pp\to ZH$ with $Z\to {\ell }^{+}{\ell }^{-}$ and $H\to b\bar{b}$, analysing the events at the parton level after hard-scatter event generation as well as after the fast simulation stage using \MadAnalysis. The analysis is implemented in \Root, demonstrating the use of this program. The program is available at https://github.com/amanmdesai/LHEReader

    hep-phPhys.Scripta(2026)·1 citation
21. 21*

    Threshold Cusp Structures in the Presence of Isospin Symmetry Breaking

    Katsuyoshi Sone🇯🇵 · Tetsuo Hyodo🇯🇵

    We study the behavior of the cusp structures focusing on the isospin-breaking effects. The properties of the near-threshold exotic hadrons are encoded in the shapes of the cusp structures. In hadron scattering, it is often the case that the thresholds of isospin partner channels are located within a narrow energy region. To analyze the scattering in such systems, it is therefore essential to study the cusp structures that emerge at two closely separated thresholds with isospin symmetry breaking. In this study, we propose a practical representation of the scattering amplitude and show that the two neighboring cusp structures are related through the isospin symmetry.

    hep-phnucl-th1 citation
22. 22*

    Covariant Cherenkov Radiation and its Friction Force

    Will Price🇺🇸 · Martin S. Formanek🇨🇿 · Johann Rafelski🇺🇸

    We derive the covariant generalization of the Frank-Tamm formula describing the Cherenkov radiation by a charged particle moving uniformly with a speed faster than the local speed of light within a homogeneous dielectric medium. We use our result to derive the covariant Cherenkov radiation reaction force and obtain a four-force explicitly orthogonal to particle four-velocity consistent with a relativistic friction force. We present the photon emission spectrum that is dependent primarily on the dielectric properties of the medium. We hint at a possible use of this work to interpret an excess of soft photons seen in relativistic hadron collisions.

    hep-phPRD(2026)·1 citation
23. 23*

    Resonant electromagnetic leptogenesis with coherent heavy-neutrino evolution

    Rin Takada🇯🇵

    We study TeV-scale electromagnetic leptogenesis generated by the gauge-invariant neutrino-dipole operators $O_{NB}$ and $O_{NW}$. The benchmark Wilson coefficients are specified at the renormalization scale ${\kappa }_N=M_1=1\mathrm{TeV}$ and related to their values at ${\kappa }_{\mathrm{match}}=3\mathrm{TeV}$ through the coupled one-loop $\nu$SMEFT evolution. The collision network contains the symmetric-phase $1\leftrightarrow 3$ and crossed $2\leftrightarrow 2$ processes generated by the linear field-strength vertices and the VEV-induced two-body $\gamma$, $Z$, and $W$ channels through the electroweak crossover. We use a factorized leading-moment, momentum-averaged Markovian treatment for two $2\times 2$ heavy-flavor density matrices, one for each helicity. Pole-resummed two-state effective couplings enter the lepton and antilepton collision tensors, while the off-diagonal density matrices describe coherent evolution and collision damping. Three resolved flavor charges are coupled to a finite-rate sphaleron equation, yielding the frozen baryon yield $Y_B^{\mathrm{FO}}$. For the benchmark ${\tilde{m}}_1^{\mathrm{EM}}=3.97\times 10^{-2}\mathrm{eV}$, the decay-only pole prescription, in which only decay contributions enter the absorptive pole matrix, gives the locally optimized positive near-resonant maximum $Y_B^{\mathrm{FO}}=+5.50\times 10^{-5}$ at $\Delta M=1.29\times 10^{-11}\mathrm{GeV}$. Adding the thermally averaged crossed-scattering moment to the pole matrix defines the decay-plus-scattering prescription and shifts the maximum to $Y_B^{\mathrm{FO}}=+8.44\times 10^{-5}$ at $\Delta M=1.83\times 10^{-11}\mathrm{GeV}$. The corresponding signed mass-splitting curves cross the observed value $Y_B^{\mathrm{obs}}$ at $\Delta M=1.68\times 10^{-5}\mathrm{GeV}$ and $2.34\times 10^{-5}\mathrm{GeV}$.

    hep-phPRD(2026)·0 citations
24. 24*

    Flux Estimates and Detection Prospects for Lunar Geoneutrinos

    Hang Hu🇨🇳 · Yaping Cheng🇨🇳 · Wan-Lei Guo🇨🇳

    The distribution of heat-producing elements (U, Th, K) within the Moon is critical for understanding its thermal evolution and formation history. Based on a refined lunar interior model, we calculate the geoneutrino fluxes at two representative detector locations that bracket the expected signal intensity. The maximum flux is found to be slightly lower than the corresponding predicted fluxes for the KamLAND site on Earth, while the minimum flux is approximately a factor of 8.63 lower than this maximum value. The angular distributions of geoneutrinos arriving at the two locations were further computed. Finally, we evaluate the detection prospects for lunar geoneutrinos using three reaction channels: inverse beta decay reaction, elastic scattering on electrons, and a novel radiochemical approach based on ${\bar{\nu }}_e{+}^3$He $\to e^{+}{+}^3$H. For each reaction, we calculate the expected event rates and briefly discuss the potential for measuring the total geoneutrino flux, as well as the relative contributions from U, Th, and K.

    hep-ph0 citations
25. 25*

    Light-cone sum rules with $B$-meson distribution amplitudes for the $B\to p$ form factors in $B$-mesogenesis models

    Aritra Biswas🇩🇪 · Alexander Khodjamirian🇩🇪 · Ali Mohamed🇩🇪

    New decay modes of $B$-meson into a baryon and invisible dark antibaryon $\Psi$ are among the most distinctive signatures of the $B$-mesogenesis scenario. We concentrate on the proton mode and consider two versions of the underlying interaction of $\Psi$ with quarks, the so-called models $(d)$ and $(b)$. To estimate the width of the $B^{+}\to p\Psi$ decay, we obtain the $B^{+}\to p$ transition form factors, applying QCD light-cone sum rules (LCSRs) with $B$-meson distribution amplitudes with an accuracy up to twist-5, while interpolating the proton with a current. This method is independent of the previously applied one, which was based on the nucleon distribution amplitudes. We estimate the partial width of the $B^{+}\to p\Psi$ decay as a function of the dark antibaryon mass. Furthermore, we use the ratio of this width to the inclusive $B\to X_N\Psi$ width, the latter predicted earlier using the heavy quark expansion method. This ratio, which is independent of the effective coupling, when combined with the minimal inclusive branching fraction of $O(10^{-4})$, necessary for the feasibility of $B$-mesogenesis, yields lower limits on the $B^{+}\to p\Psi$ branching fraction. We confront these limits with the most recent upper bounds obtained from BaBar and Belle/Belle II searches for the decays of $B^{+}$-meson into a proton and missing energy. The comparison indicates that experimental upper bounds on the branching fraction of $B\to p\Psi$ at the level of $10^{-8}-10^{-7}$ are needed for a decisive probe of this invisible mode of $B$ decays.

    hep-phPRD(2026)·2 citations
26. 26*

    The PYTHIA Facility

    Christian Bierlich🇸🇪 · Leif Lönnblad🇸🇪 · Torbjörn Sjöstrand🇸🇪

    The development and operation of large-scale particle physics facilities rely not only on accelerators and detectors, but also on sustained, high-precision simulation infrastructure. Originating in Lund in the late 1970s and continuously developed in Sweden for nearly five decades, PYTHIA has evolved into one of the most widely used Monte Carlo event generators in high-energy physics. Today it functions as a facility-scale software infrastructure underpinning the physics programmes of major international experiments, including those at the Large Hadron Collider, and plays a central role in validation, tuning, and uncertainty evaluation. In this article, we present PYTHIA as a Swedish contribution to big science facilities. We outline its historical development, analyze its contemporary user base through citation and text-based studies, and map its integration across experimental frameworks, generator ecosystems, validation infrastructures, and emerging machine-learning workflows. These analyses show that PYTHIA We discuss the operational model and sustainability challenges associated with maintaining long-lived research software at facility scale. As particle physics moves toward the High-Luminosity LHC era and future facilities such as the EIC and FCC, continued investment in robust, interoperable simulation infrastructure remains essential. We discuss the operational model and sustainability challenges associated with maintaining long-lived research software at facility scale. As particle physics moves toward the High-Luminosity LHC era and future facilities such as the EIC and FCC, continued investment in robust, interoperable simulation infrastructure remains essential.

    hep-phHyperfine Interact.(2026)·3 citations
27. 27*

    Exploring ${\tilde{R}}_2$ Leptoquarks and Majorana Neutrinos via same-sign dimuons at the HL-LHC

    Subham Saha🇮🇳 · Arvind Bhaskar🇮🇳 · Manimala Mitra🇮🇳

    We study the phenomenology of scalar leptoquark (sLQ) ${\tilde{R}}_2$ coupled to right-handed neutrinos (RHNs) at the High-Luminosity Large Hadron Collider (HL-LHC), focusing on signatures that depart from those targeted by conventional sLQ searches at the LHC. If sLQ is heavier than the RHN, for $\mathcal{O}(1)$ Yukawa, the decay of sLQ to RHN and jet can dominate, leading to distinctive final states that are only weakly constrained by existing analysis. We consider the same sign dimuon and multi-jet signature. This is particularly a unique and clean lepton-number violating signature, benefiting from low Standard Model backgrounds and directly sensitive to the Majorana nature of the RHN. A comprehensive analysis is performed by combining the sLQ pair and single production mechanisms at $\sqrt{s}=14\text{TeV}$, allowing us to assess the sensitivity reach of HL-LHC over a wide range of sLQ masses and Yukawa couplings. We demonstrate that pair production dominates the sensitivity at the TeV scale, while single production becomes increasingly important for multi-TeV sLQ masses, enabling the HL-LHC to probe regions of parameter space beyond the reach of current direct and indirect constraints. Our results highlight the strong complementarity between production modes and emphasize the unique capability of the HL-LHC to test sLQ scenarios involving RHNs. The framework presented here provides a well-motivated target for future experimental searches and offers a pathway toward simultaneously probing sLQ dynamics and parameter space of a Majorana RHN.

    hep-ph1 citation
28. 28*

    Effective degrees of freedom, trace anomaly and c-theorem like condition in the hadron resonance gas model

    Hiroaki Kouno🇯🇵 · Riki Oshima🇯🇵 · Kouji Kashiwa🇯🇵

    The relation between the effective degrees of freedom (EDOF) and the trace anomaly is studied in the hadron resonance gas (HRG) model. If we regard the thermodynamical relation as the evolution equation and define the EDOF as P/T^4, where P and T are the pressure and the temperature, respectively, we obtain the equation which relates to the trace anomaly. The structure of the equation resembles that of the so-called c-theorem, which asserts that the EDOF should not increase as the energy scale parameter decreases, in the two dimensional conformal field theory. There is a stationary point where the trace anomaly (modified trace anomaly) vanishes, and the scale symmetry is restored. To investigate the limiting temperature of the HRG model with the excluded volume effects, we consider two types of the c-theorem like conditions for the EDOF. The first condition requires that the EDOF should not decrease when T increases. This condition is equivalent to the condition that the trace anomaly (modified trace anomaly) should not be negative. The second condition requires that the EDOF should be convex downwards as a function of T. It is found that the first condition gives the limiting temperature of the HRG model with the excluded volume effect which is much higher than the crossover transition temperature obtained by the lattice QCD calculation and, at zero baryon number density, is close to the transition temperature in the pure gluonic theory, while the second one gives the limiting temperature which almost coincides with the one obtained by using the normalized baryon number fluctuation in the previous study and is consistent with the critical point predicted by the lattice QCD calculation.

    hep-phhep-exhep-latnucl-ex+10 citations
29. 29*

    Sensitivity to sub-GeV dark matter in forthcoming spallation-source neutrino experiments

    D. Aristizabal Sierra🇨🇱 · V. De Romeri🇪🇸 · D. K. Papoulias🇩🇪 · G. Sanchez Garcia🇲🇽

    Sub-GeV thermal dark matter weakly interacting with the Standard Model through vector-portal mediators provides a well-motivated and predictive framework that remains challenging to probe with conventional direct detection experiments. Motivated by the rapid development of neutrino facilities based on spallation neutron sources, we study the sensitivity of future coherent elastic neutrino-nucleus scattering experiments to light dark matter produced in neutral pion decays. We consider scalar dark matter interactions mediated by two different vector portals, a generic dark photon and a baryophilic vector mediator. The neutral pion yield is calculated through a GEANT4 simulation and the results are compared with those obtained with the Sandford-Wang parametrization. We show that predictions based on either approach do not produce significant differences. Our results demonstrate that upcoming low-threshold neutrino detectors at the European Spallation Source (ESS), the Japan Proton Accelerator Research Complex (J-PARC) and the China Spallation Neutron Source (CSNS) may test regions in parameter space not yet explored, or be competitive with existing bounds. We point out that these facilities will strengthen the global experimental program searching for secluded sectors.

    hep-phhep-exJHEP(2026)·3 citations
30. 30*

    One-point energy correlator for deep inelastic scattering at small $x$

    Zhong-Bo Kang🇺🇸 · Robert Kao🇺🇸 · Meijian Li🇪🇸 · Jani Penttala🇺🇸

    We derive the expressions for the one-point energy correlator (OPEC) in deep inelastic scattering in the high-energy (small-$x$) limit within the Color Glass Condensate framework. The OPEC is computed as a function of the angle between the energy flow and the target proton or nucleus, enabling a systematic exploration of different momentum scales in the scattering process. Owing to the momentum sum rule, the dependence on fragmentation functions cancels, leaving the dipole amplitude as the only nonperturbative input. As a result, the OPEC provides a clean and direct probe of gluon saturation dynamics at small $x$. We present numerical results for representative kinematic configurations relevant to the future Electron--Ion Collider, demonstrating sizable nuclear suppression effects and highlighting the sensitivity of this observable to saturation phenomena.

    hep-phhep-exnucl-exnucl-th7 citations
31. 31*

    Supernova $\nu$ flavour conversions in DUNE: the slow, the fast and the standard

    A. Giarnetti🇮🇹 · J. T. Penedo🇮🇹

    The flavour composition of a future supernova neutrino signal is expected to carry measurable imprints of flavour conversion processes in the dense stellar medium. In this work, we analyse the sensitivity of the upcoming Deep Underground Neutrino Experiment (DUNE) to three phenomenologically distinct effects: slow energy-dependent collective oscillations, fast energy-independent collective oscillations, and standard MSW conversions. By integrating GLoBES and MultiNest and using benchmark neutrino fluxes at emission, we assess the potential of DUNE to extract the underlying flux parameters and discriminate among conversion scenarios.

    hep-phJHEP(2026)·0 citations
32. 32*

    The Latent Information Geometry of Jet Classification

    Rebecca Maria Kuntz🇩🇪 · Tilman Plehn🇩🇪 · Björn Malte Schäfer🇩🇪 · Benedikt Schosser🇩🇪 · Sophia Vent🇩🇪

    Latent representations are an important theme in modern machine learning. Any network training with the notion of locality introduces a latent geometry which we can analyze with the help of differential geometry, specifically information geometry. We introduce the main concepts needed to analyze learned latent geometries, specifically curvature and nonmetricities, and show how they can be used for decoder and classifier geometries. We then apply our new methods to understand the physics behind binary quark-gluon classification and three-fold fat jet tagging.

    hep-ph3 citations
33. 33*

    New results on small-x resummation for splitting functions

    Marco Bonvini🇮🇹 · Stefano Frixione🇮🇹 · Giovanni Stagnitto🇮🇹

    We revisit the basic steps necessary to obtain next-to-leading-logarithmic accurate small-$x$ results for the DGLAP splitting functions, and their implementations within the HELL framework. We derive new analytical all-order results for the leading-logarithmic $gg$ anomalous dimension, the $qg$ and $gg$ finite Green functions, and most importantly for the $qg$ anomalous dimension, which allows us to arrive for the first time at a properly resummed $qg$ splitting kernel. We use these results as cornerstones of a new implementation of small-$x$ splitting-function resummation which is more solid and numerically better behaved with respect to those available thus far. All of these novelties are included in the upcoming 4.0 version of HELL.

    hep-phJHEP(2026)·3 citations
34. 34*

    Matter Unification and Lepton Flavour Violation

    Hridoy Debnath🇺🇸 · Pavel Fileviez Perez🇺🇸

    We explore the idea of quark-lepton unification at low energies. In particular, we discuss the minimal framework for matter unification at the multi-TeV scale, in which neutrino masses are necessarily generated via the inverse seesaw mechanism. To assess the testability of this theory for physics beyond the Standard Model, we analyze current experimental constraints and derive the corresponding lower bound on the symmetry breaking scale. We reexamine the impact of existing limits from lepton number violating meson decays, taking into account the freedom associated with unknown quark-lepton mixing angles. Furthermore, we study the correlation between bounds from meson decays and $\mu \to e$ conversion. We demonstrate that the upcoming $\mu \to e$ conversion experiment at Fermilab can play a crucial role in probing quark-lepton unification at the multi-TeV scale.

    hep-phhep-exhep-thPRD(2026)·1 citation
35. 35*

    Physics Opportunities with a Fixed-Target Program at the Electron-Ion Collider

    C.-J. Naïm🇺🇸 · A. Sorensen🇺🇸 · D. Brown🇺🇸 · D. Cebra🇺🇸 · R. Corliss🇺🇸 · J. M. Durham🇺🇸 · R. Vogt🇺🇸

    A fixed-target program at the Electron-Ion Collider (EIC) would broaden the facility's scientific reach by providing key measurements for studies of cold nuclear matter (CNM), the QCD phase diagram, and nuclear reactions relevant for space radiation. Constraining CNM effects is essential for interpreting observables in proton-nucleus ($p+A$) and nucleus-nucleus ($A+A$) collisions, yet these effects are poorly understood at low center-of-mass energies. In particular, the range $\sqrt{s}\approx 10$--20 GeV, where several CNM effects may compete at similar scales, has not been explored with high statistical precision. Mapping the QCD phase diagram similarly requires high-statistics $A+A$ data with broad rapidity and transverse-momentum coverage to probe the onset of deconfinement and the possible location of the QCD critical point (CP). Currently, such data are limited at 4.5 GeV $<\sqrt{s_{NN}}<7.7$ GeV A fixed-target program at the EIC would fill these gaps, providing CNM baselines and complementary data for QCD CP studies. By delivering high luminosity and systematic measurements across a broad range of nuclear targets, the program would link $p+A$ and $A+A$ systems at the same center-of-mass energies, enabling a unified, quantitative description of cold QCD matter and clarifying the interpretation of QGP signatures in $A+A$ collisions at low energies where comparable $p+A$ data are lacking. Finally, the program would offer a unique opportunity to measure nuclear cross sections critical for improving cosmic-ray models, including studies of space-radiation protection for both autonomous spacecraft and long-duration human spaceflight.

    ↳ nucl-exhep-exhep-phnucl-th1 citation
36. 36*

    Relativistic Effects in Femtoscopy and Deuteron Formation

    Stanislaw Mrowczynski🇵🇱

    For a long time studies of femtoscopic correlations have provided information about space-time characteristics of particle sources in high-energy collisions. Recently, the correlation functions have been also used to determine interaction parameters of correlated particles which is especially important for short-lived particles, for which scattering experiment are impossible. The abundance of experimental data and their high accuracy require an improved theoretical approach to femtoscopic correlations. We discuss relativistic effects and their role in detail. Since a general relativistic approach is currently unavailable, due to serious theoretical difficulties, the correlation functions must be computed in the center-of-mass frame where the correlated particles are mostly nonrelativistic. This requires transforming the source function to this frame, the consequences of which we discuss. Since the deutron formation has a similar physical origin to femtoscopic correlations, we also discuss relativistic effects in the former process. We illustrate our considerations with calculations of some correlation functions and the deuteron coalescence coefficient to demonstrate a magnitude of relativistic effects. We also argue that a discrepancy between the coalescence coefficient computed with the source radii inferred from the baryon-baryon correlation functions and the experimental data can be removed by taking into account the relativistic elongation of the source radius in the center of mass of correlated particles.

    ↳ nucl-thhep-phnucl-exPRC(2026)·0 citations
37. 37*

    Yukawa Textures with Enhanced Symmetries in Heterotic Calabi-Yau Compactifications

    Jun Dong🇯🇵 · Tatsuo Kobayashi🇯🇵 · Shuhei Miyamoto🇯🇵 · Hajime Otsuka🇯🇵

    We clarify the structure of Yukawa couplings and mass matrices for matter fields in heterotic string theory on smooth Calabi-Yau threefolds with standard embedding. The topological structure of Calabi-Yau threefolds leads to interesting Yukawa textures that cannot be derived from group-theoretical symmetries, e.g., the so-called Weinberg texture in the case of two generations of matter fields. Furthermore, we find that a $U(2)$ flavor symmetry, which plays an important role in controlling higher-dimensional operators in the Standard Model effective field theory, emerges at specific loci in the moduli space of multi-Higgs fields. Small perturbations around these loci generate semi-realistic patterns of quark masses and mixings.

    ↳ hep-thhep-phJHEP(2026)·3 citations
38. 38*

    New axion bounds derived from the 100-parsec Gaia DR3 white dwarf luminosity function

    Martín L. Alberino🇦🇷 · Marcelo M. Miller Bertolami🇦🇷 · María E. Camisassa🇪🇸 · Andrea Caputo🇨🇭 · Santiago Torres🇪🇸

    The axion, a well-motivated hypothetical particle arising in extensions of the Standard Model, can be produced copiously within the hot, compact cores of white dwarf stars. The shape of the white dwarf luminosity function (WDLF) is a powerful tool for constraining theoretical particles that would imply an additional cooling channel in white dwarfs. In this work, and for the first time, we use the 100-parsec Gaia DR3 white dwarf sample and compare it with theoretical predictions. We have simulated synthetic populations of white dwarfs using a population synthesis code based on Monte Carlo techniques, incorporating realistic observational errors, and based on state-of-the-art white dwarf models that incorporate the anomalous cooling caused by the presence of axions. Axion bremsstrahlung emission rates were implemented using the latest theoretical calculations. We find that, for the brightest white dwarfs in the sample ($M_{\mathrm{Bol}}<10$), the ${\chi }^2$ statistic is largely insensitive to the assumed stellar formation rate (SFR), which is typically the dominant uncertainty in modeling the Galactic-disk WDLF. The resulting ${\chi }^2$ analysis disfavors a sizable additional cooling contribution. This conclusion contrasts with earlier studies in which axion-electron couplings in the range $0.7\times 10^{-13}<g_{ae}<2.1\times 10^{-13}$ provided mildly improved fits to the Galactic-disk WDLF. We attribute the discrepancy to simplifying assumptions in previous modeling and to the substantially improved observational quality of the 100-pc Gaia DR3 sample. We obtain the upper limit $g_{ae}<1.68\times 10^{-13}$ ($95\%$ C.L.), which is among the strongest available.

    ↳ astro-ph.SRastro-ph.HEhep-ph5 citations
39. 39*

    QCD phase transition at finite isospin density and magnetic field

    Chujun Ke🇨🇳 · Gaoqing Cao🇨🇳

    The QCD phase transition is explored at finite isospin density and magnetic field within the extended two-flavor Nambu--Jona-Lasinio model. By adopting the Ginzburg-Landau approximation, we study the transitions from normal chiral symmetry breaking phase to pion superfluidity or rho superconductivity. To avoid the artificial divergence for a large isospin chemical potential, we adopt the Landau representation rather than the proper-time one for the fermion propagators in a constant magnetic field. For the Landau representation, the same cutoff to the Landau energies, rather than to Landau levels, should be adopted to regularize the divergences from the summations over Landau levels. Then, the Ginzburg-Landau coefficients for pion and rho mesons are worked out both analytically and numerically in random phase approximation. The results show that pion superfluidity is favored for a small magnetic field while rho superconductivity is favored for a large magnetic field when increasing isospin chemical potential, in line with the magnetic enhancement (deduction) of the lowest energy of ${\pi }^{+}({\rho }^{+})$ meson. The novel rho superconductivity phase at large magnetic field and finite isospin density implies an interesting and nontrivial interplay between QCD and QED.

    ↳ nucl-thhep-ph1 citation
40. 40*

    Midterm Status Report of the ILC Technology Network Activities

    ILC Technology Network

    The ILC Technology Network (ITN) was established in 2022 by the ILC International Development Team, a subcommittee of the International Committee for Future Accelerators, to advance engineering studies toward the realisation of the International Linear Collider (ILC). While the ITN work packages focus on engineering activities for the ILC, their topics are also relevant to a broad range of accelerator applications in particle physics and beyond. These work packages are being carried out now by laboratories in Asia and Europe in close collaboration. This report summarises the current status of the ITN activities.

    ↳ physics.acc-phhep-exhep-ph0 citations
41. 41*

    Naturalness and Fisher Information

    James Halverson🇺🇸 · Thomas R. Harvey🇺🇸 · Michael Nee🇺🇸

    Fine-tuning and naturalness, the sensitivity of low-energy observables to small changes in the fundamental parameters of a theory, are cornerstones of physics beyond the Standard Model. We propose a new measure of fine-tuning based on information theory. To each point in parameter space we associate a probability distribution over observables. Divergence measures encode the sensitivity of observables to model parameters and determine a Riemannian metric on parameter space. By Chentsov's theorem, the physically motivated metric is the Fisher information metric, up to scaling. We propose a rescaled fine-tuning matrix ${\mathcal{F}}_{ij}$ derived from the Fisher information matrix, whose non-zero eigenvalues serve as our measure of fine-tuning. When the number of observables exceeds the number of parameters, ${\mathcal{F}}_{ij}$ admits a natural geometric interpretation as the pullback of the Euclidean metric from observable space to the submanifold of admissible predictions, with large eigenvalues corresponding to highly stretched directions and indicative of fine-tuning. Our measure reproduces the familiar Barbieri--Giudice criterion as a special case, while generalising it to multiple correlated parameters. We illustrate its behaviour on dimensional transmutation, the Wilson--Fisher fixed point, a simple model of the hierarchy problem, and the electron Yukawa coupling, finding agreement with physical intuition in each case.

    ↳ hep-thhep-exhep-ph2 citations
42. 42*

    Modified Teukolsky formalism: Null testing and numerical benchmarking

    Fawzi Aly🇺🇸 · Mahmoud A. Mansour🇯🇵 · Luis Lehner🇨🇦 · Dejan Stojkovic🇺🇸 · Dongjun Li🇺🇸 · Pratik Wagle🇩🇪

    Next-generation gravitational-wave detectors will make black-hole ringdown an increasingly sensitive probe of small departures from General Relativity in the strong-field regime. This motivates obtaining high-precision predictions of gravitational effective field theory, as spectral shifts can be quite small. Here we perform a focused stress test of the modified-Teukolsky framework by designing two null diagnostics. First, we consider an action with redundant operators that must produce zero first-order vacuum QNM shifts. Second, we exploit a Ricci-flat identity relating two physical cubic Riemann to test such a relation is satisfied by the ringdown spectra obtained. We compute the shifts using two independent numerical approaches: the eigenvalue-perturbation and generalized continued-fraction (Leaver-type) methods. Both null tests are passed across multiple multipoles and overtones, and the control-operator results agree in magnitude with the benchmark values reported in Ref. [1]. These validations support using the framework for obtaining accurate predictions for robust strong-field tests, with straightforward extensions to rotating backgrounds and coupling with matter fields.

    ↳ gr-qcastro-ph.HEhep-phhep-th+2PRD(2026)·6 citations
43. 43*

    Auxiliary counterterms and their role in effective field theory

    Manuel Pavon Valderrama🇨🇳

    Effective field theories include contact-range interactions (or counterterms) for two reasons: representing the unknown short-range physics in a model independent manner and ensuring the cutoff independence of observables. Both are intertwined: cutoff independence alone (modulo truncation errors) already generates counterterms encoding physical information not present in the known long-range physics. Yet, there is also residual cutoff dependence, which is smaller than the uncertainties that are achievable within the effective field theory description and thus can be safely neglected in most settings. If one insists on exact cutoff independence though, new counterterms will be required, but they encode no new physical information and are thus what one could call redundant, or auxiliary, counterterms. It happens that auxiliary counterterms are still useful for solving certain inconsistencies that appear during renormalization or for improving the convergence of the effective field theory expansion. Examples of these use cases are discussed, including the interpretation of the improved actions or the relation between perturbative and non-perturbative renormalization.

    ↳ nucl-thhep-phEPJA(2026)·2 citations
44. 44*

    From strong interactions to Dark Matter: the non-perturbative QCD sphaleron rate

    Claudio Bonanno🇪🇸

    Acceptance plenary talk for the 2025 Kenneth G.~Wilson Award for Excellence in Lattice Field Theory: For significant contributions to the understanding of topology in QCD, QCD-like, and large-$N_c$ gauge theories, including algorithmic developments to reduce topological freezing, studies of Dirac spectral properties, and axion phenomenology.

    ↳ hep-lathep-phhep-thPoS(2026)·0 citations
45. 45*

    Meson spectrum and low-energy constants in large-$N$ QCD

    Claudio Bonanno🇪🇸 · Margarita García Pérez🇪🇸 · Antonio González-Arroyo🇪🇸 · Ken-Ichi Ishikawa🇯🇵 · Masanori Okawa🇯🇵

    We present new non-perturbative results about the meson spectrum and the low-energy constants of QCD in the 't Hooft large-$N$ limit, $N\to \infty$ with $N_{\mathrm{f}}/N\to 0$. These are obtained from lattice Monte Carlo simulations of the Twisted Eguchi-Kawai (TEK) model up to $N=841$. More precisely, we will discuss: our findings for the meson mass spectrum; the determination of the radial Regge trajectories in the $\pi$ and $\rho$ channels; the computation of the coefficients of the $1/N$ expansion of the chiral condensate, of the pion decay constant, and of the next-to-leading-order coupling ${\bar{\ell }}_4$, up to $\mathcal{O}(1/N^3)$ from the combination of TEK and standard finite-$N$ results.

    ↳ hep-lathep-phhep-thPoS(2026)·1 citation
46. 46*

    Spatially inhomogeneous confinement-deconfinement phase transition in accelerated gluodynamics

    Victor V. Braguta🇷🇺 · Vladimir A. Goy🇷🇺 · Jayanta Dey🇷🇺 · Artem A. Roenko🇷🇺

    This study explores confinement-deconfinement transition properties of SU($3$) Yang--Mills theory under weak accelerations at finite temperatures, using first-principles lattice simulations. The system is formulated in the Rindler spacetime, and the properties are studied from the perspective of a co-accelerating observer situated at the center of the lattice. We found that spatially separated confinement and deconfinement phases can coexist in the Rindler spacetime within certain intervals of temperature and acceleration. The position of the boundary between the phases is calculated as a function of temperature for several accelerations, and it is in accordance with the TE prediction, although a small deviation is observed. Moreover, in the weak acceleration regime, the critical temperature of the system is found to coincide with that of non-accelerated gluodynamics.

    ↳ hep-latgr-qchep-phhep-th+1PoS(2026)·1 citation
47. 47*

    Recent developments and applications of the relativistic chiral nuclear force

    Li-Sheng Geng🇨🇳 · Jun-Xu Lu🇨🇳 · Qing-Yu Zhai🇨🇳 · Zhi-Wei Liu🇨🇳 · Shihang Shen🇨🇳

    The nuclear force is central to our understanding of complex nuclear phenomena and to the applications of nuclear techniques. The nonperturbative nature of the low-energy strong interaction and the color confinement have made an ab initio understanding of the nuclear force a challenge for almost a century since the pioneering work of Yukawa. Since 1990, chiral effective field theory (ChEFT) has become the de facto standard for describing nuclear interactions--most prior studies employed heavy-baryon chiral perturbation theory. Only recently, there have been successful attempts to construct a chiral nuclear force employing covariant baryon chiral perturbation theory. In this work, we review recent developments and applications of relativistic chiral nuclear forces. We first elaborate on the necessity of relativistic/covariant theories, then present the construction of the first high-precision relativistic chiral nuclear force up to next-to-next-to-leading order (NNLO), and discuss the ongoing progress in higher-order nucleon-nucleon (NN) and $nd$ scattering, as well as their applications in nuclear matter, finite nuclei, and hypernuclear systems. Finally, we summarize the achievements and outline the future outlook of this research field.

    ↳ nucl-thhep-phnucl-exParticles(2026)·1 citation
48. 48*

    Cancellation of loop corrections to soft scalar power spectrum

    Yohei Ema🇺🇸 · Muzi Hong🇯🇵 · Ryusuke Jinno🇯🇵 · Kyohei Mukaida🇯🇵

    We prove the absence of scale-invariant one-loop corrections to the superhorizon curvature perturbations from small-scale (potentially enhanced) scalar perturbations in a general inflationary setup, including the transient ultra-slow-roll scenario. We demonstrate this by analyzing the symmetry structure of an in-in effective field theory for the soft curvature perturbations, and by explicitly performing one-loop calculations, integrating out hard modes in the soft limit of external momenta. The dilatation symmetry, respected by a counter term necessary for the tadpole cancellation, guarantees the cancellation of scale-invariant corrections.

    ↳ astro-ph.COhep-phhep-th6 citations
49. 49*

    $P$--$V$ criticality, Joule--Thomson expansion, and holographic heat engine of charged Hayward-AdS black holes with a cloud of strings and perfect fluid dark matter

    Ahmad Al-Badawi🇯🇴 · Faizuddin Ahmed🇮🇳 · İzzet Sakallı🇹🇷

    We construct the charged Hayward-anti-de Sitter (AdS) black hole (BH) with a cloud of strings (CS) and perfect fluid dark matter (PFDM), and analyze its extended thermodynamic phase structure. The Hayward parameter $g$ replaces the central singularity with a de Sitter (dS) core, while the CS parameter $a$ and the PFDM parameter $\beta$ encode astrophysically motivated matter content. Treating the cosmological constant as pressure, we derive the thermodynamic quantities, verify the Smarr relation, and establish $P$--$V$ criticality with a van der Waals (vdW)-like small-large BH phase transition and mean-field critical exponents. The Gibbs free energy (GFE) exhibits the characteristic swallowtail below the critical pressure. The Joule-Thomson (JT) expansion yields $T_i^{\min }/T_c\approx 0.247$, roughly half the Reissner--Nordström-AdS value. The parameters $g$ and $Q$ contract the cooling region, $\beta$ expands it, and $a$ reshapes it non-monotonically. A holographic heat engine with a rectangular cycle gives efficiencies $\eta =0.362$--$0.396$ and Carnot benchmarking ratios $\eta /{\eta }_C=0.625$--$0.791$ across six configurations. The CS parameter improves the engine efficiency by reducing the enthalpy at fixed thermodynamic volume, while the PFDM parameter degrades it by adding gravitational enthalpy without contributing to the mechanical work.

    ↳ gr-qchep-phhep-th1 citation
50. 50*

    Spin hydrodynamics on a hyperbolic expanding background

    Rajeev Singh🇷🇴 · Alexander Soloviev🇸🇮

    We study relativistic spin hydrodynamics on the hyperbolic $\kappa =-1$ flow background recently identified by Grozdanov. This background corresponds to an $SO(2,1)$-invariant, transversely expanding solution with finite spacetime support in Minkowski space, in contrast to the well-known Gubser flow $(\kappa =+1)$ which possesses $SO(3)$ symmetry and infinite transverse extent. Working within the formulation of perfect-fluid spin hydrodynamics, we derive the exact evolution equations for all spin components of the spin potential on the $\kappa =-1$ background. We find that the enhanced early-time expansion rate and the presence of a causal edge lead to a stronger localization of spin dynamics compared to the Gubser case. Remarkably, the azimuthal component of the spin potential oscillates as it decays in the forward lightcone, in stark contrast to the Gubser flow. Thus, our results establish the $\kappa =-1$ flow as a distinct and physically meaningful benchmark for studying spin dynamics in expanding relativistic fluids with finite spacetime support.

    ↳ nucl-thhep-phhep-th4 citations
51. 51*

    Isocurvature Constraints on Dark Matter from Evaporated Primordial Black Holes

    G. Franciolini🇮🇹 · D. Racco🇨🇭

    We revisit the scenario in which stable particles of a dark sector are produced through the complete evaporation of light primordial black holes (PBHs) formed in the early Universe. We investigate in detail the role of isocurvature perturbations that may arise in this framework. PBHs inherit Poisson fluctuations on unobservable small scales at formation; however, in the presence of primordial non-Gaussianity that couples long- and short-wavelength modes, these fluctuations can source isocurvature perturbations on cosmological scales. Such perturbations are unavoidably transferred to the dark sector particles emitted via Hawking evaporation. We highlight the potential impact of isocurvature constraints on dark sector particles produced through PBH evaporation. Along the way, we re-assess the constraints on this scenario arising from the overproduction of dark matter (DM), accounting for both PBH evaporation and gravitational production (freeze-in) during (after) inflation, as well as bounds from warm DM and the overproduction of scalar-induced gravitational waves.

    ↳ astro-ph.COgr-qchep-phPRD(2026)·10 citations

* 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.