HEP Phenomenology·hep-ph

Fri·Jul 3, 2026Friday·July 3, 2026

35 papers—31 primary·4 cross-listed

01
Can Primordial Black Holes Be Seeds for Early Galaxies in Models Satisfying the Covariant Entropy Bound?
Sidan A🇺🇸 · Tom Banks🇺🇸 · Willy Fischler🇺🇸
We argue that cosmological models obeying the Covariant Entropy Bound (CEB) mathematically favor states with no localized excitations or one large black hole containing all the energy in a constrained initial state. In order to get a long radiation-dominated era, one must postulate that at a very early time, most horizon volumes of the universe contained tiny black holes that decayed into radiation. A previous work by two of the authors showed that such a scenario could fit the data on the Cosmic Microwave Background (CMB). In order to account for dark matter, we also postulate some random black holes of at least horizon size at that time. A reasonable distribution of such primordial black holes can account for all of dark matter as well as the early galaxies seen by the James Webb Space Telescope. Some of the dark matter may also be in Planck-scale remnants of the decaying black holes. We describe our model both in terms of approximate solutions to General Relativity and a speculative quantum gravity model whose hydrodynamics matches the flat $p = \pm ρ$ FRW model that saturates the CEB.
hep-phastro-ph.COgr-qchep-th1 citation
02
No Evidence for Superradiant Axions in LIGO-Virgo-KAGRA GWTC-5 Binary Black Hole Spins
Orion Ning🇺🇸 · Benjamin R. Safdi🇺🇸 · Catherine Welch🇺🇸
The quantum chromodynamics (QCD) axion and axion-like particles may form bound clouds around spinning black holes (BHs) when their Compton wavelength is comparable to the BH gravitational radius, depleting the BH spin through what is known as a $superradiance$ instability. Using binary BH (BBH) spin measurements obtained from the LIGO-Virgo-KAGRA GWTC-5 catalog, the most extensive public BBH catalog to date containing $N = 257$ mergers with BH masses spanning roughly $5$ - $135$ $M_{⊙}$ , we perform a hierarchical Bayesian analysis in the context of a BH spin population model to constrain ultralight axions. The presence of axions at a given mass would imprint a unique signature in the observed mass-spin relation relative to the formation distribution. We find no evidence for axions across more than two decades in mass, excluding axion masses $1.7 \times 1 0^{- 14} eV ≲ m_{a} ≲ 3.3 \times 1 0^{- 12} eV$ at 95% confidence. Because prior superradiance bounds in this range derive from X-ray spin measurements with substantial modeling systematics, this result represents one of the strongest robust lower bounds on the QCD axion mass.
hep-phastro-ph.COastro-ph.HEgr-qc6 citations
03
Axion Misalignment Across First-Order Phase Transitions
Galymzhan Baltabay🇪🇪 · Francesco D'Eramo🇮🇹 · Ville Vaskonen🇪🇪
When the axion mass is generated during a first-order phase transition and becomes non-vanishing only inside expanding true-vacuum bubbles, the standard picture of misalignment production is qualitatively modified. Using lattice simulations in an expanding universe, we study dark matter production within such a framework and identify two distinct regimes. For rapid transitions, the onset of oscillations is delayed until bubble percolation, enhancing the relic abundance. For slower transitions, spatial gradients generated by expanding bubbles suppress the effective misalignment angle through the bubble misalignment mechanism. We derive a semi-analytical expression for the relic density that provides a unified description of both regimes and accurately reproduces the simulation results. Finally, we show how this mechanism also modifies isocurvature perturbations and the small-scale matter power spectrum, with important implications for axion minicluster formation.
hep-phastro-ph.CO0 citations
04
Electron stability constrains neutrino time delays
Mauricio Bustamante🇩🇰 · José Manuel Carmona🇪🇸 · José Luis Cortés🇪🇸 · Ardit Gkioni🇪🇸 · Maykoll A. Reyes🇪🇸
Superluminal neutrino propagation, induced by Lorentz-invariance violation (LIV), is strongly constrained by vacuum pair emission, $ν \to ν + e^{-} + e^{+}$ , a process ordinarily forbidden, which rapidly degrades the energy of high-energy neutrinos. Consequently, observable neutrino time delays are often preferentially associated with subluminal propagation, prompting LIV interpretations of claimed time delays between high-energy cosmic neutrinos and gamma rays. However, this expectation is at odds with the observed stability of high-energy electrons. The same Lorentz-violating correction associated with subluminal neutrino propagation opens the overlooked complementary decay channel $e^{-} \to e^{-} + ν + ν ˉ$ , leading to electron instability. We derive constraints on LIV from recent observations of TeV--PeV astrophysical electrons. These electron stability limits rule out LIV invoked to explain delays of high-energy cosmic neutrinos. Consequently, neutrino time delays are constrained on both the superluminal and subluminal sides. Therefore, observable delays require either purely astrophysical origins, a realization of LIV that affects all particle species equally, or physics beyond the standard effective-field-theory framework.
hep-phastro-ph.HEhep-exhep-th0 citations
05
Local Conformal Predictions for Calibrated Surrogates
Suprio Dubey🇩🇪 · Henning Bahl🇩🇪 · Anja Butter🇩🇪 · Jürgen Hesser🇩🇪 · Tilman Plehn🇩🇪
Neural network surrogates for LHC scattering amplitudes require trustworthy uncertainty estimates, a challenging task given the non-Gaussian systematics. We target it using conformal prediction, a distribution-free post-processing to complement trained surrogates with calibrated uncertainties. We find that standard conformal predictions struggle to provide locally calibrated uncertainties. This leads us to introduce FALCON, a novel conformal prediction method that learns locally calibrated confidence intervals. Our simple examples illustrate the power of distribution-free uncertainty quantification for ultra-fast event generation at the LHC.
hep-ph2 citations
06
Neutron stars as thermometers for reheating induced dipole dark matter
Sahabub Jahedi🇨🇳
We investigate the electromagnetic interactions of dipole dark matter (DM) within an effective field theory framework, considering both standard and non-standard cosmological scenarios. We first study the prospects of DM production via both the freeze-out and freeze-in mechanisms within the standard radiation-domination. We then investigate how the viable DM parameter space is modified in a non-standard cosmological scenario due to entropy dilution during reheating. Existing constraints on the parameter space are discussed, and we highlight the discovery potential of future direct detection experiments to probe these scenarios. We further investigate the implications of neutron star heating for dipole DM. Due to the momentum-dependent nature of the interaction, dipole DM is captured efficiently by neutron stars, thereby making neutron star heating a sensitive probe of the dipole DM parameter space.
hep-phastro-ph.COastro-ph.HE1 citation
07
One-loop matching of QCD currents to power-suppressed two-jet operators
Martin Beneke🇩🇪 · Aleksey V. Rusov🇩🇪 · Michel Stillger🇩🇪
We compute the matching of QCD quark-antiquark currents onto the set of the two-particle and three-particle two-jet operators in soft-collinear effective theory (SCET) at next-to-leading order (NLO) in the perturbative QCD series, including for the first time operators up to second order in the power expansion in the transverse momentum over energy. These results contribute to the ongoing programme of computing power corrections and summing power-suppressed logarithmically enhanced terms for event shapes in the two-jet region and deep-inelastic scattering in the Bjorken- $x \to 1$ limit. The three-particle operators depend on the partonic momentum fractions of two partons moving into the same direction. When one of the momentum fractions approaches zero, the coefficient functions are shown to satisfy endpoint factorization relations, which allow for a consistent cancellation of endpoint singularities among various terms in the complete factorization formula for power corrections.
hep-ph1 citation
08
The theory of electric dipole moments: the view from below
Jordy de Vries🇳🇱
Permanent electric dipole moments (EDMs) of nucleons, nuclei, atoms, and molecules are among the most sensitive probes of CP violation beyond the Standard Model and are intimately connected to the strong CP problem and the origin of the matter-antimatter asymmetry of the universe. This review presents the theory of EDMs from the bottom up, tracing the chain of connections that links CP-violating interactions at level of elementary particles to observable EDMs across a wide range of systems. Starting from a general CP-odd effective Lagrangian at the quark-gluon level comprising the QCD theta term, quark EDMs and chromo-EDMs, the Weinberg operator, and CP-odd four-fermion interactions, I show how chiral perturbation theory organizes the nonperturbative QCD dynamics into a small set of hadronic low-energy constants, whose relative sizes are determined by the chiral representation of the underlying source. These hadronic interactions feed into calculations of nuclear EDMs and Schiff moments, which in turn enter atomic and molecular structure calculations that connect to experimentally accessible observables in diamagnetic and paramagnetic systems. Special attention is given to the recently identified sensitivity of paramagnetic systems to hadronic CP violation, which opens a new and relatively unexplored window on the quark-gluon sector. The complementarity of the full EDM portfolio including the neutron, light nuclei, atoms, and molecules, and the role of theory in disentangling the underlying source of CP violation is discussed throughout.
hep-phnucl-thphysics.atom-ph1 citation
09
An introduction to Hammer v2: Helicity Amplitude Module for Matrix Element Reweighting
Michele Papucci🇺🇸 · Dean J. Robinson🇺🇸
The Hammer software library provides fast and efficient reweighting of large simulated datasets containing semileptonic $b$ -hadron decays to any beyond Standard Model (BSM) theory, or to any form-factor description of the hadronic matrix elements. By enabling reweighting to a different underlying theoretical model after the computationally-expensive detector simulation step has already been completed, Hammer permits experimental analyses to employ forward-folding fitting strategies to recover underlying physical parameters without biases, or to properly characterize theory systematic uncertainties. This publication details upgrades to Hammer functionalities and its application programming interface (API) for version 2.x, and also provides associated documentation of the library's structure, syntactical conventions, and code flow. Substantial optimization of Hammer's internal tensor library now enables computational complexity to generically scale almost linearly with amplitude tensor rank times size rather than as a quartic, enabling reweighting into very high dimension spaces, such as the product of BSM Wilson coefficient and form factor parameter linear spaces, while also retaining Monte Carlo uncertainties. Updated Python bindings are implemented with bijective correspondence to the C++ interface, allowing full access to library functionalities.
hep-ph0 citations
10
Hadronization of $Λ_{c}^{+}$ baryons from recombination model in Pb+Pb collisions at the Large Hadron Collider
Jing-Zong Zhang🇨🇳 · Hua Zheng🇨🇳 · Lilin Zhu🇨🇳
The production of $Λ_{c}^{+}$ baryons in Pb+Pb collisions at $s_{N N} = 5.02$ TeV is investigated within the quark recombination framework, including the energy loss of light and charm quarks inside the hot and dense medium. The model simultaneously describes the transverse momentum ( $p_{T}$ ) spectra of $Λ_{c}^{+}$ baryons, $Λ_{c}^{+} / D^{0}$ yield ratio, which is attributed to the dominance of quark recombination mechanism in the Quark-Gluon Plasma (QGP), and the second harmonic coefficient of $Λ_{c}^{+}$ baryons with emphasis on the effects of minijets on the azimuthal anisotropy. Furthermore, we extend the theoretical calculation to Pb+Pb collisions at $s_{N N} = 2.76$ TeV and make predictions for $Λ_{c}^{+}$ baryons and $Λ_{c}^{+} / D^{0}$ yield ratio. The simultaneous description of the yield, baryon-to-meson ratio, and azimuthal anisotropy further validates that the recombination model is an effective hadronization mechanism in heavy-ion collisions.
hep-phPRC(2026)·0 citations
11
Gravitational Waves from Multiple First-Order Phase Transitions in a Scenario with Early Matter Domination
Rouzbeh Allahverdi🇺🇸 · Fazlollah Hajkarim🇺🇸
Non-standard cosmological histories with epochs of early matter domination (EMD) arise in various top-down models of the early universe. Typically, in the latter stage of EMD, temperature decreases more slowly than in a radiation dominated universe because of entropy generation from decay of the species that drives EMD. A time-dependent decay rate can significantly modify this picture and even lead to a period with increasing temperature. We study non-monotonic temperature evolution in a well-motivated scenario of EMD with a time-dependent decay rate that can give rise to multiple first-order phase transitions in both cooling and heating phases. The spectra of the ensuing gravitational waves (GW) exhibit characteristic features such as multiple peaks and a distinct behavior at high frequencies. These features allow us to determine the phase transition temperature as well as the reheating temperature at the end of the EMD. The future GW detectors can therefore provide a probe for the new physics and a window to the early thermal history.
hep-phastro-ph.CO0 citations
12
Subensemble Acceptance Method 3.0: General Corrections to Cumulants from Exact Conservation Constraints
Roman Poberezhniuk🇺🇸 · Volodymyr A. Kuznietsov🇺🇸 · Grégoire Pihan🇺🇸 · Volodymyr Vovchenko🇺🇸
We present the subensemble acceptance method 3.0 (SAM-3.0), which corrects cumulants of an observable measured in a subsystem of a large system for the effect of exact global conservation of multiple charges. The required input is the set of joint grand-canonical cumulants of the acceptance observable with the total event charges, from which the canonical cumulants follow algebraically via a closed recursion based on (multivariate) partial exponential Bell polynomials. The framework accommodates any number of observables, including non-conserved quantities such as net protons, and any number of simultaneously conserved charges, including the total energy, which yields the microcanonical ensemble. The mapping contains SAM-1.0 and SAM-2.0 as special cases and, unlike SAM-2.0, reproduces the exact binomial-acceptance limit. We also derive the leading finite-size corrections from the saddle-point expansion. We apply the method to update the hydrodynamics-based non-critical baseline (Hydro-EV) for net-proton cumulants at RHIC-BES energies, finding a refined baseline that agrees with direct canonical Monte Carlo sampling and stays close to the earlier SAM-2.0 result. We further validate the formalism against direct Monte Carlo sampling with exact simultaneous conservation of baryon number, electric charge, and strangeness, including hadronic-afterburner effects.
hep-phnucl-th2 citations
13
Hybrid Residual Correction of VMC Charmonium Masses with a Screened Funnel Interaction
Tarik Akan🇹🇷 · Metin Yalvac🇹🇷
In this study, we combine residual correction with the physical treatment of charmonium masses within a Quantum Chromodynamics (QCD) motivated potential-model framework via variational Monte Carlo (VMC). The aim is not to propose a new charmonium spectrum, since this sector has already been examined extensively through different potential models. Instead, the main objective is to evaluate how effectively a Machine Learning (ML) correction can improve a VMC baseline when both stages are built on the same screened funnel potential. In this workflow, the screened interaction provides the physical input and determines the underlying mass structure. The proposed run uses the variational method via VMC and deterministic eigenvalue diagonalization in the process of mass calculation. In total, ten charmonium states are calculated, among which seven use the experimental reference masses. The VMC step generates a large set of configurations and local energy estimators that are fed into the neural network (NN) residual corrector at the sample level, while the corrections and experimental uncertainties are collected at the state level. It then learns the residual difference between the raw physics baseline and the internal reference targets. This hybrid procedure reduces the systematic mass offset of the raw calculation across the studied states. For the experimentally verified seven states, the correction reduces the MAE from $438.1 MeV$ to $24.1 MeV$ , corresponding to a $94.5%$ reduction. These results show that ML can serve as a residual-correction layer for potential-model spectroscopy.
hep-ph0 citations
14
Phenomenology of genuine twist-three distributions from a global QCD analysis
Guillermo Portela🇪🇸 · Alexey Vladimirov🇪🇸
We present an extraction and phenomenological study of genuine twist-three parton distribution functions (PDFs) through a global QCD analysis of the structure function $g_{2}$ in deep-inelastic scattering (DIS), its moment $d_{2}$ , and single-/double-spin asymmetries in semi-inclusive DIS (SIDIS). The unified description of these processes clearly confirms the universality of genuine twist-three PDFs and the validity of QCD factorization theorems at this subleading level. The extraction is accompanied by several validation tests, tests of sum rules, comparisons with earlier literature, computation forces and average transverse momentum of partons. As a by-product, we also obtain Sivers and worm-gear-T transverse momentum dependent (TMD) distributions, which allows us to construct a tomographic picture of the proton based on substantially broader data.
hep-ph1 citation
15
Refined Sensitivity Estimates for Single-Molecule Magnet Dark Matter Detectors
Andrew Eberhardt🇯🇵 · Tomoya Fukui🇯🇵 · Ryosuke Takehara🇯🇵 · Ryotaro Ohno🇯🇵 · Yuta Mizukami🇯🇵 · Kenichiro Hashimoto🇯🇵 · Takanori Fukushima🇯🇵 · Shigeki Matsumoto🇯🇵 · Tom Melia🇯🇵 · Kouki Nozaki🇯🇵 · Surjeet Rajendran🇺🇸
We revisit the sensitivity of Single Molecule Magnet (SMM) crystals as detectors for low-mass dark matter. In previous work, we established the concept of the ``magnetic bubble chamber'', where energy deposited by dark matter triggers a magnetic avalanche in a metastable crystal. The original sensitivity estimates relied on a conservative criterion requiring the spin relaxation time to be strictly shorter than the thermal diffusion time. Here, we demonstrate that this criterion effectively ignores the stochastic nature of spin relaxation. We derive a refined analytic estimate which accounts for the fraction of spins that relax even when diffusion is fast. We show that the Zeeman energy released by this fraction contributes to local heating, significantly lowering the energy threshold for avalanche formation. We present simulation results confirming this effect and report on experimental verification of the assumed low-temperature thermal properties of two representative SMM crystals, Mn $_{12}$ -acetate and Mn $_{32}$ . Together, these efforts extend this pathfinder program toward the realization of SMM-based detectors with controlled material properties and enhanced dark matter sensitivity.
hep-phphysics.ins-det1 citation
16
Dynamics of Self-Interacting Dark Sectors
Esau Cervantes🇵🇱
This thesis investigates the dynamics of self-interacting dark sectors in the early Universe populated through the freeze-in mechanism. The main focus is on scenarios with self-number-changing reactions of the form $2 \leftrightarrow 3$ , and on how these interactions modify the thermal history and phenomenology of the dark sector. Several realizations are studied, including scalar theories with $Z_{2}$ and $Z_{3}$ symmetries, self-interacting dark matter coupled to an unstable mediator, and cannibal dark matter production during non-instantaneous reheating. The thermal evolution is obtained by solving coupled Boltzmann equations for the relevant number densities and temperatures, accounting for both freeze-in production and cannibal interactions. The resulting parameter space can be strongly constrained, effectively invisible, or potentially accessible to future searches, depending on the realization considered. Finally, the thesis studies a hidden U(1) gauge sector populated via freeze-in, where continuous energy injection can induce an inverse first-order phase transition and temporarily restore the symmetric phase, linking phase-transition dynamics and chemical equilibration in hidden sectors.
hep-ph0 citations
17
One-loop proton decay from Peccei-Quinn symmetry
H. B. Câmara🇵🇹
We promote the accidental $B + L$ symmetry of the Standard Model to a Peccei-Quinn (PQ) symmetry while realizing spontaneous proton decay radiatively. The PQ anomaly sector consists of vector-like quarks (VLQs), providing a Kim-Shifman-Vainshtein-Zakharov-type axion solution to the strong CP problem. After spontaneous PQ breaking, a residual $Z_{2}$ symmetry remains, which forbids tree-level proton decay. The VLQs required to generate the QCD anomaly, together with scalar mediators, odd under the residual $Z_{2}$ , induce one-loop proton decay through the effective operator $u_{R} u_{R} d_{R} e_{R}$ . We study its ultraviolet completions, featuring distinct vector-like fermion and scalar representations, and show that the resulting models lead to distinct predictions for the axion-to-photon coupling, testable in helioscope and haloscope experiments. We investigate proton and neutron decay pheneomenology focusing on the channel $p \to e^{+} π^{0}$ . We also discuss axion dark matter in pre- and post-inflationary cosmology.
hep-phPLB(2026)·0 citations
18
$Λ$ hyperons in core-collapse supernovae: Equilibration and neutrino opacities
Ruben Zatini🇪🇸 · Jorge Martin Camalich🇪🇸 · Pasquale Dario Serpico🇫🇷 · Tobias Fischer🇵🇱
Strange hadrons are commonly included in dense-matter equation-of-state models by imposing chemical equilibrium, but the weak-interaction timescales required to establish it in core-collapse supernovae have not been systematically assessed. In this paper we compute the $Λ$ -hyperon production rates in the hot, dense, and isospin-asymmetric conditions characteristic of post-collapse proto-neutron stars. We find that local $Λ$ chemical equilibration is driven by nonleptonic strangeness-changing reactions, especially $N N \leftrightarrow N Λ$ scattering, on timescales of order $1 0^{- 11}$ - $1 0^{- 10}$ s, many orders of magnitude shorter than macroscopic proto-neutron-star evolution timescales. Using an effective-field-theory framework constrained by hypernuclear weak-decay data, we find that short-range contact interactions dominate the nonleptonic rates, beyond a pure one-meson-exchange description. Semileptonic channels are too slow to set the equilibrium $Λ$ abundance, but they open additional absorption channels for low-energy muon neutrinos and antineutrinos, such as $ν_{μ} + Λ \to μ^{-} + p$ and $p + μ^{-} + ν ˉ_{μ} \to Λ$ . At low energies, these $Λ$ -induced neutrino opacities exceed the corresponding nucleonic contributions for muon (anti)neutrinos, possibly influencing the evolution of the muon lepton number during proto-neutron-star deleptonization. These results support local chemical equilibrium for $Λ$ hyperons under the conditions studied and provide new weak-interaction input for flavor-dependent neutrino transport, muonization, and proto-neutron-star evolution.
hep-phastro-ph.HEnucl-th0 citations
19
Light tetraquark states with $J^{P C} = 1^{--}$ from QCD sum rules
Yi-Wei Jiang🇨🇳 · Hua-Xing Chen🇨🇳 · Er-Liang Cui🇨🇳 · Ding-Kun Lian🇨🇳 · Wen-Ying Liu🇨🇳 · Niu Su🇨🇳
We perform a systematic QCD sum rule study of light tetraquark states with $J^{P C} = 1^{--}$ in the diquark--antidiquark picture. A complete set of local interpolating currents is constructed and projected onto six flavor-isospin configurations ( $q = u / d$ ): the isoscalar $q q q ˉ q ˉ$ , $q s q ˉ s ˉ$ , and $ss s ˉ s ˉ$ sectors, the isovector $q q q ˉ q ˉ$ and $q s q ˉ s ˉ$ sectors, and the isotensor $q q q ˉ q ˉ$ sector. The lowest masses in these sectors are derived to be $1.6 4_{- 0.14}^{+ 0.15}$ ~GeV, $1.8 6_{- 0.14}^{+ 0.14}$ ~GeV, $2.3 4_{- 0.30}^{+ 0.23}$ ~GeV, $1.5 3_{- 0.19}^{+ 0.17}$ ~GeV, $1.8 6_{- 0.14}^{+ 0.14}$ ~GeV, and $2.2 4_{- 0.14}^{+ 0.12}$ ~GeV, respectively. We further compare the present $1^{--}$ tetraquark spectrum with previous QCD sum rule results for the $1^{-+}$ tetraquark and hybrid states~\cite{Su:2025bhv}, aiming to provide useful information for distinguishing tetraquark and hybrid configurations in the light hadron spectrum. As an additional improvement, we complete the previously missing isotensor $1^{-+}$ tetraquark entry and obtain its lowest mass to be $M = 2.1 9_{- 0.24}^{+ 0.26} GeV$ , which is included in the spectral comparison.
hep-ph0 citations
20
Searching for single production of a vector-like $Y$ quark decaying into $bW$ at the FCC-eh
Liangliang Shang🇨🇳 · Weifan Zhu🇨🇳 · Bingfang Yang🇨🇳 · Stefano Moretti🇬🇧
We investigate the exclusion and discovery potential for single production of a vector-like $Y$ quark with electric charge $Q = - 4/3$ , followed by the decay $Y \to bW$ , at the FCC-eh. The $Y$ quark is allowed to couple to both first- and third-generation down-type quarks. The analysis is performed for an electron-beam polarization of $P_{e} = - 80%$ at $s = 3.46$ , $5.29$ , and $6.9 TeV$ . Both leptonic and hadronic $W$ -boson decay channels are considered. In the hadronic channel, the boosted $W$ -boson is reconstructed as a $W$ -jet, and kinematic observables are used to suppress the Standard Model (SM) backgrounds. By performing a detailed detector simulations and event analysis, we present the $2 σ$ exclusion limits and $5 σ$ discovery reaches in the $g^{*}$ -- $m_{Y}$ plane, where $g^{*}$ is $Y$ coupling strength to the SM quarks. We find that the hadronic channel can provide stronger exclusion and discovery sensitivities, which are improved with increasing $s$ at the FCC-eh.
hep-ph0 citations
21
Sideband Structure of Axion Electrodynamics
Run-Min Yao🇨🇳 · Xiao-Jun Bi🇨🇳 · Peng-Fei Yin🇨🇳 · Qing-Guo Huang🇨🇳
We develop a Floquet--Bloch sideband formulation of the linearized Maxwell--axion system in a coherent periodic axion background. Linearizing around prescribed magnetic and axion fields, we show that the pump generates a sideband ladder of photon and axion branches. Near an isolated folded degeneracy, this ladder reduces to a two-mode crossing whose algebra is fixed by the symplectic signatures of the colliding modes. In temporal fixed-momentum evolution, same-Krein-sign collisions give stable avoided crossings, whereas opposite-sign collisions give parametric instabilities, unifying the axion-photon difference channel with the Mathieu and Masaki-Aoki-Soda resonances. In stationary fixed-frequency transfer, the corresponding flux signatures distinguish bounded forward conversion from forward-backward stop bands and distributed reflection. Ray projection of a temporal pump gives a related but local WKB description of driven forward mixing, with an effective wavenumber distinct from the true axion momentum. External-field diagrams reproduce the sideband selection rules, and full temporal monodromy calculations verify the instability topology and finite-coupling shifts.
hep-phastro-ph.HEhep-th0 citations
22
A Comprehensive Analysis of $B_{s} \to D_{s}^{**} ℓ ν_{ℓ}$ Decays Within and Beyond the Standard Model
Karthik Jain🇮🇳 · Tarun Kumar🇮🇳 · Barilang Mawlong🇮🇳 · Shantanu Sahoo🇮🇳
We examine the exclusive semileptonic decays $B_{s} \to D_{s}^{**} ℓ ν_{ℓ}$ , with $D_{s}^{**} =$ ${D_{s 0}^{*}, D_{s 1}^{*}, D_{s 1}, D_{s 2}^{*}}$ , within the Standard Model and beyond, using form factors evaluated in the Heavy Quark Effective Theory, including corrections up to $O (α_{s}, Λ/ m_{Q})$ . A data-driven approach is employed to extract Heavy Quark Effective Theory parameters, and the resulting synthetic data are used to parameterize the form factors via the $z$ -expansion. With the resulting form factor information across the full kinematic region, we compute various observables derived from the two-fold angular decay distribution, and predict precise lepton flavor universality ratios: $R_{D_{s 0}^{*}} = 0.158 (20)$ , $R_{D_{s 1}^{*}} = 0.045 (5)$ , $R_{D_{s 1}} = 0.073 (4)$ , $R_{D_{s 2}^{*}} = 0.066 (9)$ . We also analyse potential new physics effects using the Weak Effective Theory and the Standard Model Effective Field Theory, performing a global analysis considering both real and complex Wilson coefficients. Furthermore, we investigate new physics contributions arising from the general Two Higgs Doublet Model. We evaluate the sensitivity of decay observables to new physics, highlighting their potential to probe deviations from the Standard Model in future measurements. Notably, the scalar and tensor new physics operators induce large sensitivity, with some observables deviating by more than $2 σ$ from Standard Model predictions.
hep-phhep-exhep-lat0 citations
23
A Maximum-Entropy Method for Zero-Skewness Valence GPDs Constrained by Nucleon Electromagnetic Form Factors
Seung-il Nam🇰🇷
We formulate a reduced-profile maximum-entropy method (MEM) framework for constructing constrained zero-skewness valence-quark generalized parton distribution (GPD) transverse profiles from the four nucleon electromagnetic form factors $F_{1}^{p} (t)$ , $F_{1}^{n} (t)$ , $F_{2}^{p} (t)$ , and $F_{2}^{n} (t)$ . The form-factor sum rules fix only $x$ -integrated moments of the GPDs; the forward limit of $H_{v}^{q}$ is fixed separately by the valence parton distribution functions, and the normalization of $E_{v}^{q}$ by the flavor anomalous magnetic moments. These complementary constraints are combined through the ansatz $H_{v}^{q} (x, t) = q_{v} (x) exp [t f_{H}^{q} (x)]$ and $E_{v}^{q} (x, t) = e_{v}^{q} (x) exp [t f_{E}^{q} (x)]$ , where the positive profile functions encode the $x$ -dependent transverse structure. Rather than attempting an unrestricted functional inversion, we use the entropy functional as a regularizing criterion on a low-dimensional positive profile manifold. In the numerical proof-of-concept calculation, a smooth elastic form-factor input and analytic forward distributions are adopted, together with the reduced form $f (x) = 0.05 + (1 - x)^{2} exp (c_{0} + c_{1} x + c_{2} x^{2})$ , which suppresses local modes that elastic moments alone cannot constrain. Within this reduced ansatz, the resulting profiles reproduce the imposed elastic moment constraints, satisfy the forward normalizations after discrete-grid normalization, and give impact-parameter distributions with the expected transverse shrinkage at large $x$ . The construction provides a controlled zero-skewness baseline for connecting elastic form-factor constraints to $x$ -dependent transverse profiles, and it offers a stable starting point for future analyses incorporating empirical form-factor fits, modern PDF inputs, lattice-QCD generalized form factors, and hard exclusive observables.
hep-phnucl-th0 citations
24
New constraints on non-unitary neutrino mixing from 8 years of IceCube DeepCore atmospheric neutrino data
Sharmistha Chattopadhyay🇺🇸 · Anil Kumar🇮🇳 · Sanjib Kumar Agarwalla🇮🇳
The mixing between flavor and mass eigenstates of active neutrinos is described by a $3 \times 3$ unitary matrix. However, the presence of additional heavy sterile neutrino states can lead to a non-unitary neutrino mixing scenario. Atmospheric neutrinos, with their wide range of baselines and energies, provide an excellent probe of such effects. In particular, Earth matter effects in neutrino oscillations play an important role, as the neutral-current potential contributes non-trivially in the presence of non-unitarity. In this work, we use 8 years of publicly available atmospheric neutrino data of IceCube DeepCore to probe this non-unitary neutrino mixing scenario. This high-purity $ν_{μ}$ CC sample provides strong sensitivity, especially to the non-unitary parameters appearing at leading order in the $ν_{μ} \to ν_{μ}$ channel. The data sample is found to be consistent with the standard unitary mixing framework with no significant deviation. Using this data sample, we place the most stringent bound to date of $α_{33} > - 0.027$ at 90% CL, while the other non-unitary parameters are constrained at competitive levels.
hep-phhep-exphysics.ins-det0 citations
25
Symmetry Analysis of Compact Tetraquark States and Implications for the Fully Charmed Candidates $X (6600)$ , $X (6900)$ , and $X (7100)$
Shuai Yin🇨🇳 · Ti Gong🇨🇳 · Jingya Zhu🇨🇳
Motivated by recent experimental observations, we investigate the $J^{P}$ distribution of low-energy compact tetraquark states using symmetry analysis based on inherent nodal structures. Assuming tetrahedral and square configurations for the $q q q ˉ q ˉ$ system, we derive the allowed orbital structures from the restricted representations of $S_{4}$ onto $S_{2} \times S_{2}$ for $L \leq 3$ . The accessible-state distribution is particularly prominent in the $J^{P} = 2^{+}$ , $2^{-}$ , and $3^{-}$ sectors, with the $2^{+}$ sector showing the strongest low-energy preference. We further find that the symmetry-driven distribution is qualitatively similar to that of the three-flavor four-quark system, and that the dominant $J^{P} = 2^{+}$ pattern persists under phenomenological weightings inspired by chromomagnetic interaction (CMI) considerations. These results suggest that the low-lying compact tetraquark spectrum is primarily constrained by symmetry, while the detailed distribution exhibits sensitivity to dynamical weightings. Applying this framework to the fully charmed candidates $X (6600)$ , $X (6900)$ , and $X (7100)$ , we find that their observed $J^{P C} = 2^{++}$ quantum numbers are consistent with a low-lying compact tetraquark interpretation. The present analysis identifies the relative ordering of the $1^{-}$ and $1^{+}$ states as a sensitive channel, suggesting a direction for future non-perturbative investigations.
hep-ph1 citation
26
Chebyshev Approximations of Feynman Integrals for Collider Physics
Samuel Abreu🇨🇭 · Afonso Guerreiro🇵🇹 · Ben Page🇧🇪
We present a novel approach for solving canonical differential equations for Feynman integrals based on an approximation of the integrals with Chebyshev polynomials. By exploiting the analyticity properties of Feynman integrals, the method constructs rapidly converging polynomial approximations along a path, enabling highly efficient numerical evaluation. Moreover, we introduce an adaptive approximation method that dynamically samples to optimise convergence. We implement this framework in double-precision arithmetic and demonstrate its stability across physical phase space using a series of two-loop, five-point examples. Our proof-of-principle implementation proves competitive with state-of-the-art one-fold integral methods, while requiring little to no case-by-case intervention to handle spurious singularities.
hep-phhep-th2 citations
27
Event-axis TMD measurements in $e^{+} e^{-}$ and SIDIS
Daniel Diaz Fernandez🇪🇸 · Patricia Andrea Gutierrez Garcia🇪🇸 · Ignazio Scimemi🇪🇸 · Wouter Waalewijn🇳🇱
Transverse-momentum-dependent (TMD) fragmentation in $e^{+} e^{-}$ collisions can be studied by measuring hadrons with respect to the thrust axis, and has been measured at Belle. This provides a complementary way to extract TMD fragmentation functions, avoiding the need to disentangle the two TMD fragmentation functions that enter conventional back-to-back hadron-pair measurements. Starting from the established factorization theorems for this observable, we complete the operator-level formulation of the soft ingredients and perform one-loop checks using the $δ$ -regulator. We also extend existing results for 1-jettiness factorization in semi-inclusive deep-inelastic scattering (SIDIS), where analogous measurements give access to the TMD parton distribution functions of the incoming hadron. For phenomenology, we discuss the nonperturbative effects and propose a model that captures both the event-shape dependence and correlations between the event-shape and transverse-momentum measurements. We resum the transverse-momentum and thrust logarithms, explore several schemes for treating the latter, and implement it in artemide. As a first validation, we compare to simulated $e^{+} e^{-}$ data from Pythia8.3. We find that the proposed nonperturbative model is flexible enough to describe the simulated data, with fitted parameters of the expected size in powers of $Λ_{QCD} / Q$ . In this test, the resummation of the logarithms of $q_{T} / (τ Q)$ appears to have little impact on the fit quality, but changes the fit parameters.
hep-phhep-exnucl-exnucl-th2 citations
28
Transverse-spin dependent energy-energy correlators in proton-proton collisions within the dihadron fragmentation framework
Zhong-Bo Kang🇺🇸 · Andreas Metz🇺🇸 · Daniel Pitonyak🇺🇸 · Congyue Zhang🇺🇸
We calculate energy-energy correlations for two hadrons produced inside a jet in transversely polarized proton-proton collisions. We make numerical predictions based on a simple model that utilizes a previous global QCD analysis of dihadron fragmentation and transversity parton distribution functions. The results show remarkable agreement with a very recent STAR measurement. We also find the data at large jet transverse momentum have a slight preference for extractions of transversity that are consistent with lattice QCD computations of the nucleon tensor charges. Overall, this work provides further evidence for the underlying non-perturbative mechanism of near-side energy-energy correlators as well as highlights the potential for these observables to probe transverse-spin effects inside the nucleon.
hep-phhep-exnucl-exnucl-th1 citation
29
The $D_{s 1} (2460)$ and other open-charm $1^{+}$ states in relativistic chiral effective field theory
Ze-Rui Liang🇨🇳 · Qi-Chao Xiao🇨🇳 · Zhi-Hui Guo🇨🇳 · De-Liang Yao🇨🇳
We derive the pertinent chiral potentials for charmed vector meson interactions with light pseudoscalar bosons in a relativistic U(3) chiral effective field theory up to next-to-leading order. Predictions for the $S$ - and $P$ -wave scattering lengths are obtained for all the relevant elastic channels. A comparison with the most recent -- and currently the sole -- lattice QCD data on the $S$ -wave $I = 1/2$ $D^{*} π$ scattering length at a pion mass of $391$ ~MeV reveals good agreement, thereby validating the estimation of low energy constants via heavy quark spin symmetry. Within the relativistic formalism, we confirm that the $D_{s 1} (2460)$ can be identified with a bound state pole, while the $D_{1} (2430)$ corresponds to the interplay of two poles: a lower one on the second Riemann sheet and a higher one on the third Riemann sheet. We show that the $D_{s 1} (2460)$ and the lower $D_{1} (2430)$ pole originate from the same flavor SU(3) triplet, whereas the higher $D_{1} (2430)$ pole belongs to the SU(3) sextet. All these states are not of $q ˉ q$ nature, as they flow to complex infinity in the large $N_{C}$ limit. Our results provide quantitative benchmarks for future lattice QCD and femtoscopic studies.
hep-ph0 citations
30
Identifying $Σ (1380)$ and $Σ (1430)$ in the $J / ψ \to Λ π Σ ˉ$ reaction
Wen-Tao Lyu🇨🇳 · Eulogio Oset🇪🇸 · De-Min Li🇨🇳 · En Wang🇨🇳
We study the $J / ψ \to Λ π Σ ˉ$ reaction by looking at the $π^{+} Λ$ mass distribution at low energies, in search of signals for the low lying $Σ^{+}$ states. Apart from a clear signal of the $Σ (1385) (3/ 2^{+})$ state, we find a smaller peak for the predicted $Σ (1430) (1/ 2^{-})$ , which has already been confirmed by the Belle Collaboration. A first analysis, considering only the $π Λ$ interaction, shows that the low energy part of the spectrum is better reproduced including contributions from the $Σ (1430)$ and the predicted $Σ (1380) (1/ 2^{-})$ state that has been claimed before from analyses of different experiments. However, when we consider the $π Σ ˉ$ interaction the need for the $Σ (1380)$ disappears.
hep-ph1 citation
31
A critical look at low-scale cosmological phase transitions in the PTA era
Simone Biondini🇩🇪 · Philipp Schicho🇨🇭
Motivated by the recent evidence for a stochastic gravitational-wave (GW) background reported by pulsar timing array (PTA) collaborations, we perform a precision study of low-scale phase transitions in a dark Abelian Higgs sector, a minimal gauge theory of spontaneous symmetry breaking relevant for cosmological phase transitions. Using dimensionally reduced high-temperature effective field theory, we quantify the impact of thermal resummation, higher-order matching corrections, and higher-dimensional operators on the phase-transition thermodynamics and the resulting GW signal. We find that the parameter region favored by current PTA observations lies close to the boundary of validity of the effective field theory, where higher-dimensional operators become increasingly important. Even within this controlled region, the predicted signal remains disfavored by the PTA data, despite the substantial shifts induced by higher-order thermal corrections. We further delineate parameter regions where the dark and visible sectors are thermally and hydrodynamically coupled or decoupled, and revisit the dark matter phenomenology, identifying asymmetric freeze-out as naturally compatible with both the observed relic abundance and the gauge couplings favored by strong phase transitions. Our results underscore the importance of systematically controlled finite-temperature calculations for reliable GW predictions from low-scale cosmological phase transitions.
hep-phastro-ph.CO2 citations
32
Secondary Production of Photons from ALP Dark Matter interacting with a Cosmological Magnetic Field
Abdias Aires🇨🇦 · Robert Brandenberger🇨🇦 · Ashu Kushwaha🇯🇵
Under the assumption that dark matter is a coherently oscillating pseudoscalar field coupled to electromagnetism by the usual Chern-Simons term, we study the production of secondary photons from dark matter fluctuations coupled to a pre-existing magnetic field, taking into account the spectral distribution of the magnetic field. Specifically, we apply the formalism to the case of a large-scale magnetic field generated previously via a parametric resonance instability due to the same Chern-Simons coupling. However, our analysis is applicable to any spectrum of cosmological scale magnetic field fluctuations present at the time of recombination. We show that obtaining a sufficiently large flux of photons in the Lyman-Werner frequency range is consistent with constraints from CMB and X-ray observations.
↳ astro-ph.COgr-qchep-phhep-th1 citation
33
X-ray Fourier lag-frequency spectra modulated by stochastic turbulent acceleration in the jets of high-frequency-peaked BL Lac
Guang-Cheng Xiao🇨🇳 · Wen Hu🇨🇳 · Da-Guo Jiang · Jun-Xian Wang🇨🇳 · Zhen-Yi Cai · Da-Hai Yan · Fang-Wu Lu
X-ray interband time lags are key diagnostics of jet physics and are frequently detected in high-frequency peaked BL Lac (HBL) objects at different epochs with various X-ray telescopes. In this work, we theoretically investigate Fourier lag-frequency spectra using a generic one-zone leptonic model incorporating the stochastic turbulent acceleration (STA), which plays a crucial role in shaping the emitted photon spectra. We demonstrate that the competition between STA, radiative cooling, and escape processes not only gives rise to two well-defined time-lag regimes: hard/positive and soft/negative lags, but also reveals the existence of a transition between the two regimes. Our results indicate that time lags in the transitional and soft-lag regimes can be clearly amplified and modified by STA's suppression of high-energy electron cooling, and nonlinear synchrotron self-Compton (SSC) cooling can further amplify the emergence of time lags. We conclude that the adopted model offers a unifying quantitative framework for interpreting the diverse time-lag signatures observed in the X-ray flares of HBLs. Additionally, SSC cooling effects can account for the relatively large lags observed in TeV-bright flares, as well as the observed trend between lag amplitude and flare duration: the larger the flare duration, the larger the lag.
↳ astro-ph.HEhep-phPRD(2026)·0 citations
34
Lattice study of primordial black hole formation in bumpy axion inflation
Masahiro Kawasaki🇯🇵 · Kai Murai🇯🇵 · Shunsuke Tsuchida🇯🇵
We study primordial black hole (PBH) formation in axion $U (1)$ inflation using lattice simulations. In axion $U (1)$ inflation with a bumpy potential, the curvature perturbations can be enhanced in a narrow range of wavenumbers, potentially leading to PBH formation. After confirming that our lattice simulations reproduced the known curvature power spectra for chaotic inflation and simple axion $U (1)$ inflation, we calculate the curvature power spectrum in the bumpy axion inflation model in the strong backreaction regime. We find that large curvature perturbations are generated, which lead to PBH production with an abundance sufficient to account for dark matter.
↳ astro-ph.COhep-ph1 citation
35
Gravitational Waves from Primordial Black Holes: Connecting Low-Frequency Scalar-Induced Signatures to High-Frequency Binary Mergers
Ashu Kushwaha🇯🇵
Formation of primordial black holes (PBHs) requires a significant enhancement of curvature perturbations. This enhancement generates a twofold gravitational wave (GW) signature: a \emph{low-frequency} stochastic background of scalar-induced GWs (SIGWs) and a distinct \emph{high-frequency} signal from subsequent PBH binary mergers. Assuming a monochromatic PBH mass function, we use PBH abundance constraints on the primordial curvature power spectrum to evaluate the stochastic SIGW background. We also compute the stochastic GW background from mergers of the corresponding PBH binaries, incorporating merger-rate suppression effects to obtain realistic estimates. Furthermore, we derive a model-independent correspondence between the characteristic frequencies of these two signals. This unified framework links these otherwise distinct GW channels, enabling the same primordial fluctuations to be probed across widely separated frequency bands.
↳ astro-ph.COgr-qchep-ph0 citations

Affiliations

first authorsco-authorsvia INSPIRE