HEP Phenomenology·hep-ph

Fri·Aug 21, 2026Friday·August 21, 2026

32 papers—22 primary·10 cross-listed

01
On the Flavor Yukawa coupling for the Lepton Mass Hierarchy and the Koide Relation
Olivier Rousselle🇫🇷
This article proposes a geometric flavor mechanism to address the charged lepton mass hierarchy and formally derive the empirical Koide relation. Governed by a topological condensation $U (3) \to U (1) \times Z_{3}$ , the flavor vacuum couples a continuous isotropic background (the $U (1)$ singlet) to a discrete generation-splitting network (the $Z_{3}$ octet). Mechanical stability imposes a strict stress-free condition on this vacuum, requiring the expansive energy of the continuous sector to perfectly balance the cohesive topological tension of the discrete lattice. Furthermore, the geometric projection of the continuous internal space onto the discrete nodes generates a topological action phase that rigorously locks the internal flavor angle at $θ_{F} = - 2/9$ . By integrating these geometric constraints into the Yukawa Lagrangian, this framework perfectly recovers the Koide mass spectrum ( $Q = 2/3$ ) of the charged leptons (electron, muon, tau).
hep-ph0 citations
02
On trace invariance and energy-dependent entanglement in muon decay
Saulo Carneiro🇧🇷 · Fernando César Sobrinho🇧🇷
We revisit a proposed correction to the muon magnetic anomaly measurement and compare it with energy-binned scans reported by the Fermilab $g - 2$ collaboration. The central point is that, for a relativistic three-body decay inferred from an ensemble of detected positrons, the relevant neutrino partial trace is defined on the asymptotic state at the detector, not on an idealised state at the decay vertex. Because the fitted positron sample mixes events with different decay times, flight times, energies and acceptances, tracing over the unobserved neutrino helicities leaves a time-dependent mixed state in the observed sector. Using angular-momentum balance, we obtain an energy-dependent correction in the positron energy interval $E_{p} \in (1.5, 2.9)$ GeV. The corrected experimental interval for the muon anomaly moves towards the BaBar- and $τ$ -based determinations, while remaining compatible at the $1 σ$ level with both data-driven and lattice-based Standard Model evaluations. We then fit digitised public $R (E_{p})$ scans for Fermilab's runs $1$ to $6$ , with two one-parameter hypotheses: a constant shift and the entanglement-motivated energy-dependent shift. Within digitisation accuracy, the differences in $χ^{2}$ remain modest and the current binned data do not provide decisive discrimination between them.
hep-phquant-ph0 citations
03
Heavy quark transport in quark-gluon plasma beyond the non-relativistic limit
Krishna Rajagopal🇺🇸 · Bruno Scheihing-Hitschfeld🇺🇸 · Urs Achim Wiedemann🇨🇭
The dynamics of heavy quarks in quark-gluon plasma (QGP) formed in heavy ion collisions provide a unique window to characterize its properties. Existing approaches to describe heavy quarks in medium rely either on quasiparticle-based models of QGP, or on assuming that the momentum transfer from the medium follows Gaussian statistics. However, neither of these assumptions can be taken for granted in QCD. In fact, in the prototypical theory that is strongly coupled $N = 4$ SYM, it has been long known there are no momentum-carrying quasiparticles, and furthermore, we have recently shown that the momentum transfer from the medium is far from being Gaussian [arXiv:2501.06289]. Since then, we showed that the asymmetry of said momentum transfer between energy loss and energy gain -- which affects all moments of the distribution, not only its Gaussian characteristics -- is, in fact, universal [arXiv:2504.21139]. Therefore, in order to connect the initial heavy quark production cross section with the final hadron spectrum in a way that is consistent with QFT principles, new methods are needed. In this talk, we present a new transport description of heavy quarks that encodes all of the non-Gaussian features of the momentum transfer from the medium, all of which can be defined and in principle calculated in QCD, without relying on any assumptions regarding the strength of the coupling. As a demonstrative example, we discuss heavy quark equilibration in $N = 4$ SYM. This paves the way towards extracting novel information about fundamental properties of QGP.
hep-phnucl-th0 citations
04
Universal Two-Loop Current--Current Renormalization of Four-Fermion Operators
Jason Aebischer🇨🇭 · Sudeepan Datta🇨🇭 · Pol Morell🇪🇸 · Marko Pesut🇨🇭 · Javier Virto🇪🇸
The complete one- and two-loop gauge and scalar current--current contributions to the running of arbitrary dimension-six four-fermion operators are reported. The results are obtained in a basis-independent and renormalization-scheme-agnostic fashion and are valid for arbitrary gauge groups. The complete gauge and scalar contributions, including the genuine one- and two-loop poles, counterterm insertions, wave-function renormalization, finite evanescent insertions, diagram multiplicities, and the associated color, charge and Yukawa factors are provided for the most general renormalizable Lagrangian with gauge and scalar interactions. The results enable the derivation of leading- and next-to-leading-order current--current anomalous-dimension matrices for arbitrary Effective Field Theories (EFTs) and constitute a significant step toward the complete two-loop renormalization of general EFTs.
hep-ph0 citations
05
NAE, Statistically
Ranit Das🇺🇸 · Jonathan Ostertag-Henning🇩🇪 · Tilman Plehn🇩🇪 · Lorenz Vogel🇩🇪
Searches for new physics using neural anomaly scores have transformative potential, but suffer from a lack of statistical interpretability. The normalized autoencoder (NAE) provides a probabilistic interpretation of the standard bottleneck architecture, tying the anomaly score to a learned likelihood. We validate this relation for a toy model, test it for jets using a dual-NAE setup, and show how a Bayesian NAE learns this likelihood with an uncertainty.
hep-ph0 citations
06
Solar Constraints on Heavy Neutral Leptons with $ν_{τ}$ Mixing
Vedran Brdar🇺🇸 · Samiur R. Mir🇺🇸 · Xun-Jie Xu🇨🇳
The mixing of heavy neutral leptons (HNLs) with tau neutrinos remains largely unconstrained compared to their mixing with electron and muon neutrinos. In this work, we investigate the potential of solar neutrinos to improve constraints on HNL- $ν_{τ}$ mixing in the MeV mass range. Due to neutrino oscillations, the Sun is a copious source of neutrinos of all flavors, and the partial conversion of electron neutrinos into muon and tau neutrinos occurs already during their propagation through the solar interior. Tau neutrinos can produce HNLs through scattering with protons in the Sun, provided nonzero HNL- $ν_{τ}$ mixing is present. The HNLs escape the Sun and subsequently decay through the same interaction. For $O (10)$ MeV HNL masses, the dominant visible decay yields electrons and positrons that can be detected by space-based solar observatories. Using data from the Solar and Heliospheric Observatory (SOHO), we search for such signals and derive constraints on the squared HNL- $ν_{τ}$ mixing matrix element, $∣ U_{τ N} ∣^{2}$ , reaching below the $1 0^{- 2}$ level for HNL masses of $\sim 5$ MeV. These constraints improve upon existing terrestrial limits in this mass range by more than an order of magnitude.
hep-ph0 citations
07
TeV-scale leptogenesis in a parity symmetric neutrino mass model
Keisuke Harigaya🇺🇸 · Gio Leone🇺🇸
We study leptogenesis via out-of-equilibrium decays of right-handed neutrinos in a parity symmetric extension of the Standard Model with gauge group $S U (3)_{c} \times S U (2)_{L} \times S U (2)_{R} \times U (1)_{X}$ , spontaneously broken to the Standard Model gauge group at a scale $v_{R}$ . We focus on the minimal Higgs realization, in which the strong CP problem is resolved without invoking additional symmetries. In this framework, lepton number is violated through Yukawa interactions, while neutrino masses arise only at higher loop order, a feature that permits the CP-violating quantum corrections to right-handed neutrino decays to be parametrically large. For thermal production of right-handed neutrinos, we find that successful leptogenesis requires $v_{R} ≳ 6 \times 1 0^{12}$ GeV. Non-thermal production, however, relaxes this bound dramatically, requiring only $v_{R} ≳ 10$ TeV, a scale accessible to collider searches for new particles and searches for rare processes.
hep-phastro-ph.CO0 citations
08
Bayesian Forecasts on Cosmic Superstring Searches with LISA
Satyabrata Datta🇨🇳 · Rome Samanta🇮🇹
Cosmic superstrings are well-motivated early-Universe sources of stochastic gravitational waves, with phenomenology controlled by the string tension $G μ$ and the intercommutation probability $P$ . We study whether LISA can reconstruct these parameters and distinguish different superstring signal models in the presence of instrumental noise and astrophysical foregrounds. We consider two phenomenological models. In Model I, reduced intercommutation acts only as an amplitude enhancement of a cusp-dominated spectrum, $Ω_{SS}^{I} = P^{- β} Ω_{cusp}$ . In Model II, the signal is a cusp--kink mixture, $Ω_{SS}^{II} = P^{- β} [p_{c} Ω_{cusp} + (1 - p_{c}) Ω_{kink}]$ , so that $P$ controls both amplitude and spectral shape. Using simulated LISA data, we perform Bayesian inference with noise uncertainties, unresolved extragalactic compact-binary backgrounds, and a flexible Galactic double-white-dwarf foreground. We compare the models using Bayesian evidences and map the $(G μ, P)$ posterior geometry with marginalized widths, correlations, covariance anisotropy, principal eigenvalues, posterior area, and bias. We find that reduced intercommutation generically produces strong $G μ$ -- $P$ correlations, because the data often constrain an amplitude-like combination. However, when the cusp--kink spectral difference lies in the LISA band and the signal is sufficiently loud, Model II can be favored and the posterior can retain genuine shape information. As an optimistic foreground scenario, we also compute the Bayes factor using a reduced tanh Galactic foreground template, finding improved model discrimination when the foreground shape is constrained.
hep-phastro-ph.COgr-qchep-th0 citations
09
WIMP Freeze-Out in Diffusive Unimodular Gravity
Cesar Bonilla🇨🇱 · Esteban Gonzalez🇨🇱 · Carlos Maldonado🇨🇱
We study a non-standard cosmology (NSC) scenario within the Unimodular Gravity (UG) framework, sourced by a scalar field $ϕ$ that undergoes energy diffusion, parametrized by the diffusion parameter $x$ , the initial energy densities rate $κ \equiv ρ_{ϕ} / ρ_{γ} ∣_{ini}$ , and the end-of-domination temperature $T_{end}$ . We compare this UG+NSC scenario with standard NSC and $Λ$ CDM cosmologies for WIMP Dark Matter (DM) production via the freeze-out mechanism. We find that energy diffusion reshapes the allowed $(m_{χ}, ⟨ σ v ⟩)$ parameter space, where $m_{χ}$ is the DM mass and $⟨ σ v ⟩$ is the thermally averaged annihilation cross section, opening regions otherwise excluded by DM overproduction in $Λ$ CDM, and shifting the mass and cross-section ranges accessible to WIMP candidates depending on $x$ , $κ$ , $T_{end}$ , and the barotropic index $ω$ of $ϕ$ . As a concrete application, we implement this framework for the Real Singlet Scalar WIMP and test its $(m_{χ}, λ_{H S})$ parameter space against current direct detection bounds from the LZ experiment, showing that energy diffusion opens previously unconstrained regions in the Higgs-portal coupling $λ_{H S}$ and thereby alters the detectability prospects of this benchmark model in future searches.
hep-phastro-ph.CO0 citations
10
Photon bremsstrahlung from heavy quarks in a dense nuclear matter
Le Zhang🇨🇳 · Shanshan Cao🇨🇳 · De-Fu Hou🇨🇳 · Guang-You Qin🇨🇳
We study the bremsstrahlung photon production from a hard jet parton induced by rescattering with a dense nuclear medium. Using the charged current interaction channel of deep inelastic scattering between an electron and a large nucleus, we derive the spectrum of medium-induced photons emitted from high-energy heavy and light quarks at the next-to-leading twist in a unified framework. Going beyond the collinear expansion approximation, we show that the photon spectrum is determined by the full momentum distribution of the gluon exchanged between the propagating quark and the medium, or equivalently, by the differential elastic scattering rate of the hard quark inside the medium. Modeling the gluon field with a static Debye screened potential reduces the photon spectrum to a dependence on the transverse momentum distribution of the exchanged gluon. This work provides a more reliable input for future phenomenological studies of quark mass effects on jet-induced photon production in relativistic heavy-ion collisions.
hep-ph0 citations
11
Cosmic Evolution of the Standard Model Flavor Charges
Chee Sheng Fong🇧🇷 · Sergio Manuel Cubides Pérez🇧🇷
Since all the Standard Model (SM) parameters have been measured to precision at the percent level or smaller, one would aim to have a framework which describes baryogenesis as precise as possible, where the measured SM parameters are used as inputs. At high temperature before the electroweak symmetry breaking, the SM contains 15 approximate $U (1)$ symmetries with the associated flavor charges. To describe the evolutions of these flavor charges in a flavor-basis-covariant manner such that physical observables are flavor-basis-independent, a total of five density matrices in flavor spaces are required: three for quarks and two for leptons. Taking into account the quantum chromodynamics and electroweak sphaleron interactions together with all the Yukawa interactions, we obtain the complete flavor-covariant Boltzmann equations. By imposing chemical equilibrium in the lepton sector, we further derive a new effective quark-flavor-covariant formalism which can be used when baryogenesis occurs through number asymmetry generation in the quark sector. To verify the consistency of this complete formalism, we first apply it to leptogenesis scenarios, reproducing previous results which utilize the effective lepton-flavor-covariant formalism up to small corrections due to the quark chemical equilibrium approximations used in the latter formalism. Then, for the first time, we apply the complete formalism as well as the effective quark-flavor-covariant formalism to a cloistered baryogenesis scenario where number asymmetries are generated in the quark sector, showcasing the good agreement between the results from the two formalisms. Finally, we release the first generic baryogenesis public code BOLEH (BaryOn and Lepton charge Evolution in the Hot big bang) where all the SM interactions are taken into account.
hep-ph0 citations
12
Electroweak Baryogenesis in Top-Philic Type-III Two-Higgs-Doublet Model motivated by the $t t ˉ$ Excess at the LHC
Yoshiki Matsuoka🇯🇵
The CMS and ATLAS Collaborations have reported a $t t ˉ$ threshold enhancement possibly involving a pseudoscalar toponium quasi-bound state and an elementary pseudoscalar. Identifying the elementary pseudoscalar with the CP-odd Higgs boson, we investigate electroweak baryogenesis in the top-philic Type-III two-Higgs-doublet model (2HDM), whose scalar sector may support a strong first-order electroweak phase transition. We compare two scenarios: explicit CP violation and transitional CP violation (TCPV). In the first, a complex additional top-quark Yukawa coupling induces a spatially varying phase of the top-quark mass across the bubble wall. This generates a chiral asymmetry that electroweak sphalerons convert into baryon asymmetry. In TCPV, CP symmetry would be broken inside the bubble wall but preserved in the vacuum in the absence of explicit CP violation. A small explicit CP-violating bias would favor one of the otherwise CP-conjugate wall configurations, avoiding exact cancellation of the generated baryon asymmetry. This could allow baryogenesis without large explicit CP violation, potentially alleviating electric dipole moment constraints. Combining a one-loop finite-temperature analysis of bubble nucleation with transport calculations, we find that electroweak baryogenesis with explicit CP violation remains possible, although this conclusion depends on the thermal-resummation schemes. No viable TCPV solution is found in the parameter regions explored.
hep-phhep-exhep-th0 citations
13
Minimal Quark-Lepton Complementarity from a Rigid Deformation of Tri-Bimaximal Mixing
Gazal Sharma🇮🇳 · Gaurav Katoch🇮🇳
We propose a minimal three-family realization of quark--lepton complementarity (QLC) in which the non-trivial correlation matrix is an exactly unitary, rigid deformation of tri-bimaximal mixing. In a canonical TBM convention the deformation is a rotation about the normalized axis $n_{g g} = (2, 1, 2)^{T} /3$ , with rotation angle fixed by the Cabibbo angle, $α_{g g} = - 3 θ_{C} /4$ . The resulting ansatz, $\UPMNS = \VCKM^{†} \UTBM R_{n_{g g}} (- 3 θ_{C} /4)$ , contains no new continuous parameter in the Dirac lepton-mixing sector once the structural choice is fixed. With the 2025 Particle Data Group CKM fit it predicts $θ_{12} = 33.2 9^{\circ}$ , $θ_{13} = 8.4 6^{\circ}$ , $θ_{23} = 49.1 9^{\circ}$ , and $\dcp = 180.7 9^{\circ}$ , with CKM-induced uncertainties much smaller than present oscillation errors. We derive leading Wolfenstein sum rules; in particular, the real deformation preserves the CKM-induced suppression $\Jcp = - A η λ^{3} /6 + O (λ^{4})$ and hence a near-CP-conserving phase. A retrospective simplicity scan shows that the pair $(2, 1, 2), 3/4$ ranks first among 5510 oriented primitive-integer/rational candidates when tested on epoch-matched 2016 and 2018 oscillation data. In an enlarged 49,622-candidate 2018 scan it is second in raw score but remains first among candidates no more complex than itself under several independent simplicity measures; profiling the rotation strength for the fixed $(2, 1, 2)$ axis gives $r_{BF} = 0.74941$ . We formulate the deformation by a convention-covariant flavor-space generator and give an exact effective eigenframe realization $M_{ν} = A I + B \Sgg + C \Sgg^{2}$ . The construction is presently allowed in normal ordering, with the atmospheric sector providing its strongest pressure; its upper-octant atmospheric angle and near- $π$ Dirac phase provide sharp falsifiability targets.
hep-ph0 citations
14
Tracing Vacuum Hadronization with Conserved Currents
Weiyao Ke🇨🇳 · Hai Tao Li🇨🇳 · Wanchen Li🇨🇳 · Xiaohui Liu🇨🇳 · Ding Yu Shao🇨🇳
We show that color triality constrains the nonperturbative states that screen a Wilson-line endpoint, allowing the joint flows of net electric charge, baryon number, and strangeness to probe QCD vacuum hadronization. Whether evaluated from resolved hadrons in a jet initiated by a quark of flavor $f$ or from the corresponding charge correlators, these flows satisfy the Gell-Mann--Nishijima relation $⟨ Q_{flow} ⟩_{f} ≃ I_{3, f} + \frac{1}{2} (⟨ S_{flow} ⟩_{f} + ⟨ B_{flow} ⟩_{f})$ , where $I_{3, f}$ is the third component of the initiating-quark isospin. The net jet baryon number, $⟨ B_{flow} ⟩_{f} ≃ \frac{r _{q q}}{1 + r _{q q}}$ , directly probes the relative probability of a diquark--antidiquark vacuum excitation, with $r_{q q}$ the diquark-to-quark production ratio. Thus, for $r_{q q} ≪ 1$ , the baryon number carried by the jet is substantially suppressed relative to the initiating-quark value $B_{f} = 1/3$ . Likewise, the strange-to-light pair-production ratio, defined by $u u ˉ : d d ˉ : s s ˉ = 1 : 1 : r_{s}$ , is encoded in the measured jet strangeness $⟨ S_{flow} ⟩_{f} ≃ S_{f} + \frac{3 r _{s}}{2 + r _{s}} (\frac{1}{3} - ⟨ B_{flow} ⟩_{f})$ , predicting a nonzero mean net strangeness even in $u$ - and $d$ -initiated jets. The conserved-current moments appearing in these relations are independent of the renormalization scale. Their simultaneous measurement therefore provides a direct, flavor-resolved probe of vacuum pair production and quantum-number transport during hadronization.
hep-phhep-exnucl-exnucl-th0 citations
15
Instability diagram of the massive gauge quantum fields around the nonlinear massive classical wave solution
Yoshio Kitadono🇹🇼 · Tomohiro Inagaki🇯🇵
The stability and instability in the time dynamics of quantum fluctuation of the massive gauge field coupling to the nonlinear massive wave solution is studied. In particular, the instability in the transverse polarization and longitudinal polarization modes are obtained as the two dimensional plot of the initial field value parameter and the spatial momentum of the quantum massive gauge fields with the help of the theory of the Hill's equation. We present the formalism to analyze the massive gauge field by taking into account Proca constraint and we found that our formalism can predict the time dynamics of the unstable quantum mode by the Floquet index. The resulting polarization-resolved Floquet maps show that the transverse modes possess only narrow parametric-resonance bands, whereas the longitudinal modes exhibit substantially broader regions generated by both parametric and spinodal instabilities. We also find additional low-momentum instability regions for the $W$ boson that are absent or strongly suppressed in the $Z$ sector.
hep-ph0 citations
16
Skewness dependence of the pion and kaon generalized parton distributions
Fernando Chandra🇮🇩 · Parada T. P. Hutauruk🇯🇵 · Terry Mart🇮🇩
We investigate the skewness dependence of the pion generalized parton distribution (GPD) at different momentum transfers $- t$ within the covariant Nambu-Jona-Lasinio (NJL) model, employing the Schwinger proper-time regularization scheme to regulate ultraviolet divergences and implement an effective description of quark confinement. We evolve the pion GPDs for various values of $- t$ and $ξ$ to the scales $μ^{2} = 4$ and $27 GeV^{2}$ . We find that the valence-quark distributions are suppressed with increasing $- t$ and $ξ$ , with the suppression becoming more pronounced at the lower scale, $μ^{2} = 4 GeV^{2}$ . In the forward limit, $ξ = 0$ and $- t = 0$ , the predicted pion valence-quark distribution at $μ^{2} = 27 GeV^{2}$ is in good agreement with the available experimental data and the global JAM analysis. The corresponding pion gluon distribution at $μ^{2} = 4 GeV^{2}$ , obtained through next-to-leading-order (NLO) DGLAP evolution, is also consistent with the JAM analysis. We further find that the pion and kaon valence-quark distributions exhibit a strong dependence on $- t$ but only a weak dependence on $ξ$ , whereas the corresponding gluon distributions show weak dependence on both $- t$ and $ξ$ . The generalized form factors of the pion and kaon at $μ^{2} = 4 GeV^{2}$ are in good agreement with the corresponding lattice-QCD results.
hep-phnucl-th0 citations
17
Lattice-data-driven specific heat and isentropic bulk modulus of SU(3) gluon matter at finite temperature
Wei Shen🇨🇳 · Zhen-Yan Lu🇨🇳 · Muhammad Waqas🇨🇳 · Xun Chen🇨🇳 · Zhi-Jun Ma🇨🇳 · Guang-Xiong Peng🇨🇳
We investigate the specific heat and isentropic bulk modulus of finite-temperature pure SU(3) gauge matter within a lattice-data-driven phenomenological framework. The equation of state is formulated in terms of a temperature-dependent effective gluon mass constrained { by lattice QCD pressure data as input, allowing the pressure}, trace anomaly, gluon number density, energy per thermally active gluonic mode, and derivative-sensitive response functions to be derived in a thermodynamically consistent manner. The resulting pressure and trace anomaly reproduce the characteristic lattice behavior across the deconfinement region, while the effective gluonic degrees of freedom increase rapidly above $T_{c}$ . The normalized specific heat $C_{V} / T^{3}$ develops a pronounced enhancement in the vicinity of $T_{c}$ , reflecting the rapid temperature variation of the energy density across the deconfinement region. The isentropic bulk modulus $K_{S} / T^{4}$ also rises sharply across the transition region, indicating a substantial stiffening of the equation of state. At high temperatures, both response functions gradually approach values close to their massless conformal Stefan--Boltzmann reference values, with $(C_{V} / T^{3})_{SB} = 32 π^{2} /15 ≃ 21.06$ and $(K_{S} / T^{4})_{SB} = 32 π^{2} /135 ≃ 2.34$ . These findings indicate that the specific heat and isentropic bulk modulus provide complementary constraints on the temperature evolution of nonconformal dynamics in pure SU(3) gauge matter.
hep-phhep-thnucl-th0 citations
18
Exploring chiral dynamics with low-energy electron- and positron-nucleon scattering
C. Weiss🇺🇸
Low-energy lepton-nucleon scattering probes various expressions of the long-distance dynamics in the baryon sector of QCD, governed by chiral symmetry breaking and the $Δ$ resonance. We discuss some specific studies that could be performed with combined electron- and positron-nucleon scattering at lab energies $E_{e \pm} ≲$ 500 MeV. They include: (a) chiral dynamics in the low- $Q^{2}$ nucleon elastic form factors (peripheral charge and current densities); (b) two-photon exchange effects in the target normal single-spin asymmetry and beam charge asymmetry in elastic and inclusive scattering ( $Δ$ excitation); (c) nucleon generalized polarizabilities in virtual Compton scattering with beam charge asymmetry measurements.
hep-ph0 citations
19
Negative diffusion in the Functional Renormalization Group flow for the Quark-Diquark Model
Johannes Poeplau🇩🇪 · Ashutosh Dash🇩🇪 · Dirk H. Rischke🇩🇪
We investigate the Quark-Diquark Model (QDM) with the Functional Renormalization Group (FRG) in the Local Potential Approximation. In a recent work [arXiv:2510.01066 [hep-ph]], problems were reported in applying this method at low temperatures and large quark chemical potentials, which were attributed to numerical artifacts. In this work, we trace the origin of these problems to the occurrence of a negative diffusion coefficient during the FRG flow of the derivative of the effective potential, leading to strong oscillations of the latter quantity. We show that negative diffusion is a model feature and not a numerical artifact. We propose a regularization scheme which introduces a hyperdiffusion term to remove these oscillations and demonstrate its effectiveness for studies of the phase diagram of the QDM. Regularizing the negative diffusion in the FRG flow is particularly important to reliably study phenomena such as color superconductivity and inhomogeneous phases, which might emerge in the high-density, low-temperature region of the QCD phase diagram.
hep-phhep-thnucl-th0 citations
20
Extraction of DVCS amplitudes off the nucleon
C. Mezrag🇫🇷 · P. Sznajder🇵🇱 · J. Wagner🇵🇱
This work presents a modern extraction of deeply virtual Compton scattering (DVCS) amplitudes off the proton and off the neutron through a global analysis of experimental data. These amplitudes serve as a crucial intermediate quantity linking generalized parton distributions (GPDs) to experimental observables. The analysis relies on a novel extraction framework recently integrated into the PARTONS software ecosystem. We employ two distinct modelling approaches for the DVCS amplitudes, both utilizing machine learning techniques: one model-agnostic and the other theory-augmented. For the first time, we incorporate the extraction of helicity-flip amplitudes, which are particularly sensitive to higher-twist effects. Furthermore, we compare our extracted amplitudes to timelike Compton scattering (TCS) data using the established relations between DVCS and TCS, serving as an important test of universality of GPDs. We also extract the DVCS subtraction constant, for which ab initio predictions from lattice QCD have been obtained. This allows us to confront these predictions with DVCS data for the first time, initiating a new virtuous cycle between first-principles theory and phenomenology.
hep-ph0 citations
21
QED radiative effects in semi-inclusive deep-inelastic scattering: traditional and factorized approaches
Igor Akushevich🇺🇸 · Haiyan Gao🇺🇸 · Alexander Ilyichev🇧🇾 · Shuo Jia🇺🇸 · Vladimir Khachatryan🇺🇸 · Youjie Lin🇨🇳 · Tianbo Liu🇨🇳 · W. Melnitchouk🇺🇸
Semi-inclusive deep-inelastic scattering (SIDIS) of leptons is a vital tool for probing the three-dimensional momentum space partonic structure of the nucleon. Reliable extraction of the intrinsic collinear or transverse momentum dependent parton distributions from SIDIS data requires careful treatment of QED radiative effects beyond the Born level. In this work we perform a detailed comparative analysis of QED effects in SIDIS using the traditional Bardin-Shumeiko approach, augmented by the electron structure function method, and a more recent factorized approach that treats QED and QCD radiation on equal footing. We compare analytical and numerical results of these approaches for the unpolarized $π^{+}$ electroproduction cross sections off the proton and the Collins and Sivers transverse single-spin asymmetries, and identify the sources of discrepancies between the calculations, which for the cross sections can reach up to $\approx 2%$ , $\approx 7%$ , and $\approx 5%$ at Jefferson Lab, HERMES, and EIC kinematics, respectively. To provide a unified approach for reliably extracting partonic information from future SIDIS measurements, we propose a hybrid framework that employs the salient features of both frameworks in their respective regions of applicability.
hep-phhep-exnucl-exnucl-th0 citations
22
Production of quarkonium pairs via the fragmentation mechanism
Franco Barattini🇨🇱 · Benjamin Guiot🇨🇱 · Marat Siddikov🇨🇱
In this manuscript, we analyze the contribution of fragmentation mechanisms to the inclusive hadroproduction of heavy quarkonium pairs, taking into account both single- and double-hadron (dihadron) fragmentation channels. To estimate the contribution of the latter mechanism, we construct a microscopic perturbative model of the dihadron fragmentation function, which is valid in the limit of large invariant masses of the heavy quarkonium pair. Using the Color Glass Condensate framework to evaluate the $Q Q ˉ$ production amplitude, we find that in LHC kinematics, the single fragmentation of heavy quarks into quarkonium is only a minor correction, whereas dihadron fragmentation can provide a sizable contribution, on par with the contributions of single- and double-parton scattering.
hep-ph0 citations
23
Detectable subhalo impacts in Milky Way streams
Junyang Lu🇨🇳 · Elias Bernreuther🇺🇸 · Tongyan Lin🇺🇸 · Vincent S. H. Lee🇺🇸 · Ana Bonaca · Ethan O. Nadler🇺🇸
Dark matter subhalos leave gravitational imprints in the stellar streams of the Milky Way. Observing individual strong impacts of subhalos offers a compelling way to constrain and discover potentially dark subhalos down to $1 0^{6} M_{⊙}$ , allowing for new tests of the particle physics properties of dark matter. We develop a pipeline and statistical framework to forecast the expected number of detectable subhalo impacts on stellar streams, based on morphological and kinematic data from surveys such as LSST and Via. Starting from a catalog of confirmed stellar streams, we focus our efforts on 14 promising streams that are relatively well-modeled with a particle spray algorithm. Our criteria for a detectable impact is a deviation at 95% CL from the best-fit polynomial proxy model for the stream, which accounts for stream modeling uncertainties and regulates the effect of distant impacts that are degenerate with these uncertainties. Among the 14 streams studied, we find that 5 streams have an expected number of detectable impacts greater than 0.2. With LSST and Via data, the stream Jet has $5.1 5_{- 0.95}^{+ 1.10}$ expected detectable impacts, followed by Orphan-Chenab ( $1.4 0_{- 0.47}^{+ 0.62}$ ), ATLAS-Aliqa Uma ( $1.2 5_{- 0.44}^{+ 0.60}$ ), GD-1 ( $0.5 5_{- 0.28}^{+ 0.43}$ ), and Palomar 5 ( $0.4 0_{- 0.23}^{+ 0.39}$ ), where error bars are the 95% containment on the Poisson mean. These values rely on the assumed subhalo population, which can give a factor of few systematic uncertainty in the predictions. We also consider effects of different particle dark matter models on the number of impacts, finding a suppression by a factor of $\sim 4$ for warm dark matter and fuzzy dark matter models at their current mass bounds and an $O (1)$ enhancement for a toy model of self-interacting dark matter.
↳ astro-ph.GAastro-ph.COhep-ph0 citations
24
The EEC-Hedron: Positivity Bounds on Energy Correlators
Bianka Meçaj🇺🇸 · Ian Moult🇺🇸 · Hidde Stoffels🇬🇧 · Matthew T. Walters🇬🇧 · Yuan Xin🇺🇸
We study the constraints placed by energy positivity on general unitary quantum field theories. We show that the coefficients in the partial wave expansion of energy-energy correlators all must lie within a bounded region of parameter space, which we call the ``EEC-hedron''. For the particular case of conformal field theories, these positivity constraints on energy correlators lead to bounds on the allowed values of coefficients in the operator product expansion. We demonstrate this approach in the 3d Ising and $O (2)$ CFTs, deriving new bounds on OPE coefficients in both theories.
↳ hep-thhep-ph1 citation
25
The QCD crossover temperature and curvature coefficient from unbiased exponential resummation at physical quark masses in (2+1)-flavor lattice QCD
Sabarnya Mitra🇩🇪
We present the first application of the unbiased exponential resummation method to the determination of the QCD pseudocritical temperature $T_{pc}$ at vanishing baryon chemical potential $μ_{B}$ . By reconstructing the finite-density baryon number susceptibility $χ_{2}^{B}$ , we define two thermal-derivative observables whose peak positions yield $T_{pc}^{T} = 160.2 (4) (3)$ MeV and $T_{pc}^{C} = 158.1 (5) (3)$ MeV. We also show that the pseudocritical temperature, $T_{pc}^{χ}$ obtained from the peak of the fourth-order baryon number susceptibility $χ_{4}^{B}$ is consistent with these determinations and with previous lattice-QCD results based on Taylor expansions \cite{Bollweg:2022Pade}. Further, we demonstrate that scaling relations \cite{Bollweg:2022fqq} between $χ_{4}^{B}$ and the thermal derivatives of $χ_{2}^{B}$ yield mutually consistent estimates of the leading second order curvature coefficient $κ_{2}^{B}$ at the corresponding pseudocritical temperatures. A direct analysis of the $μ_{B}$ dependence of the pseudocritical temperatures provides an independent but substantially less constrained determination of the curvature, which remains statistically consistent with the scaling-based estimates. These results demonstrate the consistency of unbiased exponential resummation with the expected scaling behavior and establish it as a complementary approach for probing the QCD crossover at small finite baryon density.
↳ hep-lathep-phhep-thnucl-ex+10 citations
26
Stochastic Schwinger Effect: de Sitter and beyond
Lucas Vicente García-Consuegra🇬🇧 · Azadeh Maleknejad🇬🇧
We develop a stochastic formulation of the Schwinger effect in de Sitter spacetime using the Schwinger--Keldysh (in-in) formalism, tailored to particle production by non-stationary gauge backgrounds in the early Universe. Treating the gauge field as a prescribed classical stochastic ensemble, we integrate out massless charged matter and derive the corresponding influence functional and particle-production kernel to leading non-trivial order in the gauge coupling. Conformal invariance allows the result to be extended directly from de Sitter to generic spatially flat FLRW spacetimes, without relying on asymptotic out states. We establish the infrared safety and classicality conditions of the stochastic description and clarify its relation to the conventional static Schwinger effect. We further extend the framework to massless conformally coupled scalars and to weakly coupled non-Abelian gauge sectors, including Standard Model and hidden-sector examples, in regimes where thermal corrections are negligible. Our results provide a general framework for matter creation by stochastic gauge fields in inflation, preheating, and non-thermal BSM sectors, connecting quantum field theory in curved spacetime with early-Universe and high-energy phenomenology.
↳ hep-thastro-ph.COgr-qchep-ph2 citations
27
Kerr Quasinormal Modes without Variable Separation: A Two-Dimensional Hyperboloidal Teukolsky Solver with Physics-Informed Neural Networks
Antonio Ferrer-Sánchez🇪🇸 · Daniela D. Doneva🇪🇸 · José D. Martín-Guerrero🇪🇸 · Stoytcho S. Yazadjiev🇧🇬 · Roberto Ruiz de Austri-Bazan🇪🇸 · Yolanda Vives-Gilabert🇪🇸 · José A. Font🇪🇸
We use physics-informed neural networks (PINNs) to solve the gravitational quasinormal-mode (QNM) eigenvalue problem for Kerr spacetime directly in the two-dimensional hyperboloidal formulation of the Teukolsky equation. This formulation does not require separation of variables and thus retains the coupled radial--angular structure. Such a scheme provides a prototype for calculating the QNMs of beyond-Kerr black holes for which the perturbation equations are non-separable. Sequences with increasing angular momentum are constructed, reaching close to the extremal limit. We focus on the fundamental modes $(ℓ, m, n) = (2, 0, 0)$ , $(2, 1, 0)$ , $(2, 2, 0)$ , $(3, 3, 0)$ and $(4, 4, 0)$ , together with the first overtone $(2, 2, 1)$ . Independent benchmark evaluation shows that every reported real and imaginary frequency component remains below $0.5%$ error, with a median deviation of $0.1%$ . This accuracy is maintained in the near-extremal regime, where the damping rate becomes small and the modes are longest-lived. The results establish a non-spectral numerical route to multidimensional black-hole perturbation eigenproblems which does not match the substantially higher precision of dedicated Kerr solvers but offers greater flexibility and requires less analytical pre-processing. Non-separable rotating backgrounds and coupled systems, such as gravitational--electromagnetic Kerr--Newman perturbations, are natural extensions of the same construction.
↳ gr-qchep-phphysics.comp-ph0 citations
28
Quintessential \alpha-attractors, updated
Renata Kallosh🇺🇸 · Andrei Linde🇺🇸 · Marina Shmakova🇺🇸 · Yusuke Yamada🇰🇷
Quintessential $α$ -attractor models of single-field inflation and evolving dark energy were constructed about a decade ago. Recently, it was pointed out that some of them might be disfavored due to dark-radiation constraints on gravitational waves and the higher values of $n_{s}$ favored by ACT. Here we present a class of updated quintessential $α$ -attractor models in which a single field describes both inflation and evolving dark energy, yields higher values of $n_{s}$ , and admits reheating scenarios consistent with the dark-radiation bound on $Δ N_{eff}$ . Depending on the value of the cosmological constant $Λ$ , these models interpolate between $Λ$ CDM with $Λ > 0$ (future dS universe), dynamical dark energy with $Λ = 0$ (future Minkowski universe), and dynamical dark energy with $Λ < 0$ (future cosmological collapse). We also study quintessential $α$ -attractor models based on an axion-inflaton complex scalar field with hyperbolic geometry, which describe inflation and dark energy of a ``phantom illusion'' type compatible with DESI DR2.
↳ astro-ph.COgr-qchep-phhep-th1 citation
29
Universal Relations for Neutron Stars from Asymptotic Analysis
Syo Kamata🇯🇵 · Josuke Minamiguchi🇯🇵 · Shuhei Minato🇯🇵
Dimensionless observables of neutron stars, such as the moment of inertia, the tidal deformability, the spin-induced quadrupole moment, and the compactness, satisfy the I--Love--Q and Love-- $C$ universal relations to percent-level accuracy over a wide range of equations of state. We investigate analytically the origin of this insensitivity in the stellar structure equations. We derive asymptotic expansions of these relations directly from the differential equations and boundary conditions for slowly rotating, tidally deformed stars described by a general piecewise-polytropic equation of state. Although the differential equations allow several forms of the asymptotic expansion, we find that only one class is consistent with the observed universality, and we use this class to analyze the universal relations. Because the observables are determined at the stellar surface, information about the deep-interior equation of state can enter them only through the parameters that survive in the asymptotic expansion at the surface. We find that the universal relations depend only on three parameters: two integration constants and one polytrope index of the outermost segment. By determining how these parameters deform the relations, we show that, throughout the region of parameter space occupied by realistic equations of state, the resulting deviations remain at the percent level, consistent with the observed accuracy of the universal relations. Within the same formalism, we classify violations of universality according to the additional degrees of freedom or input data responsible for them. Since the construction relies only on the underlying differential equations and boundary conditions, the same procedure can be applied to other systems once the corresponding equations and boundary conditions are specified.
↳ gr-qcastro-ph.HEhep-ph0 citations
30
Imaginary time evolution of a quantum system through analytic continuation from real-time quantum simulation
Peng Guo🇺🇸 · Anto Shibu · Joshua Lin🇺🇸 · Yong Zhao🇺🇸
Though quantum computing naturally offers an advantage for simulations of real-time quantum systems, implementing Imaginary-Time Evolution (ITE) is comparatively more difficult. Nevertheless, quantum implementations of ITE are useful both in cases where classical implementations have associated sign problems, and also as an exact method of preparing eigenstates on quantum computers. In this work we present an algorithm to obtain ITE of a generic quantum Hamiltonian by performing analytic continuation of measured real-time correlation functions. We present simulations and demonstrations on IBM quantum hardware of 1D Fokker-Planck equations for classical diffusion process and imaginary-time evolution of integrated correlation functions in 1D quantum mechanical scattering as examples to demonstrate the effectiveness of the method.
↳ quant-phcond-mat.otherhep-lathep-ph+10 citations
31
Non-Minimally Coupled Warm Inflation in the Defining Frame
Adrián Casado-Turrión🇱🇹 · Paulo B. Ferraz🇵🇹 · Mindaugas Karčiauskas🇱🇹 · José Jaime Terente Díaz🇵🇹
Warm inflation in $F (Φ) R$ scalar-tensor theories of gravity is investigated in the `defining' frame, where the theory and its parameter values are specified. Translating the resulting dynamics to the Einstein frame, we find that the dissipation ratio is suppressed by the modified-gravity effects. Thus, although the effective warm-inflation dynamics can be consistently analysed in either frame, the dissipative regimes need not coincide between them. In particular, we find that quantum perturbations can dominate over thermal fluctuations in the scalar power spectrum even in a high-temperature, strong-dissipation regime in the defining frame. Finally, we compute the scalar spectral index and tensor-to-scalar ratio for a non-minimal coupling function $F (Φ) = 1 + ξ (Φ/ m_{P})^{2}$ with a quartic potential and both constant and quadratic field-dependent dissipation coefficients, and identify benchmark points compatible with current CMB constraints.
↳ astro-ph.COgr-qchep-ph0 citations
32
Correspondence between hydrodynamic frames, transport coefficients, and hydrodynamic modes in relativistic fluids
Md Hasanujjaman🇮🇳 · Mahfuzur Rahaman🇮🇳
The choice of hydrodynamic frame directly influences the numerical values of transport coefficients in relativistic dissipative hydrodynamics. We derive the exact transformation between the Eckart and Landau--Lifshitz frames and show that their thermal conductivities are related by an enthalpy-dependent factor. Using a baryon-rich relativistic fluid described by a Boltzmann nucleon gas equation of state, we find that the Landau--Lifshitz thermal conductivity is suppressed relative to the Eckart conductivity, with the difference increasing with temperature and baryon chemical potential. A linearized analysis of sound propagation demonstrates that the sound attenuation coefficient remains identical in both frames, confirming the frame invariance of physical observables. Our results show that the frame dependence of transport coefficients reflects only the different decomposition of dissipative effects into heat-flow and diffusion currents, while the underlying transport physics remains unchanged. These findings underscore the importance of specifying the hydrodynamic frame when comparing transport coefficients from heavy-ion collisions, lattice QCD, and kinetic-theory calculations.
↳ nucl-thhep-ph0 citations

Affiliations

first authorsco-authorsvia INSPIRE