Mon·Apr 6, 2026Monday·April 6, 2026

1. 01*

   Modified Entanglement Patterns in Four-Flavor Neutrinos from Quantum-Gravity Interactions

   Bipin Singh Koranga🇮🇳 · Baktiar Wasir Farooq · Y. Prem Kumar Singh

   We investigate the influence of quantum-gravity (QG) induced corrections on the entanglement entropy associated with four-flavor neutrino oscillations in vacuum, incorporating an additional sterile neutrino in the (3+1) framework. Using the von Neumann entropy as a measure of quantum correlations, we analyze how Planck-scale suppressed modifications to the neutrino mass-squared differences and the extended mixing matrix affect the evolution of entanglement during successive oscillation cycles. The quantum-gravity corrections are implemented through a dimension-5 effective field theory operator that modifies the four-flavor PMNS matrix and all six mixing angles above the GUT scale. We find that the atmospheric mixing angle \theta_{23} undergoes the largest deviation due to Planck-scale effects, while angles \theta_{14}, \theta_{24}, and \theta_{34} remain essentially unchanged. The resulting QG-corrected oscillation probabilities produce characteristic deviations in the entanglement entropy profile as a function of L/E, providing a sensitive probe of Planck-scale physics within a four-flavor neutrino phenomenology framework.

   hep-ph0 citations
2. 02*

   Nelson-Barr Models with Vector-Like Quark Doublets

   G. H. S. Alves🇧🇷 · C. C. Nishi🇧🇷 · L. Vecchi🇮🇹

   We investigate Nelson--Barr solutions to the strong CP problem in which spontaneous CP violation is transmitted to the Standard Model through mixing with a vector-like partner of the SM quark doublet. We show that these constructions constitute compelling and phenomenologically viable alternatives to the more widely studied singlet-based NB models. A key result of our analysis is that an accidental symmetry of the renormalizable theory delays the leading contributions to \bar{\theta} until three loops, naturally suppressing hadronic CP violation. We outline the main phenomenological constraints, including future EDM experiments, as well as the main differences between these scenarios and generic models with doublet vector-like quarks.

   hep-phPRD(2026)·1 citation
3. 03*

   Probing Freeze-In Dark Matter via a Spin-2 Portal at the LHC with Vector Boson Fusion and Machine Learning

   Junzhe Liu🇺🇸 · Alfredo Gurrola🇺🇸

   The persistent absence of signals in traditional dark matter searches has intensified interest in scenarios beyond the canonical weakly interacting massive particle paradigm. In this work, we investigate the collider phenomenology of feebly interacting dark matter produced via the freeze-in mechanism through a spin-2 portal. We consider a framework in which a massive graviton-like mediator couples minimally and universally to the energy--momentum tensor of both the Standard Model (SM) and the dark sector. Such interactions arise naturally in extra-dimensional constructions and effective theories of gravity, providing a theoretically well-motivated and predictive setup. We systematically connect early-Universe cosmology with collider observables by identifying regions of parameter space consistent with freeze-in conditions and the observed dark matter relic abundance, and examining their testability at the Large Hadron Collider (LHC). Focusing on bosonic fusion production channels, which are particularly sensitive to spin-2 interactions, we analyze invisible mediator decay signatures and assess current and projected experimental sensitivities. To enhance sensitivity in this challenging regime of feeble couplings, we develop a search strategy based on machine-learning algorithms. Our results demonstrate that collider searches can probe substantial regions of the cosmologically viable freeze-in parameter space, highlighting the high-luminosity LHC as a powerful laboratory for feebly interacting dark sectors. This study establishes a concrete and complementary pathway to test freeze-in dark matter scenarios through spin-2 portals, thereby bridging gravitationally motivated new physics, cosmology, and high-energy collider experiments.

   hep-ph2 citations
4. 04*

   Dual Implications of Quark Mass Hierarchies to Flavor Structure

   Ying Zhang🇨🇳

   To solve the mystery of flavor structure, we demonstrate two implications emerging from the hierarchical masses of quarks: one for the mass matrix itself and one for the CKM mixing. These implications naturally lead to a non-redundant, ordered, and family-unified quark flavor structure, which serves as a candidate to replace the unclear Yukawa interactions of the Standard Model.

   hep-ph0 citations
5. 05*

   The Fate of Ultra-Collinear Modes in On-Shell Massive Sudakov Form Factors

   Marvin Schnubel🇳🇱 · Jakob Schoenleber🇺🇸 · Robert Szafron🇺🇸

   Individual multi-loop diagrams for the massive Sudakov form factor contain an infinite tower of ultra-collinear momentum regions. We show that, for the on-shell form factor in QCD, these contributions cancel to all orders as a consequence of gauge invariance, so the leading-power SCET${}_{\mathrm{II}}$ factorization formula is unchanged. Using the $\eta$ rapidity regulator, we compute the soft function and the massive jet function of the quark and gluon Sudakov form factors through two loops and resum logarithms at NNLL accuracy, including hierarchies of fermion masses. We also show that with a gauge-boson mass regulator, the infinite tower of modes is truncated and ultra-collinear and ultra-soft modes become manifest and factorize explicitly, providing a direct EFT derivation of the regulated infrared dependence.

   hep-ph1 citation
6. 06*

   Probing Proton Structure via Physics-Guided Neural Networks in Holographic QCD

   Wei Kou🇨🇳 · Xurong Chen🇨🇳

   Describing the proton structure function $F_2$ in the non-perturbative and transition regimes of quantum chromodynamics (QCD) remains a significant theoretical challenge. In this work, we introduce a Physics-Guided Neural Network (PGNN) that integrates Holographic QCD with deep learning. By embedding the five-dimensional ${\text{AdS}}_5$ Dirac equation and the string diffusion kernel directly into the computational graph, the network is strictly constrained to the physical proton mass ($M_p\equiv 0.938\text{ GeV}$). Applying this framework to high-precision SLAC deep inelastic scattering data yields a global fit of ${\chi }^2/\text{d.o.f.}\simeq 0.91$. Rather than relying on predetermined empirical forms, the network dynamically extracts the transition between the $s$-channel bulk fermion mechanism (hadronic resonance excitations) and the $t$-channel holographic Pomeron exchange (diffractive background), identifying a kinematic crossover near $x\approx 0.19$. Furthermore, the optimization naturally recovers a Pomeron intercept of ${\alpha }_0\approx 1.0786$ and generates higher-twist scale-breaking effects through the evolution of resonance mass spectra. This demonstrates that embedding analytical differential equations into neural networks provides an interpretable, data-driven approach for phenomenological studies of strongly coupled systems.

   hep-phhep-th1 citation
7. 07*

   Non-equilibrium Dynamical Attractors and Thermalisation of Charm Quarks in Nuclear Collisions at the LHC Energy

   Shile Chen🇨🇳 · Vincenzo Nugara🇮🇹 · Maria Lucia Sambataro🇮🇹 · Salvatore Plumari🇮🇹 · Vincenzo Greco🇮🇹

   We study the non-equilibrium dynamics, thermalisation and attractor behaviour of charm quarks in a longitudinally expanding Quark-Gluon Plasma within the Relativistic Boltzmann Transport approach in 1+1D Bjorken expansion. Considering both a strong AdS/CFT coupling scenario with constant $2\pi T{D}_s=1$ and a temperature-dependent diffusion coefficient $D_s^{\text{lQCD}}(T)$ from the recent unquenched lattice QCD data, we analyse the evolution of effective temperature, momentum moments and distribution functions for different initial conditions, including FONLL and EPOS4HQ spectra. We find that charm quarks exhibit dynamical attractors; however, the temperature dependence of $D_s^{\text{lQCD}}(T)$ leads to significantly longer relaxation times compared to the strong coupling limit. While dynamical attractors occur within $\sim 1-1.5\mathrm{fm}$ for $2\pi T{D}_s=1$, they are delayed to $\sim 5\mathrm{fm}$ for $D_s^{\text{lQCD}}(T)$, becoming comparable to the lifetime of the Quark-Gluon Plasma phase in ultra-relativistic collisions. This indicates that charm quarks may not fully thermalise, especially in small systems such as peripheral or light-ion collisions. We further show that, for $D_s^{\text{lQCD}}(T)$, the deviation from equilibrium becomes as large as $\delta f_{HQ}/f_{eq}\sim p_T^{\beta }\sim \mathcal{O}(1)$ already at $p_T\simeq 3\mathrm{GeV}$, rising with $\beta \sim 4.5$, thus questioning the applicability of viscous hydrodynamics to charm dynamics.

   hep-ph1 citation
8. 08*

   Applying Self-organizing Maps to the Inverse Problem

   Vaidehi Tikhe🇮🇳 · N. Kirutheeka🇮🇳 · Sourabh Dube🇮🇳

   In the inverse problem in particle physics, given an unexpected observation, one aims to identify a unique choice from amongst several competing hypotheses. We explore a novel approach of applying self-organizing maps to the inverse problem in a search for vector-like leptons in a trilepton final state. We define an approach combining the inherent clustering of these maps and elements of supervised learning. We compare the performance of this approach with a multiclassfying neural network. We find that the method using self-organizing maps competes well (despite not using any standard model processes in the training), and provides additional tools that would help characterize any observed excesses in searches.

   hep-phhep-ex0 citations
9. 09*

   Quantum gravity contributions to the gauge and Yukawa couplings in proper time flow

   Gabriele Giacometti🇮🇹 · Kamila Kowalska🇵🇱 · Daniele Rizzo🇪🇪 · Enrico Maria Sessolo🇵🇱 · Dario Zappala🇮🇹

   We derive quantum gravity contributions to the beta functions of the gauge and Yukawa couplings of a matter theory using the Schwinger proper-time flow equation. Working in the Einstein-Hilbert truncation, we investigate the gauge-fixing and regulator dependence of the corresponding renormalization group equations. We quantify the sensitivity of our results on unphysical parameters by evaluating the gravitational correction to the running matter couplings at the interactive fixed point of gravity and we compare our findings with existing determinations in alternative schemes. We finally confront the derived contributions with the typical size they should assume to generate observable low-scale predictions in the Standard Model and in several scenarios of new physics.

   hep-phhep-thPRD(2026)·7 citations
10. 10*

    All-heavy tetraquarks with different flavors

    Wei-Xiang Wang🇨🇳 · Lin-Qin Xie🇨🇳 · Jun-Jie Liu🇨🇳 · Zhi-Biao Liang🇨🇳 · Ming-Sheng Liu🇨🇳 · Xian-Hui Zhong🇨🇳

    In a nonrelativistic potential quark model framework, we carry out a precise calculation of the mass spectrum of the all-heavy tetraquarks with different flavors, $bb\bar{b}\bar{c}$, $cc\bar{c}\bar{b}$, $bb\bar{c}\bar{c}$, and $bc\bar{b}\bar{c}$, by adopting the explicitly correlated Gaussian method. A complete mass spectrum for the $1S$ states is obtained. For the $bb\bar{b}\bar{c}$, $cc\bar{c}\bar{b}$, $bb\bar{c}\bar{c}$, and $bc\bar{b}\bar{c}$ systems, the $1S$ states are predicted to lie in the mass ranges of $\sim (16.06,16.14)$, $\sim (9.65,9.74)$, $\sim (12.89,12.94)$, and $\sim (12.75,12.99)$~GeV, respectively.Moreover, by using the obtained masses and wave functions, we evaluate the fall-apart decay properties within a quark-exchange model.The results show that the $1S$ states of the all-heavy tetraquarks with different flavors may have narrow fall-apart decay widths,which ranging from a few tenths to several MeV. Some all-heavy tetraquarks with different flavors may have good potentials to be established at LHC in their optimal fall-apart decay channels, such as ${\rm Y}J/\psi$, ${\rm Y}{B}_c^{-}$, and $J/\psi B_c^{+}$.

    hep-ph3 citations
11. 11*

    Sign-Locked Gravitational Baryogenesis from Bulk Viscosity and Cosmological Particle Creation

    Yakov Mandel

    We study a concrete realization of gravitational baryogenesis in which a small bulk-viscous deformation of an otherwise radiation-dominated early universe generates a sign-definite curvature source. The key point is thermodynamic irreversibility: positive entropy production makes the driving term monotonic and therefore avoids the freeze-out cancellation that suppresses rapidly oscillating or sign-changing sources. Motivated by a simple first-order transfer-function diagnostic, we analyze the standard curvature-current operator ${\mathcal{L}}_{\mathrm{int}}=(c/M^2){\partial }_{\mu }R{J}_{B-L}^{\mu }$ in a near-radiation background with effective pressure $p_{\mathrm{eff}}=p-3\zeta H$ and $\zeta =\xi \rho /H$. For $\xi >0$ one finds $R\ne 0$, $\dot{R}>0$, and a baryon asymmetry $\eta \propto \xi T_D^5/(M^2{\bar{M}}_{\mathrm{Pl}}^3)$. We derive the viable $(T_D,M,\xi )$ region, include entropy dilution from a finite viscous epoch, and show that the observed ${\eta }_{\mathrm{obs}}\simeq 8.6\times 10^{-11}$ can be reproduced in a parameter region consistent with current cosmological bounds while maintaining EFT control. The highest-scale benchmarks should be read conditionally on a very high reheating scale in view of current tensor limits. A particle-creation sector of heavy GUT-scale fields then provides a phenomenological motivation for the required range $\xi \sim 10^{-4}$--$10^{-3}$. We also discuss the known higher-derivative instability of gravitational baryogenesis and the role of stabilized or completed embeddings.

    hep-phgr-qc1 citation
12. 12*

    What Are Pulsar Companions Made of? Using Gravitational Tides to Probe Their Compositions

    Liam Colombo-Murphy🇺🇸 · Lucas Brown🇺🇸 · Stefano Profumo🇺🇸 · M. Grant Roberts🇺🇸 · Aya Westerling

    Low eccentricity, short orbital period pulsar companions may provide a probe to study novel dense and stable exoplanet internal compositions due to the potentially significant orbital evolution they experience caused by strong gravitational tides. We model the tidal characteristics such as apsidal motion constants, orbital precession, and tidal deformability for a variety of equations of state to be compared with values recovered via pulsar timing for a sample of four systems: PSR J1719-1438b, PSR J0636+5128b, PSR J2322+2650b, and PSR J1807-2459A b. With this method, we hope to place stringent limits on the chemical and structural composition of these objects. Through limiting the internal composition of pulsar companions, we aim to elucidate their unique history and formation.

    ↳ astro-ph.HEastro-ph.EPastro-ph.SRhep-ph0 citations
13. 13*

    Electromagnetic instantons and asymmetric Hawking radiation of black holes

    Archil Kobakhidze🇦🇺 · Elden Loomes

    We argue that the topological structure of Abelian gauge theories, such as Maxwell electrodynamics, in the background of a Euclidean Schwarzschild black hole manifests itself through an asymmetry in Hawking radiation. In particular, the topology of the black hole manifold, characterised by a non-contractible 2-sphere and Euler characteristic $\chi =2$, admits non-trivial gauge-field configurations. These take the form of 2-form field strengths that are closed but not exact. From a topological perspective, such configurations are classified by the second cohomology group, which is isomorphic to $\mathbb{Z}\oplus \mathbb{Z}$, and are labelled by integer electric ($n$) and magnetic ($m$) charges, $(n,m)$. Self-dual ($n=m$) and anti-self-dual ($n=-m$) dyonic configurations carry vanishing Euclidean energy and are fully compatible with the Euclidean Schwarzschild geometry. More general dyonic configurations, by contrast, are interpreted as off-shell Euclidean field configurations. Nevertheless, both classes contribute to the thermal equilibrium vacuum and to finite-temperature correlation functions in the corresponding Lorentzian framework. Furthermore, because of the non-trivial topology, the electromagnetic ${\theta }_{\mathrm{EM}}$-term contributes to the physical observables. In particular, it sources $CP$-asymmetric Hawking radiation, observable as an imbalance between left- and right-polarised photons in the emission spectrum. We briefly discuss some implications of this phenomenon.

    ↳ hep-thhep-ph1 citation
14. 14*

    The analytic structure of the QCD propagators, confinement, and deconfinement

    Giorgio Comitini🇮🇹

    We present the first complete calculation of the analytic structure of the zero-spatial-momentum finite-temperature Landau-gauge gluon propagator carried out at one loop by a massive deformation of QCD perturbation theory -- the screened massive expansion -- at temperatures ranging from $T=0$ to $T\approx 3T_c$. We find no signatures of deconfinement in the form of meaningful changes in said structure. We argue that, beyond Euclidean space, massive perturbative methods -- including the Curci-Ferrari model -- might be missing crucial dynamical information as a consequence of the perturbative violation of QCD's Ward identities.

    ↳ hep-thhep-phActa Phys.Polon.Supp.(2026)·0 citations
15. 15*

    A Closer Look at Constrained Instantons

    Takafumi Aoki🇯🇵 · Masahiro Ibe🇯🇵 · Satoshi Shirai🇯🇵

    Instantons play a crucial role in understanding non-perturbative dynamics in quantum field theories, including those with spontaneously broken gauge symmetries. In the broken phase, finite-size instanton-like configurations are no longer exact stationary points of the Euclidean action, in contrast to the symmetric phase. Non-perturbative effects in this setting are therefore typically studied within the constrained instanton framework. However, a previous study pointed out a possible difficulty in constructing consistent constrained instanton solutions based on conventional gauge-invariant constraints. In this work, we revisit the asymptotic structure of constrained instantons and re-examine the claimed difficulty. By carefully tracking the behavior of the solutions near the spatial origin and at infinity, we show that the required boundary conditions can be satisfied without encountering the inconsistency. We explicitly construct consistent constrained instantons in both massive ${\varphi }^4$ theory and Yang--Mills theory with spontaneous symmetry breaking, and we support our analytic matching procedure with numerical solutions. Our results establish that conventional gauge-invariant constraints can be consistently employed in semiclassical computations when asymptotic expansions are treated properly.

    ↳ hep-thhep-phJHEP(2026)·1 citation
16. 16*

    Quantum mutual information, coherence and unified relations of top quarks in QCD processes

    Duo-Duo Chen🇨🇳 · Xue-Ke Song🇨🇳 · Liu Ye🇨🇳 · Dong Wang🇨🇳

    As the most massive particle in the Standard Model, the top quark's exceptionally short lifetime preserves its spin polarization information through direct decay, making it an ideal system for probing quantum correlations in high-energy physics. In this letter, we presents a comprehensive investigation of quantum correlations in top quark-antiquark pairs produced through QCD. We employ multiple quantum information theoretic measures including quantum mutual information, relative entropy of coherence, complete complementarity relations, and the intrinsic relationship, establishing their dependence on kinematic variables. Furthermore, we find that for quarks and gluons initial mixing, as the probability of gluons Wgg increases, the maximum of the left-hand side of the intrinsic relation also increases. We thus believe the current findings are beneficial to insight into the systemic quantumness in QCD.

    ↳ quant-phhep-phPLB(2026)·4 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.