Tue·Jul 23, 2024Tuesday·July 23, 2024

1. 01*

   Implications of Sgr A${}^{\ast }$ on the $\gamma$-rays searches of Bino Dark Matter with $(g-2{)}_{\mu }$

   Utpal Chattopadhyay🇮🇳 · Debottam Das🇮🇳 · Sujoy Poddar🇮🇳 · Rahul Puri🇮🇳 · Abhijit Kumar Saha🇮🇳

   We analyse the impact of dark matter density spike around the Milky Way's supermassive black hole (SMBH), Sgr A${}^{\ast }$, in probing the Bino-dominated neutralino dark matter (DM) ${\tilde{\chi }}_1^0$ within the MSSM, which typically produces relatively faint signals in the conventional DM halos. In particular, we explore the indirect search prospects of sub-TeV Bino-Higgsino and Bino-Wino-Higgsino DM in the MSSM, consistent with the supersymmetric predictions required to explain the anomalous magnetic moment of the muon. Typical over-abundance of Bino DM is ameliorated with slepton and/or Wino coannihilations. The lightest neutralino, thus, may be associated with a compressed supersymmetric particle spectrum, which, in general, is difficult to probe at conventional LHC searches. Similarly, for a rather tiny Higgsino mixing, ${\tilde{\chi }}_1^0$ does not offer much prospect to assess its predictions at dark matter direct detection searches. Accommodating the inclusive effects of density spike, here, we present the requisite boost factor to facilitate $\gamma -$ray searches of Bino-dominated DM in the MSSM, especially focusing on the Fermi-LAT and HESS observations.

   hep-phastro-ph.COJCAP(2025)·4 citations
2. 02*

   Non-linear gauge-Higgs CP violation

   Akanksha Bhardwaj🇺🇸 · Christoph Englert🇬🇧 · Dorival Gonçalves🇺🇸 · Alberto Navarro🇺🇸

   A critical element of the LHC physics program is the search for an additional source of CP violation. This is largely unexplored in the context of non-linear Higgs physics, which is naturally described in Higgs Effective Field Theory (HEFT). Relevant new higher-dimensional operators modify the production rate and branching ratios of the Higgs boson, de-correlating different Higgs multiplicities. In this work, we consider single Higgs and Higgs pair production via weak boson fusion from the perspective of gauge-Higgs CP violation through the lens of Higgs non-linearity. This generalizes existing rate-based searches and analyses by the ATLAS and CMS experiments. Particular focus is given to the phenomenological differences in the expected BSM sensitivity pattern when comparing HEFT constraints with Standard Model Effective Field Theory (SMEFT) limits.

   hep-phPRD(2024)·5 citations
3. 03*

   Exotic Particles at the DUNE Near Detector from Charged Pion Scattering

   Diana Forbes🇺🇸 · Yonatan Kahn🇺🇸 · Rachel Nguyen🇺🇸

   Fixed-target proton-beam experiments produce a multitude of charged pions that rescatter in the beam dump. These charged pion scattering events can be an additional irreducible source of exotic particles which couple to photons or hadrons. We analyze the sensitivity of the DUNE Near Detector complex to millicharged particles (MCPs) and heavy axion-like particles (ALPs) with low-energy couplings to gluons. Using the framework of chiral perturbation theory, we demonstrate regimes of parameter space where the charged pion production channel dominates over previously-considered production mechanisms for both MCPs and ALPs, thereby improving the sensitivity of DUNE to these new particles compared to previous studies.

   hep-phhep-exPRD(2024)·2 citations
4. 04*

   Constraints on light dark sector particles from lifetime difference of heavy neutral mesons

   Girish Kumar🇺🇸 · Alexey A. Petrov🇺🇸

   Heavy meson decays with missing energy in the final state offer interesting avenues to search for light invisible new physics such as dark matter (DM). In this context, we show that such new physics (NP) interactions also affect lifetime difference in neutral meson-antimeson mixing. We consider general dimension-six effective quark interactions involving a pair of DM particles and calculate their contributions to lifetime difference in beauty and charm meson systems. We use the latest data on mixing observables to constrain the relevant effective operators. We find that lifetime differences provide novel and complementary flavor constraints compared to those obtained from heavy meson decays.

   hep-phhep-exPRD(2024)·3 citations
5. 05*

   Improved constraints on Higgs boson self-couplings with quartic and cubic power dependencies of the cross section

   Hai Tao Li🇨🇳 · Zong-Guo Si🇨🇳 · Jian Wang🇨🇳 · Xiao Zhang🇨🇳 · Dan Zhao🇨🇳

   Precise determination of the Higgs boson self-couplings is essential for understanding the mechanism underlying electroweak symmetry breaking. However, owing to the limited number of Higgs boson pair events at the LHC, only loose constraints have been established to date. Current constraints are based on the assumption that the cross section is a quadratic function of the trilinear Higgs self-coupling within the $\kappa$ framework. Incorporating higher-order quantum corrections from virtual Higgs bosons would significantly alter this functional form, introducing new quartic and cubic power dependencies on the trilinear Higgs self-coupling. To derive this new functional form, we propose a specialized renormalization procedure that tracks all Higgs self-couplings at each calculation step. Additionally, we introduce renormalization constants for coupling modifiers within the $\kappa$ framework to ensure the cancellation of all ultraviolet divergences. With new functional forms of the cross sections in both the gluon-gluon fusion and vector boson fusion channels, the upper limit of ${\kappa }_{{\lambda }_{3H}}={\lambda }_{3H}/{\lambda }_{3H}^{\mathrm{SM}}$ set by the ATLAS (CMS) collaboration is reduced from 6.6 (6.49) to 5.5 (5.39). However, extracting a meaningful constraint on the quartic Higgs self-coupling ${\lambda }_{4H}$ from Higgs boson pair production data remains challenging. We also present the invariant mass distributions of the Higgs boson pair at different values of ${\kappa }_{\lambda }$, which could assist in setting optimal cuts for experimental analysis.

   hep-phhep-exCPC(2025)·19 citations
6. 06*

   Standard Model anomalies and vacuum stability for lepton portals with extra $U(1)$ symmetry

   Carlo Branchina🇮🇹 · Hyun Min Lee🇰🇷 · Kimiko Yamashita🇯🇵

   Recently, the experimental values of the muon $(g-2{)}_{\mu }$ and of the $W$ boson mass $m_{{}_W}$ have both indicated significant deviations from the SM predictions, motivating the exploration of extensions with extra particles and symmetries. We revisit a lepton portal model with $U(1{)}^{\prime }$ gauge symmetry where an extra Higgs doublet, a scalar singlet and one $SU(2{)}_L$ singlet vector-like fermion are introduced. In this model, $(g-2{)}_{\mu }$ can be explained by extra one-loop contributions from the vector-like lepton and the $Z^{\prime }$ boson, whereas $m_{{}_W}$ can be increased by a tree-level mixing between the $Z$ and $Z^{\prime }$. Setting the $Z^{\prime }$ and lepton couplings at low energies to account for the SM anomalies, we perform a Renormalization Group analysis to investigate on the high-energy behaviour of the model, in particular on the issue of vacuum stability. We find that in the alignment limit for the two Higgs doublets, the Landau pole and the scale where perturbativity is lost are of order $10-100\mathrm{TeV}$, not far from the scales experimentally reached so far, and sensibly lower than the stability scale. We show how the Landau pole can be increased up to $\sim 10^9\mathrm{GeV}$ in a misaligned scenario where the experimental anomalies are still accommodated and a positive shift of the Higgs quartic coupling to improve stability can be achieved.

   hep-phhep-thJHEP(2025)·1 citation
7. 07*

   Holographic Schwinger effect in flavor-dependent systems

   Sheng Lin🇨🇳 · Xuan Liu🇨🇳 · Xun Chen🇨🇳 · Gen-Fa Zhang🇨🇳 · Jing Zhou🇨🇳

   The holographic Schwinger effect is investigated in systems with $N_f=0$, $N_f=2$, and $N_f=2+1$ using the Einstein-Maxwell-dilaton (EMD) model, incorporating equation of state and baryon number susceptibility information from lattice quantum chromodynamics (QCD). It is found that the critical electric field is smallest for $N_f=0$, indicating that the Schwinger effect is more likely to occur than in systems with $N_f=2$ and $N_f=2+1$. The critical electric field decreases with increasing chemical potential and temperature across all systems. Additionally, potential analysis confirms that the maximum total potential energy increases with the number of flavors, suggesting that existing particles may reduce the probability of particle pair production.

   hep-phPRD(2025)·10 citations
8. 08*

   Approximate magic symmetry in a cobimaximal scenario of Majorana neutrinos

   Diana C. Rivera-Agudelo🇨🇴 · S. L. Tostado🇨🇴 · Nelson E. Valderrama-Florez🇨🇴

   The searches for an underlying pattern in neutrino masses have motivated different proposals for textures in the neutrino mass matrix, which is also related to particular arrangements of the mixing matrix. Current experimental determinations of neutrino mixings have restricted some of the most studied proposals. In this work, we propose a new combined constraint on the neutrino mass matrix arising from the cobimaximal mixing and the magic symmetry in a model-independent fashion. We show that both conditions cannot be fulfilled simultaneously in an exact but rather in an approximate way. We have found that the Majorana CP phases are tightly restricted within this approach, leading to well-defined regions in the neutrinoless double beta decay amplitude. The small symmetry breaking requirement allows us to determine the Majorana phases for specific values of the lightest neutrino mass, consistent with current bounds on the mixing angles, neutrinoless double-beta decay, and cosmology results.

   hep-phInt.J.Mod.Phys.A(2025)·3 citations
9. 09*

   Strong-Coupling Extrapolation of Gell-Mann--Low Functions

   V.I. Yukalov🇷🇺 · E.P. Yukalova🇷🇺

   Gell-Mann-Low functions can be calculated by means of perturbation theory and expressed as truncated series in powers of asymptotically small coupling parameters. However, it is necessary to know there behavior at finite values of the parameter and, moreover, their behavior at asymptotically large coupling parameters is also important. The problem of extrapolation of weak-coupling expansions to the region of finite and even infinite coupling parameters is considered. A method is suggested allowing for such an extrapolation. The basics of the method are described and illustrations of its applications are given for the examples where its accuracy and convergence can be checked. It is shown that in some cases the method allows for the exact reconstruction of the whole functions from their weak-coupling asymptotic expansions. Gell-Mann-Low functions in multicomponent field theory, quantum electrodynamics, and quantum chromodynamics are extrapolated to their strong-coupling limits.

   hep-phcond-mat.stat-mechPhys.Part.Nucl.(2024)·0 citations
10. 10*

    Heavy four-quark mesons $bc\overline{b}\overline{c}$: Scalar particle

    S. S. Agaev🇦🇿 · K. Azizi🇮🇷 · H. Sundu🇹🇷

    Parameters of the heavy four-quark scalar meson $T_{\mathrm{bc}\overline{\mathrm{b}}\overline{\mathrm{c}}}$ with content $bc\overline{b}\overline{c}$ are calculated by means of the sum rule method. This structure is considered as a diquark-antidiquark state built of scalar diquark and antidiquark components. The mass and current coupling of $T_{\mathrm{bc}\overline{\mathrm{b}}\overline{\mathrm{c}}}$ are evaluated in the context of the two-point sum rule approach. The full width of this tetraquark is estimated by taking into account two types of its possible strong decay channels. First class includes dissociation of $T_{\mathrm{bc}\overline{\mathrm{b}}\overline{\mathrm{c}}}$ to mesons ${\eta }_c{\eta }_b$, $B_c^{+}{B}_c^{-}$, $B_c^{\ast +}{B}_c^{\ast -}$ and $B_c^{+}(1^3{P}_0)B_c^{\ast -}$. Another type of processes are generated by annihilations $\overline{b}b\to \overline{q}q$ of constituent $b$-quarks which produces the final-state charmed meson pairs $D^{+}{D}^{-}$, $D^0{\overline{D}}^0$, $D^{\ast +}{D}^{\ast -}$, and $D^{\ast 0}{\overline{D}}^{\ast 0}$. Partial width all of these decays are found using the three-point sum rule method which is required to calculate strong couplings at corresponding meson-meson-tetraquark vertices. Predictions obtained for the mass $m=(12697\pm 90)\mathrm{MeV}$ and width $\Gamma [T_{\mathrm{bc}\overline{\mathrm{b}}\overline{\mathrm{c}}}]=(142.4\pm 16.9)\mathrm{MeV}$ of this state are compared with alternative results, and are useful for further experimental investigations of fully heavy resonances.

    hep-phhep-exhep-latPLB(2024)·16 citations
11. 11*

    ALPs and HNLs at LHC and Muon Colliders: Uncovering New Couplings and Signals

    Marta Burgos Marcos🇪🇸 · Arturo de Giorgi🇪🇸 · Luca Merlo🇪🇸 · Jean-Loup Tastet🇪🇸

    Axion-like particles (ALPs) and heavy neutral leptons (HNLs) are two well-motivated classes of particles beyond the Standard Model. It is intriguing to explore the new detection opportunities that may arise if both particle types coexist. Part of the authors already investigated this scenario in a previous publication, within a simplified model containing an ALP and a single HNL, identifying particularly promising processes that could be searched for at the LHC. In this paper, we first consider the same setup with a broader range of both production processes and final states, both at the High-Luminosity LHC and at a future muon collider. Subsequently, we expand it to the more realistic scenario with at least two HNLs, necessary to describe the active neutrino masses. Different phenomenological signals are expected and we examine the complexities that emerge in this setup. This study paves the way for dedicated analysis at (forthcoming) colliders, potentially pinpointing the dynamics of ALPs and HNLs.

    hep-phSciPost Phys.(2025)·22 citations
12. 12*

    Z_5 two-component dark matter in the Type-II seesaw mechanism

    XinXin Qi🇨🇳 · Hao Sun🇨🇳

    We consider the Z5 two-component dark matter model within the framework of the Type-II seesaw mechanism. Due to the new annihilation processes related to triplets, the light component cannot necessarily be dominant in the dark matter relic density, which is different from the Z5 two-component dark matter model in the SM. The model is considered to explain the excess of electron-positron flux measured by the AMS-02 Collaborations in this work, which is encouraged by the decay of the triplets arising from dark matter annihilations in the Galactic halo. We discuss the cases of the light and heavy components determining dark matter density within a viable parameter space satisfying relic density and direct detection constraints, and by fitting the antiproton spectrum observed in the PAMELA and AMS experiments, we find that the parameter space is flexible and the electron-positron flux excess can be obtained in both cases with the mass of two dark matter particles being larger than that of the triplets'.

    hep-phEPJC(2025)·5 citations
13. 13*

    Attractor for 1+1D viscous hydrodynamics with general rapidity distribution

    Shile Chen🇨🇳 · Shuzhe Shi🇨🇳

    Attractor, supposed to be one of the possible answer for the early applicability of hydrodynamics in the evolution with different initial conditions, has attracted great attention to the fast decreasing of degrees of freedom in heavy ion collision. We found attractor behaviors for 1+1D viscous hydrodynamics with general rapidity distribution based on MIS theory. Meanwhile, we also observe that a rapid expansion in the fluid velocity is essential for a rapid early time attractor.

    hep-phnucl-thPRC(2025)·10 citations
14. 14*

    Locality in collider tests of Quantum Mechanics with top quark pairs

    Regina Demina🇺🇸 · Gabriel Landi🇺🇸

    Tests of quantum properties of fundamental particles in high energy colliders are starting to appear. However, such experiments may suffer from the locality loophole. We argue for criteria that take into account the space-like separation between measurements for the case of spin correlations in top quark pairs produced at the LHC. We derive bounds considering three different definitions of what constitutes the quantum measurement - the decay of top quarks, the decay of W bosons, and the stable decay products contacting a macroscopic device.

    hep-phPRD(2025)·11 citations
15. 15*

    Unitarization of electron scattering with an external potential at NLO in QED

    J. A. Oller🇪🇸 · Marcela Peláez🇺🇾

    We have calculated the one-loop scattering amplitude of an electron by an external Coulomb potential in QED free of infrared divergences. This feature is achieved by applying the Faddeev-Kulish formalism, which implies a redefinition of both the asymptotic electronic states and of the $S$ matrix. Additionally, we have also derived the infrared-finite one-loop partial-wave amplitudes for this process by applying a recent method in the literature. Next, these partial-wave amplitudes are unitarized based on analyticity and unitarity by employing three different methods of unitarization: the algebraic $N/D$ method, the Inverse Amplitude Method and the first iterated $N/D$ method. Then, we have studied several partial waves both for physical momentum and for complex ones to look for bound-state poles. The binding momentum for the fundamental bound state in $S$ wave is discussed with special detail. This is a wide-ranging method for calculating nonperturbative partial-wave amplitudes for infinite-range interactions that could be applied to many other systems.

    hep-phhep-thJHEP(2024)·3 citations
16. 16*

    Perturbative and nonperturbative QCD corrections in polarized nucleon structure functions and spin asymmetries of nucleons

    F. Zaidi🇮🇳 · M. Sajjad Athar🇮🇳 · S. K. Singh🇮🇳

    We have studied the deep inelastic scattering (DIS) of polarized charged leptons from polarized nucleon targets and evaluated the polarized nucleon structure functions $g_{1N,2N}(x,Q^2)$ as well as the nucleon asymmetries $A_{1N,2N}(x,Q^2)$ for protons and neutrons. The higher order perturbative corrections up to the Next-to-Next-to-the-Leading Order (NNLO), using the parameterization of Polarized Parton Distribution Functions (PPDFs) given by Borsa, Stratmann, Vogelsang, de Florian and Sassot (BDSSV24) in the 3-flavor $\overline{\text{MS}}$ scheme, along with the nonperturbative corrections$-$namely the twist-3 corrections and the Target Mass Corrections (TMC)$-$have been included in the calculations. The numerical results for the polarized nucleon structure functions, the nucleon asymmetries and the sum rule integrals of the nucleon structure functions$-$corresponding to the Ellis-Jaffe, Bjorken, and Burkhardt-Cottingham sum rules$-$have been evaluated numerically and are found to be in agreement with the experimental results from SLAC, CERN, DESY and JLab. The benchmarking of the PPDFs of BDSSV24 at NNLO using the present data on polarized nucleon structure functions and other observables will be useful in studying the nuclear medium effects in the scattering of the charged leptons from nuclei at the JLab, EIC, DESY, etc., and the scattering of the (anti)neutrinos from polarized nucleons and nuclei at the proposed neutrino factories.

    hep-phPRD(2025)·2 citations
17. 17*

    Phenomenology of bubble size distributions in a first-order phase transition

    Danny Marfatia🇺🇸 · Po-Yan Tseng🇹🇼 · Yu-Min Yeh🇹🇼

    In a cosmological first-order phase transition (FOPT), the true and false vacuum bubble radius distributions are not expected to be monochromatic, as is usually assumed. Consequently, Fermi balls (FBs) and primordial black holes (PBHs) produced in a dark FOPT will have extended mass distributions. We show how gravitational wave (GW), microlensing and Hawking evaporation signals for extended bubble radius/mass distributions deviate from the case of monochromatic distributions. The peak of the GW spectrum is shifted to lower frequencies, and the spectrum is broadened at frequencies below the peak frequency. Thus, the radius distribution of true vacuum bubbles introduces another uncertainty in the evaluation of the GW spectrum from a FOPT. The extragalactic gamma-ray signal at AMEGO-X/e-ASTROGAM from PBH evaporation may evince a break in the power-law spectrum between 5 MeV and 10 MeV for an extended PBH mass distribution. Optical microlensing surveys may observe PBH mass distributions with average masses below $10^{-10}{M}_{\odot }$, which is not possible for monochromatic mass distributions. This expands the FOPT parameter space that can be explored with microlensing.

    hep-phastro-ph.COhep-exEPJC(2025)·7 citations
18. 18*

    Model-independent analysis of new physics effects in $B\to K_2^{\ast }(1430){\mu }^{+}{\mu }^{-}$ decay

    Juhi Vardani (Indian Institute of Technology Jodhpur, Jodhpur, India)🇮🇳 · Ria Sain (Department of Physics, Indian Institute of Technology Guwahati, Assam, India)🇮🇳

    Recently, the LHCb Collaboration provided updated measurements for the lepton flavour ratios $R_K$ and $R_{K^{\ast }}$. The currently observed values align with the predictions of the standard model. In light of these recent updates, our investigation delves into the repercussions of new physics characterized by universal couplings to electrons and muons. We specifically focus on their impact on various observables within the $B\to K_2^{\ast }(1430)(\to K\pi ){\mu }^{+}{\mu }^{-}$ decay. These observables include the differential branching ratio, forward-backward asymmetry ($A_{FB}$), longitudinal polarization asymmetry ($F_L$), and a set of optimized observables ($P_i$). Our findings indicate that the branching ratio of $B\to K_2^{\ast }(\to K\pi ){\mu }^{+}{\mu }^{-}$ decay can be suppressed up to $25\%$ for various new physics solutions. Furthermore, all permissible new physics scenarios demonstrate finite enhancement in the muon forward-backward asymmetry $(A_{FB})$ as well as an increase in the value of the optimized angular observable $P_2$. Moreover, in the presence of new physics zero crossing points for $A_{FB}$ and $P_2$ shift towards higher $q^2$. The current data have a mild deviation from SM predictions in $P_5^{\prime }$ observable in the low-$q^2$ bin. We also explored massive $Z^{\prime }$ models, which can generate universal 1D new physics scenarios, characterized by $C_9^{NP}<0$, $C_9^{NP}=-C_{10}^{NP}$, and $C_9^{NP}=-C_9^{\prime }$. Using additional constraints coming from $B_s-\overline{B_s}$ mixing and neutrino trident process, we find that the conclusions of the model-independent analysis remain valid.

    hep-phEPJC(2024)·4 citations
19. 19*

    Power counting of the pion-dilaton effective field theory

    Maarten Golterman🇺🇸 · Yigal Shamir🇮🇱

    Confining QCD-like theories close to the conformal window have a ``walking'' coupling. This is believed to lead to a light singlet scalar meson in the low-energy spectrum, a dilaton, which is the pseudo Nambu--Goldstone boson for the approximate scale symmetry. Extending chiral perturbation theory to include the dilaton requires a new small parameter to control the dilaton mass and its interactions. In our previous work we derived a systematic power counting for the dilaton couplings by matching the effective low-energy theory to the underlying theory using mild assumptions. In this paper we examine two alternative power countings which were proposed in the literature based on a phenomenological picture for the conformal transition. We find that one of these power countings fails, in fact, to generate a systematic expansion; the other coincides with the power counting we derived. We also point out that the so-called $\Delta$-potential coincides with the tree-level potential of the former, invalid, power counting.

    hep-phhep-latPRD(2025)·4 citations
20. 20*

    Electroweak hierarchy from conformal and custodial symmetry

    Thede de Boer🇩🇪 · Manfred Lindner🇩🇪 · Andreas Trautner🇩🇪

    We present "Custodial Naturalness" as a new mechanism to explain the separation between the electroweak (EW) scale and the scale of potential ultraviolet completions of the Standard Model (SM). We assume classical scale invariance as well as an extension of the SM scalar sector custodial symmetry to $\mathrm{SO}(6)$. This requires a single new complex scalar field charged under a new $\mathrm{U}(1{)}_{\mathrm{X}}$ gauge symmetry which partially overlaps with $B-L$. Classical scale invariance and the high-scale scalar sector $\mathrm{SO}(6)$ custodial symmetry are radiatively broken by quantum effects that generate a new intermediate scale by dimensional transmutation. The little hierarchy problem is solved because the Higgs boson arises as an elementary (i.e. non-composite) pseudo-Nambu-Goldstone boson (pNGB) of the spontaneously broken $\mathrm{SO}(6)$ custodial symmetry. The minimal setting has the same number of parameters as the SM and predicts new physics in the form of a heavy $Z^{\prime }$ with fixed couplings to the SM and a mass of $m_{Z^{\prime }}\approx 4-100\mathrm{TeV}$, as well as a light but close-to invisible dilaton with a mass $m_{h_{\Phi }}\approx 75\mathrm{GeV}$.

    hep-phhep-exPLB(2025)·13 citations
21. 21*

    Searching for dark matter with the Th-229 nuclear lineshape from laser spectroscopy

    Elina Fuchs🇩🇪 · Fiona Kirk🇩🇪 · Eric Madge🇮🇱 · Chaitanya Paranjape🇮🇱 · Ekkehard Peik🇩🇪 · Gilad Perez🇮🇱 · Wolfram Ratzinger🇮🇱 · Johannes Tiedau🇩🇪

    The recent laser excitation of the low-lying Th-229 isomer transition is starting a revolution in ultralight dark matter searches. The enhanced sensitivity of this transition to the large class of dark matter models dominantly coupling to quarks and gluons will ultimately allow us to probe coupling strengths eight orders of magnitude smaller than the current bounds from optical atomic clocks, which are mainly sensitive to dark matter couplings to electrons and photons. We argue that, with increasing precision, observations of the Th-229 excitation spectrum will soon give world-leading constraints. Using data from the pioneering laser excitation of Th-229 by Tiedau et al. [Phys. Rev. Lett. 132, 182501 (2024)], we present a first dark matter search in the excitation spectrum. While the exclusion limits of our detailed study of the lineshape are still below the sensitivity of currently operating clock experiments, we project the measurement of Zhang et al. [Nature 663, 63 (2024)] to surpass it.

    hep-phnucl-exphysics.atom-phPRX(2025)·47 citations
22. 22*

    Thermalization and hotspot formation around small primordial black holes

    Minxi He🇰🇷 · Kazunori Kohri🇯🇵 · Kyohei Mukaida🇯🇵 · Masaki Yamada🇯🇵

    We quantitatively analyze a basic question: what is the stationary solution of the background plasma temperature profile around a black hole (BH)? One may naively expect that the temperature profile continuously decreases from the Hawking temperature at the surface of the BH towards an outer region. We show analytically and numerically that this is not the case because local thermal equilibrium cannot be maintained near the surface of the BH and also because the high-energy particles emitted from Hawking radiation cannot be instantaneously thermalized into the background plasma. The temperature profile has a plateau within a finite distance from the BH, and even the overall amplitude of background temperature at a distance far away from the BH is significantly suppressed compared with the naive expectation. The main reason for these counterintuitive results comes from the fact that the size of the BH is too small that particles of Hawking radiation goes far away within the typical time scale of interactions.

    hep-phastro-ph.COJCAP(2024)·15 citations
23. 23*

    Axion Window on New Macroscopic Forces

    Luca Di Luzio🇮🇹 · Hector Gisbert🇪🇸 · Fabrizio Nesti🇮🇹 · Philip Sørensen🇮🇹

    Axion-mediated forces are enhanced by the presence of CP-violating axion couplings, which are however tightly constrained by electric dipole moment (EDM) searches. We discuss the underlying hypotheses behind different sources of CP violation at high energies and the interplay between axion-mediated force experiments and EDM observables. Specifically, we identify various mechanisms, based on new sources of CP violation or Peccei-Quinn symmetry breaking, that can significantly relax EDM constraints, leading to a substantial redefinition of the QCD axion window for axion-mediated forces. By considerably enlarging the QCD axion parameter space, our results provide a well-motivated target for experiments probing scalar axion couplings to matter fields. These include fifth-force tests of gravity, as well as searches for spin-dependent forces via precision magnetometry, proton storage rings and ultracold molecules.

    hep-phPRD(2024)·8 citations
24. 24*

    $W$-Boson Exotic Decay into Three Charged Leptons at the LHC

    Yifan Fei🇨🇳 · Peiran Li🇺🇸 · Zhen Liu🇺🇸 · Kun-Feng Lyu🇺🇸 · Maxim Pospelov🇺🇸

    We investigate the $W$ boson's exotic decay channel, $W\to \ell \ell \ell \nu$, at the LHC. Although the four-body final states suppress the decay branching ratio, the large production of $W$ bosons makes detecting and precisely measuring this decay probability entirely feasible. Our simulation study indicates that this tiny branching ratio can be measured with sub-percent precision at the HL-LHC. This decay channel can also constrain Standard Model extensions. Using the $L_{\mu }-L_{\tau }$ model as a benchmark, we find that the current bound on the gauge coupling for $Z^{\prime }$ mass in the range of $[4,75]$ GeV can significantly improve.

    hep-phPRD(2024)·4 citations
25. 25*

    Novel two component dark matter features in the $Z_2\times Z_2$ 3HDM

    Rafael Boto🇵🇹 · Pedro N. Figueiredo🇵🇹 · Jorge C. Romão🇵🇹 · João P. Silva🇵🇹

    We discuss the constraints and phenomenology of the $Z_2\times Z_2$ three Higgs doublet model (3HDM) with two inert scalars, originating two dark matter (DM) particles. We elucidate the competing vacua and we submit the model to all theoretical and current experimental constraints. We find unexplored regions of parameter space and investigate their experimental signatures. In particular, we find regions where the two DM particles contribute equally to the relic DM density.

    hep-phJHEP(2024)·16 citations
26. 26*

    Cosmological selection of a small weak scale from large vacuum energy: a minimal approach

    Susobhan Chattopadhyay🇮🇳 · Dibya S. Chattopadhyay🇮🇳 · Rick S. Gupta🇮🇳

    We present a minimal cosmological solution to the hierarchy problem. Our model consists of a light pseudoscalar and an extra Higgs doublet in addition to the field content of the Standard Model. We consider a landscape of vacua with varying values of the electroweak vacuum expectation value (VEV). The vacuum energy in our model peaks in a region of the landscape where the electroweak VEV is non-zero and much smaller than the cutoff. During inflation, due to exponential expansion, such regions of the landscape with maximal vacuum energy, dominate the universe in volume, thus explaining the smallness of the electroweak scale with respect to the cutoff. The pseudoscalar potential in our model is that of a completely generic pseudogoldstone boson$-$not requiring the clockwork mechanism$-$and its field value never exceeds its decay constant or the Planck scale. Our mechanism is robust to the variation of other model parameters in the landscape along with the electroweak VEV. It also predicts a precise and falsifiable relationship between the masses and couplings of the different Higgs boson mass-eigenstates. Moreover, the pseudoscalar in our model can account for the observed dark matter relic density.

    hep-phastro-ph.COhep-exhep-thPRL(2025)·14 citations
27. 27*

    Atoms as electron accelerators for measuring the $e^{+}{e}^{-}\to$hadrons cross section

    Fernando Arias-Aragón🇮🇹 · Luc Darmé🇫🇷 · Giovanni Grilli di Cortona🇮🇹 · Enrico Nardi🇮🇹

    The hadronic vacuum polarization contribution to $(g-2{)}_{\mu }$ can be determined via dispersive methods from $e^{+}{e}^{-}\to$hadrons data. We propose a novel approach to measure the hadronic cross section ${\sigma }_{\mathrm{had}}$ as an alternative to the initial-state radiation and energy scan techniques, which relies on positron annihilation off atomic electrons of a high $Z$ target (${}^{238}$U, $Z=92$). We show that by leveraging the relativistic electron velocities of the inner atomic shells, a high-intensity $12$GeV positron beam, such as the one foreseen at JLab, can allow to measure ${\sigma }_{\mathrm{had}}$ with high statistical accuracy from the two-pion threshold up to above $\sqrt{s}\sim 1$GeV.

    hep-phhep-exPRL(2025)·13 citations
28. 28*

    Lepton-Flavor-Violating ALP Signals with TeV-Scale Muon Beams

    Brian Batell🇺🇸 · Hooman Davoudiasl🇺🇸 · Roman Marcarelli🇺🇸 · Ethan T. Neil🇺🇸 · Sebastian Trojanowski🇵🇱

    We explore the feasibility of using TeV-energy muons to probe lepton-flavor-violating (LFV) processes mediated by an axion-like particle (ALP) $a$ with mass $\mathcal{O}(10\text{GeV})$. We focus on $\mu \tau$ LFV interactions and assume that the ALP is coupled to a dark state $\chi$, which can be either less or more massive than $a$. Such a setup is demonstrated to be consistent with $\chi$ being a candidate for dark matter, in the experimentally relevant regime of parameters. We consider the currently operating NA64-$\mu$ experiment and proposed FASER$\nu$2 detector as both the target and the detector for the process $\mu A\to \tau Aa$, where $A$ is the target nucleus. We also show that a possible future active muon fixed-target experiment operating at a 3 TeV muon collider or in its preparatory phase can provide an impressive reach for the LFV process considered, with future FASER$\nu$2 data providing a pilot study towards that goal. The implications of the muon anomalous magnetic moment $(g-2{)}_{\mu }$ measurements for the underlying model, in case of a positive signal, are also examined, and a sample UV completion is outlined.

    hep-phhep-exPRD(2024)·30 citations
29. 29*

    Entanglement Enabled Intensity Interferometry in ultrarelativistic ultraperipheral nuclear collisions

    James Daniel Brandenburg🇺🇸 · Haowu Duan🇺🇸 · Zhoudunming Tu🇺🇸 · Raju Venugopalan🇺🇸 · Zhangbu Xu🇺🇸

    An important tool in studying the sub-femtoscale spacetime structure of matter in ultrarelativistic heavy-ion collisions is Hanbury-Brown-Twiss (HBT) intensity interferometry of identical particles in the final state of such collisions. We show here that a variant of an entanglement enabled intensity interferometry ($E^2{I}^2$) proposed by Cotler and Wilczek provides a powerful alternative to HBT interferometry in extracting fundamental nonperturbative features of QCD at high energies. In particular, we show that the spatial distributions of color singlet (pomeron) configurations in nuclei can be obtained from exclusive resonant decays of $\rho$-mesons into ${\pi }^{\pm }$-pairs in ultrarelativistic ultraperipheral nuclear collisions (UPCs) at RHIC and the LHC. The $E^2{I}^2$ framework developed here is quite general. It can be employed to extract information on the spin structure of pomeron couplings as well as enhance the discovery potential for rare odderon configurations from exclusive vector meson decays into few-particle final states both in UPCs and at the Electron-Ion Collider.

    hep-phhep-thnucl-exnucl-thPRResearch(2025)·15 citations
30. 30*

    Crescendo Beyond the Horizon: More Gravitational Waves from Domain Walls Bounded by Inflated Cosmic Strings

    Yunjia Bao🇺🇸 · Keisuke Harigaya🇺🇸 · Lian-Tao Wang🇺🇸

    Gravitational-wave (GW) signals offer a unique window into the dynamics of the early universe. GWs may be generated by the topological defects produced in the early universe, which contain information on the symmetry of UV physics. We consider the case in which a two-step phase transition produces a network of domain walls bounded by cosmic strings. Specifically, we focus on the case in which there is a hierarchy in the symmetry-breaking scales, and a period of inflation pushes the cosmic string generated in the first phase transition outside the horizon before the second phase transition. We show that the GW signal from the evolution and collapse of this string-wall network has a unique spectrum, and the resulting signal strength can be sizeable. In particular, depending on the model parameters, the resulting signal can show up in a broad range of frequencies and can be discovered by a multitude of future probes, including the pulsar timing arrays and space- and ground-based GW observatories. As an example that naturally gives rise to this scenario, we present a model with the first phase transition followed by a brief period of thermal inflation driven by the field responsible for the second stage of symmetry breaking. The model can be embedded into a supersymmetric setup, which provides a natural realization of this scenario. In this case, the successful detection of the peak of the GW spectrum probes the soft supersymmetry breaking scale and the wall tension.

    hep-phastro-ph.COJHEP(2024)·7 citations
31. 31*

    Gravitational Wave Duet by Resonating Binary Black Holes within Ultralight Dark Matter

    Jeong Han Kim🇰🇷 · Xing-Yu Yang🇰🇷

    Gravitational wave observations have significantly broadened our capacity to explore fundamental physics beyond the Standard Model, providing crucial insights into dark matter that are inaccessible through conventional methods. Here, we investigate the resonant interactions between binary black hole systems and solitons, self-gravitating configurations of ultralight bosonic dark matter, which induce metric perturbations and generate distinct oscillatory patterns in gravitational waves. Upcoming experiments such as the Laser Interferometer Space Antenna could detect the oscillatory patterns in gravitational waveforms, providing an evidence for solitons. Because the effect relies solely on gravity, it does not assume any coupling of the dark sector to Standard Model particles, highlighting the capability of future gravitational-wave surveys to probe dark matter.

    ↳ astro-ph.COastro-ph.HEgr-qchep-phPRD(2025)·14 citations
32. 32*

    Constraints on Interacting Dark Energy Models from the DESI Baryon Acoustic Oscillation and DES Supernovae Data

    Tian-Nuo Li🇺🇸 · Peng-Ju Wu🇺🇸 · Guo-Hong Du🇺🇸 · Shang-Jie Jin🇺🇸 · Hai-Li Li🇨🇳 · Jing-Fei Zhang🇺🇸 · Xin Zhang🇺🇸

    The recent results from the first year baryon acoustic oscillations (BAO) data released by the Dark Energy Spectroscopic Instrument (DESI), combined with cosmic microwave background (CMB) and type Ia supernova (SN) data, have shown a detection of significant deviation from a cosmological constant for dark energy. In this work, we utilize the latest DESI BAO data in combination with the SN data from the full five-year observations of the Dark Energy Survey and the CMB data from the Planck satellite to explore potential interactions between dark energy and dark matter. We consider four typical forms of the interaction term $Q$. Our findings suggest that interacting dark energy (IDE) models with $Q\propto {\rho }_{\mathrm{de}}$ support the presence of an interaction where dark energy decays into dark matter. Specifically, the deviation from $\Lambda$CDM for the IDE model with $Q=\beta H_0{\rho }_{\mathrm{de}}$ reaches the $3\sigma$ level. These models yield a lower value of Akaike information criterion than the $\Lambda$CDM model, indicating a preference for these IDE models based on the current observational data. For IDE models with $Q\propto {\rho }_{\mathrm{c}}$, the existence of interaction depends on the form of the proportionality coefficient $\Gamma$. The IDE model with $Q=\beta H{\rho }_{\mathrm{c}}$ yields $\beta =0.0003\pm 0.0011$, which essentially does not support the presence of the interaction. In general, whether the observational data support the existence of interaction is closely related to the model. Our analysis helps to elucidate which type of IDE model can better explain the current observational data.

    ↳ astro-ph.COgr-qchep-phApJ(2024)·201 citations
33. 33*

    Emergent electromagnetism

    Erick I. Duque🇺🇸

    We introduce the concept of emergent electric field. This is distinguished from the fundamental one in that the emergent electric field directly appears in observations through the Lorentz force, while the latter enters the phase space as the canonical momentum of the electromagnetic field. In Hamiltonian classical electromagnetism this concept naturally appears after introducing the topological $\theta$ term. Furthermore, we show that in the spherically symmetric model the concept of emergent electric field allows us to formulate a modified theory of electromagnetism that is otherwise impossible. The relation between the fundamental and the emergent electric fields is derived from the imposition of general covariance of the electromagnetic strength tensor, which is a nontrivial task in the canonical formulation the modified theory is based on. We couple this theory to emergent modified gravity, where a similar distinction between spacetime and gravity is made such that the spacetime, which defines the observable geometry, is an emergent field composed of the fundamental gravitational field. In this more encompassing emergent field theory coupling gravity and electromagnetism, we show that the spherically symmetric model contains a nonsingular black hole solution where not only modified gravity but also modified electromagnetism is crucial for a robust singularity resolution and to avoid the existence of (super)extermal black holes.

    ↳ gr-qchep-phPRD(2024)·6 citations
34. 34*

    Anisotropic flow fluctuation as a possible signature of clustered nuclear geometry in O-O collisions at the Large Hadron Collider

    Suraj Prasad🇮🇳 · Neelkamal Mallick🇮🇳 · Raghunath Sahoo🇮🇳 · Gergely Gábor Barnaföldi🇭🇺

    Nuclei having $4n$ number of nucleons are theorized to possess clusters of $\alpha$ particles (${}^4$He nucleus). The Oxygen nucleus (${}^{16}$O) is a doubly magic nucleus, where the presence of an $\alpha$-clustered nuclear structure grants additional nuclear stability. In this study, we exploit the anisotropic flow coefficients to discern the effects of an $\alpha$-clustered nuclear geometry with respect to a Woods-Saxon nuclear distribution in O--O collisions at $\sqrt{s_{\mathrm{NN}}}=7$ TeV using a hybrid of IP-Glasma + MUSIC + iSS + UrQMD models. In addition, we use the multi-particle cumulants method to measure anisotropic flow coefficients, such as elliptic flow ($v_2$) and triangular flow ($v_3$), as a function of multiplicity class. Anisotropic flow fluctuations, which are expected to be larger in small collision systems, are also studied for the first time in O--O collisions. It is found that an $\alpha$-clustered nuclear distribution gives rise to an enhanced value of $v_2$ and $v_3$ for the low-multiplicity events. Consequently, a rise in $v_3/v_2$ is also observed for the 0--10\% multiplicity class. Further, for $\alpha$-clustered O--O collisions, fluctuations of $v_2$ are larger for the highest multiplicity events, which decrease as the final-state multiplicity decreases. In contrast, for a Woods-Saxon ${}^{16}$O nucleus, $v_2$ fluctuations show an opposite behavior with decreasing multiplicity. When confronted with experimental data, this study may reveal the importance of the nuclear density profile on the discussed observables and provide physics validation for the hybrid model discussed in this work.

    ↳ nucl-thhep-exhep-phnucl-exPLB(2025)·22 citations
35. 35*

    Dipole Cosmology in $f(Q)$-gravity

    Andronikos Paliathanasis🇿🇦

    Symmetric teleparallel $f(Q)$-gravity allows for the presence of a perfect fluid with a tilted velocity in the Kantowski-Sachs geometry. In this dipole model, we consider an ideal gas and we investigate the evolution of the physical parameters. The tilt parameter is constrained by the nonlinear function $f(Q)$ through the non-diagonal equations of the field equations. We find that the dynamics always reduce to the vacuum solutions of STEGR. This includes the Kasner universe, when no cosmological term is introduced by the $f(Q)$ function, and the isotropic de Sitter universe, where $f\left(Q\right)$ plays the role of the cosmological constant. In the extreme tilt limit, the universe is consistently anisotropic and accelerated. However, the final solution matches that of STEGR.

    ↳ gr-qcastro-ph.COhep-phmath-ph+1Phys.Dark Univ.(2024)·14 citations
36. 36*

    Primordial Black Holes and Scalar-induced Gravitational Waves in Sneutrino Hybrid Inflation

    Adeela Afzal🇵🇰 · Anish Ghoshal🇵🇱 · Stephen F. King🇬🇧

    We investigate the possibility that primordial black holes (PBHs) can be formed from large curvature perturbations generated during the waterfall phase transition in a supersymmetric scenario where sneutrino is the inflaton in a hybrid inflationary framework. We obtain a spectral index ($n_s\simeq 0.966$), and a tensor-to-scalar ratio ($r\simeq 0.0056-10^{-11}$), consistent with the current Planck data satisfying PBH as dark matter (DM) and detectable Gravitational Wave (GW) signal. Our findings show that the mass of PBH and the peak in the GW spectrum is correlated with the right-handed (s)neutrino mass. We identify parameter space where PBHs can be the entire DM candidate of the universe (with mass $10^{-13}{M}_{\odot }$) or a fraction of it. This can be tested in future observatories, for example, with amplitude ${\Omega }_{\mathrm{GW}}{h}^2$ $\sim 10^{-9}$ and peak frequency $f\sim 0.1$ Hz in LISA and ${\Omega }_{\mathrm{GW}}{h}^2\sim 10^{-11}$ and peak frequency of $\sim 10$ Hz in ET via second-order GW signals. We study two models of sneutrino inflation: Model$-1$ involves canonical sneutrino kinetic term which predicts the sub-Planckian mass parameter $M$, while the coupling between a gauge singlet and the waterfall field, $\beta$, needs to be quite large whereas, for the model$-2$ involving $\alpha -$attractor canonical sneutrino kinetic term, $\beta$ can take a natural value. Estimating explicitly, we show that both models have mild fine-tuning. We also derive an analytical expression for the power spectrum in terms of the microphysics parameters of the model like (s)neutrino mass, etc. that fits well with the numerical results. The typical reheat temperature for both the models is around $10^7-10^8$~GeV suitable for non-thermal leptogenesis.

    ↳ astro-ph.COhep-phhep-thPRD(2025)·10 citations
37. 37*

    Impacts of dark energy on weighing neutrinos after DESI BAO

    Guo-Hong Du🇺🇸 · Peng-Ju Wu🇺🇸 · Tian-Nuo Li🇺🇸 · Xin Zhang🇨🇳

    Recently, DESI has released baryon acoustic oscillation (BAO) data, and DES has also published its five-year supernova (SN) data. These observations, combined with cosmic microwave background (CMB) data, support a dynamically evolving dark energy at a high confidence level. When using cosmological observations to weigh neutrinos, the results of weighing neutrinos will be significantly affected by the measurement of dark energy due to the degeneracy between neutrino mass and the dark-energy equation of state. Therefore, we need to understand how the dynamical evolution of dark energy in the current situation will affect the measurement of neutrino mass. In this work, we utilize these latest observations and other additional distance measurements to discuss the mutual influence between neutrinos and dark energy, then calculate the Bayes factor to compare models. We consider three neutrino mass hierarchies including degenerate hierarchy (DH), normal hierarchy (NH), and inverted hierarchy (IH), as well as three dark energy models including $\Lambda \mathrm{CDM}$, $w\mathrm{CDM}$, and $w_0{w}_a\mathrm{CDM}$ models. Cosmological data combined with the prior of particle physics experiments can provide strong to decisive evidence favoring the $w_0{w}_a\mathrm{CDM}+\sum m_{\nu }$ model with NH. In the $w_0{w}_a\mathrm{CDM}$ model, using the CMB+DESI+DESY5 data, we obtain constraints on the total neutrino mass, $\sum m_{\nu }<0.171\mathrm{eV},0.204\mathrm{eV},0.220\mathrm{eV}$, for DH, NH, and IH, respectively. Furthermore, taking into account the neutrino hierarchy or incorporating additional distance measurements results in a more pronounced deviation from the $\Lambda$CDM model for dark energy. The latter, particularly, exhibits a deviation at a confidence level that surpasses $4\sigma$.

    ↳ astro-ph.COgr-qchep-phEPJC(2025)·64 citations
38. 38*

    Early-Time Observations of SN 2023wrk: A Luminous Type Ia Supernova with Significant Unburned Carbon in the Outer Ejecta

    Jialian Liu · Xiaofeng Wang · Cristina Andrade · Pierre-Alexandre Duverne · Jujia Zhang · Liping Li · Zhenyu Wang · Felipe Navarete · Andrea Reguitti · Stefan Schuldt · Yongzhi Cai · Alexei V. Filippenko and 35 other authors

    We present extensive photometric and spectroscopic observations of the nearby Type Ia supernova (SN) 2023wrk at a distance of about 40 Mpc. The earliest detection of this SN can be traced back to a few hours after the explosion. Within the first few days the light curve shows a bump feature, while the B - V color is blue and remains nearly constant. The overall spectral evolution is similar to that of an SN 1991T/SN 1999aa-like SN Ia, while the C II $\lambda 6580$ absorption line appears to be unusually strong in the first spectrum taken at $t\approx -$15.4 days after the maximum light. This carbon feature disappears quickly in subsequent evolution but it reappears at around the time of peak brightness. The complex evolution of the carbon line and the possible detection of Ni III absorption around 4700 Å and 5300 Å in the earliest spectra indicate macroscopic mixing of fuel and ash. The strong carbon lines is likely related to collision of SN ejecta with unbound carbon, consistent with the predictions of pulsational delayed-detonation or carbon-rich circumstellar-matter interaction models. Among those carbon-rich SNe Ia with strong C II $\lambda 6580$ absorption at very early times, the line-strength ratio of C II to Si II and the B-V color evolution are found to exhibit large diversity, which may be attributed to different properties of unbound carbon and outward-mixing ${}^{56}$Ni.

    ↳ astro-ph.SRastro-ph.HEhep-phApJ(2024)·3 citations
39. 39*

    Obviating PBH overproduction for SIGWs generated by Pulsar Timing Arrays in loop corrected EFT of bounce

    Sayantan Choudhury🇮🇳 · Siddhant Ganguly🇮🇳 · Sudhakar Panda🇮🇳 · Soumitra SenGupta🇮🇳 · Pranjal Tiwari🇮🇳

    In order to unravel the present situation of the PBH overproduction problem, our study emphasizes the critical role played by the equation of state (EoS) parameter $w$ within the framework of effective field theory (EFT) of non-singular bounce. Our analysis focuses on a wide range of EoS parameter values that are still optimal for explaining the latest data from the pulsar timing array (PTA). As a result of our study, the most advantageous window, $0.31\le w\le 1/3$, is identified as the location of a substantial PBH abundance, $f_{\mathrm{PBH}}\in (10^{-3},1)$ with large mass PBHs, $M_{\mathrm{PBH}}\sim \mathcal{O}(10^{-7}-10^{-3})M_{\odot }$, in the SIGW interpretation of the PTA signal. When confronted with PTA, we find that the overproduction avoiding circumstances are between $1\sigma -2\sigma$, while the EoS parameter lies inside the narrow window, $0.31<w\le 1/3$. We propose a regularized-renormalized-resummed (RRR) scalar power spectrum that is large enough to produce EoS dependent scalar generated gravitational waves compatible with PTA evidence, while satisfying the perturbativity, causality, and unitarity criteria, within the range of $0.88\le c_s\le 1$.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2024)·34 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.