Thu·May 7, 2026Thursday·May 7, 2026

1. 01*

   Pressure-Energy Equations of State of the Nucleon

   Keh-Fei Liu🇺🇸

   The pressure-energy equations of state in the nucleon are derived from the gravitational form factors, which parametrize matrix elements of the energy-momentum tensor (EMT), together with EMT conservation. The pressure and energy densities naturally separate into two distinct components. The static pressure distribution, arising from the Lorentz trace part of the EMT, as manifested in the spatial stress $\frac{1}{3}{T}^{ii}$, is equal to minus the corresponding trace part of the energy density. This relation may be interpreted as a consequence of the full or partial depletion of the gluon and quark condensates through the pressure-volume relation. The resulting trace anomaly- and sigma term-induced pressure is shown, through its volume scaling, to play a pivotal role in QCD confinement. In contrast, the dynamic pressure distribution, associated with the traceless part of the stress tensor equals $1/d$ of the corresponding traceless part of the energy density, where $d$ is the spatial dimension. These static and dynamic components together satisfy the pressure-balance condition in the nucleon. We further show that the same pressure-energy equations of state hold for vortices in type-II superconductors, where the static pressure-energy relation originates from the depletion of the Cooper-pair condensate. Moreover, these equations of state are identical to those of the $\Lambda \mathrm{CDM}$ cosmological model, where the static pressure-energy relation is generated by the cosmological constant.

   hep-phhep-lathep-thPRD(2026)·2 citations
2. 02*

   Long Inflation Screens Euclidean-Wormhole Initial States

   Imtiaz Khan🇨🇳 · Pirzada🇨🇳 · G. Mustafa🇨🇳 · Farruh Atamurotov🇺🇿 · Chengxun Yuan🇨🇳

   Euclidean wormholes can prepare inflation in non--Bunch--Davies initial states, but long Lorentzian expansion screens this memory from the CMB. We derive a visibility bound for Euclidean-matched Bogoliubov data: the pivot excitation satisfies $|{\beta }_{\ast }|\lesssim e^{-2N_{\mathrm{pre}}}$, and smooth Euclidean filters confine residual signatures to a comoving edge $k_w=a_{i}M$. Only near-minimal inflation, or an edge inside the observable window, leaves detectable scalar, tensor, and higher-point imprints. For longer inflation, wormhole-prepared perturbations are driven to the Bunch--Davies prediction. Euclidean memory therefore, becomes a quantitative bound on inflationary duration, with direct targets in CMB polarization and large-scale structure: the longer inflation lasts, the less of the wormhole remains on the sky.

   hep-ph6 citations
3. 03*

   Indications for New Higgs Bosons

   Andreas Crivellin🇪🇸 · Saiyad Ashanujjaman🇩🇪 · Sumit Banik🇺🇸 · Siddharth P. Maharathy🇿🇦 · Guglielmo Coloretti🇮🇹

   After the Higgs discovery, the question of whether particles beyond those of the Standard Model exist is more pressing than ever. In this context, the scalar sector is particularly promising, since it lies at the core of the internal problems of the Standard Model, while extensions of it allow us to resolve them and can provide explanations for Dark matter, non-zero neutrino masses, inflation etc. In these proceedings, we review the indications for new Higgs bosons at the electroweak scale with masses of $\approx$95 GeV and $\approx$152 GeV. These excesses are most significant in the di-photon channel but are supported by weaker-than-expected limits in other decay modes. While for the 95 GeV candidate the production mechanism is mostly unknown, the (hypothetical) 152 GeV Higgs is dominantly produced in association with leptons, $(b)$ jets and missing energy, pointing towards the Drell-Yan production of an $SU(2{)}_L$ triplet with $Y=0$. Interestingly, this model predicts $t\to H^{\pm }b$ with $H^{\pm }\to WZ$, which resembles the signature of $t\bar{t}Z$ production in the Standard Model and is in fact preferred by current data. Finally, we investigate the possibility that the significant tensions between the Standard Model predictions and the measurements in differential top-quark distributions are due to contamination from new physics involving both the 152 GeV and the 95 GeV scalar.

   hep-phhep-exPoS(2026)·2 citations
4. 04*

   Emergence of conformal properties in Finite Grand Unified Theories via reduction of couplings

   Luis Enrique Reyes Rodríguez (Mexico U.) · Myriam Mondragón (Mexico U.)🇲🇽

   Zimmermann's Reduction of Couplings (RoC) method is a powerful tool for addressing the problem of the excess of parameters in a field theory, as it yields relations among couplings that are invariant under the renormalization group. Its usefulness becomes particularly evident when constructing predictive supersymmetric GUT models that are free of UV-divergences to all orders. Within this scale-invariant framework, we show that a SUSY model satisfying the conditions of all-loop finiteness exhibits a conformal regime induced by superpotential operators compatible with the RoC. In the soft-breaking sector, the method was shown to lead to a set of scale-invariant relations between the soft couplings and the parameters of the dimensionless sector, among which a sum rule for the scalar masses is particularly notable. These relations closely resemble the typical AMSB relations, while avoiding the tachyonic mass spectrum thanks to the sum rule. Based on this observation, we provide new evidence for a connection between the reduction of parameters in the dimensionful SSB sector and the emergence of an anomaly-mediated (AMSB-like) pattern, under the assumption that the finite Grand Unified Theory is connected to an effective $N=1$, $d=4$ Weyl-invariant SUGRA theory. In this process, we find that an all-order finite model with this property requires a specific form of the Kähler potential, whose structure coincides with that studied in no-scale supergravity scenarios.

   hep-phhep-th0 citations
5. 05*

   Production of $D_s{\bar{D}}_s$ and $D\bar{D}$ bound states in the $B$ decays within the Bethe-Salpeter framework

   Zhen-Yang Wang🇨🇳 · Jing-Juan Qi🇨🇳 · Zhen-Hua Zhang🇨🇳 · Xin-Heng Guo🇨🇳

   Within the Bethe--Salpeter framework, we investigate the production of possible $D_s{\bar{D}}_s$ $(X_{s\bar{s}})$ and $D\bar{D}$ $(X_{q\bar{q}})$ bound states in $B$ decays. The bound state properties of the two heavy meson systems are studied in the one-boson-exchange model, and the resulting normalized Bethe--Salpeter wave functions are used to calculate the branching fractions of $B^{+}\to X_{s\bar{s}}{K}^{+}$ and $B^{+}\to X_{q\bar{q}}{K}^{+}$. We find that bound state solutions for the $D\bar{D}$ system exist for all the three coupling sets considered, whereas the $D_s{\bar{D}}_s$ system supports a bound-state solution only in a restricted parameter region. The predicted branching fractions are in the ranges of $1.09\times 10^{-5}$--$20.06\times 10^{-4}$ for the $D_s{\bar{D}}_s$ bound state and $1.56\times 10^{-6}$--$4.14\times 10^{-4}$ for the $D\bar{D}$ bound state. In particular, if $X(3915)$ is interpreted as a predominantly $D_s{\bar{D}}_s$ bound state, its production

   hep-phhep-exPRD(2026)·2 citations
6. 06*

   Landscape of Spontaneous CP Violation

   Yuichiro Nakai🇨🇳

   Spontaneous CP violation (SCPV) provides a promising solution to the strong CP problem, explaining the smallness of the QCD $\theta$-angle while generating the Cabibbo-Kobayashi-Maskawa (CKM) phase. In the present work, we review and discuss the realization of SCPV in the supersymmetric framework, which addresses critical issues such as the naturalness of the scale of SCPV and the presence of problematic higher dimensional operators and radiative corrections spoiling the mechanism. It is explicitly shown that SCPV is realized along flat directions and stabilized through supersymmetry-breaking effects and a non-perturbative dynamics, predicting light SCPV sector particles feebly coupled to the Standard Model particles. Furthermore, we discuss the issue of baryon asymmetric Universe in the SCPV framework and point out that the Affleck-Dine mechanism can successfully generate the observed baryon asymmetry with a low reheating temperature compatible with the gravitino dark matter. Our framework predicts a nonzero neutron electric dipole moment which is within the reach of near-future experiments.

   hep-phastro-ph.COhep-exhep-th0 citations
7. 07*

   On the Consistency of Covariant Light-Speed Variation in Doubly Special Relativity

   Hao Li🇨🇳 · Jie Zhu🇨🇳

   Doubly special relativity (DSR) introduces an observer-independent energy scale while preserving a deformed relativistic notion of covariance. In many realizations, this leads to an energy-dependent speed of light (light-speed variation, LSV). We investigate the consistency of such observer-independent LSV through a thought experiment involving an inertial box emitting two photons in opposite directions. We first distinguish two classes of LSV scenarios: those with the standard velocity-composition law, and those with observer-independent speed-energy relations, as in DSR. Focusing on the latter, we perform a quantitative analysis within the DSR1 model based on the $\kappa$-Poincaré algebra. In the subluminal case ($\ell <0$), we derive a critical rapidity above which the boosted box overtakes its own photon, and show that this rapidity is physically attainable even after taking macroscopic effects into account. Within a standard particle interpretation, this leads to tensions in particle counting and inertial motion across frames. Unlike previously discussed issues in DSR, this effect does not appear to be resolvable by relative locality alone. Our results point to a structural tension among observer-independent LSV, relativistic covariance, and standard notions of particle propagation in DSR frameworks.

   hep-ph0 citations
8. 08*

   Gravitational Waves from Higgs Preheating after Inflaton $Z_2$-Symmetry Breaking

   Hua Zhou (Southwest University of Science and Technology)🇨🇳 · Qing Yu (Southwest University of Science and Technology)🇨🇳 · Wei Cheng (Chongqing University of Posts and Telecommunications)🇨🇳 · Ruo-Peng Zhang (Chongqing Vocational Institute of Engineering)🇨🇳

   In this paper, nonperturbative lattice simulations are used to study Higgs preheating and the associated gravitational wave (GW) background after the inflaton $Z_2$ symmetry is broken during inflation. This symmetry breaking generates both trilinear and quartic inflaton-Higgs interactions during preheating. The quartic inflaton-Higgs coupling is characterized by $q_{\varphi h}\equiv {\lambda }_{\varphi h}/{\lambda }_{\varphi }$, while the trilinear interaction enters jointly through $q_{\varphi h}$ and $q_{ϵ}\equiv m_{\varphi }/(\sqrt{{\lambda }_{\varphi }}{\varphi }_0)$. The Higgs self-coupling parameter $q_h\equiv {\lambda }_h/{\lambda }_{\varphi }$ determines the onset of backreaction through the effective mass induced by Higgs self-interactions. Our simulations show that efficient preheating requires both a sufficiently broad resonance band and delayed backreaction. For ${\lambda }_{\varphi }=10^{-13}$, the viable parameter region is approximately $10<q_{\varphi h}<10^4$, $q_h<10^3$, and $q_{ϵ}<10^{-5}$. Smaller $q_{ϵ}$ keeps the system in a quartic-dominated regime and suppresses the rapid drift of resonance bands, while smaller $q_h$ delays the end of preheating by weakening self-interaction-induced backreaction. The amplified Higgs inhomogeneities source GW through the transverse-traceless part of the anisotropic stress tensor. The lattice results show that the GW spectrum grows rapidly during parametric resonance, broadens through rescattering, and saturates in the nonlinear stage. At late times, the spectrum develops a broad peak with amplitude ${\Omega }_{\mathrm{gw}}\sim 10^{-6}$ at production. After redshifting to the present day, the peak frequency is $f\sim 10^9\mathrm{Hz}$ with present-day amplitude ${\Omega }_{\mathrm{gw},0}{h}^2\sim 10^{-10}$. These results suggest that high-frequency GW from Higgs preheating may be detectable by future resonant-cavity detectors.

   hep-ph0 citations
9. 09*

   Fundamental or Composite? The Higgs Enigma

   Alon E. Faraggi🇬🇧

   The discovery of the Higgs boson by the ATLAS and CMS experiments concluded a glorious century of experimental particle physics discoveries, from Rutherford's discovery of the nucleus in 1911, through the discoveries of quarks and leptons from the 1950s to the 1970s, to the discoveries of the weak vector bosons in the 1980s. It cemented the Standard Model of particle physics as providing the viable parameterisation of all sub-atomic observables up to the TeV scale and possibly up to the GUT and Planck scales. The experimental determination of the Higgs properties and parameters will shed light on these fundamental theories. A particularly pertaining question from the point of view of String Phenomenology is whether the Higgs boson is a fundamental or composite particle. The fermionic Z2xZ2 orbifolds provide bench mark models to explore how the parameters of the Standard Model can arise from a theory of quantum gravity, as well as for physics Beyond the Standard Model. Observation that the Higgs is composite will nullify much of the work that have gone into heterotic string model building over the past 40 years and will indicate the relevance of other classes of string vacua or possibly other approaches to quantum gravity. An ideal facility in the near future to investigate this question is a hadron collider at 50-60 TeV that utilises contemporary magnet technology and can be built in 10-15 years from decision.

   hep-phhep-exhep-thPoS(2026)·0 citations
10. 10*

    Singlet-doublet dark matter induced radiative neutrino mass and TeV scale leptogenesis

    Partha Kumar Paul🇮🇳 · Narendra Sahu🇮🇳 · Shashwat Sharma🇮🇳

    The singlet-doublet dark matter (SDDM) model is a well-motivated WIMP framework that accommodates viable dark matter over a broad range of parameter space. In this work, we explore the possibility of TeV-scale leptogenesis within two realizations of the SDDM setup: Majorana SDDM scenario and Dirac SDDM scenario. The light neutrino mass, in either case, arises radiatively at one loop level. The particles running in the loop are responsible for Dark matter relic and TeV-scale leptogenesis while satisfying other phenomenological constraints. In the Majorana setup, the Standard Model is extended by three generations of singlet fermions $N_i$ and doublet fermions ${\Psi }_i$, and a singlet scalar $\varphi$. The \textit{CP}-violating, out-of-equilibrium decays of the heavier singlets ($N_{2,3}$) generate baryon asymmetry via the leptogenesis route, while the first generation of singlet-doublet fermions give rise to the usual SD Majorana dark matter. In the Dirac setup, the standard model is extended by three generations of complex scalars (${\varphi }_i$) and right-handed Dirac partners (${\nu }_{R_i}$) of SM neutrinos (${\nu }_{L_i}$), along with a pair of singlet-doublet fermions $\chi$ and $\Psi$. The \textit{CP}-violating out-of-equilibrium decays of the scalar fields ${\varphi }_i$ generate baryon asymmetry via the Dirac leptogenesis route. We show that in the Majorana setup, successful leptogenesis is possible even in the sub-TeV regime, while in the Dirac setup, the scale of leptogenesis is at a few TeV. With the particle mass at the TeV scale, the model remains promising for collider experiments, particularly through signatures such as prompt decays and displaced vertex searches. In addition, the presence of Dirac neutrinos can contribute to $\Delta N_{\mathrm{eff}}$, providing complementary cosmological signatures.

    hep-phastro-ph.COhep-exhep-th2 citations
11. 11*

    New Predictions for the Lifetimes of Doubly Heavy Baryons and the $B_c$ Meson

    Lovro Dulibić🇭🇷 · Blaženka Melić🇭🇷 · Ivan Nišandžić🇭🇷

    We present updated predictions for the lifetimes of all weakly decaying doubly heavy baryons, including $bb$, $cc$, and $bc$ baryons, as well as for the $B_c$ meson. The analysis includes NNLO corrections to the leading dimension-three contribution, NLO corrections to the chromomagnetic term, and the complete set of currently known NLO corrections to the dimension-six heavy-light quark spectator contributions, including penguin terms. We also compare the results in the $\overline{\mathrm{MS}}$, kinetic, and, where applicable, ${\rm Y}$ mass schemes. For the $bc$ baryons, we present predictions for both possible ground-state diquark-spin assignments, $S_{bc}=0$ and $S_{bc}=1$. In the kinetic scheme we obtain the lifetime hierarchies $\tau ({\Xi }_{bb}^0)<\tau ({\Xi }_{bb}^{-})\simeq \tau ({\Omega }_{bb}^{-})$, $\tau ({\Xi }_{cc}^{+})<\tau ({\Omega }_{cc}^{+})<\tau ({\Xi }_{cc}^{++})$, $\tau ({\Xi }_{bc}^0)\lesssim \tau ({\Omega }_{bc}^0)<\tau ({\Xi }_{bc}^{+})$ for $S_{bc}=0$, and $\tau ({\Xi }_{bc}^{\prime 0})<\tau ({\Omega }_{bc}^{\prime 0})<\tau ({\Xi }_{bc}^{\prime +})$ for $S_{bc}=1$. We also revisit the $B_c$ lifetime and discuss the impact of the newly included Darwin term.

    hep-phhep-exJHEP(2026)·3 citations
12. 12*

    The $T_{bc}$ tetraquarks near the $B\bar{D}$ threshold

    Halil Mutuk🇹🇷

    We study the doubly heavy open-flavor tetraquarks $T_{bc}^{(0)}$ ($J^P=0^{+}$) and $T_{bc}^{(1)}$ ($J^P=1^{+}$) in the dynamical diquark model, describing the system as a heavy antidiquark--light diquark pair interacting through the lattice-QCD ${\Sigma }_g^{+}(1S)$ Born--Oppenheimer potential. Solving the radial Schrödinger equation yields $M(T_{bc}^{(0)})=7.143$--$7.158$ GeV and $M(T_{bc}^{(1)})=7.217$--$7.222$ GeV, with hyperfine splittings of ${\Delta }_{HF}\simeq 59$--$79$ MeV. The splitting is driven mainly by the mass difference between symmetric and antisymmetric heavy-antidiquark configurations, while the chromomagnetic interaction contributes linearly with $\partial {\Delta }_{HF}/\partial {\kappa }_{\bar{b}\bar{c}}=2$, consistent with heavy-antidiquark spin algebra. The mean separation, $⟨r⟩\simeq 0.45$--$0.46$ fm, and inverse radius, $⟨1/r{⟩}^{-1}\simeq 0.33$--$0.34$ fm, exhibit weak parameter dependence and support a compact diquark--antidiquark interpretation. Relative to open-flavor thresholds, the scalar state lies essentially at the $B\bar{D}$ threshold and may appear either as a weakly decaying bound tetraquark or as a narrow near-threshold resonance. In contrast, the axial-vector state is consistently predicted as an $S$-wave resonance located $23$--$28$ MeV above $B^{\ast }\bar{D}$ and about $70$ MeV below $B{\bar{D}}^{\ast }$, implying a line shape strongly influenced by the nearby $B^{\ast }\bar{D}$ threshold.

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

    Nonthermal leptogenesis via cosmological gravitational particle production is tested by inflationary gravitational waves

    Tammi Chowdhury🇨🇦 · Leah Jenks🇺🇸 · Edward W. Kolb🇺🇸 · Andrew J. Long🇺🇸 · Evan McDonough🇨🇦

    We explore the coincidence of scales between cosmic inflation and right-handed neutrinos in seesaw models. We show that inflation models, which will be tested by next-generation CMB experiments, can produce right-handed neutrinos in sufficient abundance to explain the observed baryon asymmetry of the universe. The model can be tested by gravitational wave signatures from cosmic inflation and particle production.

    hep-phastro-ph.COgr-qchep-th2 citations
14. 14*

    On the equivalence of unitarization prescriptions for the Sommerfeld enhancement

    Barry E. Cimring🇺🇸 · Tracy R. Slatyer🇺🇸

    The annihilation of self-interacting dark matter with long-range interactions can be significantly enhanced at low velocities through the Sommerfeld effect. At special points in parameter space, where near-zero-energy resonances exist in the spectrum of the theory, the standard calculation of this enhancement appears to violate unitarity. Recently, several approaches have been proposed to regulate this behavior, some introducing explicit ultraviolet (UV) scales and others not, raising the question of whether these prescriptions are consistent. In this paper, we compare these approaches and show that even in nominally cutoff-dependent methods, the regulated Sommerfeld-enhanced cross sections are independent of the UV regulator to a good approximation, and that when the unitarity-preserving corrections are large, the regulation schemes coincide to leading order. We use these insights to write down a regulator-independent prescription for unitarization applicable to multi-state systems, where the modified enhancement can be written solely in terms of the standard enhancement factor, the hard annihilation amplitude, and the $S$-matrix for scattering in the long-range potential.

    hep-phastro-ph.COhep-th1 citation
15. 15*

    Monochromatic neutrinos from scotogenic dark matter

    Ricardo Cepedello🇪🇸 · Pablo de la Torre🇪🇸 · Manuel Masip🇪🇸

    The scotogenic model defines a framework for radiative neutrino masses and provides a viable dark matter candidate. Since the scotogenic dark matter is leptophilic, indirect searches appear as an especially interesting possibility. Here we propose a simple variation of the model with a very distinct phenomenology. The scotogenic fermion singlets are naturally grouped into pseudo-Dirac pairs of mass of 0.1-1 TeV. We show that the lightest one constitutes a dark matter candidate that near threshold annihilates with a 90% branching ratio into neutrino pairs. The model gives the observed relic abundance consistently with the bounds from direct searches and with all neutrino and charged lepton data. We also show that, for a sub-MeV dark matter particle, the model suggests a scenario that could address the lithium problem.

    hep-phastro-ph.HEPRD(2026)·0 citations
16. 16*

    First next-to-next-to-leading-order extraction of fragmentation functions for Lambda hyperons

    Valerio Bertone🇫🇷 · Alessia Bongallino🇪🇸 · Amedeo Chiefa🇬🇧 · Miguel G. Echevarria🇪🇸 · Gunar Schnell🇪🇸

    We present MAPFF1.0_Lambda, the first global analysis at next-to-next-to-leading order in perturbative QCD of the collinear unpolarised fragmentation functions of Lambda hyperons. The fit is based on data from single-inclusive electron-positron annihilation, and from both neutral-current and -- for the first time -- charged-current semi-inclusive deep-inelastic scattering. We have adopted a statistical framework based on Monte Carlo sampling and parametrised fragmentation functions in terms of a neural network. The fragmentation function set comprises a total of seven independent parton flavours, allowing for the first independent determination of valence-quark distributions. Our analysis offers new insights into the hadronisation mechanism of strange baryons and establishes a baseline for future phenomenological and experimental investigations.

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

    Spiral structure and logarithmic evolution of deuteron form factors: evidence for a transitional regime in QCD

    Yaroslav D. Krivenko-Emetov🇦🇹 · Iryna Myroshnykova🇦🇹

    We present a consistent analysis of elastic electron--deuteron scattering combining perturbative quantum chromodynamics (pQCD) scaling, helicity amplitudes, and phenomenological parameterizations of deuteron form factors. Particular attention is paid to logarithmic corrections governed by anomalous dimensions of six-quark operators and to two-photon exchange (TPE). Three classes of parameterizations corresponding to different dynamical regimes are considered: pre-asymptotic valence-quark dominance, effective higher-twist contributions, and modified logarithmic evolution. A global fit to the world data for the structure functions $A(Q^2)$ and $B(Q^2)$, differential cross sections, and tensor polarization observables is performed using a combined strategy of global and local minimization. The best description of the complete data set is achieved within the $f_1$ parameterization, which incorporates pre-asymptotic logarithmic behavior and correlated valence-quark dynamics. Among the considered models, $f_1$ gives the smallest value of ${\chi }^2/\mathrm{dof}$. The obtained results indicate that the presently accessible momentum-transfer region corresponds to a transitional regime between hadronic and quark--gluon descriptions. Helicity-conserving amplitudes dominate, whereas the asymptotic pQCD regime has not yet been fully realized. This may indicate nontrivial multiquark correlations related to hidden-color configurations in the short-distance deuteron structure. The tensor polarization observable $t_{21}$ is especially sensitive to the asymptotic behavior of the helicity amplitudes. Future measurements at larger $Q^2$ may provide a decisive test for distinguishing between the considered dynamical scenarios.

    hep-phnucl-th0 citations
18. 18*

    Nonlocal Nonstabilizerness from Holographic Schwinger Pair Production

    Sebastian Grieninger🇺🇸

    We analyze the emergence of nonlocal magic in Schwinger pair creation in strong non-Abelian (chromo)electric fields using holography. The produced quark--antiquark pair is entangled into a color singlet, yet accelerates into causally disconnected Rindler wedges. Using the Casini--Huerta--Myers conformal mapping and the probe-brane framework, we compute the refined Rényi entropy and its derivative, which captures the antiflatness of the entanglement spectrum for a spherical bipartition. We find that for boundary spacetime dimension $d>2$, the entanglement spectrum is non-flat, implying the dynamical generation of nonlocal magic in the pair creation process. Interestingly, the nonlocal magic in the holographic dual can be obtained from the free energy of the probe action.

    ↳ hep-thgr-qchep-phnucl-th+1PRD(2026)·6 citations
19. 19*

    Neutrino Flavor Transformation in Collapsing Supermassive Objects

    Kyle S. Kehrer🇺🇸 · George M. Fuller🇺🇸 · Ian Padilla-Gay🇺🇸 · Chad T. Kishimoto🇺🇸

    The collapse of supermassive stars (SMSs, $M\gtrsim 10^4{M}_{\odot }$) to black holes is accompanied by a prodigious flux of neutrinos of all flavors. These are produced thermally via $e^{\pm }$ annihilations, mostly in the core and just before gravitational trapped surface formation. There, the ratio of fluxes for ${\nu }_e{\bar{\nu }}_e$-pairs to ${\nu }_{\mu }{\bar{\nu }}_{\mu }/{\nu }_{\tau }{\bar{\nu }}_{\tau }$-pairs is $\sim$\,5-to-1. This is because at SMS temperature scales, ${\nu }_e{\bar{\nu }}_e$ pairs have both charged and neutral current production channels, whereas ${\nu }_{\mu }{\bar{\nu }}_{\mu }/{\nu }_{\tau }{\bar{\nu }}_{\tau }$-pairs only have neutral current production channels. We point out that the typical energies of these neutrinos, and the run of density in collapsing radiation-dominated supermassive configurations, leads to Mikheyev-Smirnov-Wolfenstein (MSW) resonances inside these objects for the atmospheric neutrino mass splitting scale, $\Delta m_{atm.}^2\sim 2.4\times 10^{-3}$ eV${}^2$. In the normal neutrino mass hierarchy, adiabatic flavor transformation through the MSW resonances would then swap the fluxes ${\nu }_e\leftrightharpoons {\nu }_{\mu ,\tau }$, whereas, in the inverted neutrino mass hierarchy, the anti-neutrino fluxes are swapped, ${\bar{\nu }}_e\leftrightharpoons {\bar{\nu }}_{\mu ,\tau }$. We also examine the prospects for collective neutrino flavor oscillations in these environments. Implications for flavor oscillation's effects on neutrino energy deposition and neutrino-induced nucleosynthesis in the SMS's outer layers are examined, as are prospects for detections of SMS collapses through various means.

    ↳ astro-ph.COhep-phhep-th0 citations
20. 20*

    Medium Characterization with Hard Probes: From Cherenkov Light in QED to Jet Drift in QCD

    Hasan R. Rahman🇺🇸

    This dissertation presents a unified framework for medium characterization with hard probes spanning from Cherenkov light in quantum electrodynamics (QED) to jet drift in quantum chromodynamics (QCD). We first develop a dispersive fit to the refractive index $n(\lambda )$ of liquid argon (LAr) by incorporating anomalous dispersion at the 106.6 nm resonance for the first time. We show that the angular distribution of Cherenkov radiation is highly sensitive to the peak of the refractive index and contributes a significant excess over isotropic scintillation in certain angular bins. This work is important for precision Particle Identification (PID) for experiments like DUNE and CCM. Transitioning to high-energy nuclear collisions, we utilize ``jet drift'' -- the flow-induced deflection of partons -- as a tomographic probe of the Quark-Gluon Plasma (QGP). Using the Anisotropic Parton Evolution (APE) Monte Carlo simulation across various collision systems (PbPb, AuAu, and UU), we disentangle how the jet modification depends on medium size, temperature, and geometry. We show that jet drift exhibits distinct systematics in observables like the elliptic flow ($v_2$) and dihadron acoplanarity ($\Delta \varphi$), which helps disentangle it from conventional energy loss. Together, these studies demonstrate how the angular and kinematic signatures of hard probes revolutionize our ability to resolve the fundamental properties of matter.

    ↳ nucl-thhep-phhep-th0 citations
21. 21*

    New Exponential and Polynomial $\xi$-attractors

    Renata Kallosh🇺🇸 · Andrei Linde🇺🇸

    We introduce a new family of cosmological attractors with non-minimal coupling of gravity and non-canonical kinetic terms. In the Einstein frame, these models transform into a class of exponential and polynomial attractors with the spectral index $n_s$ spanning a broad range $1-2/N\le n_s<1-1/N$, and $r$ can decrease to zero in the limit $\xi \to \infty$. This is sufficient to match any combination of Planck, BICEP/Keck, ACT, SPT, and DESI data. We present a supergravity implementation of these models.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2026)·4 citations
22. 22*

    Gravitational wave emission from nonspherical collapse in an early matter-dominated era using N-body simulations

    Albert Escrivà🇯🇵 · Tomohiro Harada🇯🇵 · Kazunori Kohri🇯🇵 · Takahiro Terada🇯🇵 · Chul-Moon Yoo🇯🇵

    We study the dynamics of the collapse of a nonspherical overdense patch during an early matter-dominated era and the associated production of gravitational waves (GWs) using a semirelativistic N-body framework that we develop. The collapsing patch is initialized through a Zel'dovich deformation of a homogeneous sphere and evolved in an Einstein--de Sitter background, while the emitted signal is computed directly from the numerical quadrupole evolution. We show that a reliable prediction of the signal requires a fully numerical treatment of the nonlinear collapse dynamics. In particular, fitting-based procedures and Zel'dovich-based estimates fail to capture the post-shell-crossing evolution and can over/under-estimate the emitted power of the GWs. After averaging over realizations weighted by the Doroshkevich and BBKS (peak theory) distributions, we find that the two spectra have similar shapes and remain within the same overall order of magnitude at the peak amplitude, although the BBKS result is systematically smaller. The dominant contribution arises from peaks of relatively modest height, around $\nu \simeq 3$, while a larger variance significantly enhances the signal. Finally, by varying the horizon mass and reheating temperature, we map the present-day GW spectra to the sensitivity bands of different classes of detectors. In this way, the signal can populate a broad range of frequencies, from pulsar timing arrays to very high-frequency experiments, showing that GWs from nonspherical collapse can provide a probe of the pre-BBN thermal history.

    ↳ astro-ph.COgr-qchep-ph2 citations
23. 23*

    Molien--Weyl Singlet Counting and BFSS${}_2$--Factorization in Gaussian Matrix QM

    Badis Ydri🇩🇿

    We study the singlet-sector structure of mass-deformed BFSS${}_{d+1}$ matrix quantum mechanics by combining the large--\(d\) Gaussian reduction with the Molien--Weyl projection. The Gaussian reduction captures the bulk matrix dynamics through a gauged harmonic oscillator, while the Molien--Weyl integral imposes the Gauss law and reorganizes the physical Hilbert space into holonomy-projected singlet excitations. We show that the very-low-temperature bosonic singlet spectrum is universally controlled by the quadratic Gram operators \(\Tr(X_aX_b)\), whose number is \(d(d+1)/2\). For \(N=2\), this result is established by explicit residue computations and character methods; for \(N>2\), it is supported by the character analysis. Thus the infrared spectrum begins as a collection of BFSS${}_2$--like Gram towers, although higher invariant structures generally modify the full partition function. We also give a Hamiltonian derivation of the exceptional exact factorization at \((d,N)=(2,2)\), where the BFSS${}_3$ singlet partition function equals the cube of the BFSS${}_2$ one for all temperatures. This rigidity is special to the \(SU(2)\) invariant tensor structure and explains why \(d=1\) and \(N=2\) are exceptional regimes without a deconfinement crossover. Finally, we extend the Gram-counting picture to supersymmetric BFSS/BMN models and indicate how the Molien--Weyl formulation can benchmark Monte Carlo simulations in both \(X_a\)-space and holonomy space.

    ↳ hep-thgr-qchep-lathep-ph4 citations
24. 24*

    Chiral Magnetic Effect and Negative Magnetoresistance across the phase diagram of finite-density SU(2) gauge theory

    P. V. Buividovich🇬🇧 · L. von Smekal🇩🇪 · D. Smith🇩🇪

    We study the signatures of the Chiral Magnetic Effect (CME) in $SU(2)$ gauge theory with $N_f=2$ flavours of dynamical fermions at finite temperature $T$, quark chemical potential $\mu$ and a weak external magnetic field $eB$. We consider both the correlator of the axial density and the vector current, which gives direct access to the out-of-equilibrium CME, and the correlator of two vector currents, which probes the CME indirectly via the enhancement of the longitudinal electric conductivity (Negative Magnetoresistance, NMR). We find that the CME response extracted from the vector-axial correlator exhibits a rather weak dependence on temperature and density in the quark-gluon plasma regime, and is very close to the universal value for free massless quarks. The CME is mildly suppressed at low temperatures and large densities in the hadronic phase. In contrast, the NMR behaves in a qualitatively different way across the phase diagram, and is strongly suppressed at either large densities or temperatures. The magnitude of the NMR response appears to be considerably smaller than the prediction based on the lowest Landau level calculation for free quarks. Our findings suggest that for relatively small magnetic field strengths $eB\lesssim m_{\pi }^2$ the relation between the CME and NMR might not be as direct as expected. We also do not find statistically significant indications for an enhancement of the CME strength in the vicinity of the crossover or second-order phase transition lines in the $(\mu ,T)$ phase diagram.

    ↳ hep-lathep-phhep-thPRD(2026)·0 citations
25. 25*

    Exponential Quintessence: Analytic Relationship Between the Current Equation of State Parameter and the Potential Parameter

    Naoto Maki🇯🇵 · Kazunori Kohri🇯🇵

    Motivated by the indications of time-varying dark energy equation of state reported from DESI, we investigate a quintessence model with an exponential potential $V_0{e}^{-\lambda \varphi /m_{\mathrm{pl}}}$. We derive an analytical relationship between the current equation of state parameter for the quintessence field and the potential parameter $\lambda$ required to realize radiation and matter domination. Our results provide a useful analytical relation for inferring the potential parameter $\lambda$ from the observed current equation of state parameter. Furthermore, based on this framework, we provide a new approximate analytical upper bound on the potential parameter $\lambda$ for current accelerated expansion. Concretely, we obtain $\lambda <1.94$ as an approximate analytic estimate by adopting ${\Omega }_{\varphi 0}=0.685$.

    ↳ astro-ph.COgr-qchep-phhep-th3 citations
26. 26*

    Are PTA measurements sensitive to gravitational wave non-Gaussianities?

    Chiara Cecchini🇮🇹 · Jonas El Gammal🇮🇹 · Gabriele Franciolini🇮🇹 · Mauro Pieroni🇪🇸

    Observing non-Gaussianities in the timing residuals of Pulsar Timing Arrays (PTAs) has recently attracted attention as a potential discriminator between astrophysical and cosmological origins of the observed Gravitational Wave (GW) signal. In this work, we show that even in an idealized signal-dominated setup, after decorrelating the data to avoid spurious detections, statistical tests applied to PTA data cannot distinguish between a Gaussian and a non-Gaussian amplitude distribution of the GWB in a model-agnostic way. In particular, without making strong assumptions on the GW spectrum or the properties of the population, the sensitivity to any distinctive non-Gaussian feature is washed out.

    ↳ astro-ph.COastro-ph.HEgr-qchep-ph1 citation
27. 27*

    Ultraviolet completion of Starobinsky inflation

    Ignatios Antoniadis🇺🇸 · Chrysoula Markou🇮🇹 · Dimitri V. Nanopoulos🇬🇷

    We construct an $N=1$ supergravity action whose bosonic part contains an arbitrary function of the scalar curvature, the so-called $F(R)$ gravity. As in $R+R^2$ supergravity, it can be described in terms of two chiral superfields of no-scale supergravity: one contains the scalaron which plays the role of the Starobinsky inflaton and the other contains the goldstone fermion of spontaneously broken supersymmetry during the inflation plateau. Its (complex) scalar component acquires a non-tachyonic mass in the presence of the string dilaton and can be set to zero, together with the pseudoscalar partner of the scalaron, so that the scalar potential is reduced to the one of $F(R)$ gravity. In a perturbative expansion in powers of $R$, one obtains a small deformation of the Starobinsky cosmological model that solves the problem of initial conditions within the validity of the effective field theory, below the scale of tower of states predicted by the swampland distance conjecture. We also show that a particular example of an underlying microscopic theory with such properties is provided by a four-dimensional heterotic string model containing the Standard Model of particle physics.

    ↳ hep-thgr-qchep-ph3 citations
28. 28*

    Perturbative, Nonperturbative and Exact Aspects of Crystalline Phases in the Gross-Neveu Model

    Francesco Benini🇮🇹 · Ohad Mamroud🇮🇹 · Tomas Reis🇨🇭 · Marco Serone🇮🇹

    We study the crystalline phase of the $O(2N)$ Gross--Neveu model with a chemical potential for $a\le N-2$ of the fermions. We analyze the problem in three independent ways: using perturbative QFT methods, a semiclassical large $N$ analysis, and integrability techniques (both at finite and large $N$). The resulting picture is consistent across all three approaches: at sufficiently large chemical potential $h$, an inhomogeneous phase emerges in which $a$-particle bound states condense and which, at large $N$, corresponds to a periodically oscillating chiral condensate. In this phase, the usual dynamically generated scale $\Lambda$ is replaced by two new dynamically generated scales ${\Lambda }_{\mathrm{n}}$ and ${\Lambda }_{\mathrm{c}}$. These two scales govern the multiple nonperturbative effects in the theory, corresponding in particular to the mass gaps of neutral and charged excitations on top of the inhomogeneous vacuum, respectively. They also control the nonperturbative corrections to observables such as the free energy and provide the parameters characterizing the oscillatory profile of the mean field at large $N$. In this paper, we provide the necessary details of each of the three methods, thereby complementing the results announced in a previous, shorter publication.

    ↳ hep-thcond-mat.stat-mechcond-mat.str-elhep-lat+11 citation
29. 29*

    Constraints on the inflationary vacuum and reheating era from NANOGrav

    Debtosh Chowdhury🇮🇳 · Rounak Nath🇮🇳 · Sudipta Show🇮🇳

    NANOGrav and various pulsar timing array experiments recently reported compelling evidence for a stochastic gravitational wave background (SGWB). Such a background may originate from several astrophysical or cosmological sources. Assuming an inflationary origin, we use the latest NANOGrav 15-year dataset to constrain inflationary parameters, including the tensor spectral index ($n_t$), tensor-to-scalar ratio ($r$), and explore the implications for reheating through constraints on the reheating equation of state (${\omega }_{\text{re}}$) and reheating temperature ($T_{\text{re}}$). We find a preference for an extremely blue-tilted tensor spectrum and a non-instantaneous reheating epoch. Despite no concrete evidence on primordial vacua, inflationary vacuum is commonly assumed to be the Bunch-Davies vacuum. In this work, we study modifications to the GW spectrum arising from a two-parameter Bogoliubov family of non-Bunch-Davies vacua. Within this framework, we find that NANOGrav observations favour a subclass of non-Bunch-Davies vacuum, known as the alpha-vacuum. In addition, our analysis demonstrates that the observations strikingly narrow the range of the parameter $\alpha$ that characterizes the vacua. Our analysis indicates that the NANOGrav data can accommodate both matter- and radiation-like reheating scenarios for the standard Bunch-Davies vacuum case. However, within the non-Bunch-Davies framework considered here, a non-matter-like reheating is preferred because matter-like reheating requires relatively large $\alpha$, violating both the NANOGrav upper bound and the backreaction constraint. We further show that a frequency-dependent parametrization of $\alpha$ beyond a threshold frequency can yield a minimal solution that alleviates the blue-tilted issue. Finally, we highlight the possibility of testing such frequency dependence of $\alpha$ through future GW experiments.

    ↳ astro-ph.COhep-exhep-phhep-th0 citations
30. 30*

    Modeling $\Lambda$ polarization in Au$+$Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV using relativistic spin hydrodynamics

    Matteo Buzzegoli🇷🇴 · Aleksandar Gecic🇷🇴 · Rajeev Singh🇷🇴

    We investigate spin polarization dynamics in relativistic heavy-ion collisions using ideal relativistic spin hydrodynamics, employing non-boost-invariant longitudinal solutions as the hydrodynamic background. Operating in the small-polarization regime, where spin evolves perturbatively on top of the bulk expansion, we first analyze a $(1+1)$D setup with transverse homogeneity. In this framework, symmetry-constrained initial conditions for the spin potential lead to non-trivial evolution and generate both local and global $\Lambda$ hyperon polarization consistent with qualitative experimental trends, though they fail to reproduce observed azimuthal structures. To address this limitation, we extend the framework by incorporating transverse flow and spatial anisotropy at freeze-out, constructing a $novel$ $(1+1+2)$D model that preserves the longitudinal dynamics. We demonstrate that the inclusion of a longitudinal spin acceleration component, coupled with transverse expansion, results in the emergence of a quadrupole pattern in the longitudinal polarization. The resulting momentum-dependent and integrated observables exhibit qualitative and reasonably good quantitative agreement with experimental data for Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV. Finally, we provide predictions for the in-plane transverse spin polarization, an observable that, to our knowledge, has not yet been experimentally measured.

    ↳ nucl-thhep-ph0 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.