HEP Phenomenology·hep-ph

Fri·Jun 26, 2026Friday·June 26, 2026

34 papers—23 primary·11 cross-listed

01
Magnetic monopole plasma oscillations and implications for TeV blazars
Mariia Khelashvili🇮🇹 · Takeshi Kobayashi🇮🇹 · Andrew J. Long🇺🇸
Magnetic monopoles arise in many beyond Standard Model scenarios, symmetrize Maxwell's equations, and their existence would be tied to the quantization of electric charge. It has been argued that, when placed in an astrophysical magnetic field, monopoles can induce a magnetic version of plasma oscillations. In this work, we explore monopole-induced oscillations of the intergalactic magnetic field (IGMF). We show that monopole-induced oscillations of the magnetic field lead to collimation of electrically charged particle trajectories, reducing the usual deflection by the magnetic field. The collimation effect impacts the deflection angle in the electromagnetic cascades of TeV blazars and leads to a decrease in the angular size of blazar secondary GeV halos. Therefore, the constraints on the secondary halo angular size from combined H.E.S.S. and Fermi-LAT observations translate into bounds on the magnetic monopole abundance. The bounds on the magnetic monopole flux obtained in this work from blazar 1ES 0229+200, depending on the IGMF strength, can be as strong as $F ≲ 6 \times 1 0^{- 23} cm^{- 2} s^{- 1} str^{- 1}$ for low-mass monopoles $m ≲ 1 0^{6} GeV$ , stronger than existing laboratory and astrophysical bounds. The bound becomes subdominant to current constraints if the present-day IGMF value is stronger than $B ≳ 1 0^{- 12} G$ . At the same time, in the case of non-zero monopole abundance, the IGMF lower bound from TeV observations itself should be revised, resulting in a stronger lower bound at higher monopole number density.
hep-phastro-ph.COastro-ph.HE1 citation
02
Constraining Multiple Kinetically Mixed Dark Photons
Joerg Jaeckel🇩🇪 · Sebastian Monath🇩🇪
Extra U(1) gauge bosons under which Standard Model particles are uncharged, aka dark photons, are a simple and well-motivated extension of the Standard Model. There could be a single, but also several or even many such dark photons. However, most studies consider only a single dark photon. Here, we want to look at the more general case of multiple dark photons interacting with the Standard Model via kinetic mixing. We consider a range of standard probes, Cavendish experiments, light-shining-through-walls experiments, as well as energy loss in stars. To explore the rather high-dimensional parameter space of the masses and the kinetic mixing matrix, we pursue a statistical approach, considering different distributions for the kinetic mixing parameters.
hep-ph0 citations
03
Axial-Vector Lattice Benchmarks Reveal a Common Medium Response of Meson Screening in Hot QCD
Jie Ren🇨🇳 · Chen Chen🇨🇳 · Fei Gao🇨🇳 · Si-xue Qin🇨🇳
Meson screening masses trace the evolution of hadronic correlations toward quasi-free quark--antiquark screening in hot QCD. Combining lattice QCD (LQCD) benchmarks with a symmetry-preserving Dyson--Schwinger baseline, we identify a flavor-dependent axial-vector quasi-free onset, $x_{f g}^{*} = T_{f g}^{*} / T_{c}$ : an operational high-temperature matching scale at which the axial-vector screening mass has approached the corresponding free-field value after ordinary chiral restoration or parity-partner convergence has set in. On the finite interval $1 \leq x ≲ x_{f g}^{*}$ , independent light/strange and charm-containing lattice benchmarks are organized by a common medium-response function with one flavor-sector parameter. One axial-vector point fixes this parameter; the remaining axial-vector data test its temperature dependence, and vector screening masses validate it without vector input. A reduced-mass interpolation then yields lattice-testable quasi-free onsets and screening spectra for light-charm and bottom-containing sectors. The resulting onset scales provide common reference points for future lattice and continuum studies of meson dissolution across flavor.
hep-phhep-exhep-latnucl-ex+10 citations
04
Double-real corrections to color singlet decay in a parton-shower inspired scheme
John M. Campbell🇺🇸 · Stefan Höche🇺🇸 · Max Knobbe🇺🇸
We introduce a local infrared subtraction method for next-to-next-to-leading order QCD calculations in color singlet decays, which is modeled on the evolution algorithm of a parton shower. Overlapping singularities in the multipole radiation pattern are disentangled by partial fractioning, and the kinematics mapping corresponds to iterated next-to-leading order kinematics. We verify that the double-real remainder to $e^{+} e^{-} \to q q ˉ$ is rendered finite in the single and double unresolved limits and investigate the numerical convergence of the Monte-Carlo integral. We compute the phase-space integrals of the scalar counterterms in the back-to-back configuration, both analytically and with the help of numerical techniques based on sector decomposition.
hep-ph0 citations
05
Supercool with PPO: Exploring Supercooled Phase Transitions via Reinforcement Learning
Wan-Zhe Feng🇨🇳 · Zong-Huan Ye🇨🇳 · Zi-Hui Zhang🇨🇳
Gravitational waves from cosmological first-order phase transitions provide a powerful probe of hidden sectors and beyond the Standard Model physics. However, identifying phenomenologically relevant benchmark points remains computationally challenging, since viable and detectable signals typically occupy only a small fraction of the scanned parameter space. In this work, we introduce a reinforcement learning strategy based on Proximal Policy Optimization (PPO) to accelerate the search for gravitational wave signals from supercooled phase transitions in a minimal dark $U (1)_{x}$ sector. We construct a numerical reinforcement learning environment that maps the microscopic model parameters to the corresponding phase transition and gravitational wave observables, using a gauge-independent low-temperature formulation of the effective action. Several reward designs are developed to guide the agent toward parameter regions producing large gravitational wave amplitudes, broad frequency coverage, and detector sensitive benchmark points. We compare the PPO scans with conventional Monte Carlo scans in both narrow and broad windows of the $U (1)_{x}$ vacuum expectation value. Our results demonstrate that PPO provides an efficient goal-directed search strategy for gravitational wave phenomenology and offers a broadly applicable framework for learning-assisted exploration of high-dimensional scientific parameter spaces.
hep-ph0 citations
06
Thermal Emission of Dark Photons from Earth's Core
Hooman Davoudiasl🇺🇸
Dark photons in the sub-eV regime may be produced by the Earth's hot core, representing a much less extreme environment than stellar cores. We consider this possibility and estimate constraints on the kinetic mixing parameter $ε$ that governs dark photon coupling to charged particles, using Earth core cooling arguments and via dark matter direct detection experiments. Our estimates do not find new constraints on the relevant parameter space from these considerations. Depending on the underlying parameters governing the thermal production of dark photons in the Earth, either core cooling or a future experiment, like Oscura with 30 kg-yr of exposure, can constrain $ε$ about one order of magnitude above the current astrophysical bounds, over the dark photon mass range $\sim 1 0^{- 4} - 0.1$ ~eV.
hep-phhep-ex1 citation
07
Kinetic freeze-out and diffusion dynamics in small-system asymmetric collisions at sqrt(sNN)=200 GeV in light of a generalized Fokker-Planck distribution
M. Waqas🇨🇳 · Wolfgang Bietenholz🇲🇽 · Khusniddin K. Olimov🇺🇿 · Muhammad Ajaz🇸🇦 · Jihane Ben Slimane🇸🇦 · Laila A. Al-Essa🇸🇦 · A. Haj Ismail🇦🇪
A generalized Fokker-Planck solution is used to examine the transverse momentum ( $p_{T}$ ) spectra of neutral pions generated in small-system asymmetric collisions, $p$ -Al, $p$ -Au, $d$ -Au, and $^{3}$ He-Au, at $s_{N N} = 200$ GeV. This framework provides a cohesive explanation of particle production over a broad range of transverse momenta. We extract the energy scale governing the transition between a thermal and a hard regime, the effective temperature ( $T$ ), and the exponents determining the high-momentum falloff from fits to PHENIX data. $T$ increases systematically with the collision centrality and colliding system size, ranging from about 0.33 GeV in peripheral $p$ -Al collisions to 0.45 GeV in central $^{3}$ He-Au collisions. This increase is correlated with the average number of participant nucleons, $< N_{p a r t} >$ , and the charged-particle pseudorapidity density, $< d N_{c h} / d η >$ , indicating that larger and more central collisions create a denser, more strongly interacting medium that freezes out at a higher temperature. The acquired transition scale and power-law exponents follow consistent patterns across systems and centralities, revealing details about the sharpness of the transition from thermal to hard processes, and the relative strength of momentum-space diffusion versus drag. Interestingly, when the gold target dominates the collision geometry in the largest system ( $^{3}$ He-Au), the transition scale becomes nearly independent of centrality, signifying saturation of the diffusion process. Our findings demonstrate that the generalized Fokker-Planck solution is a sensitive probe of transport properties and non-extensive dynamics in the quark-gluon plasma produced even in small-system relativistic collisions, and it consistently describes pion spectra in this set of collisions.
hep-phnucl-th0 citations
08
Flavor Alignment and Mass Hierarchy: Doing Everything Scotogenically
Ernest Ma🇺🇸
Flavor alignment and mass hierarchy in quarks are shown to be achievable together in a renormalizable theory using the dark sector, while keeping only the one Higgs doublet of the standard model.
hep-phPLB(2026)·0 citations
09
An Ultraviolet Finite Theory of Scalars
Francesco Calisto🇺🇸 · Clifford Cheung🇺🇸
We construct a theory of scalars that is free of short-distance infinities to all orders in perturbation theory. Loop divergences are neutralized by momentum-dependent interactions that are ghost free and polynomially bounded. The finite counterparts of the usual one-loop scalar self-energy and beta function are straightforwardly computed. In a variant of this model, the one-loop mass renormalization is zero due to an inversion that swaps the ultraviolet and the infrared.
hep-ph2 citations
10
Unitarity Cuts, t-channel Divergences and the KLN Theorem for Unstable Particles
Marko Beocanin🇦🇺 · Michael A. Schmidt🇦🇺
Many phenomenological calculations involving massless or unstable particles suffer from divergences as mediating particles go on-shell. One way to deal with these divergences is via the Kinoshita-Lee-Nauenberg (KLN) theorem, which guarantees that by summing over all physically-degenerate processes, the divergences cancel and inclusive observables remain finite. However, actually implementing this theorem in practice requires handling disconnected diagrams, ill-defined distributional objects, threshold behavior and subtle regulator dependence. In this work, we formulate practical prescriptions for dealing with some of these issues by studying the KLN cancellation in an illustrative model exhibiting a t-channel divergence. We demonstrate intricate cancellations across several regularization schemes, connect our results to the complex-analytic structure of the underlying amplitudes, and take steps towards constructing a finite, fixed-order, inclusive t-channel collider observable. This work highlights both the utility of the KLN theorem, and also the technical subtleties and open questions involved with applying it in practice.
hep-phhep-th0 citations
11
Unified study of hyperon semileptonic decays in a relativistic three-quark model
Ru-Hui Ni🇨🇳 · Zhen-Yang Wang🇨🇳 · Jia-Jun Wu🇨🇳 · Bing-Song Zou🇨🇳
We present a unified theoretical study of semileptonic decays of ground state octet hyperons using the relativistic three-quark model (R3QM). A key innovation of our approach is that all baryon wave functions are determined by fitting the baryon mass spectrum with a semirelativistic potential model, leading to predictions for weak transition amplitudes without free parameters. Adopting these wave functions, we calculate the decay widths, branching fractions, lepton flavor universality ratios, as well as the angular correlation and spin asymmetry parameters for the octet channels. The calculated values agree with the available experimental data and give predictions for channels with limited experimental information. We further compute the complete set of octet transition form factors without any additional free parameters, so that the weak current can be examined beyond the rate observables. In the well measured $Λ \to p ℓ^{-} ν ˉ_{ℓ}$ channel, the calculated leading vector and axial-vector form factors, $f_{1} (0)$ and $g_{1} (0)$ , agree well with recent lattice QCD results, and the $g_{1} / f_{1}$ ratio is consistent with recent BESIII measurements. Beyond the leading vector and axial-vector terms, the complete form factor set separates the weak magnetism, second class, and the pole contribution associated with the partially conserved axial current (PCAC) relation. The weak magnetism term $f_{2}$ shows the clearest channel dependence compared with lattice QCD results, and its smaller values in some channels may point to transverse current strength not fully saturated by pure $q q q$ valence components. This work provides a framework for connecting octet hyperon weak form factors to the spin--flavor and spatial structure of baryons at the quark level, and gives testable weak current observables for future hyperon semileptonic decay measurements.
hep-phhep-ex0 citations
12
Holographic light-quark energy loss in a spinning plasma
Yan-Qing Zhao🇨🇳 · Zhou-Run Zhu🇨🇳
In this work, we investigate light-quark energy loss in a strongly coupled plasma described by a spinning black-brane background obtained from the large-black-hole limit of the Myers--Perry geometry. The parameter $a$ characterizes the boost/rotation of the dual fluid in this holographic setup and is related to the angular velocity in the corresponding limit. We employ two complementary probes, the falling-string and shooting-string descriptions, to compute the stopping distance and the instantaneous energy loss of a light quark moving either transverse or parallel to the rotation axis. The results show that light quarks thermalize more readily in a hot environment. For parallel propagation, a counter-propagating configuration facilitates thermalization, whereas a co-propagating configuration suppresses it. For transverse propagation, increasing the magnitude of the rotational motion promotes thermalization. In addition, the instantaneous energy loss increases along the trajectory of the endpoint.
hep-ph0 citations
13
Torsional four-fermion interaction for Majorana neutrinos
Indrajit Ghose🇮🇳 · Amitabha Lahiri🇮🇳
Fermions generate spacetime torsion, which can be eliminated, leaving behind an effective four-fermion interaction. This term will contribute an effective mass for neutrinos propagating through matter, similar to the Wolfenstein term coming from electroweak interactions. When the neutrinos are Majorana fermions and become massive via the Type I SeeSaw mechanism, there can be additional effects due to sterile neutrinos interacting with all fermions via the torsion-induced term, as well as due to the presence of new mixing parameters. We consider different scenarios with one sterile and one or two active neutrinos -- when the torsional interaction is diagonal in the mass basis and when it is not -- and analytically find these modifications. The T violation in the 2+1 scenario is discussed for some specific mixing between the torsion fields and the mass fields.
hep-phgr-qc0 citations
14
CHESS: CHEbyshev pSeudo-Spectral transport for Feynman integral differential equations
Yuanche Liu🇨🇳 · Yang Zhang🇨🇳
We present CHESS (CHEbyshev pSeudo Spectrum), a Wolfram Language package for high-precision one-dimensional transport of {\epsilon}-factorized differential equations for Feynman master integrals. The solver works with the matrix obtained by pulling a differential one-form to a chosen path. This matrix may be supplied directly, or assembled from constant matrices and precomputed scalar pullbacks of the one-forms. The program combines Chebyshev-Lobatto spectral collocation, sparse matrix assembly, sequential propagation in the {\epsilon}-expansion, and residue-based regularization of spurious regular singular endpoints. Benchmarks for large multi-scale integral families show rapid node convergence and agreement with independent reference data where such data are available. In the fixed local-series comparison used here, the Chebyshev transports also give shorter wall times; the reported process-tree memory usage is comparable for the smaller parallel runs and lower for the largest benchmark system in that comparison.
hep-phhep-thphysics.comp-ph5 citations
15
RG Running of Multiple Neutrino Mixing Parameters at Oscillation Experiments
Peter B. Denton🇺🇸 · Shao-Feng Ge🇨🇳 · Chui-Fan Kong🇰🇷 · Pedro Pasquini🇧🇷
If the new physics scale is within the energy scale of neutrino oscillation experiments, it may lead to a renormalization group (RG) running effect between the production and detection processes as well as between different experiments. It is then possible to use multiple neutrino oscillation experiments to disentangle the multiple RG running parameters. We investigate this effect in a general model-independent sense for a variety of flavor structures in the context of upcoming experiments DUNE-ND, JUNO-TAO, and FASER $ν$ 2 that span a large range in neutrino energies and many different flavor combinations. We find strong sensitivity to the running effects of new physics with combination of these experiments, especially the possibility of addressing the non-trivial degeneracies.
hep-phhep-ex1 citation
16
Coherent collective response in many-qubit systems for dark matter detection
Ryuichiro Kitano🇯🇵 · Ryoto Takai🇯🇵
We propose an array of Ramsey-type interferometers using $N$ superposition states, $(∣0 ⟩ + ∣1 ⟩)^{\otimes N}$ , as a sensor to detect wave-like dark matter. After exposure to the dark matter wave, which induces coherent qubit transitions, the signal is the imbalance between the numbers of 0 and 1 outcomes. The signal-to-noise ratio in this scheme is proportional to $N α^{2}$ , where $α$ is the coupling of dark matter to the qubits, and thus the sensitivity to the coupling scales as $δ α \sim 1/ N$ . For comparison, in the detection scheme based on the Rabi-type transition, $∣0 ⟩ \to ∣1 ⟩$ , this scaling is achieved only when $N$ highly entangled qubits are used. Since the Ramsey-type measurement does not require entangled states, one can consider much larger $N$ by simply placing a large number of qubits within the de Broglie wavelength of the dark matter. We demonstrate that, using trapped-ion qubits in linear Paul traps as the sensor, the projected sensitivity to the coupling matches or surpasses existing laboratory, astrophysical, and cosmological bounds for $N ≳ 1 0^{6}$ - $1 0^{8}$ . We also evaluate its sensitivity to high-frequency gravitational waves. Our general framework should, in principle, be useful for other quantum sensing platforms.
hep-phgr-qcphysics.atom-phquant-ph0 citations
17
Global analysis of a minimally extended scotogenic model
Huchan Lee🇫🇷 · Sin Kyu Kang🇰🇷
We perform a global analysis of a minimally extended scotogenic model motivated by observed non-zero neutrino masses, viable dark matter (DM) candidates, and the instability of the Standard Model (SM) vacuum at high-energies. We examine the bounded-from-below conditions, vacuum stability, and RG-driven perturbativity bounds arising from the extended scalar sector, alongside a comprehensive set of flavor and electroweak (EW) precision observables - including the muon anomalous magnetic moment $Δ a_{μ}$ , the radiative decays $ℓ_{α} \to ℓ_{β} γ$ and $ℓ_{α} \to 3 ℓ_{β}$ , and the $μ \to e$ conversion rate, the oblique parameters, and leptonic decays of $Z$ and $H$ bosons. A numerical scan reveals four notable features: the DESI BAO bound would rule out the inverted hierarchy if confirmed by other experiments; the oblique parameters are projected to be within the reach of future precision measurements; the viable fermionic DM candidate mass lies in the range $120 - 350 GeV$ , while the CP-odd scalar is constrained to $350 - 600 GeV$ ; and our result on $Z \to Invisible$ is compatible with the world average at the $3 σ$ level and is favored by the recent ATLAS measurement at the $3 σ$ level.
hep-ph1 citation
18
Magnetic moments of decuplet baryons in isospin asymmetric magnetized strange matter
Hrishika P · Manpreet Kaur🇮🇳 · Suneel Dutt🇮🇳 · Harleen Dahiya🇮🇳 · Arvind Kumar🇮🇳
We investigate the in-medium masses and magnetic moments of decuplet baryons $(Δ, Σ^{*}, Ξ^{*}, Ω^{-})$ in isospin asymmetric magnetized strange matter at finite temperature within a unified chiral effective framework. Medium modifications of baryons are implemented using the chiral SU(3) quark mean-field (CQMF) model, where constituent quarks interact via scalar ( $σ$ , $ζ$ , $δ$ ) and vector ( $ω$ , $ρ$ , $ϕ$ ) meson fields considering the Dirac sea effects. The external magnetic field is incorporated through Landau quantization of charged particles together with anomalous magnetic moments (AMM) of baryons. The resulting in-medium mass of constituent quarks and decuplet baryons obtained from the CQMF model are subsequently employed as input to the chiral constituent quark model ( $χ$ CQM) to evaluate magnetic moments of baryons. Contributions from valence quarks, sea quark spin polarizations, and orbital angular momentum of the quark sea are taken into account. Our results provide a systematic understanding of how dense, hot, and magnetized environments influence the magnetic properties of decuplet baryons.
hep-ph0 citations
19
Stochastic gravitational wave spectrum from cosmic string emitting gauge bosons and Majorana fermions
Nobuchika Okada🇺🇸 · Osamu Seto🇯🇵
The effect of particle radiation on the spectrum of the stochastic gravitational wave background (SGWB) from cosmic strings is studied. We consider cosmic strings in an Abelian-Higgs model coupling with Majorana fermion whose mass is generated by the Higgs field, motivated by a gauged $U (1)_{B - L}$ model, in which the Majorana fermions are identified with right-handed neutrinos. Taking the energy loss by particle radiation into account, we evaluate the resultant SGWB spectrum and demonstrate the emergence of very high frequency cutoff due to the particle radiation.
hep-phastro-ph.CO0 citations
20
Thermodynamical analysis of QGP using effective PNJL model with Quasiparticle approach
Yogesh Kumar🇮🇳 · Himanshu Aggarwal🇮🇳 · R. S. Laishram🇮🇳 · Poonam Jain🇮🇳 · Om Prakash🇮🇳 · Sanjay Tyagi🇮🇳 · Pargin Bangotra🇮🇳 · Vinod Kumar🇮🇳 · Yagyadatta Goswami🇮🇳 · M. K. Sahu🇮🇳
We study the thermodynamics of the quark-gluon plasma using an effective Two flavor Polyakov Nambu Jona Lasinio (PNJL) model extended by a quasiparticle description for quarks and gluons, incorporating temperature dependent quark masses within the PNJL framework. Two variants, Quasiparticle Model-I and Quasiparticle Model-II, are implemented to investigate bulk thermodynamic observables such as pressure, energy density, entropy density, specific heat, and the speed of sound. The combined framework yields a robust baseline for the description of hot QGP dynamics in the high temperature regime at vanishing chemical potential and zero magnetic field. Systematic comparison with lattice QCD results shows an excellent agreement and clear improvement over conventional PNJL implementations. We observe that both variants complement each other, offering mutually consistent insight into quasiparticle mass effects and medium response in the deconfined phase. This mutual consistency validates the physical foundation of the overall quasiparticle mechanism, reinforcing the credibility of the calculated Equation of State. Finally, the quasiparticle model extension improves PNJL from a descriptive tool to a more qualitative phenomenological approach, enabling an improved description of the strong interacting quark-gluon plasma.
hep-phActa Phys.Polon.B(2026)·0 citations
21
Hard-Region Fermion Self-Energy and Fermion--Photon Vertex in Thermal QED through Two Loops
Ali Hataei🇮🇷
In massless thermal QED in a general covariant $R_{ξ}$ gauge, we compute hard-region contributions to the fermion self-energy and the off-shell fermion--photon vertex at one-loop next-to-leading power and two-loop leading power in the soft-momentum expansion. The zero-temperature counterterms are also included to renormalize these hard amplitudes. Chiral invariance restricts the off-shell two-fermion-- $N$ -photon vertex to vector ( $γ_{μ}$ ) and axial-vector ( $γ_{μ} γ_{5}$ ) Dirac structures. The vector part is constrained by the Ward--Takahashi identity (WTI), while the axial part is transverse to the photon momentum. The symmetries and hermiticity of the theory impose definite constraints -- including reality, momentum reversal, and fermion-leg exchange properties -- which lead to selection rules in the soft expansion: a contribution at power $r$ can be nonzero only when $r + N + 1$ is even, with $N = 0$ for the self-energy. At the integrand level, we decompose the amplitudes into independent statistical and gauge sectors, and verify the WTI and axial transversality sector by sector. Notably, the gauge-dependent sectors split into mixed metric--longitudinal and fully longitudinal sectors at two loops. The latter vanishes at leading power and reappears at next-to-leading power while satisfying the constraints. We show that these hard-region self-energy corrections do not generate a finite contribution to the fermion damping rate. These results provide hard-region input for mass shifts and inclusive rates, as well as for the construction of the next-to-leading-order fermionic effective Lagrangian.
hep-ph0 citations
22
StringSpinner 2.0: Enabling quark spin effects in PYTHIA for $e^{+} e^{-}$ annihilation
A. Kerbizi🇸🇪 · L. Lönnblad🇸🇪
The StringSpinner package, which implements quark spin effects in the PYTHIA event generator using the string+ $^{3} P_{0}$ model of hadronization, is extended to handle the process $e^{+} e^{-} \to q q ˉ \to ha d r o n s$ at leading order. The correlations between the spin states of the $q q ˉ$ pair produced in the reaction are described by a joint spin density matrix. The spin correlations are propagated along the string fragmentation chain by using the rules of the string+ $^{3} P_{0}$ model and are implemented for the production of pseudoscalar and vector mesons. The new version of the package can be used to simulate spin effects in $e^{+} e^{-}$ annihilation like the Collins and the Artru-Collins asymmetries. It can also be applied to the study of other spin effects in hadronization predicted by the string+ $^{3} P_{0}$ model with a user-defined joint spin density matrix of the $q q ˉ$ pair. To showcase the usage of the package the polar angle dependence of the Collins asymmetries for back-to-back pions is studied and compared with the available data.
hep-ph1 citation
23
The Effect of Topological Defects and Magnetic Flux on Tetraquarks Using the Analytical Exact Iteration Method
N. H. Gerish🇪🇬 · M. Abu-Shady🇪🇬 · E. M. Khokha🇪🇬
Investigating the non-perturbative behavior of QCD and the dynamics of strong interaction is crucial for the study of heavy quarkonia and the understanding of exotic fully-heavy tetraquarks. In this work, using the analytical exact iteration method (AEIM), the analytical eigenvalue solutions of the non-relativistic Schrödinger equation are obtained in the presence of topological defects and external magnetic flux. The interactions are modelled using a modified Cornell potential supplemented by harmonic and inverse quadratic terms. We demonstrate that the energy levels are distinctly shifted by the topological defect parameter ( $α$ ). The mass spectra of heavy quarkonia ( $c c ˉ$ and $b b ˉ$ ) and fully-heavy tetraquarks ( $cc c ˉ c ˉ$ and $bb b ˉ b ˉ$ ) across several radial and orbital excitation states are successfully calculated using this approach. The computed masses of bottomonium and charmonium accord well with current theoretical predictions and experimental findings. Our findings for the heavy tetraquarks are in line with previous theoretical investigations that consider tetraquarks as configurations of diquarks and antidiquarks. The numerical results demonstrate that a nontrivial interaction between the confining potential and the background space-time geometry governs the mass hierarchy of these exotic hadronic states, providing high-precision data with excellent agreement with established theoretical models and experimental benchmarks.
hep-phhep-thmath-phmath.MP0 citations
24
Interpreting "Interpretability" and Explaining "Explainability" in Machine Learning in Physics
Rikab Gambhir🇺🇸 · Luisa Lucie-Smith🇩🇪 · Jesse Thaler🇺🇸
We review the concepts of interpretability and explainability as they apply to machine learning in physics. We define interpretability as concerning the structural transparency of a model (the ability to understand or approximate its inner workings) and explainability as concerning the scientific content of a model (the ability to map it onto domain knowledge). We discuss the trade-offs each entails (interpretability vs. expressivity; explainability vs. adaptability), the contexts in which each is needed, and the intrinsic and post-hoc tools available for achieving them. Throughout, we emphasize that machine-learned models are subject to the same scientific questions as classical models, differing only in scale, and that interpretability and explainability are best understood as deliberate modeling choices rather than inherent properties. We also emphasize the importance of task specification and intervention plans as a core aspect of model design.
↳ physics.data-anastro-ph.GAcs.LGhep-ph2 citations
25
Studying the QCD Matter produced in Heavy-Ion Collisions using the MUSES Calculation Engine
Johannes Jahan🇺🇸 · Kevin P. Pala🇧🇷 · Yumu Yang🇺🇸 · Isabella Danhoni🇺🇸 · Prachi Garella🇺🇸 · Jonathan Gonzales🇺🇸 · Joaquin Grefa🇺🇸 · Mauricio Hippert🇧🇷 · Surkhab Kaur Virk · Micheal Kahangirwe🇺🇸 · Musa R. Khan🇺🇸 · Feyisola Nana and 33 other authors
The equation of state of hot and dense matter is essential for describing heavy-ion collisions at all collision energies. Here, we explore the capabilities of the latest version of the MUSES Calculation Engine, $Calliope$ , focusing on software modules and workflows that compute the equation of state and observable properties of the matter produced in heavy-ion collisions. These include several equations of state, ranging from first-principles lattice QCD to phenomenological approaches, with or without a critical point, and with phase-space dimensionality ranging from two dimensions defined by temperature $T$ and baryon chemical potential $μ_{B}$ , to four dimensions after the addition of strangeness and electric-charge chemical potentials $μ_{S}$ and $μ_{Q}$ . We also discuss modules that provide additional thermodynamic quantities and observables relevant for heavy-ion modeling, including elements of the pressure Hessian matrix and transport coefficients. Workflow examples are constructed that merge two equations of state thermodynamically consistently to extend phase-diagram coverage, and feed the results into an equation of state inverter to produce inputs suitable for hydrodynamic simulations. Finally, we apply this framework to perform a relativistic viscous hydrodynamic simulation with equations of state with an extended $T$ and $μ_{B}$ coverage and a movable critical point, including effects from transport coefficients that phenomenologically encode critical scaling, at collision energies $s_{N N} = 7.7, 19.6$ , and $39$ GeV.
↳ nucl-thhep-ph6 citations
26
Isospin breaking corrections to a lattice QCD calculation of $ε^{'}$
Norman H. Christ🇺🇸 · Erik Lundstrum🇺🇸
Because of the $Δ I = 1/2$ rule, the effects of electromagnetism and the isospin-breaking light quark mass difference on the direct CP violation parameter $ε^{'}$ may be as large as 25\% and are consequently of immediate interest. In a lattice QCD calculation the effects of isospin breaking on the various features of kaon decay can be clearly distinguished and those effects enhanced by the $Δ I = 1/2$ rule on $ε^{'}$ explicitly identified. We show that all such enhanced effects can be captured in a QCD + QED lattice calculation in which the exchanged photon has an energy in an accessible, intermediate range between 0.5-2.0 GeV. Short-distance effects ( $2.0 GeV ≲ E_{γ}$ ), usually treated in QCD and electroweak perturbation theory, are not enhanced by the $Δ I = 1/2$ rule, beyond the well-understood contribution of the two electroweak penguin operators. Infrared photons do not contribute to $ε^{'}$ while low-energy photons ( $E_{γ} ≲ 0.5$ GeV) are not $Δ I = 1/2$ rule enhanced or are suppressed by one order in chiral perturbation theory (ChPT). An explicit ChPT estimate of this low-energy-photon contribution, a contribution that is difficult to determine in a finite-volume lattice calculation, suggests that the effect on $ε^{'}$ is on the order of 0.5\%.
↳ hep-lathep-ph0 citations
27
Applicability of kinetic theory in strongly coupled thermal quantum systems
Shile Chen🇨🇳 · Shuzhe Shi🇨🇳 · Pengfei Zhuang🇨🇳
In this work, we construct one-dimensional interacting lattice spinor theories with discretization in momentum space. We focus on strongly interacting Schwinger and Nambu--Jona-Lasinio models and perform ab-initio calculation of their single-particle and two-particle momentum distribution functions at finite temperature. We observe, at low temperature, high-momentum tail in single-particle and two particle distribution which reveals relative momentum in fermion-antifermion boundstates, as well as quasi-free spinor gases behavior at high temperature. The non-vanishing connected four-momentum function reveals the quantum coherence in momentum space under thermal equilibrium of the system and indicate the single particle correlation would remember more microscopic details within a thermal system. Overall, for a high-enough temperature at which the thermal kinetic energy comparable with the interaction, we observe that the two-particle correlation is subdominant compared to the single particle distributions, which indicates the applicability of kinetic theory.
↳ nucl-thhep-ph0 citations
28
Projected sensitivity of the ANUBIS detector to heavy neutral leptons
Martin Bauer🇬🇧 · Rachel Bentham🇬🇧 · Oleg Brandt🇬🇧 · Sofie Nordahl Erner🇬🇧 · Anna Mullin🇬🇧 · David Peng🇬🇧 · Theo Reymermier🇫🇷 · Paul Swallow🇬🇧
Long-Lived Particles (LLPs) are a common feature in various extensions to the Standard Model (SM) that seek to address known limitations. The ANUBIS detector has been proposed to extend the sensitivity of the ATLAS experiment at the LHC to LLPs by instrumenting the ceiling of the ATLAS detector cavern. This article presents the projected sensitivity of ANUBIS to Heavy Neutral Leptons (HNLs). For a minimal Majorana HNL model that only couples to a single flavour of lepton ( $e$ or $μ$ ) ANUBIS reaches a maximum sensitivity of $∣ V_{1 e} ∣^{2} = 1.8 \times 1 0^{- 8}$ and $∣ V_{1 μ} ∣^{2} = 1.9 \times 1 0^{- 8}$ for a HNL mass of $m_{N_{1}} = 6.4$ GeV and 6.3 GeV respectively. This provides complementary coverage to other proposed LLP experiments in the HNL parameter-space, with potential for significant improvement during ANUBIS data-taking through advances in analysis strategies. The results are obtained with SET-ANUBIS, a flexible framework to evaluate the sensitivity of ANUBIS to a variety of LLP models.
↳ hep-exhep-ph1 citation
29
Non-topological solitons in biadjoint scalar field theory
Kymani Armstrong-Williams🇬🇧 · Chris D. White🇬🇧
Biadjoint scalar theory has been widely studied, due to its being closely related to the double copy correspondence linking gauge, gravity and related theories. In this paper, we continue a programme of work in elucidating non-linear solutions of this theory, and find a family of new solutions that are richer and more complex than previous cases. Using an ansatz that can be embedded in any choice of non-abelian colour groups, we demonstrate the existence of non-topological solitons, whose existence is protected by carrying a U(1) charge associated with certain rotations in colour space. The solutions are time-dependent, and closely related to the well-known Q-ball solutions in other scalar field theories. We also show explicitly that our solution set contains those that are stable under small perturbations within a consistent truncation of the theory, and have finite energy in addition to being localised.
↳ hep-thhep-ph2 citations
30
Spherical Collapse and Halo Formation in a Cosmology with Decaying Dark Matter and a Semi-Cosmographic Dark Energy
Mohit Yadav🇮🇳 · Tapomoy Guha Sarkar🇮🇳
We investigate nonlinear structure formation in a cosmological model combining one-body decaying dark matter (DDM) with a semi-cosmographic reconstruction of dark energy. In this scenario, a nonrelativistic dark-matter component decays into relativistic dark radiation with decay rate $Γ = τ_{ddm}^{- 1}$ , while the dark-energy sector is reconstructed directly from the expansion history rather than being fixed to a cosmological constant. Using DESI DR1 BAO and compressed ShapeFit measurements, we constrain the background evolution and propagate the resulting posterior into the nonlinear regime through spherical collapse and halo abundance calculations. This provides a unified framework connecting a reconstructed dark-energy sector and decaying dark matter (DDM) to the nonlinear formation of cosmic structures. We find that the reconstructed dark-energy equation of state can deviate from the $Λ$ CDM value, $w = - 1$ , while the critical density threshold for collapse remains close to its standard prediction. The most pronounced signatures emerge in the abundance of massive halos, reflecting modifications to the growth of structure driven by both dark-matter decay and dynamical dark energy. By combining DESI DR1 clustering constraints with halo mass function measurements from the DESI Legacy Imaging Surveys DR9, we obtain joint constraints on the DDM lifetime and dark-energy parameters, demonstrating that halo abundances provide a powerful complementary probe of non-standard dark-sector physics.
↳ astro-ph.COhep-ph0 citations
31
Approximating Feynman integrals using complete monotonicity and Stieltjes properties
Sara Ditsch🇩🇪 · Johannes M. Henn🇩🇪 · Prashanth Raman🇩🇪
We present two novel approaches for the numerical evaluation of Feynman integrals based on their universal analytic properties related to positivity, namely complete monotonicity (CM) and Stieltjes properties. Building on recent results, we exploit the fact that scalar Feynman integrals in the Euclidean region are completely monotonic functions, meaning that all their derivatives have a fixed sign. Building on this observation, the CM bootstrap allows one to reconstruct integrals from differential equations without explicit boundary data, yielding rigorous bounds. The second method is based on a refinement of CM. We prove that Feynman integrals, within a certain range of parameters, are not only CM but in fact Stieltjes functions. This enables the use of Padé approximants with provable convergence properties in the cut complex plane, providing an efficient method for analytic continuation and fast numerical evaluation. We illustrate the method with simple examples such as the massive bubble integral and discuss applications to multi-loop integrals, including the 20-loop banana integral. Finally, we comment on a number of extensions of these novel avenues for computing Feynman integrals.
↳ hep-thhep-ph0 citations
32
Rapidity-even directed flow splitting of protons and antiprotons as a probe of baryon stopping in relativistic heavy-ion collisions
Tribhuban Parida🇮🇳 · Sandeep Chatterjee🇮🇳
We compare the rapidity-even directed flow $v_{1}^{even}$ in Au+Au collisions at Beam Energy Scan (BES) energies for baryons and anti-baryons within a (3+1)-dimensional viscous relativistic hydrodynamics coupled to hadronic transport framework. The double-junction baryon stopping picture motivates a rapidity-even component in the baryon deposition in the initial state. We demonstrate that the split in the $v_{1}^{even}$ of protons and anti-protons is sensitive to the rapidity extension of the baryon deposition that we associate with the double junction baryon stopping. Particularly, we find that the mid-rapidity curvature $\frac{d ^{2} Δ v _{1}^{even} ( p - p ˉ )}{d y ^{2}} ∣_{y = 0}$ is a robust discriminator of the initial state baryon rapidity profiles. A simultaneous measurement of $Δ v_{1}^{even}$ and its curvature at mid-rapidity could constrain both the baryon diffusion strength and the baryon stopping profile, providing access to the physics of baryon stopping in relativistic heavy ion collisions.
↳ nucl-thhep-phnucl-ex1 citation
33
HALO II: Constraining Hubble constant $H_{0}$ through continuum delay fitting of Fairall 9
Amit Kumar Mandal🇵🇱 · Francisco Pozo Nuñez🇩🇪 · Vikram Kumar Jaiswal🇵🇱 · Mohammad Hassan Naddaf🇧🇪 · Bożena Czerny🇵🇱 · Swayamtrupta Panda🇨🇱 · Paulina Karczmarek🇵🇱 · Grzegorz Pietrzyński🇵🇱 · Shivangi Pandey🇵🇱 · R. Edelson🇺🇸 · B. M. Peterson🇺🇸 · Michal Zajaček🇨🇿 and 19 other authors
The Hubble tension remains one of the most significant unresolved problems in modern cosmology. A key question is whether it may arise from underestimated systematic uncertainties in the different measurement techniques. In this context, new independent methods are of exceptional importance. We therefore pursue a novel approach to determining the Hubble constant, $H_{0}$ based on continuum time delay and spectral energy distribution (SED) modeling in active galactic nuclei (AGNs). Unlike conventional techniques, this method is entirely independent of the cosmic distance ladder and does not require cross-calibration against other distance indicators. As a result, it enables a direct determination of $H_{0}$ , free from the arbitrary normalizations that often affect indirect measurements. We conducted a dedicated monitoring campaign of the Seyfert galaxy Fairall 9 and further developed the {\tt H0RIZON-AGN} model to interpret the resulting observations. The model incorporates the effects of radiation reprocessing in the surrounding cold accretion disk, enabling a more realistic description of the observed continuum delays. Through the simultaneous modeling of the continuum lag-spectrum and the broadband SED of Fairall 9, we derived a Hubble constant of $H_{0} = 72. 4_{- 3.7}^{+ 3.4} km s^{- 1} Mp c^{- 1}$ . Achieving a measurement precision of approximately 5% from a single source demonstrates the considerable potential of this method for independent determinations of the Hubble constant. Our determination of $H_{0}$ is broadly consistent, within the current uncertainties, with both early- and late-Universe measurements. Future applications of the method to larger datasets, particularly those provided by the Vera Rubin Observatory, are expected to reduce the uncertainty to below 1%, thereby establishing this approach as a powerful independent probe of the Hubble tension.
↳ astro-ph.GAastro-ph.COgr-qchep-ph+10 citations
34
The gauge invariance of non-perturbative vertex prescriptions
M.E. Carrington🇨🇦 · A.R. Frey🇨🇦 · B.A. Meggison
We study the gauge invariance of different continuum methods to include non-perturbative effects in gauge theories. We work with three dimensional quantum electrodynamics and implement vertices using two different methods: a set of coupled Schwinger-Dyson (SD) integral equations, and the self-consistent equations obtained from the 3-particle irreducible (3PI) effective action. We work in Landau gauge and assess the extent to which results are gauge invariant by checking how well the Ward identity is satisfied. Our results show that there is a fairly significant violation of the Ward identity at large coupling, although the 3PI effective theory is slightly better than the SD vertex. We also compare the results of both calculations with the commonly used Ball-Chiu ansatz and show that the agreement of the ansatz with both non-perturbative vertices is fairly good at small coupling but deviates more significantly at large coupling. We compare results for the two point functions of the theory and discuss the possible implications for phase transitions.
↳ hep-thhep-ph0 citations

Affiliations

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