Fri·May 22, 2026Friday·May 22, 2026

1. 01*

   The Higgs-top-$Z$ mass coincidence relation after NNLO matching

   E. Torrente-Lujan🇪🇸

   The relation $M_H^2\simeq M_Z{M}_t$, previously proposed as a non-trivial Higgs mass coincidence, is reconsidered with present electroweak inputs and with a scheme-consistent matching analysis. With the 2025 PDG values for $M_Z$, $M_W$ and $M_H$, and the ATLAS-CMS direct top-mass combination, the pole-level ratio is ${\rho }_{Zt}=M_Z{M}_t/M_H^2=1.00362\pm 0.00261$. Thus an exact pole-level geometric relation predicts either $M_H=125.426\pm 0.120\mathrm{GeV}$ or $M_t=171.898\pm 0.302\mathrm{GeV}$, which is still a $1.4\sigma$ test rather than an exclusion. By contrast, the companion arithmetic relation gives ${\rho }_{Wt}=(M_W+M_t)/(2M_H)=1.00994\pm 0.00159$ and is not a viable exact mass sum rule. We then evaluate the complete NNLO weak-scale $\overline{\mathrm{MS}}$ matching formulae at $\mu =M_t$. In the standard convention one obtains ${\hat{\rho }}_{Zt}(M_t)=\sqrt{g_2^2+g_Y^2}{y}_t/(4\sqrt{2}\lambda )=0.96714\pm 0.00361$. Consequently, the exact running-coupling boundary condition $\lambda =g_Z{y}_t/(4\sqrt{2})$ at the top scale would predict $M_H=123.19\pm 0.20\mathrm{GeV}$, or equivalently $M_t=177.81\pm 0.50\mathrm{GeV}$ when $M_H$ is held fixed. This is incompatible with the measured point. A possible symmetry explanation must therefore act on pole-level threshold quantities, or provide a finite matching factor ${\kappa }_{\mathrm{th}}=1.0340\pm 0.0039$ at the electroweak scale. We formulate this requirement as a target for custodial/top-Higgs or triality-like symmetry extensions.

   hep-phhep-exhep-th0 citations
2. 02*

   Deep Neural Networks for Heavy Lepton-Flavor-Violating Higgs Searches at the LHC

   Akmal Ferdiyan🇮🇩 · Reinard Primulando🇮🇩 · Fiki Taufik Akbar🇮🇩 · Bobby Eka Gunara🇮🇩

   We study lepton-flavor-violating (LFV) decays of a heavy Higgs boson, $H\to \mu \tau$, in the Type-III two-Higgs-doublet model by recasting the CMS search at $\sqrt{s}=13$ TeV with 35.9 fb${}^{-1}$ using fast detector simulation in the mass range 200-450 GeV. We develop a deep neural network (DNN) classifier trained on final-state kinematic variables that, with mass-dependent threshold optimization, reduces the expected 95% CL upper limits on the signal cross section by 42-46% in the 0-jet channel and 36-40% in the 1-jet channel relative to the standard collinear mass ($M_{\mathrm{col}}$) baseline. We apply SHAP interpretability analysis to identify the visible mass $m_{\mathrm{vis}}$ as one of the dominant discriminating feature, reflecting the characteristic neutrino momentum fraction of the $\tau$ decay. We show that supplementing the $M_{\mathrm{col}}$ analysis with a simplified mass-dependent pre-selection, $m_{\mathrm{vis}}<f\cdot m_H$ with $f=0.7$ (0-jet) and $f=0.8$ (1-jet), consistently improves the sensitivity over the $M_{\mathrm{col}}$-only baseline without requiring multivariate infrastructure. In addition, a DNN regression model trained to predict the ratio $m_H/M_{\mathrm{col}}$ corrects the systematic prediction bias inherent in the collinear approximation, maintaining an absolute mass prediction error below 1 GeV for signals up to 400 GeV and improving the mass resolution by 12% (0-jet) and 21% (1-jet) at $m_H=450$ GeV. These results demonstrate a clear path toward significantly enhanced sensitivity in LFV Higgs searches at the LHC.

   hep-ph0 citations
3. 03*

   Semileptonic sum rules in heavy-to-light charm decays

   Motoi Endo🇯🇵 · Syuhei Iguro🇯🇵 · Satoshi Mishima🇯🇵 · Takeru Uchiyama🇯🇵 · Ryoutaro Watanabe🇨🇳

   We investigate semileptonic sum rules in heavy-to-light charm decays, motivated by analogous relations in $b\to c$ and $b\to u$ transitions. Focusing on the $c\to d\overline{\ell }\nu$ decays, $D\to \pi \overline{\ell }\nu$, $D\to \rho \overline{\ell }\nu$, and ${\Lambda }_c\to n\overline{\ell }\nu$, we examine a relation among their lepton-flavor universality ratios $R_H^{\mu e}$. Although the charm sum rule is less precise than the relations in bottom-hadron decays, current low-energy and high-$p_T$ constraints on new physics restrict the actual deviation from the relation to below the percent level. The relation can therefore provide a useful consistency check of charm semileptonic measurements. As an application, we derive a prediction for the yet-unmeasured ratio $R_n^{\mu e}$ in ${\Lambda }_c\to n\overline{\ell }\nu$.

   hep-phhep-ex0 citations
4. 04*

   Symmetry Breaking as Quantum Gate: Entropy and Weak Mixing Angle

   Qing-Hong Cao🇨🇳 · Yandong Liu🇨🇳 · Haotian Qi🇨🇳 · Hao Zhang🇨🇳 · Haoran Zhao🇨🇳

   We establish a correspondence between two independent entropic probes -- the variation of Rényi mutual information (RMI) across the electroweak symmetry breaking (EWSB) transition and the stabilizer Rényi entropy (SRE) -- in tree-level $2\to 2$ elastic scatterings. After angular averaging, the RMI (helicity basis) and the SRE (fixed beam basis) exhibit identical dependence on ${\sin }^2{\theta }_W$ within each neutral-current channel. We trace this correspondence to a common physical origin that it's the Yukawa mass insertion acts as a $-\mathrm{i}Y$ quantum gate in chirality space. Minimizing entropies across all processes yields ${\sin }^2{\theta }_W$ values matching purely axial vector-like couplings in $Z$ boson exchanged channel.

   hep-phhep-thquant-ph6 citations
5. 05*

   $b\to c\bar{u}q$ decay and CP violating observables in the presence of new physics contributions

   Xuanning Guo🇨🇳 · Albertus Hariwangsa Panuluh🇯🇵 · Hiroyuki Umeeda🇨🇳 · Jinglong Zhu🇨🇳

   In this work, a comprehensive analysis for processes related to $b\to c\bar{u}q(q=d,s)$ transitions are carried out, including new physics contributions. In light of a recent tension between branching fractions for $B_{(s)}\to D_{(s)}^{(\ast )}M$ ($M$ represents a meson) decays in the QCD factorization approach and relevant experimental results, phenomenological constraints on complex-valued Wilson coeffients are discussed. Analyzed observables contain direct CP asymmetry ($A_{\text{CP}}$) in $B^{-}\to D^0{\pi }^{-}$ decays and $\gamma /{\varphi }_3$, one of the angles in the unitarity triangle, combined with others from ${\tau }_{B^{+}}/{\tau }_{B_d}$, $\Delta {\Gamma }_q/{\Gamma }_q$, and $A_{\mathrm{SL}}^q(q=d,s)$. We constrain the complex Wilson coefficients at $1\sigma$ and $2\sigma$ levels under color-singlet and color-rearranged scenarios. These constraints yield correlated predictions for $\Delta {\Gamma }_d/{\Gamma }_d$, $A_{\mathrm{SL}}^d$ and $A_{\text{CP}}$.

   hep-phhep-ex0 citations
6. 06*

   MAcNLOPS for ZZ Pair Production at the LHC

   Yuxiao Che🇸🇪 · Rikkert Frederix🇸🇪

   We present an implementation of the MAcNLOPS matching prescription for $pp\to ZZ$ production in a MadGraph5_aMC@NLO + Pythia8 setup. Starting from a standard MC@NLO event sample, negative H events are removed and compensated by a veto applied to the first shower emission of the S events. The implementation is validated against MC@NLO for radiation-sensitive and inclusive diboson observables. Agreement is found up to a rather small power-suppressed contribution affecting the very low-pT region. The method removes all negative H weights with negligible additional computational cost, while negative S weights are left unchanged, showing that MAcNLOPS is a promising alternative to MC@NLO with a reduced fraction of negative weights.

   hep-phEPJC(2026)·0 citations
7. 07*

   Equation of State at High Baryon Densities from a Thermodynamically Informed Neural Network

   Musfer Adzhymambetov🇺🇦

   We present a four-dimensional equation of state for strongly interacting matter at finite temperature and conserved charge densities, constructed using a deep neural network. It is designed for direct use in hybrid models of relativistic heavy-ion collisions: it reproduces hadron resonance gas thermodynamics at typical particlization scales, is consistent with lattice QCD at low baryon chemical potential, and extrapolates into the high-density region inaccessible to either approach, which is precisely the regime targeted by RHIC BES, FAIR, HADES, and CBM. Thermodynamic consistency throughout the full phase space is enforced via a physics-informed loss function. We demonstrate the developed equation of state by implementing it at zero net strangeness and fixed electric-to-baryon charge ratio within the integrated hydrokinetic model.

   hep-phnucl-th0 citations
8. 08*

   Probing freeze-in dark matter using Bose-Einstein condensate in neutron star

   Deep Ghosh🇮🇳 · Anirban Das🇮🇳

   Neutron star (NS) is one of the most promising astrophysical targets to probe non-gravitational interaction of dark matter (DM) with visible matter. Their compactness makes them an ideal object which can capture particle DM efficiently over its lifetime using the DM-nucleon scattering cross-section. If DM particles are bosonic, then the captured DM population may form a Bose-Einstein condensate at the center of the NS, increasing the DM density significantly. In this work, we study the phenomenology of such scenario with enhanced DM annihilation rate due to the increased density in a condensate. The enhanced DM annihilation makes the NS surface `hotter' than in the standard cooling scenario. We show that the annihilation rate is enhanced by a factor of $\mathcal{O}(10^{15}-10^{20})$ if DM forms a condensate, and DM with freeze-in value annihilation cross-section can heat up the NS to higher temperatures, bringing it within the reach of James Webb Space Telescope. It also allows us to probe DM-nucleon scattering cross section within the neutrino fog regime which will complement the terrestrial direct detection searches. Moreover, the enhanced annihilation from the condensate changes the lower limits on s-wave DM annihilation cross-section for capture-annihilation equilibrium and the formation of a black hole inside the NS. Finally, we show an example of a scalar DM model where such small annihilation and DM-nucleon scattering cross sections can generically arise.

   hep-phastro-ph.COastro-ph.HE1 citation
9. 09*

   Symbolic Classification-Enabled LHC Limits Online BSM Global Fits

   Shehu AbdusSalam🇮🇷

   Global fits of Beyond the Standard Model (BSM) physics often involve a two-way interplay between theory and experiment. Theoretical models provide guidance for experimental searches, while experimental results, in turn, constrain theoretical frameworks. A crucial aspect of this feedback loop is the direct inclusion of measurements and exclusion limits ``online'' global fits, i.e. during the parameter scans aspects of the global fits. However, incorporating the Large Hadron Collider (LHC) limits into such analyses has been computationally prohibitive, often due to time taken per parameter point exceeding the scales acceptable for global fit frameworks. In this study, we show that LHC limits can be incorporated ``online'' global fits by leveraging approximations derived from symbolic regression techniques. We utilize a dataset of ATLAS constraints from searches for electroweakino productions to derive a mathematical expression capable of classifying the phenomenological Minimal Supersymmetric Standard Model (pMSSM) parameter space as allowed or excluded. This is subsequently incorporated for making a global fit of the pMSSM to data, including the LHC Run-2 limits.

   hep-phcs.LGcs.SChep-ex+10 citations
10. 10*

    Pseudo-Nambu-Goldstone inflation with $Z_N$ symmetric waterfall fields

    Hyun Min Lee🇰🇷 · Adriana G. Menkara🇩🇪

    We propose a hybrid inflation model where a pseudo-Nambu-Goldstone boson inflaton couples to $N$ waterfall scalar fields respecting a $Z_N$ symmetry. We identify the phases for the inflation and the consequent waterfall transition, concretely, in $Z_2$, $Z_3$ and $Z_4$ cases. From the Coleman-Weinberg potential for the inflaton, we show that the quadratically divergent corrections coming from the waterfall sector are cancelled due to the $Z_N$ symmetry, while the logarithmically divergent corrections are absent only for $N>2$, ensuring the radiative stability of the inflaton potential. We show the parameter space for a successful inflation with the loop-corrected inflaton potential in each model and compare the results between different discrete symmetries. We further analyze the vacuum structure of the models and the reheating process due to the $Z_N$-invariant Higgs-portal couplings for the waterfall fields. We find that the reheating temperature can be smaller than the mass of the waterfall field condensate such that the $Z_N$ symmetry is not restored after reheating and there is no domain wall problem in the models. We also comment on the possibility of multi-component dark matter from the $Z_N$ partners of the waterfall field condensate.

    hep-phhep-th0 citations
11. 11*

    Two photon decay width of the fully charmed tetraquarks: revisiting prospects for ultraperipheral collisions

    Longjie Chen🇵🇱 · Wolfgang Schäfer🇵🇱 · Antoni Szczurek🇵🇱

    We discuss the role of fully heavy tetraquarks in ultraperipheral collisions $AA\to AAJ/\psi J/\psi$ and $AA\to AA\gamma \gamma$. Two-photon couplings to scalar and tensor tetraquarks are considered. We use relatively recent results of four-body calculation of fully heavy tetraquark wave function within the extended relativized quark model. The corresponding radiative decay widths for different tetraquark states are evaluated using NRQCD factorisation, with LDMEs extracted from the four-body wave functions at the origin. The results are collected in tables. The cross sections for production of pairs of $J/\psi$ mesons and diphotons in UPC of ${}^{208}Pb+{}^{208}Pb$ collisions are presented. While the couplings for $T_{4c}\left(0^{++},2^{++}\right)\to \gamma \gamma$ are calculated based on the model wave functions, simplified couplings are used for $T_{4c}\left(0^{++},2^{++}\right)\to J/\psi J/\psi$. When calculating the energy dependence of the resonant $\gamma \gamma \to J/\psi J/\psi$ and $\gamma \gamma \to \gamma \gamma$ cross section, we employ the total decay widths measured at ${\Gamma }_{\mathrm{tot}}=0.446\mathrm{GeV}$ for $X(6600)$ while ${\Gamma }_{\mathrm{tot}}=0.135\mathrm{GeV}$ for $X(6900)$ in latest CMS data. The resonant terms are compared with continuum contributions for both considered channels. While for the $J/\psi J/\psi$ channel the resonant contributions are larger than continuum ones, for the $\gamma \gamma$ channels the situation is reversed. The latter result is in clear disagreement with the result obtained from the näive use of vector dominance picture.

    hep-ph2 citations
12. 12*

    Emergent Neutrino Texture Geometry from Dark Matter and Lepton Flavor Violation in the Scotogenic Model

    Avinanda Chaudhuri🇮🇳

    We investigate the emergence of approximate neutrino texture structures in the minimal scotogenic model through large-scale Casas--Ibarra parameter scans subject to lepton flavor violation and dark matter constraints. We demonstrate that approximate suppressions can dynamically emerge from phenomenological consistency conditions. The interplay between relic density requirements, radiative neutrino mass generation, and lepton flavor violating observables induces a nontrivial flavor geometry in parameter space. Particular suppressions in the $(e\mu )$ and $(e\tau )$ sectors arise naturally, while diagonal entries strongly resist cancellation. We further compare normal and inverted mass hierarchies, analyze reduced versus full Casas--Ibarra geometries, and identify approximate scaling relations linking dark matter and flavor observables. Our results suggest that emergent flavor structures may represent dynamical consequences of radiative neutrino mass generation rather than externally imposed flavor symmetries.

    hep-ph0 citations
13. 13*

    Rare kaon decays $K^{-}\to {\ell }^{-}{\bar{\nu }}_{\ell }{\ell }^{\prime +}{\ell }^{\prime -}$: Standard Model predictions from lattice QCD

    R. Di Palma🇮🇹 · R. Frezzotti🇮🇹 · G. Gagliardi🇮🇹 · V. Lubicz🇮🇹 · G. Martinelli🇮🇹 · C.T. Sachrajda🇬🇧 · F. Sanfilippo🇮🇹 · S. Simula🇮🇹 · N. Tantalo🇮🇹

    Weak decays of charged kaons with an additional lepton-antilepton pair, $K^{-}\to {\ell }^{-}{\bar{\nu }}_{\ell }{\ell }^{\prime +}{\ell }^{\prime -}$ ($K_{\ell 2{\ell }^{\prime }}$), are suppressed at order $O(G_F^2{\alpha }_{\mathrm{em}}^2)$ in the Standard Model (SM) and provide sensitive probes of its flavour structure, as well as independent determinations of the Cabibbo angle $|V_{us}|$. In this Letter we present the SM predictions for all four channels with $\ell ,{\ell }^{\prime }=e,\mu$, based on the first complete lattice QCD calculation of the structure-dependent form factors reported in a companion paper [1]. Using the PDG value [2] $|V_{us}{|}^{\mathrm{PDG}}=0.22431(85)$, we obtain branching fractions with controlled uncertainties and precisions ranging from $2\%$ to $7\%$, depending on the channel. For the three modes with published measurements, our results agree with experiment. For the $K_{\mu 2\mu }$ mode, for which no published experimental result is available, we compare our prediction with the preliminary NA62 result, finding agreement at the $1.4\sigma$ level. Conversely, the measured decay rates can be used together with our results to extract $|V_{us}|$ from these modes. A weighted average over the two most precise channels, $K_{\mu 2e}$ and $K_{\mu 2\mu }$, yields $|V_{us}|=0.2283(42)$, corresponding to a $1.8\%$ determination. These results pave the way for using $K_{\ell 2{\ell }^{\prime }}$ decays as precision probes of the SM.

    hep-phhep-lat1 citation
14. 14*

    Scale-Invariant Open Quantum Systems

    Carlos Argüelles🇺🇸 · Gabriela Barenboim🇪🇸 · Gonzalo Herrera🇺🇸 · Tanvi Krishnan🇺🇸 · Héctor Sanchis🇪🇸

    We develop a complete theoretical framework for open quantum systems coupled to scale-invariant environments. We show that such environments are universally described by unparticle baths characterized by a single scaling dimension $d_{\mathcal{U}}$. This work provides the proof of the uniqueness theorem, the formalism of the resulting non-Markovian dynamics, and applications to several physical systems. From the uniqueness theorem, we derive the non-Markovian memory kernels, the exact noise kernel including vacuum and thermal contributions, and a fractional generalization of the Caldeira-Leggett master equation for arbitrary $d_{\mathcal{U}}$. The scaling dimension governs a rich phase structure, including a thermalization transition at $d_{\mathcal{U}}=3/2$, the Ohmic boundary at $d_{\mathcal{U}}=2$, and a decoherence transition at $d_{\mathcal{U}}=5/2$ in the thermal regime, beyond which long-time quantum coherence is protected. Three realizations are studied. For the quantum Ising model at criticality, coupling to the energy operator in $(1+1)$ dimensions gives $d_{\mathcal{U}}=3/2$, producing $1/f$ noise, while the $(2+1)$D case yields $d_{\mathcal{U}}\approx 1.413$ from the conformal bootstrap. In inflationary cosmology, massless scalar and graviton baths in de Sitter spacetime give $d_{\mathcal{U}}=2$, predicting linear decoherence growth consistent with the quantum-to-classical transition. For high-energy astrophysical neutrinos, the decoherence rate ${\Gamma }_{\mathrm{decoh}}\propto \mathcal{B}(E,T_{\mathcal{U}})L^{5-2d_{\mathcal{U}}}$ provides an observable signature of the scaling dimension. We also compare the framework with Caldeira-Leggett and Lindblad approaches, analyze the validity regimes, and discuss experimental implications for trapped-ion simulators, neutrino telescopes, and superconducting qubits.

    hep-phcond-mat.quant-gasgr-qchep-th+1PRD(2026)·0 citations
15. 15*

    Dissipative stabilization of Ostrogradsky modes in non-equilibrium field theory

    Y.M.P.Gomes🇧🇷

    In this work, we investigate higher-derivative quantum field theories and the problem of Ostrogradsky instability within an open-system Keldysh-Lindblad framework. Coupling the ghost sector to dissipative baths generates non-perturbative effective masses and dissipative widths through self-consistent gap equations. Above a critical coupling, the nonequilibrium dynamics develops bifurcated dissipative branches, signaling the emergence of a dissipative phase transition and a nontrivial critical structure in parameter space. We find that the resulting dissipative dynamics can suppress ghost excitations through two distinct mechanisms: in one branch, a large dynamically generated effective mass preserves a quasiparticle-like excitation, while in the second branch, strong dissipative broadening destroys the quasiparticle character through overdamped dynamics. Our results suggest that dissipative effects may provide a nonequilibrium mechanism for the spectral suppression of Ostrogradsky ghosts. The comparison with the healthy sector indicates that the stabilization mechanism is intrinsically tied to the ghost-like spectral structure.

    ↳ hep-thgr-qchep-ph0 citations
16. 16*

    Universalities of Defects in Quantum Field Theories

    Siwei Zhong🇺🇸

    Defects are both physically rich objects and powerful tools in modern quantum field theory. They are extended operators, such as boundaries, impurities, and probe particles, embedded in many-body systems. In this dissertation, we study the universal aspects of defect dynamics from the perspective of symmetry principles. We bring together several themes, including defect renormalization group flows, effective string theory, and impurities in atomic quantum gases.

    ↳ hep-thcond-mat.quant-gashep-ph0 citations
17. 17*

    Bootstrapping Two-Nucleon Effective Field Theories

    Q.N. Micha-Mba🇪🇸 · M.S. Sánchez🇪🇸 · P.G. Ortega🇪🇸 · J.A. Oller🇪🇸 · D.R. Entem🇪🇸

    Chiral EFT yields singular potentials that require regularization and renormalization when implemented in a dynamical equation such as the Lippmann--Schwinger equation. We employ two different approaches, renormalization with contact terms -- as is most commonly done in chiral EFT -- and the exact N/D method with multiple subtractions. We start with a toy model in which we can control the finite-range expansion of the potential, treating the full potential as the `exact' theory. To assess the statistical consistency of the approaches with the full theory, we use the bootstrap technique. We apply the same framework to study the consistency of chiral EFT at LO and NLO with the Granada phase-shift analysis in the ${}^1{S}_0$ two-nucleon partial wave. Our results show that the NLO potential significantly extends the energy range over which the theory remains valid.

    ↳ nucl-thhep-ph0 citations
18. 18*

    Blue-tilted spectral running and the JWST early galaxy tension

    Mikage U. Kobayashi🇯🇵 · Gen Chiaki · Kazutaka Kimura🇯🇵 · Kazuyuki Akitsu🇯🇵 · Kazunori Kohri🇯🇵 · Tomo Takahashi🇯🇵 · Kazuyuki Omukai

    Recently, the James Webb Space Telescope (JWST) collaboration has found the unexpectedly large abundance of massive galaxies with stellar masses of $\sim 10^{10}{M}_{\odot }$ at high redshifts $z\simeq 6.5-9$ compared with the prediction of the standard $\Lambda$CDM model. As a possible solution to the tension, we consider a blue-tilted spectrum of density perturbations with a positive running. We find that, for ${\alpha }_s\simeq 0.02$ and ${\beta }_s\simeq 0.02$, a joint analysis with CMB observations shows that the tension can be resolved at the 1$\sigma$ confidence level. Such a blue-tilted spectrum is also plausible from the perspective for formations of primordial black holes on much smaller scales in the early Universe.

    ↳ astro-ph.COastro-ph.GAhep-ph1 citation
19. 19*

    Dark photon -- Assisted Primordial Magnetogenesis

    Debottam Nandi (VIT Chennai)🇮🇳 · Debajyoti Choudhury (University of Delhi)🇮🇳

    Magnetic fields observed across cosmic scales are difficult to explain within conventional physics. A primordial origin is, thus, often assumed. While a nonminimal coupling of the inflaton with the electromagnetic field could theoretically generate magnetic fields of about $10^{-13}$ G, this approach faces significant issues, including strong-coupling and backreaction problems. ``Dark photons", arising naturally in hidden-sector extensions of the Standard Model, provide a well-motivated framework for addressing various cosmic as well as particle physics issues. We demonstrate that coupling dark photons with standard ones can result in adequate magnetogenesis without the limitations of existing models. This minimal mechanism may also provide insights into unresolved cosmic mysteries.

    ↳ astro-ph.COgr-qchep-ph1 citation
20. 20*

    Signatures of Modified Gravity on Linear Scales in a Dynamical Dark Energy Background

    Yo Toda🇯🇵 · Adrià Gómez-Valent🇪🇸

    Cosmological data from the cosmic microwave background (CMB), baryon acoustic oscillations, and Type Ia supernovae suggest that the component driving the accelerated expansion of the Universe may be dynamical at the $\sim 2.5$-$3\sigma$ CL. The best-fit CPL model produces a level of cosmic structure similar to that of $\Lambda$CDM, with both models exhibiting mild tension with redshift-space distortion data. In this {\it Letter}, we parametrize possible departures of the effective gravitational coupling from Newton's constant in the late Universe, below a comoving scale ${\lambda }_c$, using two redshift bins, $0\le z<1$ and $1\le z\le 3$. We then determine the optimal values of ${\lambda }_c$ and the amplitude of these deviations from General Relativity, assuming a background with dynamical dark energy in CPL form. We find that, in order to achieve the required suppression of structure growth at low redshifts while remaining consistent with CMB constraints -- primarily from the late-time ISW effect at low $\ell$ and lensing at high $\ell$ -- we must require modified gravity effects to have a characteristic scale of ${\lambda }_c\lesssim 150\mathrm{Mpc}$ (95\% CL). This places the relevant scales squarely within the range probed by galaxy surveys. The best-fit value is ${\lambda }_c\simeq 40\mathrm{Mpc}$, well below the 95\% CL upper limit. Using Planck PR4, DESI DR2, Pantheon+ (or DES-Dovekie) and redshift-space distortions data we confirm that a CPL background with standard gravity is moderately preferred over $\Lambda$CDM; this preference strengthens to a mildly strong level when modified gravity effects are included. This enhancement leaves the CPL parameters largely unchanged, but shifts them slightly further into the quintom region.

    ↳ astro-ph.COgr-qchep-ph2 citations
21. 21*

    Dwarf Galaxy Constraints on Interacting Fermionic Dark Matter

    Bihag Dave🇮🇳 · Raghuveer Garani🇮🇳

    Dwarf galaxies in the Local Group offer a way to test dark matter (DM) models against stellar kinematic data. In this work, we study degenerate fermionic DM in two cases: the standard non-interacting Fermi gas, and an interacting degenerate DM fluid described by a phenomenological equation of state motivated by interacting Fermi systems. These interactions modify the compressibility of the DM fluid and, in some regions of parameter space, lead to mechanically unstable branches that must be treated through a Maxwell construction. We solve the corresponding non-relativistic hydrostatic equations consistently and compute the line-of-sight velocity-dispersion profiles using the spherical Jeans equation. We then perform MCMC fits to eight classical Milky Way dwarf spheroidal galaxies. The data favor DM fermion masses in the range $100$--$300\mathrm{eV}$. We find that the interacting and non-interacting equations of state give broadly similar posterior distributions for the fermion mass, central density, and stellar anisotropy. Current data therefore do not strongly prefer an interacting equation of state over the free degenerate Fermi-gas, thereby excluding large deviations from the non-interacting limit.

    ↳ astro-ph.GAastro-ph.COhep-ph0 citations
22. 22*

    Dimming of Photon Ring due to Photon-Axion Conversion around Kerr Black Holes

    Rahul Dhyani🇮🇳 · Sauvik Sen🇬🇷 · Indrani Banerjee🇮🇳 · Ashmita Chakraborty🇬🇷 · Arindam Chatterjee🇮🇳

    We investigate photon-axion conversion in the vicinity of rotating Kerr black holes where strong gravity traps photons on near-circular trajectories, effectively enhancing the path length. We explore the observable signatures of such a conversion near the photon region. The process, driven by ambient magnetic fields, is significantly more efficient around supermassive black holes such as M87*, since the luminosity of photons increases with the mass of the BH. By numerically evaluating photon path lengths (on which the conversion depends), we analyze how key parameters-photon frequency, axion mass, photon-axion coupling, magnetic field strength, plasma density, and black hole spin-affect the conversion probability and the resultant dimming of photon spectral luminosity. We find that the conversion is most efficient at high frequencies (X-rays and gamma rays), while the frequency window associated with efficient conversion widens with an increase in the photon-axion coupling and a decrease in the electron density and the axion mass. The magnitude of dimming of the photon spectral luminosity depends primarily on the magnetic field, the photon-axion coupling and the BH spin. Our study reveals that rotating black holes generally exhibit enhanced dimming compared to static ones. Thus, if future telescopes achieving a resolution $\sim 10^{-5}$ arcsec in the X-ray/gamma-ray band detect a dimming of the photon spectral luminosity, then they can provide interesting constraints on the axion mass and its coupling with photons.

    ↳ gr-qcastro-ph.HEhep-ph0 citations
23. 23*

    Complete lattice QCD calculation of $K^{-}\to {\ell }^{-}{\bar{\nu }}_{\ell }{\ell }^{{}^{\prime }+}{\ell }^{{}^{\prime }-}$ form factors

    R. Di Palma🇮🇹 · R. Frezzotti🇮🇹 · G. Gagliardi🇮🇹 · V. Lubicz🇮🇹 · G. Martinelli🇮🇹 · C.T. Sachrajda🇬🇧 · F. Sanfilippo🇮🇹 · S. Simula🇮🇹 · N. Tantalo🇮🇹

    We present the first complete lattice QCD calculation of the four structure-dependent form factors governing the rare charged kaon decay $K^{-}\to {\ell }^{-}{\bar{\nu }}_{\ell }{\ell }^{\prime +}{\ell }^{\prime -}$, with fully controlled statistical and systematic uncertainties. Our calculation is based on gauge ensembles generated by the Extended Twisted Mass Collaboration (ETMC) with $N_f=2+1+1$ flavors of Wilson-clover twisted-mass fermions. Simulations are performed directly at the physical values of the light and strange quark masses, and include an estimate of the quark-disconnected contributions in which the virtual photon couples to sea quarks. All four form factors are determined across the kinematical region probed by experiments. The Spectral Function Reconstruction (SFR) method of Ref. [1] is employed to overcome the analytic continuation problem for dilepton invariant masses above the two-pion threshold. Finite-volume effects are investigated using ensembles with spatial extents $L\simeq [3.8,7.6]\mathrm{fm}$, while the continuum limit is obtained from three lattice spacings in the range $a\in [0.057,0.08]\mathrm{fm}$. Our results for the form factors enable the evaluation of decay rates and differential observables for all four channels, $K^{-}\to e^{-}{\bar{\nu }}_e{e}^{+}{e}^{-}$, $K^{-}\to e^{-}{\bar{\nu }}_e{\mu }^{+}{\mu }^{-}$, $K^{-}\to {\mu }^{-}{\bar{\nu }}_{\mu }{e}^{+}{e}^{-}$, and $K^{-}\to {\mu }^{-}{\bar{\nu }}_{\mu }{\mu }^{+}{\mu }^{-}$, thereby providing first-principles Standard Model predictions against which existing and upcoming measurements can be directly compared. A detailed phenomenological analysis of the decay rates and associated observables is presented in a companion paper [2].

    ↳ hep-lathep-ph2 citations
24. 24*

    Two bodies left behind

    Raúl A. Briceño🇺🇸 · Caroline S. R. Costa🇺🇸 · Hans-Werner Hammer🇩🇪 · Daniel R. Phillips🇺🇸

    We consider scenarios in which a shallow bound state undergoes breakup by a probe whose energy is high compared to the binding energy. The first two scenarios, which serve as warm-up exercises, involve a single heavy particle bound to a light particle, analogous to a core nucleus bound to a neutron. We show that in quasi-free kinematics, the leading effect comes from the heavy particle being knocked out by the probe, with corrections suppressed by inverse powers of the probe momentum. This formally justifies extracting neutron form factors from high-energy deuteron breakup in quasi-free kinematics. In Scenario 1, the probe is a local current; in Scenario 2, it is hadron scattering. In Scenarios 3 and 4 we consider, respectively, a local current and hadron scattering, but now on a three-body bound state of a heavy particle and two light particles. Hard knockout of the heavy particle leaves two low-energy particles behind, which can interact with one another. In all four scenarios, we prove that the amplitude is dominated by the nearby on-shell pole of the heavy-particle propagator and derive a closed-form expression for this contribution. When two bodies are left behind, the leading amplitude is the product of the scattering of the two light particles, a dynamical function depending on the probe, and a real function related to the bound-state wavefunction. Thus, quasi-free removal of a core nucleus from a system with halo neutrons provides access to on-shell data on multi-neutron interactions. The resulting amplitudes are relativistic and satisfy unitarity for the remnant subsystem exactly. We also provide complementary non-relativistic derivations. While the derivations are for spinless particles, the generalization to spin is straightforward, since the results depend only on quasi-free knockout kinematics; we make no assumptions about the inter-particle dynamics.

    ↳ nucl-thhep-exhep-ph0 citations
25. 25*

    New constraints on physics within and beyond the standard model from the latest CONUS datasets

    N. Ackermann🇩🇪 · H. Bonet🇩🇪 · A. Bonhomme🇩🇪 · C. Buck🇩🇪 · 1 K. Fülber🇩🇪 · J. Hakenmüller🇩🇪 · J. Hempfling🇩🇪 · G. Heusser🇩🇪 · T. Hugle🇩🇪 · M. Lindner🇩🇪 · W. Maneschg🇩🇪 · S. Mertens🇩🇪 and 9 other authors

    Its detections with pion-decay-at-rest, solar and recently with reactor antineutrinos by the CONUS collaboration render coherent elastic neutrino-nucleus scattering (CE$\nu$NS) an established tool for investigations within and beyond the Standard Model (SM). The CONUS experiment located at the nuclear power plants in Brokdorf (Germany) and Leibstadt (Switzerland) operates Germanium semiconductor detectors in a compact shield at close distance to the reactor core. An observation with $3.7\sigma$ significance is reported at the Leibstadt site, showing good agreement with its SM prediction. Physics investigations performed with the last datasets collected at the Brokdorf reactor and with the first data obtained at the Leibstadt site are summarized. By using the experimental analysis framework, the presented results contain the full systematics that underlie the experiment. Previously determined limits with neutrino-electron scattering on the neutrino magnetic moment and a neutrino millicharge are improved to ${\mu }_{\nu }<5.18\cdot 10^{-11}{\mu }_{\mathrm{B}}$ and $q_{\nu }<1.76\cdot 10^{-12}{e}_0$ (90% C.L). Further, the scale of new physics related to NSIs is improved to ${\Lambda }_{\mathrm{NSI}}$=145 GeV and limits on the coupling of light new mediators are lowered down to $4\cdot 10^{-7}$ (90% C.L.) with the new data. Finally, the determination of the Weinberg angle with CE$\nu$NS and reactor antineutrinos yields ${\sin }^2{\theta }_W=0.28_{-0.04}^{+0.03}$ at a momentum transfer of $\sim 10\mathrm{MeV}$.

    ↳ hep-exhep-ph3 citations
26. 26*

    Bottom-up open EFT for non-Abelian gauge theory with dynamical color environment

    Yoshihiko Abe🇯🇵 · Kanji Nishii🇯🇵

    We develop a bottom-up open effective field theory (EFT) for non-Abelian gauge theories within the Schwinger--Keldysh formalism. Instead of integrating out the environment completely and starting from a nonlocal influence functional, we retain the slow environmental response variables explicitly and construct a local system-environment EFT. The environmental sector is described by a dynamical color-frame variable, Stückelberg-like field, and an associated color-current sector, which gives the nontrivial interactions and dissipation between the system and the environment. The resulting construction provides a gauge-covariant Markov embedding of nonlocal and non-Markovian color response. After integrating out the retained environmental variables with retarded boundary conditions, the reduced system theory acquires nonlocal dissipative kernels and stochastic sources. We show that the hard thermal loop response arises naturally as a particular realization of the retained environmental response. Our framework provides a local open-EFT description of color transport, memory effects, and fluctuation-dissipation structure in non-Abelian plasmas, and offers a systematic starting point for dissipative Yang--Mills EFTs with dynamical environments.

    ↳ hep-thhep-phquant-ph0 citations
27. 27*

    A No-Go Theorem for the Mass-Radius Relation of Solitons

    Mohammad Hossein Namjoo🇮🇷

    We prove a no-go theorem for the mass-radius relation of localized and stable field configurations, known as solitons. Defining the mass-radius index by $\Gamma \equiv \frac{\mathrm{d}\ln M}{\mathrm{d}\ln R}$, for real scalar field theories in $d$ spatial dimensions, we show that typical non-topological, non-relativistic, and spherically symmetric solitons cannot have $\Gamma$ in the range $[0,d]$. The forces considered originate from gradient energy, self-interaction, and gravitation, with the typicality assumption excluding the fine-tuned region of the parameter space where all three forces have comparable strength. Importantly, the theorem works for an arbitrary self-interaction that, in the relativistic theory, is allowed to be non-power-law in the field, be non-analytic around the classical vacuum (where the field amplitude vanishes), or to include derivative couplings. Additionally, the theorem makes no assumptions about the explicit form of the soliton's density profile or the behavior of $\Gamma$ as a function of $R$. We also argue that the same exclusion applies to compact objects formed from self-gravitating, non-relativistic, barotropic fluids with arbitrary equations of state. As a consequence for cosmology, it is worth noting that observations favor a core in the centers of dark matter halos with $\Gamma \simeq 1.7$, which (for $d=3$) lies approximately in the middle of the excluded range. Therefore, proposals such as ultra-light or fluid-like dark matter models are essentially ruled out as natural explanations for halo cores, provided other astrophysical effects are negligible.

    ↳ astro-ph.COastro-ph.GAhep-phhep-th+1PRD(2026)·1 citation
28. 28*

    A Precise Measurement of the Fermi-LAT Galactic Center Excess Morphology and Spectrum

    Mattia Di Mauro🇮🇹

    We present a new Fermi-LAT analysis of the Galactic-center excess (GCE) designed to substantially reduce the dominant systematic uncertainties associated with interstellar-emission and source modeling in the inner Galaxy. Using an optimized multi-step fitting procedure together with an iterative source-finding pipeline, we achieve a markedly improved agreement between data and model, reducing fractional residuals to $\lesssim 10\%$ over a $40^{\circ }\times 40^{\circ }$ region centered on the Galactic center. We analyze a suite of GALPROP-based interstellar-emission models (IEMs) and complementary analysis variants (Galactic-plane masking, fits restricted to $1$-$10$ GeV, and weighted-likelihood fits) to quantify robustness. The reconstructed surface-brightness profile is strongly centrally concentrated and is well described by an approximately spherical generalized Navarro-Frenk-White morphology with inner slope $\gamma \simeq 1.15$. Bulge-tracing templates (nuclear bulge plus boxy bulge) fail to reproduce the full radial morphology, most notably for line-of-sight angles around $\theta \simeq 1^{\circ }$-$2^{\circ }$ and at $\theta \gtrsim 8^{\circ }$, whereas the DM-motivated component provides a good description over the full angular range. Moreover, the DM component remains highly significant across all IEMs and analysis choices, including fits that simultaneously include the bulge templates. We also provide an updated measurement of the GCE spectrum from $0.5$ to $1000$ GeV, confirming a peak at a few GeV and setting stringent constraints above tens of GeV, where we obtain only upper limits at the level $E^2\Phi \lesssim 10^{-8}$ GeV cm${}^{-2}$ s${}^{-1}$ sr${}^{-1}$. These results deliver a sharpened and systematically controlled characterization of the GCE morphology and spectrum, enabling more incisive tests of astrophysical and dark-matter interpretations.

    ↳ astro-ph.HEhep-ph2 citations
29. 29*

    Hybrid stars among mass gap objects are excluded by twin stars at $1.4M_{\odot }$

    Alexander Ayriyan🇵🇱 · David Blaschke🇵🇱 · Marcin Dubaj🇵🇱 · Oleksandr Vitiuk🇵🇱 · Adrian Wojcik

    We investigate the question whether compact objects in the so called mass gap ($2.5<M/M_{\odot }<5.0$) can be neutron stars or hybrid stars. Using a generic hybrid star equation of state with a first-order deconfinement transition, we map the allowed parameter space in a Seidov-type diagram and confront it with modern mass--radius constraints. We find that mass-gap hybrid stars require an extremely early onset of deconfinement and very stiff quark matter. The Bayesian analysis, however, favors equations of state with deconfinement at typical neutron-star masses around $1.4M_{\odot }$ with mass-twin stars that, if confirmed, would rule out hybrid stars as candidates for observed mass-gap compact objects.

    ↳ astro-ph.HEhep-phnucl-th0 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.