Tue·May 26, 2026Tuesday·May 26, 2026

1. 01*

   Solar Axions from Nuclear Transitions

   Tanmoy Kumar🇮🇳 · Newton Nath🇮🇳

   We investigate the possibility of detecting 14.4 keV and 9.4 keV solar axions and axion-like particles that could be produced in the M1 nuclear transitions of ${}^{57}$Fe and ${}^{83}$Kr, respectively. To do so, we used data from soft X-ray observations of the quiet Sun collected by the Solar X-ray Monitor (XSM) on board India's Chandrayaan-2 lunar mission. We observe that although the effective axion-nucleon couplings for ${}^{83}$Kr and ${}^{57}$Fe differ only slightly, their fluxes differ by nearly three orders of magnitude. Consequently, the limit on $|g_{aN}^{\mathrm{eff}}\times g_{a\gamma \gamma }|$ and only $g_{a\gamma \gamma }$ vs. $m_a$ provide more than an order-of-magnitude stronger constraint for Fe than for Kr.

   hep-phastro-ph.HEastro-ph.SRnucl-th0 citations
2. 02*

   Resonant Enhancement for the transfer of baryon number from a CP-violating hidden sector

   Can Kilic🇺🇸 · Sanjay Mathai🇺🇸

   We consider a scenario where the baryon asymmetry in the SM arises from a portal coupling to a CP-violating hidden sector, without any explicit violation of baryon or lepton number in either sector. While no net baryon number is generated, equal and opposite baryon numbers can be sequestered between the two sectors in this scenario. The observed asymmetry must be generated below the electroweak scale in order to avoid washout. By considering a benchmark model incorporating the baryon portal and a minimal hidden sector, we review the prospects of this scenario. When the asymmetry is generated via the decay of top quarks, generic input parameters for the model are sufficient. If however the asymmetry is to be generated via the decay of bottom quarks, a resonant enhancement is needed to sequester the baryon number with maximal efficiency. The scenario of mesogenesis assisted by CP-violation in a hidden sector falls into this latter category. We use analytical and numerical methods to quantify the amount of resonant enhancement that can be achieved, and we remark that the mesogenesis scenario can be discovered or ruled out in full if the relevant branching ratios can be improved by 2-3 orders of magnitude.

   hep-ph0 citations
3. 03*

   Associated $ZH$ production in gluon fusion process at NLO+NLL

   Pulak Banerjee🇮🇳 · Chinmoy Dey🇮🇳 · Niraj Koirala🇮🇳 · M.C. Kumar🇮🇳 · Vaibhav Pandey🇮🇳

   We present precise results for invariant mass distributions and inclusive cross-sections, of associated $ZH$ production through gluon fusion in QCD. We include threshold logarithms at next-to-leading-logarithmic (NLL) accuracy and match the results to full next-to-leading-order (NLO) results with exact top-quark mass dependence in the virtual amplitudes. At 13.6 TeV energy at LHC, the NLO+NLL cross-section increases the NLO counterpart by about $20\%$. For differential distributions, at 3000 GeV, the uncertainties arising out of the unphysical renormalization and factorization scales is about $20\%$ for NLO; whereas for the resummed results it is around $12\%$. We also combine these results to the Drell-Yan type results at N${}^3$LL and present the most precise results in hadron collisions.

   hep-phhep-ex1 citation
4. 04*

   Leptogenesis without on-shell right-handed neutrinos

   Simon Cléry🇩🇪 · Alejandro Ibarra🇩🇪 · Onur Yonar🇩🇪

   We propose a novel mechanism for generating the baryon asymmetry of the Universe through leptogenesis in a scenario where the right-handed neutrinos are heavier than the maximal temperature of the Universe, and are never produced on-shell neither by thermal nor by non-thermal mechanisms. We introduce a new scalar field, $\varphi$, lighter than the right-handed neutrinos, that couples to the latter via a Yukawa coupling, so that it decays into two lepton doublets and two higgs doublets via off-shell right-handed neutrinos. Then, we derive the CP asymmetry arising from the interference between tree-level and loop diagrams in the four-body decay, and we show that the generated baryon asymmetry can reproduce the observed value both in a scenario where $\varphi$ is responsible for the reheating of the Universe, and in a scenario where $\varphi$ is a generic scalar that remains in thermal equilibrium with the plasma.

   hep-phastro-ph.CO0 citations
5. 05*

   Low-lying $\Lambda$ and $\Sigma$ resonances studied with the forward $K^{\ast }$ productions off the proton induced by a high-momentum $\pi$ beam

   H. Kamano🇯🇵 · T.-S. H. Lee🇺🇸

   We develop a novel model utilizing the forward $K^{\ast }$ production reaction off the nucleon, $\pi N\to K^{\ast }MB$, induced by a high-momentum $\pi$ beam, as a tool to study low-lying $Y^{\ast }$ resonances below and just above the $\bar{K}N$ threshold. Because conventional $K^{-}p$ scattering experiments face difficulties in directly accessing this kinematic region, the proposed reaction offers a valuable complementary approach for $Y^{\ast }$ spectroscopy. The constructed model is based on the one-meson exchange mechanism, which is known to dominate forward-angle production at high energies, and the half-off-shell scattering amplitudes from the ANL-Osaka dynamical coupled-channels models (Model A and Model B). We predict various observables, including differential cross sections and angular distributions. Our results demonstrate significant enhancements in the subthreshold region of the invariant mass spectra. Notably, we show that overlapping resonances, such as a potential new $3/2^{+}$ $\Sigma$ state and the well-established $\Sigma (1385)3/2^{+}$, can constitute a single peak in the $\pi \Lambda$ mass spectrum, indicating that the existence of previously unconfirmed subthreshold states cannot be ruled out by analyzing only the existing mass spectrum data. Furthermore, we find that angular distributions provide strong discriminatory power to disentangle such overlapping states through partial-wave interference effects, while the $t^{\prime }$ and ${\varphi }_M^{\ast }$ dependencies provide crucial constraints on the high-energy production mechanisms. Our predictions for these highly sensitive observables can facilitate high-statistics measurements, which are accessible at modern hadron facilities such as J-PARC, to unravel the $S=-1$ $Y^{\ast }$ mass spectrum.

   hep-phhep-exnucl-exnucl-thPRC(2026)·0 citations
6. 06*

   Multipole structure of the nucleon tensor form factors

   Nam-Yong Ghim🇰🇷 · Ho-Yeon Won🇫🇷 · June-Young Kim🇰🇷 · Hyun-Chul Kim🇰🇷

   We investigate the multipole structure of the nucleon tensor form factors within the chiral quark-soliton model based on the $1/N_c$ expansion. Extending the previous leading-order analysis~\cite{Ghim:2025gqo}, we include the rotational $1/N_c$ corrections. These corrections provide the leading nonvanishing contributions to the flavor components that are absent at leading order, thereby completing the flavor decomposition of the tensor multipole form factors at the present order. We numerically evaluate the isoscalar tensor charge, the isovector anomalous tensor magnetic moment, and the isoscalar tensor quadrupole moment, obtaining $g_T^{u+d}=0.81$, ${\kappa }_T^{u-d}=1.97$, and $E_T^{u+d}(0)=5.98$, respectively. The isoscalar tensor charge and quadrupole moment are mainly governed by the valence-quark contribution, whereas the isovector anomalous tensor magnetic moment receives a sizable Dirac-sea contribution. We also examine the momentum-transfer dependence of the corresponding form factors. They decrease monotonically with increasing $-t$. In particular, the isovector anomalous tensor magnetic form factor shows a pronounced falloff in the small-$|t|$ region, reflecting the importance of the Dirac sea in the tensor dipole structure.

   hep-phhep-exhep-latPRD(2026)·0 citations
7. 07*

   Statistical Framework for Discovery Sensitivity and Majorana Mass Estimation in \(^{136}\)Xe Neutrinoless Double Beta Decay

   Pratima Singh🇮🇳 · Jyotsna Singh🇮🇳 · R.B. Singh🇮🇳

   Neutrinoless double-beta decay (\(0\nu\beta\beta\)) is a sensitive probe of lepton-number violation and the Majorana nature of neutrinos. In xenon-based experiments, the expected signal rate inside the region of interest (ROI) is extremely small, requiring sensitivity estimates based on Poisson statistics and a careful treatment of detector resolution, background fluctuations, and systematic uncertainties. In this work, we develop a statistical framework relating energy resolution, ROI width, background index, isotope exposure, and discovery sensitivity for \(^{136}\)Xe-based \(0\nu\beta\beta\) experiments. The formalism combines Poisson likelihood methods with realistic background modeling and includes reconstruction-related and final-state interaction (FSI) systematic effects through an effective ROI broadening approach. Using representative detector parameters for LZ, NEXT-100, KamLAND-Zen, and nEXO, we compare expected background counts, required discovery signal statistics, and half-life sensitivities at matched exposure. The corresponding sensitivities are translated into effective Majorana mass reach within both normal- and inverted-hierarchy neutrino mass ordering. The impact of uncertainties associated with the axial-vector coupling constant \(g_A\), nuclear matrix elements, and phase-space factors is also examined. Our results show that background suppression, ROI optimization, and control of detector-related systematics are essential for extending sensitivity toward the normal-ordering regime in future \(0\nu\beta\beta\) searches.

   hep-ph0 citations
8. 08*

   Freeze-in $SU(2)$ vector dark matter at low reheating temperature

   Dilip Kumar Ghosh🇮🇳 · Sourav Gope🇮🇳 · Xiao-Gang He🇨🇳 · Xuan Hong🇨🇳 · Sk Jeesun🇨🇳

   The freeze-in mechanism for dark matter (DM) requires extremely feeble interactions with the Standard Model (SM), preventing thermal equilibrium in the early Universe and typically evading experimental detection. However, for sufficiently low reheating temperatures ($T_{\mathrm{RH}}$), the observed relic abundance can be realized with larger couplings, opening prospects for experimental searches. In this work, we investigate freeze-in production of $SU(2{)}_{\mathrm{HS}}$ vector dark matter (VDM) in a low-$T_{\mathrm{RH}}$ cosmology. The framework naturally contains three mass-degenerate stable VDM candidates without the need for any additional discrete symmetry. We perform a systematic study of the dark matter phenomenology and identify the parameter space consistent with the observed relic abundance. In contrast to conventional freeze-in scenarios, the required DM couplings can be sizable, rendering part of the parameter space already constrained by existing direct searches like PandaX-4T and LZ, while a significant region remains within the reach of future experiments such as DARWIN. Though one can realize the freeze-in mechanism for an abelian $U(1{)}_X$ vector DM models as well, we find that the non-abelian structure of the $SU(2{)}_{\mathrm{HS}}$ scenario leads to a distinct feature due to a larger number of dark matter particles, resulting in an enlarged viable parameter space due to the multiplicity of dark matter states.

   hep-ph1 citation
9. 09*

   Axion-like particles and sterile neutrinos solve the $B\to K\nu \bar{\nu }$ and $B\to \pi K$ puzzles

   Bhubanjyoti Bhattacharya🇺🇸 · Alakabha Datta🇺🇸 · Girish Kumar🇺🇸 · Danny Marfatia🇺🇸

   The recent measurement of the branching ratio of $B^{+}\to K^{+}+\mathrm{inv}$ (where ``inv'' denotes invisible states) by the Belle II collaboration is enhanced relative to the standard model expectation by 2.7$\sigma$. An older puzzle persists in measurements of the branching ratios and CP asymmetries of $B\to \pi K$ decays. We address these two anomalies in flavor-changing neutral current $B$ decays, with a short-lived axion-like particle (ALP) with mass close to that of the ${\pi }^0$. In the model with the minimum number of new couplings, the ALP has couplings to the photon, top quark and a heavy sterile neutrino. The ALP contributes to the $B\to {\pi }^{0}K$ decays by mixing with the ${\pi }^0$. It contributes to $B^{+}\to K^{+}+\mathrm{inv}$ by its off-shell coupling to sterile neutrino pairs. The model can explain the excess in the total rate, but not the observed distribution of signal events. We make predictions for all $B\to K^{(\ast )}+\mathrm{inv}$ modes and for the rare kaon decays, $K^{+}\to {\pi }^{+}+\mathrm{inv}$ and $K_L\to {\pi }^0+\mathrm{inv}$. We find an appreciable contribution to the magnetic moment of the muon, and negligible contributions to the magnetic moment of the electron and $b\to s{e}^{+}{e}^{-}$.

   hep-phhep-exPRD(2026)·1 citation
10. 10*

    Fermion Mass Hierarchies and the Exceptional Jordan Algebra

    Bishnu Gupta Teli🇮🇳 · Tejinder Pal Singh🇮🇳

    We develop a spectral framework for fermion mass hierarchies based on the exceptional Jordan algebra $J_3({\mathbb{O}}_{\mathbb{C}})$. Starting from the octonionic realization of one Standard Model generation in $\mathbb{C}\otimes \mathbb{O}$, we embed the resulting three-generation structure into Hermitian Jordan elements whose eigenvalues define intrinsic spectral invariants. The ordered spectral scales generate cubic ladder structures in the symmetric representation ${\mathrm{Sym}}^3(3)$, and consistency of multiplicative hierarchy composition naturally leads to power-law relations between fermion masses and spectral scales. The construction should be viewed as a phenomenological spectral deformation of the rigid exceptional-Jordan framework discussed below: we retain the same cubic-ladder, minimal-chain, and Dynkin-reflection structure, but promote the relative normalization, hierarchy exponent, and charged-lepton octonionic phase to fitted spectral moduli. A global logarithmic fit to six charged-fermion mass ratios at $\mu =M_Z$ lowers the unpenalized log-residual relative to the rigid point, mainly through the top-to-charm ratio, while the individual ratios are not uniformly improved. The best-fit hierarchy exponent remains close to the square-root scaling regime, $p\simeq 1$. In the neutrino sector, the framework accommodates both normal and inverted ordering while remaining consistent with oscillation data and current cosmological bounds on the total neutrino mass. Thus, the proposal is an effective spectral organization of fermion hierarchies, not a parameter-free replacement for the broader rigid construction discussed below.

    hep-ph4 citations
11. 11*

    Subcritical bubble prehistory in weak first-order phase transition

    Guangshang Chen🇨🇳 · Yang Xiao🇨🇳 · Jin Min Yang🇨🇳 · Yang Zhang🇨🇳

    Standard calculations of cosmological first-order phase transitions usually assume critical bubbles to nucleate on a homogeneous symmetric vacuum background. However, this assumption can fail in weak transitions, where thermal fluctuations trigger subcritical bubbles before the standard nucleation temperature $T_n$. Motivated by this possibility, we systematically examine whether the homogeneous nucleation background approximation is self-consistent. By evolving the Gelmini-Gleiser subcritical bubble kinetics and comparing it with the standard critical bubble nucleation picture, we identify the parameter regions in which the background becomes apparently mixed. A detailed scan of these regions shows that sizable subcritical volume fractions arise when the two phases are nearly degenerate at $T_n$, the potential barrier is low, the difference of free energy between the symmetric and broken phases is moderate and the transition strength is weak. Our analysis further yields a simple criterion, ${\log }_{10}{\hat{f}}_{\xi }(T_n)\simeq -1.95$, for a percent level subcritical bubble volume fraction. Parameter points above this boundary should be treated as mixed background candidates rather than as ordinary homogeneous bounce points.

    hep-phPRD(2026)·0 citations
12. 12*

    Emerging Nonlocal Källèn-Lehmann Higgs Spectra at the LHC

    Stathes Paganis🇹🇼

    Electroweak symmetry breaking may arise from emergent nonlocal Källèn-Lehmann spectral densities in Hamiltonians with multiscalar interactions. The nonlocality scale ${\Lambda }_{NL}$ emerges naturally from the exponentially increasing degeneracy of mass eigenstates in the Higgs two-point function at scales $p^2\ge {\Lambda }_{NL}^2$. Following the renormalization of the nonlocal Higgs propagator, we provide a framework for deriving analytic expressions for non-perturbative scattering amplitudes. We demonstrate that for energies exceeding the nonlocality scale, scattering amplitudes are exponentially suppressed. Furthermore, the real part of the Higgs self-energy is suppressed at deep spacelike momenta ($p^2\sim -{\Lambda }_{NL}^2$), offering a solution to the Hierarchy problem. Such nonlocal scalar sectors are accessible to current and future LHC runs. We argue that the nonlocal Källèn-Lehmann spectral density can be constrained through a simultaneous global fit of LHC measurements in exclusive channels, including di-Higgs, electroweak di-boson, and di-photon production. This approach represents a paradigm shift in the search for new physics at high-energy colliders.

    hep-phhep-exhep-th0 citations
13. 13*

    A D_5 Model of Quarks with Explicit CP Violation

    Dong-Ping Fu🇨🇳 · Michihisa Takeuchi🇨🇳

    We investigate the quark sector of a four-Higgs-doublet model with an exact D_5 symmetry. In the framework of explicit CP violation, we considered the most general real vacuum, derived the quark mass matrices, and performed a numerical fit to the quark masses and the CKM mixing matrix at the scale mu = 1 TeV using a differential evolution algorithm, based on the 2024 PDG experimental data.The results show that the model simultaneously fits the quark mass spectrum and the CKM mixing angles with an excellent overall chi^2 = 6.97, accurately reproducing the six-quark mass hierarchy and perfectly matching the nine squared moduli of the CKM matrix. The resulting Jarlskog invariant J_CP = 3.144 \times 10^{-5} agrees with the experimental value 3.12 \times 10^{-5} within 0.19\sigma, indicating that the new source of CP violation from the complex phases in the quark Yukawa couplings alone is sufficient to generate the observed CP violation. Moreover, the hierarchical structures of the vacuum expectation values and the quark Yukawa couplings naturally explain the observed quark mass hierarchy through their interplay.

    hep-ph1 citation
14. 14*

    Odderon Form Factors in Reggeized Spin-2 Pomeron and Spin-3 Odderon Exchange in $pp$ and $p\bar{p}$ Elastic Scattering

    Dominador F. Vaso · Jr. · Prin Sawasdipol · Jingle B. Magallanes · Chakrit Pongkitivanichkul · Daris Samart

    We investigate the form-factor dependence of Reggeized tensor Pomeron and Odderon exchanges in high-energy elastic $pp$ and $p\bar{p}$ scattering. The spin structure is implemented through explicit covariant spin-2 and spin-3 projectors, kept factorized from the Reggeized scalar kernels, so that vertex effects can be separated from trajectory dynamics. Seven Odderon--proton form-factor parametrizations are tested against a global dataset including TOTEM $pp$ data at $\sqrt{s}=2.76$, $7$, $8$, and $13$~TeV and Tevatron $p\bar{p}$ data at $\sqrt{s}=1.80$ and $1.96$~TeV. A clear hierarchy is found. Six dipole, polynomial, Gaussian, and hybrid parametrizations give comparable fit qualities, ${\chi }_{\mathrm{red}}^2\simeq 1.44$--$1.48$, whereas a one-parameter exponential form, $F_{\mathbb{O}}(t)=\exp [-B|t|/2]$, yields ${\chi }_{\mathrm{red}}^2=0.98$ for 138 degrees of freedom. The fitted couplings and Regge slopes remain comparatively stable across the form-factor choices, indicating that the improvement is driven mainly by the Odderon--proton vertex rather than by large compensating shifts in trajectory parameters. The exponential form admits an impact-parameter interpretation as a Gaussian transverse profile, with an effective radius $\sqrt{⟨b^2⟩}=\sqrt{2B}\hslash c$. The extracted radii are of hadronic size and suggest a peripheral soft Odderon interaction. The shrinking $t$-range over which the single-Regge-exchange description remains accurate at increasing energy indicates the onset of absorptive and unitarity corrections. These results provide a compact phenomenological framework for connecting the $pp/p\bar{p}$ dip--bump difference with the transverse structure of $C$-odd color-singlet exchange.

    hep-phhep-thnucl-th1 citation
15. 15*

    Electromagnetic form factors of the nucleon from the instanton vacuum

    Hui-Jae Lee🇰🇷 · Yongwoo Choi🇰🇷 · Hyun-Chul Kim🇰🇷

    We investigate the electromagnetic form factors of the nucleon within an effective chiral theory derived from the QCD instanton vacuum, taking into account the finite current quark mass. The momentum-dependent dynamical quark mass, generated by the instanton-antiinstanton medium, naturally plays the role of a regulator, so that no additional regularization is required to tame the divergences arising from quark loops. The instanton parameters, the average instanton size $\bar{\rho }=0.35$ fm and the average interdistance $\bar{R}=0.86$ fm, together with the dynamical quark mass at zero virtuality $M_0=385$ MeV, are all fixed by the saddle-point equation beyond the chiral limit, leaving no adjustable free parameter in the present calculation. We compute the Sachs electric and magnetic form factors of the proton and neutron, the nucleon charge and magnetization radii, the magnetic moments, and the ratios ${\mu }_{p,n}{G}_E^{p,n}(Q^2)/G_M^{p,n}(Q^2)$. The present results are compared with the experimental data, the chiral quark-soliton model ($\chi$QSM), and the Kelly parametrization. The proton charge radius, $\sqrt{⟨r^2{⟩}_{\mathrm{ch}}^p}=0.841$ fm, is in remarkable agreement with the recent muonic-hydrogen value, and the $Q^2$ dependence of the proton form-factor ratio ${\mu }_p{G}_E^p/G_M^p$ is reproduced very well, in clear contrast to the $\chi$QSM. The overall agreement with the experimental data confirms that the effective chiral theory derived from the QCD instanton vacuum provides a consistent and predictive framework for describing the electromagnetic structure of the nucleon.

    hep-phhep-exhep-latnucl-exPRD(2026)·1 citation
16. 16*

    Predicted Exotic Doubly Heavy-Strange Pentaquarks

    Albert Feijoo🇪🇸 · Eulogio Oset🇪🇸

    We predict exotic doubly heavy--strange pentaquarks with minimal quark content $u\bar{d}sQ{Q}^{\prime }$ ($Q{Q}^{\prime }=cc,bc,bb$) within a coupled-channel unitary framework where the interaction is derived from an extension of the local hidden gauge approach to the heavy-quark sector. We obtain a robust spectrum of manifestly exotic states; two states appear in the $u\bar{d}scc$ sector, three in $u\bar{d}scb$, and four in $u\bar{d}sbb$. These emerge either as bound states or resonances, along with five additional virtual states manifested as threshold cusps. The binding mechanism is dominated by off-diagonal transitions among heavy-baryon--light-meson channels, while diagonal interactions are strongly suppressed. These results extend exotic hadron spectroscopy into the doubly heavy--strange sector and provide concrete targets for future experimental searches.

    hep-phhep-thnucl-th0 citations
17. 17*

    Spin-dependent interactions and fine structure in the negative-parity singly heavy baryons

    Zhen-Yu Li🇨🇳 · Guo-Liang Yu🇨🇳 · Zhi-Gang Wang🇨🇳 · Jian-Zhong Gu🇨🇳

    In order to meet the high-precision measurement of the current baryon spectroscopy, for the first time, we rigorously analyze the spin-dependent interactions and the fine structure of the negative-parity singly heavy baryons in the relativized quark model, which was previously unfeasible in the three-quark system. This gains access to the exploration of the strong interactions dominated by the non-perturbative QCD, and reveals how the various forms of strong interactions in a baryon compete with each other, affect the evolution of the energy levels, cause the energy level splitting and contribute to the mixing effect responsible for the formation of the fine structures. It is shown that the rigorous calculation can perfectly reproduce the data, the averaged deviation between the calculated and experimental energy levels is less than 5 MeV for the negative-parity singly heavy baryons. Therefore, the theoretical precision has reached the experimental high precision. This confirms the reliability of the calculation and also helps make reasonable assignments for the observed negative-parity baryons. The large amount of data obtained by the rigorous calculations contains a wealth of interaction information and is helpful for both of the theoretical and experimental studies. The key to the rigorous calculation in this work is the proposal of a new method, namely the two-step Gaussian expansion method. This new method not only overcomes the long-standing unresolved problem in the relativized quark model, but also provides an effective approach for the high-precision calculation of other few-body systems such as the compact tetraquarks and pentaquarks, especially for the treatment of spin-orbit interactions and tensor interactions which actually appear ubiquitously in all of quantum many-body systems.

    hep-ph0 citations
18. 18*

    Asymmetric Two-Component Scalar FIMP Dark Matter

    S. Peyman Zakeri🇮🇷

    We propose a two-component asymmetric feebly interacting massive particle (FIMP) dark matter (DM) model in which both DM candidates are complex scalar fields. The model is an extension of the standard model (SM) by two scalar DM components and a heavy scalar mediator, stabilized by a ${\mathbb{Z}}_2\times {\mathbb{Z}}_2^{\prime }$ symmetry. DM is produced via the freeze-in mechanism through the Higgs portal, while the CP-violating decay of the heavy mediator generates an asymmetry in the first component, which is partially transferred to the second component via quartic interactions. By solving the Boltzmann equations numerically, we compute the relic density and perform a detailed scan over the parameter space. The observed relic density ${\Omega }_{\text{DM}}{h}^2=0.12\pm 0.001$ is successfully reproduced for benchmark parameters $m_{{\varphi }_1}=0.1$~GeV, $m_{{\varphi }_2}=0.5$~GeV, $M_S=100$~GeV, and ${\mu }_{12}=3\times 10^{-9}$, with the second component contributing only about $5\%$ to the total abundance. We also examine phenomenological constraints. The DM self-interaction cross section lies orders of magnitude below the Bullet cluster bound ($\sigma /m<0.47$~cm${}^2$/g) and the more stringent double radio relic limit ($\sigma /m<0.22$~cm${}^2$/g). The invisible Higgs decay branching ratio is $\sim 6\times 10^{-18}$, well below the LHC upper limit, and direct detection prospects are negligible due to the small Higgs portal couplings. Our model establishes a novel connection between two-component DM, the freeze-in mechanism, and DM asymmetry.

    hep-ph0 citations
19. 19*

    A possible ${\Sigma }^{\ast }$ or ${\Lambda }^{\ast }$ resonance with $J^P=3/2^{-}$ in $K^{-}p\to K\Xi$ scattering

    Zheng-Li Luo🇨🇳 · Jia-Jun Wu🇨🇳 · Bing-Song Zou🇨🇳

    We analyze the $K^{-}p\to K^{+}{\Xi }^{-}$ and $K^{-}p\to K^0{\Xi }^0$ processes in the energy region $1.8<\sqrt{s}<2.8$ GeV within an effective Lagrangian approach. The $\Lambda (1800)$ and $\Sigma (2250)$ resonances, along with the ground states $\Sigma$ and $\Lambda$, are included. Additionally, a possible $J^P=3/2^{-}$ ${\Sigma }^{\ast }$ or ${\Lambda }^{\ast }$ resonance with a mass around 1.9 GeV and a width of approximately 200 MeV is introduced to describe the structure at 2.0 GeV in the total cross section and reproducing the threshold behavior. The two possible solutions corresponding to ${\Sigma }^{\ast }(3/2^{-})$ and ${\Lambda }^{\ast }(3/2^{-})$ cannot be distinguished by the existing data. Predictions for the polarization of the final-state $\Xi$ and the cross section of $K^{-}n\to K^0{\Xi }^{-}$ are compared with the experimental data, we find that the results of solution-II with ${\Lambda }^{\ast }(3/2^{-})$ are much better. We also discuss the possible interpretations of the introduced $3/2^{-}$ hyperon as a pentaquark candidate, e.g. an $S$-wave $K\Xi (1530)$ hadronic molecule. However, since the polarization data suffer from rather large uncertainties, more data inputs are needed in future experiments, for example, J-PARC, HIAF and JLab.

    hep-ph0 citations
20. 20*

    Particle species dependence of femtoscopic source parameters in high-energy nuclear collisions

    Dániel Kincses🇭🇺 · László Kovács🇭🇺 · Máté Csanád🇭🇺

    High-energy nuclear physics explores the properties of strongly interacting matter created in relativistic collisions of nuclei. Femtoscopy, a subfield of high-energy physics, utilizes quantum-statistical correlations of particles to characterize the space-time geometry of the particle-emitting source. Recent measurements and phenomenological investigations indicated that the shape of the source for identical pions can be well-described by Lévy-stable distributions. The significant power-law tail of the pion source observed both in experiment and in simulations has been shown to originate from the process of Lévy walk during the hadronic scattering phase of the collisions. To better understand the physical processes behind the formation of such power laws, an important next step is to investigate particle species dependence, especially the source shape of identical kaon and proton pairs. As a direct continuation of our previous studies, in this Letter, we present a detailed three-dimensional investigation of the two-particle source shape in simulations of Au+Au collisions at 200 GeV per nucleon pair collision energy using the EPOS3 model. We show the dependence of the extracted femtoscopic source parameters on particle species, centrality and average transverse mass. We find that the scale parameters do not show a clear transverse mass scaling between particle species, as there are systematic differences in the overlapping regions. The power-law exponents of pion and kaon pairs are compatible, while for protons it is higher, closer to the Gaussian limit. When new experimental measurements of kaon and proton correlations become available, these results will provide the basis of a data-model comparison.

    hep-ph0 citations
21. 21*

    Probing Axion Nucleon Coupling with Optomechanical Frequency Shift Measurements

    Jiawei Li🇨🇳 · Ka-di Zhu🇨🇳

    The search for non-baryonic dark matter remains a key focus in modern physics, with the light pseudoscalar axion serving as a well-motivated candidate. Here, we present a laboratory-scale detection scheme to constrain axion-nucleon interactions using a levitated optomechanical sensor, complementing conventional spin-precession and inverse-square-law tests. By monitoring a micro-spherical test mass levitated near alternative aluminum and silver substrate mirrors, our dual-channel differential readout extracts the spin-independent force gradient generated by two-axion exchange. This approach translates the short-range interaction directly into a resolvable splitting in the optical transmission peaks. Our evaluation indicates that for symmetric nucleon coupling , the dual-cavity platform establishes competitive upper bounds, improving upon existing constraints by up to two orders of magnitude within the $m_a$ in [0.1, 1]eV mass range.

    hep-ph0 citations
22. 22*

    Electromagnetic Signatures From Primordial Black Holes in the Solar System

    Alexandra P. Klipfel🇺🇸 · David I. Kaiser🇺🇸

    Primordial black holes (PBHs) in the asteroid-mass range, with typical masses $10^{17}\mathrm{g}\lesssim M\lesssim 10^{23}\mathrm{g}$, have drawn significant recent attention as a viable dark matter candidate. The peak frequencies of photons emitted via Hawking radiation from asteroid-mass PBHs range from infrared to $\gamma$-ray bands. We calculate expected local transit rates for extended PBH mass distributions which could comprise all the dark matter. We evaluate prospects for detecting Hawking-radiated photons from local PBH transits through the inner Solar System and from PBH explosions in the far outer edges of the Solar System. We consider several existing and proposed ground-based and space-based instruments sensitive to photons from the radio band to ultrahigh energy $\gamma$-rays. We find that proposed instruments, such as the AMEGO-X satellite, could reliably detect PBH transits within $\mathcal{O}(0.1\mathrm{AU})$ of the Earth, while the HAWC and LHAASO observatories are both sensitive to PBH explosions out to $\mathcal{O}(0.1\mathrm{pc})$ and $\mathcal{O}(0.5\mathrm{pc})$ respectively. We conclude by specifically considering potential companion electromagnetic signatures in the case of a PBH explosion about $10^3\mathrm{AU}$ from Earth, which has been suggested as a potential source for the $\sim 220\mathrm{PeV}$ ultrahigh-energy KM3-230213A neutrino event observed by the KM3NeT collaboration in 2023. Whereas we find that the recent KM3NeT event would not have yielded detectable electromagnetic signals -- due to its location on the sky, proposed distance from Earth, and the offline status of the HAWC observatory at that time -- we demonstrate that future PBH explosions at comparable distances could yield measurable electromagnetic signals at Earth, depending on alignment of the PBH burst with detector fields of view.

    hep-phastro-ph.COastro-ph.HE1 citation
23. 23*

    Unitarity bounds and form-factor predictions for $B$-meson decays

    Nico Gubernari🇬🇧

    This paper is organized around three main objectives. First, I review in a pedagogical way the unitarity bounds for form factors in $B$-meson decays, together with the parametrizations most commonly used in phenomenological analyses. These include BGL, BCL, CLN, and the Dispersive Matrix (DM) method. I also clarify the relation between BGL and DM, showing that they are two equivalent implementations of the same unitarity information. Second, I demonstrate that the standard BGL and DM constructions are strictly rigorous only when no subthreshold cuts are present. For $B$-meson decays, this requirement is fulfilled exclusively by the $B\to \pi$ FFs. To treat the generic case, I fully develop the GG parametrization introduced in previous work and show how the same logic extends to a DM-like construction. Third, I perform three combined analyses and obtain form-factor predictions over the full semileptonic region: one for $B\to \pi$ and $B_s\to K^{(\ast )}$, one for $B\to K^{(\ast )}$ and $B_s\to \varphi$, and one for $B\to D^{(\ast )}$ and $B_s\to D_s^{(\ast )}$. All numerical results, posterior samples, analysis files, and plots are provided in the supplementary material (https://github.com/gubernari/suppl-unitb).

    hep-ph3 citations
24. 24*

    On the Statistical Interpretation of Discoveries in LHC Data

    S. V. Chekanov🇺🇸 · E. J. Weik🇺🇸

    We examine discovery criteria at the Large Hadron Collider (LHC) within a model-independent framework, with particular emphasis on the statistical signatures of new physics. This study is motivated by the recent shift from model-specific searches based on a small number of distributions to broad, model-agnostic strategies, which offer substantially greater sensitivity to unexpected phenomena. We revisit the well-known criterion of a local statistical significance of $5\sigma$ for the observation of new phenomena in invariant-mass distributions and discuss how this threshold should be modified to account for look-elsewhere effects arising not only from multiple bins within a given distribution, but also from the simultaneous consideration of multiple distributions. We present a simple but statistically conservative relation between local and global significances in the presence of multiple invariant-mass distributions at the LHC, which can serve as a useful first approximation for planning future measurements.

    ↳ physics.data-anhep-exhep-phJ.Phys.G(2026)·1 citation
25. 25*

    Gravitational Waves from Post-Inflationary Magnetism: Direct and Scalar-Induced Contributions

    Subhasis Maiti🇮🇳

    We study stochastic gravitational waves generated in a post-inflationary magnetogenesis scenario with time-dependent gauge couplings during inflation and reheating. In this setup, magnetic anisotropic stress directly sources gravitational waves, while the induced curvature perturbations generate an additional scalar-induced GW component. We compare the spectral behavior of the two contributions and find that the magnetic component dominates the peak amplitude, whereas the scalar-induced contribution becomes important on larger scales. For blue magnetic spectra with $n_{\mathrm{b}}\ge 3/2$, both spectra follow the universal infrared scaling ${\Omega }_{\mathrm{GW}}(f\ll f_{\mathrm{peak}})\propto f^3$. However, their ultraviolet behaviors differ significantly for $f>f_{\mathrm{peak}}$, leading to distinct spectral features. For suitable reheating and magnetogenesis parameters, the resulting GW signal naturally extends into the nano-Hz range relevant for pulsar timing array observations, while remaining consistent with current bounds. The distinct spectral features of the two components may provide a useful probe of reheating dynamics and primordial magnetogenesis.

    ↳ astro-ph.COhep-phPRD(2026)·2 citations
26. 26*

    Pulse Modulation as a Signature of the Asteroid-Neutron Star Collision Model for High-Energy Transients

    Partha Bagchi🇮🇳 · Biswanath Layek🇮🇳 · Dheeraj Saini🇮🇳 · Anjishnu Sarkar🇮🇳 · Ajit M. Srivastava🇮🇳 · Deepthi Godaba Venkata🇮🇳

    Asteroid-neutron star collision models have been proposed as possible sources of high-energy transients, such as gamma-ray bursts (GRBs) and fast radio bursts (FRBs). The sequence of events following the impact of the asteroid and finally dissolving into the neutron star can have several other observable consequences. We propose that due to the development of the off-diagonal moment of inertia (MI) components, the merger's aftermath can lead to the wobbling of the pulsar (assuming the neutron star happens to be a pulsar). Using sample values of various parameters, viz., size, shape, the locations of the deposits, and the pre-existing pulsar deformation parameter ($\eta$), we calculate the detailed pulse profile modulation of the pulsar. We observe a distinct pattern of pulse profile modulation on a characteristic timescale enhanced by a factor of $1/\eta$ compared to the pulse timing. Importantly, even small changes in the MI components, of order $ϵ$, can produce large pulse profile modulations of order $ϵ/\eta$ (depending on the relative location of asteroid material deposition). Thus, if an asteroid-neutron star collision is responsible for a high-energy transient, the associated pulse profile modulation may serve as a falsifiable observational signature of such an event.

    ↳ astro-ph.HEhep-phnucl-thphysics.class-ph+1MNRAS(2026)·1 citation
27. 27*

    Spacetime discreteness via consistent microscopic measurement

    Weihu Ma🇨🇳 · Yu-Gang Ma🇨🇳

    The physical origin of spacetime discreteness remains a central open problem in quantum gravity, with most existing approaches relying on specific microscopic structures or model-dependent assumptions. In this letter, spacetime discreteness can arise instead as a consequence of consistent microscopic measurement. By treating infinitesimal spacetime intervals as scale-dependent measurement outcomes rather than predefined geometric entities, we formulate a Micro-Measurement Principle in which spacetime quantum fluctuations are encoded directly in the scaling structure. An equivalent dual representation of microscopic lengths leads to discrete, equidistant measurement outcomes, with the corresponding scaling-deformed uncertainty relation thereby reducing to the standard Heisenberg form. The microscopic lengths are further governed by a geometric renormalization-group flow admitting finite-length fixed points. This construction preserves Lorentz invariance and general covariance without ad hoc cutoffs or symmetry breaking. Our results show that the classical continuous-spacetime description corresponds to an unstable limiting regime, whereas a finite microscopic length and a discrete spacetime structure arise naturally from the fundamental requirements of micro-measurement consistency.

    ↳ gr-qchep-phPLB(2026)·0 citations
28. 28*

    Quantum-Corrected Q-balls in the Friedberg-Lee-Sirlin Model

    Yong-Xiang Su🇨🇳 · Qi-Xin Xie🇬🇧 · Shuang-Yong Zhou🇨🇳

    We study the real-time quantum dynamics of Q-balls in the Friedberg-Lee-Sirlin model within the inhomogeneous Hartree approximation. The mean fields are evolved self-consistently with the leading quantum two-point functions, which are implemented numerically through a stochastic ensemble representation. After introducing a renormalized formulation and a classical-limit scaling, we simulate single-Q-ball configurations in $3+1$ dimensions and compare their quantum-corrected evolution with the corresponding classical dynamics. We find a clear separation between a classical regime, where quantum fluctuations remain small and the evolution closely follows the classical solution, and a quantum regime, where the fluctuation sector carries a sizable fraction of the Noether charge. We also observe a periodic exchange of Noether charge between the mean fields and the fluctuation modes within the Hartree approximation. We further investigate the stability of quantum-corrected Q-balls and find an intermediate window in which configurations that are classically stable become unstable once Hartree fluctuations are included. Our results provide a first step toward real-time quantum simulations of Q-balls in renormalizable two-field soliton models.

    ↳ hep-thhep-lathep-ph1 citation
29. 29*

    Quantum field approach to relativistic turbulence

    Esteban Calzetta🇦🇷

    The goal of this work is apply field theory methods to discuss turbulence in relativistic real fluids. We shalltake as representtive model an Israel-Stewart framework, where the conservation laws for the energy-momentum tensor are supplemented by a Cattaneo-Maxwell equation for its viscous part, which relaxes to its Landau-Lifshitz value. We assume the parameters of the model scale with the peed of light $c$ in such a way that as $c\to \infty$ the fluid becomes an incompressible fluid obeying the Navier-Stokes equations. We find that for finite $c$ each mode of the fluid behaves as an overdamped oscillator with two decaying rates, one that converges to the K41 value and another that diverges when $c\to \infty$. There are therefore two basic flow patterns, one where the fast decaying modes are absent, and which repreduces Kolmogorov turbulence, and another made only of fast decaying modes. We point out the scaling relations that allow the latter flow pattern to sustain an entropy cascade.

    ↳ physics.flu-dynhep-ph1 citation
30. 30*

    Endpoint formulation and Molien--Weyl structure for the \(N=2\), large--\(d\) BFSS/BMN models

    Badis Ydri🇩🇿

    We study the \(N=2\), large--\(d\) sector of BFSS/BMN-type matrix quantum mechanics on the lattice in the Gaussian regime. We develop a radial endpoint formulation in which the bulk, gauge, and longitudinal degrees of freedom are integrated out, leaving transverse endpoint variables governed by an effective holonomy potential. We show that this planar endpoint formulation is equivalent to the angular Molien--Weyl description of the gauge-projected partition function, up to a universal spectator factor. This relation allows the low-temperature expansion of the endpoint partition function to be obtained from the Molien--Weyl result, whose quadratic coefficient \(d(d+1)/2\) counts Gaussian singlet states above the vacuum. We then analyze the continuum limit of the quadratic coefficient and show that it separates into a Gaussian contribution, a \(D\)-channel, and a \(\beta\)-channel. The naive Gaussian term becomes trivial, while the exact holonomy kernel generates finite continuum contributions through singular dependence on the endpoint Gaussian width and anisotropic coupling. We then study the geometry of the holonomy potential and show that its relevant saddle is a constrained boundary saddle on the aligned branch, rather than an unconstrained critical point. The associated transverse expansion captures the local saddle geometry, but any finite polynomial truncation has a trivial continuum limit. Finally, we introduce a non-polynomial toy model based on \(V_{\rm toy}(B)=-\log\cosh B\), which provides a completion of the transverse expansion and reproduces exactly the continuum \(D\)-channel contribution \(-2d\). This prepares the geometric interpretation of the \(D\)-channel as a Wishart--Stiefel entropy associated with an emergent four-dimensional geometry embedded \(\mathbb R^d\) in the endpoint formulation.

    ↳ hep-thgr-qchep-lathep-ph+23 citations
31. 31*

    Intermittency and fractal behaviour of charged particles in EPOS4 and PYTHIA8 generated events at LHC energies

    Fakhar Ul Haider🇮🇳 · Ramni Gupta🇮🇳 · Salman Khurshid Malik🇮🇳 · Balwan Singh🇮🇳 · Zarina Banoo🇮🇳 · Pryianka Choudhary

    Large number density fluctuations of the charged particles produced in heavy-ion collisions are a promising signature for exploring the QCD phase transition and critical point in the nuclear matter phase diagram. Intermittency methodology is used to probe the fractal and scale invariant nature of these fluctuations. Intermittency is the phenomenon of power-law growth of the normalized factorial moments ($F_{\mathrm{q}}$) of the number density distributions over decreasing bin size. The charged particles generated in the midrapidity region using PYTHIA8 and EPOS4 (UrQMD ON/OFF) for Pb--Pb collisions at $\sqrt{s_{\text{NN}}}$ = 5.02 TeV are studied. Scaling behaviour of $F_{\mathrm{q}}$ are studied as a function of phase space partitioning and second order moments to quantify the particle production nature within the default constraints of the two models. The scaling exponent related to the phase transition and parameters connected to fractal nature obtained for both these models show the absence of fluctuations of critical nature and multifractal behaviour.

    ↳ hep-exhep-phnucl-th0 citations
32. 32*

    Hard cutoff and gauge theories

    V. Branchina🇮🇹 · F. Contino🇮🇹 · R. Gandolfo🇮🇹 · A. Pernace🇮🇹

    According to usual calculations, the use of a hard cutoff $\Lambda$ in gauge theories leads to a violation of gauge invariance. This seems to generate a tension between gauge theories and the Wilsonian effective field theory (EFT) paradigm, where $\Lambda$ has the physical meaning of ultimate scale of the theory, the scale above which the latter has to be replaced by its UV completion. In the present work, considering the Euler-Heisenberg correction to the free Maxwell action, we present a way to introduce the Wilsonian hard UV cutoff $\Lambda$ that preserves gauge invariance at the quantum level. For both scalar and fermionic QED, we recover the well-known Euler-Heisenberg result obtained within proper-time regularization, apart from terms that are generically cutoff-suppressed. These terms, periodic in the inverse background field, might become relevant in regimes where the latter probes scales not much smaller than $\Lambda$. On the theoretical side, the methods developed in the present work represent a first step towards a new (closer in spirit to the Wegner-Houghton construction) realization of the Wilsonian renormalization group program in gauge theories.

    ↳ hep-thhep-phPRD(2026)·1 citation
33. 33*

    Linac: linear algebra with CUDA over finite fields

    Giuseppe De Laurentis🇬🇧 · Jack Franklin🇬🇧

    Solving linear systems of polynomial equations is a ubiquitous problem in both mathematics and physics. The standard approach, Gaussian elimination, scales cubically with system size and often constitutes a computational bottleneck. The algorithm's inherent parallelism makes it well-suited for modern computing architectures, namely graphics processing units (GPUs), which offer significantly higher throughput than CPUs. Additionally, the use of finite fields -- integers modulo a prime -- in place of floating-point arithmetic offers a scalable solution to the issue of numerical precision loss, which becomes increasingly problematic at large system sizes. With Linac, we present a high-performance, open-source, parallel implementation of Gaussian elimination over finite fields and floating-point arithmetic. This tool has been developed for applications to analytic reconstruction of scattering amplitudes in quantum field theory.

    ↳ physics.comp-phhep-phhep-th1 citation
34. 34*

    Core-collapse supernovae and supernova neutrinos

    B. Mueller🇦🇺 · B. Sykes🇦🇺

    Core-collapse supernovae are the terminal explosions of massive stars. After successive phases of nuclear fusion proceeding up to silicon burning, these stars form an iron core that is supported by electron degeneracy pressure. The core eventually collapses to a proto-neutron star, and in most cases the outer layers of the star are ejected by a shock wave, with a kinetic energy of order $10^{51}\mathrm{erg}$. Neutrinos and multi-dimensional fluid flow play a key role in extracting energy from the collapsed core to drive the explosion. After adumbrating the astrophysical context of stellar evolution and transient observations, this chapter sketches the modern theory of neutrino-driven supernova explosions, and discusses the key role of nuclear physics and neutrino interaction rates in the supernova problem. It also outlines the role of neutrinos and gravitational waves as probes into the supernova core.

    ↳ astro-ph.HEgr-qchep-phnucl-th2 citations
35. 35*

    Early- and Late-Time Modifications to $\Lambda$CDM: Implications for the Hubble Tension

    Rahul Dhyani🇮🇳 · Purba Mukherjee🇮🇳 · Arindam Chatterjee🇮🇳 · Anjan A Sen🇮🇳

    We investigate an extension of $\Lambda$CDM in which a fraction of cold Dark Matter (DM) decays into invisible dark radiation (DR) around the radiation-matter equality epoch, together with a non-standard dark energy (DE) equation of state characterized by $w_0$. The decaying DM component modifies the early expansion history and reduces the sound horizon at baryon drag, while the DE alters the expansion rate at the late times. A comprehensive analysis combining \texttt{Planck 2018+ACT DR6+DESI DR2+CMB lensing} datasets has been carried out to explore the viability of this framework in addressing the $H_0$ tension. This model yields a Hubble constant of $H_0=69.83\pm 0.98\mathrm{km}{\mathrm{s}}^{-1}\mathrm{Mp}{\mathrm{c}}^{-1}$, reducing the discrepancy with SH0ES measurement to $\sim 2.2\sigma$ and local distance network measurement (H0DN) to $\sim 2.9\sigma$. Further, considering \texttt{SH0ES} and \texttt{Pantheon+}, the inferred value of the Hubble constant becomes $H_0=70.20\pm 0.66\mathrm{km}{\mathrm{s}}^{-1}\mathrm{Mp}{\mathrm{c}}^{-1}$. The Bayesian evidence suggests that this framework offers a fit to the relevant cosmological datasets at a statistically similar level as $\Lambda$CDM. It is observed that correlated early- and late-time modifications to the cosmological expansion history provide a more effective route to reducing the $H_0$ tension than either class of modification alone.

    ↳ astro-ph.COhep-ph2 citations
36. 36*

    Multipole tomography of atomic nuclei with symmetry-conserved theories

    X. Sun🇨🇳 · J. Dobaczewski🇬🇧 · W. Nazarewicz🇺🇸 · H. Wibowo🇬🇧

    To define the intrinsic reference frame and multipole moments of angular-momentum-$J$-conserving many-body wave functions, we introduce two-body conditional probabilities of finding two nucleons at different positions in space. In this way, quadrupole deformations of states with $J\le 1/2$, which are not accessible via spectroscopic one-body quadrupole moments, can be characterized. We illustrate the method with nuclear density functional theory calculations for $J=0$ states of ${}^{16}$O and ${}^{20}$Ne, the latter obtained by restoring rotational symmetry of prolate or oblate intrinsic configurations. We show that the two-body quadrupole shape characterizations differ from one-body moments obtained from broken-symmetry states.

    ↳ nucl-thhep-phnucl-ex2 citations
37. 37*

    Unifying Early and Late Dark Energy: Dynamical Requirements and Obstructions

    William Giarè🇺🇸 · Jeremy Sakstein🇺🇸

    We investigate whether early- and late-time dark energy could arise from a single scalar field. Adopting a bottom-up perspective, we first identify the sequence of dynamical regimes that any unified scenario must traverse to account for both an early dark energy phase relevant for pre-recombination solutions of the Hubble tension and the late-time acceleration of the Universe. We derive the corresponding requirements on the scalar energy density and equation of state. We then adopt a complementary top-down perspective and translate these requirements into constraints on the phase-space structure of minimally coupled scalar fields with tracking-like dynamics. We show that satisfying all requirements necessitates a potential with three distinct slopes, arranged in a steep-steeper-shallow hierarchy. This conclusion remains unchanged in the presence of conformal couplings to dark matter. These results place strong constraints on attempts to construct unified models of early- and late-time dark energy. We discuss implications for model-building.

    ↳ astro-ph.COgr-qchep-ph7 citations
38. 38*

    Fermion Families and Pontryagin Class: Topological Field Theory via Colour Symmetry Extension

    Zheyan Wan🇨🇳 · Juven Wang🇬🇧 · Shing-Tung Yau🇨🇳

    Family puzzle asks why the Standard Model (SM) features exactly 3 families of quarks and leptons. Motivated by topological constraints, we study 4d fermionic anomalies with discrete $Z_n$ symmetry, classified by the 5d spin bordism group. We show that only the group-cohomology subclass H${}^5(Z_n,U(1))\cong Z_n$ can be canceled by an anomalous $Z_n$-symmetric 4d $Z_n$-gauge topological quantum field theory (TQFT), while beyond-group-cohomology $A_{Z_n}{p}_1$ involving the Pontryagin class $p_1$ cannot (except $n=2,3$). More generally, we prove that any cocycle ${\alpha }_d\in$H${}^d(Z_n,U(1))$ in odd spacetime dimension $d\ge 3$ is trivialised by the symmetry extension $1\to Z_n\to Z_{n^2}\to Z_n\to 1,$ and we construct the corresponding symmetric anomalous boundary TQFT. For $d=5$ and $n=3$, this yields a Spin$\times Z_3$-symmetric 4d $Z_3$-gauge TQFT that cancels the mixed discrete $(\mathbf{B}+\mathbf{L})$-gauge-gravitational anomaly of the SM in the absence of 3 "sterile" right-handed neutrinos ${\nu }_R$. We analyze a generalized SM with $N_c$ colors and $N_f$ families and argue that missing $N_f$ copies of the ${\nu }_R$ can be naturally replaced by a 4d anomalous $Spin{\times }_{Z_2^F}{Z}_{2N_f,\mathbf{B}+\mathbf{L}}$ symmetric $Z_N$-gauge TQFT under the anomaly cancellation, via a $Z_N$ symmetry extension construction $1\to Z_N\to Spin\times Z_{N{N}_f}\to Spin{\times }_{Z_2^F}{Z}_{2N_f}\to 1$ of anomalous topological order. For minimal nonzero $(N,N_f)$, the allowed minimal extensions are $N=1,3,4,12$, depending on divisibility of $N_f$ by 2 and 3. Combining Witten anomaly and other constraints, we prove that $N=N_c=N_f=3$, with 3 families and 3 colors, is the unique minimal solution to match with the color-center baryon-to-quark symmetry extension $1\to Z_{N_c}\to Spin{\times }_{Z_2^F}{Z}_{2N_c{N}_f,\mathbf{Q}+N_c\mathbf{L}}\to Spin{\times }_{Z_2^F}{Z}_{2N_f,\mathbf{B}+\mathbf{L}}^F\to 1$. We also prove that $A_{Z_3}{p}_1=0\mathrm{mod}3$ for the mod 3 cohomology class.

    ↳ hep-thcond-mat.str-elhep-phmath-ph+1Phys. Rev. D (2026)·2 citations
39. 39*

    Strong Constraints on Millisecond Pulsar Injection Spectra from Fermi-LAT Observations of the Galactic Center

    Jordan Koechler🇮🇹 · Pedro De la Torre Luque🇪🇸 · Mattia Di Mauro🇮🇹

    Millisecond pulsars (MSPs) are a leading explanation of the Galactic Center excess (GCE) observed in Fermi-LAT data. We constrain this scenario by jointly modeling prompt and inverse-Compton $\gamma$ rays from MSP-injected $e^{\pm }$ on the Galactic bulge, using recent Fermi-LAT GCE spectra from state-of-the-art interstellar emission models and data analysis. Current data place strong upper limits on the efficiency ratio ${\eta }_e/{\eta }_{\gamma }$ across broad $e^{\pm }$ injection scenarios, surpassing those from globular-cluster observations with MAGIC and competitive with projected CTAO sensitivities toward the Galactic bulge.

    ↳ astro-ph.HEhep-ph0 citations
40. 40*

    Time-frequency analysis of nonlinear Compton scattering via joint probability distributions

    Nikita Larin🇩🇪 · Daniel Seipt🇩🇪

    The interaction of charged particles with an intense laser pulse gives rise to a number of characteristic spectral features of emitted radiation, including the generation of harmonics, spectral broadening due to the phase-dependent ponderomotive red shift, and the emergence of intricate sub-harmonic structures. These effects are accumulated over the course of the interaction with the electromagnetic field and are therefore inherently nonlocal in nature. For a deeper understanding of strong-field quantum electrodynamics (SFQED) processes and their practical applications, it is desirable to employ tools that enable simultaneous analysis in the time and energy domains. In time-frequency analysis, such tools are provided by joint distributions (JDs). In this work, we demonstrate how a JD can be devised within the SFQED framework. Specifically, we focus on constructing a non-negative JD, which allows for a clear probabilistic interpretation. We study the properties of the proposed distribution and test its utility by applying it to the nonlinear Compton scattering in complex laser pulse configurations with carrier-envelope phase and variable polarization.

    ↳ physics.opticshep-phPRD(2026)·0 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.