HEP Phenomenology·hep-ph

Tue·Jun 30, 2026Tuesday·June 30, 2026

55 papers—32 primary·23 cross-listed

01
Pseudoscalar charmonium and bottomonium: light-front wave functions, distribution amplitudes and distribution functions
Zhen-Ni Xu🇪🇸 · Zhao-Qian Yao🇪🇸 · Cédric Mezrag🇫🇷 · Khépani Raya🇪🇸 · José Rodríguez-Quintero🇪🇸
Light-front wave functions play a central role in the program of understanding the structure of hadrons as QCD bound states. Using continuum Schwinger methods, based on Dyson-Schwinger and Bethe-Salpeter equations, they can be computed directly within a framework connected to QCD. For light pseudoscalar mesons, previous studies revealed an approximate separability of longitudinal and transverse lightcone momentum dependences in the LFWFs, leading to a simple relation between distribution functions and amplitudes. In this work, we extend those previous studies to the case of pseudoscalar charmonium and bottomonium, using the fictitious $π_{s}$ meson as a benchmark. Motivated by the observed deviations, we propose a modified non-separable LFWF ansatz that successfully reproduces the properties of heavy pseudoscalar quarkonia and allows the calculation of zero-skewness generalised parton distribution functions, electromagnetic and gravitational form factors, and transverse charge and mass distributions.
hep-ph0 citations
02
Background-Induced Forces from Quadratically Coupled Ultralight Dark Matter
Thomas Bouley🇺🇸 · Xucheng Gan🇩🇪 · Hailin Xu🇺🇸 · Tien-Tien Yu🇺🇸
Quadratically coupled ultralight scalar dark matter behaves as a coherent classical field whose interactions with matter can induce a composition-dependent force through the dark matter background. We present a complete calculation of this background-induced force beyond the spherically symmetric approximation. Using a partial-wave treatment of dark-matter scattering, we determine its angular dependence and derive an analytic description valid even when the dark-matter wavelength is much smaller than the Earth's radius. We show for the first time that Earth screening generates a characteristic frequency-band structure, splitting the signal into multiple sidebands that provide a distinctive experimental signature. We further show that the relative amplitudes of these sidebands vary annually due to the Earth's motion through the dark-matter halo, enabling the construction of a complete signal template. As an application of these results, we re-evaluate constraints from the MICROSCOPE mission, which currently provides the strongest laboratory limits on equivalence-principle violations from ultralight dark matter. We further show that proposed space-based equivalence-principle experiments, such as Galileo Galilei and STE-QUEST, can significantly enhance their sensitivity to ultralight scalar dark matter by incorporating the full frequency-band information.
hep-phastro-ph.CO4 citations
03
A directional force template for quadratically coupled ultralight dark matter
Dawid Brzeminski🇺🇸 · Aaron Pierce🇺🇸
Quadratic couplings between ultralight scalar dark matter and Standard Model fields can produce a distorted dark-matter field profile around the Earth. Gradients in the field induce a non-radial, composition-dependent force that can be suppressed at the Earth's surface while remaining accessible to space-based experiments. The MICROSCOPE satellite, which searched for violations of the equivalence principle, can constrain this force, but existing results assume a radial force, and they cannot be directly translated into an optimal bound in the anisotropic regime. We develop a signal template for this regime by organizing the force into radial and polar multipole coefficients and projecting the force onto the MICROSCOPE measurement axis. We use this template to recast the published MICROSCOPE constraint using the component of the signal that overlaps with the radial-force template. We estimate the sensitivity gain that would be provided by an analysis utilizing the additional non-overlapping signal. Such an analysis could improve sensitivity to the couplings of quadratically coupled scalar dark matter by more than an order of magnitude relative to the radial-force recast for dark matter masses $≳ 1 0^{- 9}$ eV.
hep-phgr-qc3 citations
04
Propagating data noise through the fit: the Monte Carlo replica distribution
Mark N. Costantini🇬🇧
The Monte Carlo (MC) replica method quantifies parameter uncertainties in global fits of parton distribution functions (PDFs) and Standard Model Effective Field Theory (SMEFT) Wilson coefficients by fitting a model to many noise-perturbed copies of the data and taking the empirical distribution of the best-fit parameters as the uncertainty. The method reproduces the Bayesian posterior exactly only when the model is linear in its parameters, and departs from it in the nonlinear case. We derive the leading-order distribution the method produces and compare it with the Laplace approximation of the Bayesian posterior: the two differ by a single computable matrix, the residual-weighted Hessian of the model at the best fit, whose sign and magnitude set the over- or under-estimation of the parameter uncertainties. This closed-form expression quantifies when and by how much the MC method departs from Bayesian inference. We illustrate it on two single-parameter examples solvable in closed form and point to its evaluation in full PDF and SMEFT fits as a natural next step.
hep-ph0 citations
05
Soft Contributions Stabilize NNLO QCD Corrections to Quarkonium Production and Decay
Luca Maxia🇫🇷 · Hua-Sheng Shao🇫🇷 · Lukas Simon🇫🇷 · Guoxing Wang🇫🇷
Next-to-next-to-leading order (NNLO) QCD corrections to quarkonium production and decay are known to exhibit perturbative instabilities within non-relativistic QCD. We identify the origin of this problem and propose a simple remedy. Applying our approach to $S$ -wave color-singlet quarkonium processes, we achieve substantially improved perturbative convergence and agreement with experimental data.
hep-phhep-exnucl-exnucl-th2 citations
06
Polarization interference in exclusive $V +$ jets at all orders in $α_{s}$
Trina Basu🇵🇱 · Richard Ruiz🇵🇱
Using new methods for computing helicity amplitudes with intermediate helicity-polarized gauge bosons, we revisit the transverse-longitudinal polarization interference in the $pp \to V + jets$ process for $V = γ^{*}, Z^{(*)}, W^{(*)}$ decaying to massless leptons. At each order of the strong coupling constant $α_{s}$ and remaining exclusive with respect to jet kinematics, we show that the polarization interference in $γ^{*} \to ℓ^{+} ℓ^{-}$ vanishes after phase-space integration over the kinematics of $ℓ^{\pm}$ , thereby extending well-known results for the inclusive process. Due to parity violation, cancellations are softened for the $W$ and $Z$ bosons. We give a simple formula to account for fiducial cuts. We comment on the implications for multiboson processes, and the applicability of our results to chiral gauge bosons in new physics scenarios and to polarization measurements of weak bosons in heavy ion collisions.
hep-phhep-exhep-thnucl-th1 citation
07
Defining a Minimum Resolution for Unbinned Analyses
Manuel Szewc🇦🇷
Collider analyses combine rigorous statistical techniques with state-of-the-art Machine Learning models. However, when the latter are used directly to estimate the likelihood function of the background, hard to quantify systematic effects may bias the estimation of the relevant signal parameters. To address this problem, we present the Minimum Resolution Likelihood (MRL) method, which defines a Fiducial Signal Region that effectively turns the systematic effects into statistical uncertainties. We show with examples that the resulting signal strength estimation is either unbiased or consistent with zero. We consider both toy examples and a realistic application based on the HI-SIGMA technique applied to di-Higgs searches.
hep-phhep-ex1 citation
08
New Energy-Loss Constraints on Dark Sectors from Deeply Inelastic Scattering with Initial State Radiation
Justin Cammarota🇺🇸 · John Carlton🇬🇧 · Susan Gardner🇺🇸
We employ the joint QED and QCD factorization of deeply inelastic, electron-proton scattering with generic initial state radiation to probe the possibility of exotic particle emission -- i.e., of weakly coupled particles originating from a dark or hidden sector -- through anomalous energy loss. We leverage this possibility through the consideration of phase-space-limited kinematic regions, for which the emission of an additional, undetected particle can particularly impact the associated cross-section. In this first paper, as a proof of principle, we focus on radiation from the incoming electron, considering the modification of the lepton distribution function from the emission of particles, that could have spin of up to 2 and various, well-motivated electron couplings. We illustrate the sensitivity of our approach through the computation of the modified cross-sections for the emission of MeV-GeV mass-scale, spin 0 particles in kinematics chosen for their sensitivity to initial state electron radiation and suitable to the forward-backward detection sensitivity of the ePIC detector at the EIC.
hep-ph1 citation
09
Gravitational waves from graviton bremsstrahlung in scalar leptoquark decays
Qian-Jiu Wang🇨🇳 · Hua Tong🇨🇳 · Zhao-Huan Yu🇨🇳
We study the stochastic gravitational wave background originated from graviton bremsstrahlung in decays of scalar leptoquarks, which are colored scalar bosons simultaneously coupling to a quark and a lepton. We take the scalar leptoquarks in the $SU (5)$ grand unified theory as a concrete example. Stringent experimental bounds on proton decay force these particles to be superheavy, which in turn renders their graviton bremsstrahlung, induced by quantum gravity effects, less suppressed. By solving the relevant Boltzmann equation, we trace the evolution of the scalar leptoquark number density in the early universe and use it to compute the resulting gravitational wave spectrum. We find that high-frequency gravitational wave detectors employing resonant cavity techniques offer a promising means to probe such signals.
hep-phastro-ph.CO0 citations
10
Heavy mesons from the QCD instanton vacuum beyond the static limit
Ki-Hoon Hong🇰🇷 · Yongwoo Choi🇰🇷 · Nurmukhammad Rakhimov🇰🇷 · Hyun-Chul Kim🇰🇷
We study pseudoscalar heavy mesons in the QCD instanton vacuum beyond the static limit. Finite-mass effects in the heavy-light loop are encoded in a separable effective vertex built from a profile function $ϕ (p)$ , kept distinct from the static Wilson-line form factor $F_{Q}^{(\infty)} (q)$ of the $m_{Q} \to \infty$ limit. The pseudoscalar two-point function fixes the residual mass $Λ$ and the residue-normalized meson-quark coupling, from which we evaluate the decay constant, the spin-independent kinetic matrix element, and the zero-recoil slope of the Isgur-Wise function at order $1/ m_{Q}$ . The subleading calculation is restricted to the kinetic (derivative) part of the HQET operators. For a representative vertex calibrated to the $B$ -meson decay constant and the spin-averaged $B$ -meson mass, we obtain $f_{B} = 186.8$ ~MeV, $Λ = 184.5$ ~MeV, $m_{b}^{eff} = 5.04$ ~GeV, $λ_{1}^{(\partial)} = - 0.922 GeV^{2}$ , and $ρ_{IW}^{2} = 1.105$ . The kinetic contribution yields a mass shift of order $Λ/2$ and a sizable $1/ m_{Q}$ current correction, indicating that the spin-independent nonperturbative $1/ m_{Q}$ sector is a sensitive probe of the finite-mass heavy-light vertex.
hep-ph0 citations
11
Vector-Like Lepton Pair Production With Polarized Beams at Linear Colliders:Sensitivity Projections and Chirality Observables
Haroon Sagheer🇵🇰 · Ijaz Ahmed🇵🇰 · Jamil Muhammad🇰🇷
We study pair production of a vector-like lepton doublet at polarized future linear colliders, focusing on the charged and neutral channels $e^{+} e^{-} \to τ^{'} τ ˉ^{'}$ and $e^{+} e^{-} \to ν^{'} ν ˉ^{'}$ . The benchmark masses are $M_{VLL} = 1000, 1200 GeV$ at CLIC with $s = 3 TeV$ and $M_{VLL} = 390, 460 GeV$ at ILC with $s = 1 TeV$ . Using the realistic polarization configurations LR $= (- 0.8, + 0.3)$ , RL $= (+ 0.8, - 0.3)$ , LL $= (- 0.8, - 0.3)$ , and RR $= (+ 0.8, + 0.3)$ , we evaluate tree-level production-level cross sections and construct observables designed to test the electroweak structure of the doublet. The charged channel is consistently larger than the neutral channel because it receives both photon and $Z$ exchange. In the LR configuration, the charged-channel rates reach $23.32$ and $20.28 fb$ at CLIC, and $188.83$ and $129.04 fb$ at ILC, for the two benchmark masses at each collider. We express rate reach through the projected visible-fraction requirement $f_{vis}^{95} = 3/ (L σ_{prod})$ , keeping the result independent of a specific decay selection. To quantify charged--neutral separation we use the absolute discriminator $D_{σ}$ , which reaches about $0.546$ at CLIC and $0.542$ at ILC in the LR benchmark. We also find a stable observed asymmetry separation, $∣Δ A_{L R}^{obs} ∣ ≃ 0.45$ -- $0.46$ , between the charged and neutral channels. The corresponding production-level statistical projection gives sizeable $Z_{A}$ values for the benchmark luminosities, scaling as $L_{tot} f_{vis}$ under an equal LR/RL luminosity split. These results demonstrate that the beam polarization can provide a representation-sensitive diagnostic of vector-like lepton doublets, beyond a simple rate enhancement.
hep-ph1 citation
12
Analytic two-loop electroweak corrections at high energies
Hantian Zhang🇨🇭
The high-energy behaviour of electroweak scattering amplitudes is of theoretical and phenomenological interest. In these proceedings, we summarize recent progress in analytic high-energy calculations for two-loop four-point electroweak amplitudes in the full Standard Model. As a representative application, we discuss the electroweak corrections to Higgs boson pair production, where rich structures of logarithmic and power corrections appear and sizeable effects are found in the high-energy region.
hep-phhep-th0 citations
13
Effects of Mirror Dark Matter on Neutron-Star Structure and Tidal Deformability
Jin-Cheng Jiao🇨🇳 · Cheng-Ming Li🇨🇳
Mirror dark matter (MDM) can modify neutron-star structure and tidal response through gravitational coupling. In this work, we construct an ordinary-matter equation of state (EOS) by comparing hadronic matter described by the relativistic mean-field NL3$\omega\rho$ model, and quark matter in the framework of the Nambu--Jona-Lasinio (NJL) model. The stable branch is determined through a Maxwell construction, which serves to connect distinct phases of matter. For the parameter sets considered here, $m_u=5.2~{\rm MeV}$ is the lowest light current-quark mass in the scanned range that satisfies the $2M_\odot$ maximum-mass requirement, while $m_u>5.2~{\rm MeV}$ all yield stable neutron-star configurations without a resolved macroscopic quark core. The small-radius inferences for PSR J0437--4715 and XTE J1814--338, together with the tidal-deformability constraint from GW170817, are sensitive to the dark-matter mass fraction $f_D$. The commonly used GW170817 interval $70\lesssim\Lambda_{1.4}\lesssim580$ corresponds approximately to $0.12\lesssim f_D\lesssim0.88$ in the present model. These results indicate that, even without a macroscopic quark core, MDM can provide an important mechanism for reducing the visible radius and modifying the tidal response of neutron stars.
hep-phastro-ph.HEnucl-th0 citations
14
Equilibrium Statistics as Conditional Laws and Conservation-Induced Correlations
Sunil Jaiswal🇺🇸 · Amaresh Jaiswal🇮🇳
We present a novel unified conditional-probability framework for relativistic systems in which conditioning on additive conservation laws simultaneously yields equilibrium occupation statistics and conservation-induced correlations. In this formulation, equilibrium arises as a conditional limit law of a closed system. The one-mode marginal gives Maxwell--Boltzmann, Bose--Einstein, and Fermi--Dirac statistics at leading saddle order, with the conserved quantities fixing the exponential tilt and the microscopic occupation measure determining the statistics. Expanding the two-mode marginal to Gaussian order gives the leading finite-rank covariance between modes induced by exact conservation. When contracted with observables linear in mode occupations, this covariance gives their leading exact-conservation contribution. We use this structure to define projected observables orthogonal to selected conserved quantities. By construction, their covariance has no leading exact-conservation contribution. In small collision systems, where conservation effects are less suppressed by multiplicity and can survive standard nonflow suppressions, this provides a direct way to isolate conservation-aligned contributions to long-range correlations. We demonstrate this with PYTHIA8/Angantyr-generated p+Pb events at $s_{NN} = 5.02 TeV$ by comparing ordinary and projected covariances, showing that the projection removes the conservation-aligned contribution while leaving the conservation-orthogonal covariance essentially unchanged.
hep-phhep-thnucl-th1 citation
15
CMB Test of the Higgs Origin of Dark-Photon Dark Matter
Imtiaz Khan🇨🇳 · Salvatore Capozziello🇮🇹 · G. Mustafa🇨🇳 · Chengxun Yuan🇨🇳 · Farruh Atamurotov🇺🇿
Laboratory searches determine the mass and kinetic mixing of dark-photon dark matter. The CMB isocurvature probes how its abundance depends on inflationary initial conditions. We formulate this dependence through the logarithmic response $q_{eff} = \partial ln n_{A^{'}} / \partial ln r_{i}$ of the final vector number to the primordial dark-Higgs displacement. For a smooth local abundance map, the separate-universe relation connects $q_{eff}$ to the CDM isocurvature. The uncorrelated Planck limit applies when the dark Higgs is a light and energetically subdominant spectator with weak inflaton mixing. In the quadratic conserved-number branch displacement-independent transfer gives $q_{eff} = 2$ . The all-dark-matter bound then requires $r_{i} / H_{*} > 3.5 \times 1 0^{4}$ . We calculate the dynamical map by evolving the radial mode and its tangent response through a smooth Abelian-Higgs crossover. The post-transition orbit gives the comoving action. The map contains positive, negative, and near-zero responses at finite transferred action. Tanh and error-function crossovers retain these branches. A thermal-mass profile and finite inflationary quartics shift their locations continuously. Stochastic duration and radiative stability then determine realization regions. Early symmetry breaking and momentum redshift add the remaining conditions. Low-energy measurements and the CMB response can distinguish Higgsed-vector cosmologies with identical present-day $(m_{A^{'}}, ϵ)$ and relic abundance.
hep-ph2 citations
16
Light anti-nuclei in pp collisions at the LHC: production by coalescence and interaction of anti-nucleons
Niccolò Ciavarelli🇮🇹 · Francesca Ercolessi🇮🇹 · Francesco Noferini🇮🇹 · Francesca Bellini🇮🇹
A unified afterburner framework is presented to describe nucleon--nucleon final-state interactions and light-(anti)nuclei production via coalescence in high-energy measured in pp collisions at the LHC collisions. The model reproduces qualitatively light-(anti)nuclei spectra without fine-tuning of the model parameters, as well as correlation observables, and can be extended to beyond proton--proton collisions.
hep-ph0 citations
17
An overview of scale invariance in proton structure with holographic insights
Akbari Jahan🇮🇳
The concept of self-similarity in the internal structure of the proton, rooted in scale invariance and fractal geometry, provides an intriguing framework for understanding the behaviour of parton distribution functions (PDFs), particularly in the small \textit{x} region probed in deep inelastic scattering (DIS). Phenomenological models based on self-similarity have been shown to reproduce key features of experimental data, suggesting that recursive scaling patterns may play an important role in partonic dynamics. In this work, we present an overview of scale-invariant descriptions of proton structure, focusing on self-similar models developed in earlier studies and their phenomenological implications for structure functions and parton distributions. We then explore possible conceptual connections between these fractal-inspired descriptions and modern holographic approaches to QCD, particularly within the framework of light-front holographic QCD. By comparing the scaling behaviour appearing in phenomenological models with the geometric structure underlying holographic QCD, we highlight qualitative correspondences that suggest a broader role of scale invariance in proton structure. Although the connection remains interpretive rather than derivational, it offers a complementary perspective of how fractal-like scaling observed in DIS may relate to geometric scaling in holographic descriptions of QCD.
hep-phAdv.High Energy Phys.(2026)·0 citations
18
Searching for the $G (3900)$ via the $K^{-} p \to D_{s}^{-} Λ_{c}^{+} G (3900)^{0}$ reaction
Qing Lu🇨🇳 · Cai Cheng🇨🇳 · Yin Huang🇨🇳
The nature of the $G (3900)$ structure, observed in $e^{+} e^{-} \to D D ˉ$ , remains unclear and may stem either from a genuine resonance or from charmonium interference and threshold effects. We therefore propose searching for the $G (3900)$ signal in the reaction $K^{-} p \to D_{s}^{-} Λ_{c}^{+} G (3900)^{0}$ , where the interference effects present in $e^{+} e^{-} \to D ˉ^{*} D$ are absent. We employ an effective Lagrangian approach, where the reaction proceeds via a central production mechanism dominated by $t$ -channel $D^{0}$ and $D^{* 0}$ exchanges, based on the possible interpretation of $G (3900)$ as a $P$ -wave $D ˉ^{*} D$ molecular state, whose coupling to the $D ˉ^{*} D$ channel is fixed from our previous fit to the $e^{+} e^{-} \to D ˉ^{*} D$ data. The $K ˉ N$ initial-state interaction, mediated by Pomeron and Reggeon exchanges, is also included and leads to a significant enhancement of the production cross section. If measured in future experiments, the predicted total cross sections and angular distributions can provide a promising probe of the nature of the $G (3900)$ , and in particular of its possible genuine resonance nature.
hep-phhep-exhep-th0 citations
19
$λ$ , $ρ$ , and $σ$ Regge trajectories for the hexaquark $(u ˉ (cc)) (b (b ˉ b ˉ))$ in the triquark-antitriquark picture
Xin-Ru Liu🇨🇳 · Qi Liu🇨🇳 · Jiao-Kai Chen🇨🇳
We propose Regge trajectory relations for the hexaquark $(u ˉ (cc)) (b (b ˉ b ˉ))$ by using the Regge trajectory relations for diquarks and triquarks. With these newly derived relations, we investigate five series of hexaquark Regge trajectories: the $λ$ -, $ρ_{1}$ -, $ρ_{2}$ -, $σ_{1}$ -, and $σ_{2}$ -trajectories. We demonstrate that, apart from the simplest $λ_{1}$ -trajectories, the $ρ_{1}$ -, $ρ_{2}$ -, $σ_{1}$ -, and $σ_{2}$ -trajectories cannot be constructed by merely mimicking the meson Regge trajectories, since mesons possess no internal substructures. To derive these trajectories, one must account for the structure and internal substructure of hexaquark. Without this structural information, the $ρ_{1}$ -, $ρ_{2}$ -, $σ_{1}$ -, and $σ_{2}$ -trajectories could only be obtained through direct fits to available theoretical predictions or future experimental data. We demonstrate that the $ρ_{1}$ -, $ρ_{2}$ -, $σ_{1}$ -, and $σ_{2}$ -trajectories for the hexaquark do not correspond respectively to the Regge trajectories for the triquark, antitriquark, diquark, and antidiquark. Nevertheless, their behaviors match those of the Regge trajectories for the triquark $(u ˉ (cc))$ , the antitriquark $(b (b ˉ b ˉ))$ , the diquark $(cc)$ , and the antidiquark $(b ˉ b ˉ)$ , in that respective order. Furthermore, we present rough mass estimates for the excited states corresponding to the $λ$ -, $ρ_{1}$ -, $ρ_{2}$ -, $σ_{1}$ -, and $σ_{2}$ -trajectories.
hep-ph1 citation
20
Exploring $K Ξ^{*}$ and $K^{*} Ξ$ molecular states and the triangle singularity in the $K^{-} p \to K Ξ (1530)$ reaction
Ke Wang🇨🇳 · Fei Huang🇨🇳 · Bing-Song Zou🇨🇳
We investigate the $K^{-} p \to K Ξ (1530)$ reaction within an effective Lagrangian approach, exploring possible $K Ξ^{*}$ and $K^{*} Ξ$ hadronic molecular states and the role of the triangle singularity (TS). The $Λ (2050) 3/ 2^{-}$ is interpreted as a $K Ξ^{*}$ molecule, whereas a $K^{*} Ξ$ molecule with $I (J^{P}) = 0 (3/ 2^{-})$ and mass about 2150~MeV denoted as $Λ (2150)$ can generate a TS through triangle-loop diagrams with intermediate $K^{*}$ , $Ξ$ , and $π$ . The peak structure observed in the cross section near $s = 2.25$ GeV is analyzed in terms of both the $Σ (2250)$ resonance production and the TS mechanism associated with $Λ (2150)$ . We find that the TS induces pronounced spin effects in the final state $Ξ^{*}$ , which can be probed through measurements of its spin density matrix elements. In particular, significant variations of the spin observables in the $s = 2.2$ -- $2.3$ GeV region serve as a distinct TS signature absent in a pure resonance scenario. Furthermore, for the three-body reaction $K^{-} p \to K^{+} π^{-} Ξ^{0}$ , we demonstrate that $Ξ^{*}$ spin observables can be reliably extracted from the $π$ angular distribution in the $Ξ π$ rest frame by applying an appropriate kinematic cut on the $Ξ π$ invariant mass to suppress background contributions. These predictions can be tested in future high-precision measurements at J-PARC, providing crucial insights into the nature of the TS and the possible existence of the $K^{*} Ξ$ molecular state.
hep-ph0 citations
21
Probing the structure of $χ_{c 1} (3872)$ : Heavy quark symmetries at work
Giuseppe Roselli🇮🇹
More than two decades have elapsed since the discovery of $χ_{c 1} (3872)$ . For this meson, previously denoted as $X (3872)$ , an impressive amount of theoretical and experimental studies has been devoted concerning its properties, decays and production mechanisms. Despite the extensive work, a full understanding of the nature of $χ_{c 1} (3872)$ is missing. I describe a theoretical framework based on the heavy quark large mass limit to analyze the radiative decays of heavy quarkonia, in particular the electric dipole transitions of $χ_{c 1} (2 P)$ to $S$ -wave charmonia. The results favorably compare to recent LHCb collaboration measurements for $χ_{c 1} (3872)$ , if this meson is identified with $χ_{c 1} (2 P)$ .
hep-phhep-exPoS(2026)·0 citations
22
Neutrino oscillation in a minimal length spacetime
Luísa Nadal Camargo · Thiago Oliveira Ferreira · Dimiter Hadjimichef🇧🇷 · César A. Z. Vasconcellos
We investigate how neutrino oscillations are modified in a non-commutative spacetime characterized by a minimal length scale, described by the Quesne-Tkachuk algebra. By incorporating the algebra's deformation parameter $β$ into the effective neutrino mass, we derive the 2-flavor oscillation probability in this non-commutative setting. The resulting probability depends not only on the usual mass-squared difference but also on a fourth-order mass difference scaled by $β$ . A comparison between the standard and non-commutative oscillation probabilities reveals a beat pattern arising from the additional non-commutative phase, which induces a small shift in the oscillation profiles. Finally, we extend our analysis to include the effects of a magnetic field on neutrino propagation.
hep-ph0 citations
23
Quark--hadron duality in inclusive electron--proton scattering at high $Q^{2}$ : structure functions and truncated moments from CLAS12
Y. Wunderlich🇺🇸 · A. Bulgakov🇺🇸 · K. Joo🇺🇸 · T.-S. H. Lee🇺🇸 · V. I. Mokeev🇺🇸
We present a high-precision study of quark--hadron duality in inclusive electron--proton scattering in the nucleon resonance region, extending to $Q^{2} \approx 10 GeV^{2}$ , based on recent CLAS12 cross-section measurements at Jefferson Lab. The data, taken with a 10.6~GeV beam, span $2.55 \leq Q^{2} \leq 10.4 GeV^{2}$ and cover the full resonance region up to $W \approx 2.5 GeV$ . To reach the CLAS12 kinematics, we develop a phenomenological high- $Q^{2}$ extension of the Argonne--Osaka (ANL-Osaka) dynamical coupled-channels framework, anchored to the original calculation at $Q_{0}^{2} = 2.774 GeV^{2}$ and constrained by the measured cross sections. This enables an ANL-Osaka-constrained longitudinal--transverse decomposition and determination of the proton structure function $F_{2} (W, Q^{2})$ , from which we evaluate $W$ -truncated Cornwall--Norton moments $M_{2} (Q^{2})$ . Comparison with the CJ15 global QCD analysis, including target-mass and higher-twist corrections, shows consistency at the cross-section, structure-function, and truncated-moment levels, providing quantitative evidence for both local and global quark--hadron duality at substantially higher $Q^{2}$ than previously explored. We further identify a threshold effect in the partonic calculation: the finite- $Q^{2}$ corrections do not enforce the physical pion-production threshold, and the residual discrepancy in the first resonance region is consistent with this effect rather than a breakdown of duality. Within the coupled-channel description, the single-pion channel alone underestimates the inclusive resonance-region strength above the $Δ (1232)$ , which is carried predominantly by the multi-meson channels, as required for duality.
hep-phnucl-ex0 citations
24
Size Dependence of the Sommerfeld Enhancement for Puffy Dark Matter
Wu-Long Xu🇨🇳 · Jin Min Yang🇨🇳 · Wen-Na Yang🇨🇳
We examine the size effects in the Sommerfeld enhancement factor for puffy dark matter annihilation. First, we use the partial-wave method to study the case of puffy dark matter for which only a charge density distribution is given without specifying its internal structure. We find that by using two dimensionless parameters, we can provide a characterization of the resonance structure of the Sommerfeld enhancement. Using this approach, we demonstrate that the finite size of dark matter particle is another fundamental factor, in addition to low velocity, that affects the Sommerfeld enhancement. Then, as an example of puffy dark matter with nontrivial internal structures, we perform the analysis for the nugget-type dark matter, whose Sommerfeld enhancement factor is found to exhibit a resonant behavior similar to that of point-like particles.
hep-phastro-ph.HEhep-th0 citations
25
Light Neutralino Dark Matter in a Supersymmetric Pati-Salam Framework
Ali Muhammad🇨🇳 · Imtiaz Khan🇨🇳 · Tianjun Li🇨🇳 · Shabbar Raza🇵🇰 · Mussawir Khan🇨🇳
We investigate the low-energy phenomenology of the MSSM arising from the supersymmetric $S U (4)_{C} \times S U (2)_{L} \times S U (2)_{R}$ Pati-Salam framework, focusing on neutralino dark matter in bulk annihilation and Higgs/Z-funnel regions. Using a comprehensive parameter scan consistent with radiative electroweak symmetry breaking and a neutralino LSP, we analyze collider, flavor, and dark matter constraints for both signs of {\mu}. To isolate genuine bulk annihilation from coannihilation, we impose the mass-splitting condition $R_{ϕ ~} \equiv (m_{ϕ ~} - m_{χ ~_{1}^{0}}) / m_{χ ~_{1}^{0}} ≳ 10%$ . We identify a viable bulk region with a bino-like LSP and a light right-handed stau NLSP. These solutions satisfy all experimental constraints, including LHC searches, flavor observables, and the Planck 2018 relic density, predicting upper bounds $m_{χ ~_{1}^{0}} ≲ 110 GeV$ and $m_{τ ~_{1}} ≲ 120 GeV$ . This parameter space lies within the reach of future CEPC and FCC-ee colliders. We also analyze Higgs- and Z-funnel regions. Current direct-detection limits strongly constrain light Higgsino-assisted resonances for {\mu}>0. Conversely, for {\mu}<0, destructive interference in Higgs-mediated scattering suppresses the direct-detection cross section, allowing a viable Z-funnel region to survive below the projected LZ 1000-day sensitivity. These results highlight the negative-{\mu} Pati-Salam framework as a predictive, testable scenario for upcoming dark matter and lepton collider experiments
hep-ph0 citations
26
Soft-Radiation-Induced Decoherence of Heavy-Quark Spin Entanglement at the Electron-Ion Collider
Sanskriti Agrawal🇮🇳 · Muneeb Zahoor🇮🇳 · Raktim Abir🇮🇳
Using the soft-gluon theorem, we identify a soft-recoil mechanism by which unresolved gluon radiation induces decoherence in the spin correlations of heavy quark-antiquark pairs produced in deep-inelastic scattering. We show the eikonal soft contribution preserves the Born spin structure, whereas the subleading soft term generates stochastic recoil-induced rotations of the spin-correlation plane. Upon tracing over the unresolved gluon, these rotations produce an effective dephasing channel: the normal-axis correlation remains unchanged at this order, while the in-plane spin coherences are suppressed. We estimate the resulting reduction of concurrence and Bell-CHSH violation, and propose a radiation-binned EIC observable based on the ratio of in-plane to normal spin correlations. This observable isolates the characteristic anisotropic suppression predicted by the soft-recoil mechanism and provides a measurable handle on radiation-induced spin decoherence of an entangled quark-antiquark pair produced in a deep-inelastic scattering process.
hep-phhep-exhep-thnucl-th+13 citations
27
Dynamical criterion for biased domain-wall formation
Wen-Yuan Ai🇨🇳
In the presence of a bias term, the conventional condition for forming a domain-wall network is $p_{fv} > p_{c} ≃ 0.31$ , with $p_{fv} / (1 - p_{fv}) = exp (- Δ V (0) / V_{b} (0))$ , where $p_{fv}$ is the false-vacuum fraction immediately after the phase transition, $Δ V (0)$ is the zero-temperature energy splitting between the false and true vacua and $V_{b} (0)$ is the zero-temperature barrier height measured from the true vacuum. This criterion, however, cannot be generally valid, since it is insensitive to the dynamics of the phase transition. In this work, we derive a dynamical criterion for domain wall formation in the presence of a bias term. We evaluate $p_{fv}$ at the freeze-out temperature of the false-vacuum correlation volumes $T_{fo}$ , obtaining a substantially stricter criterion. The same dynamical picture also yields a necessary consistency condition for applying scaling-regime gravitational-wave estimates, $T_{fo} > T_{ann}$ , where $T_{ann}$ is the annihilation temperature inferred from the scaling-regime dynamics.
hep-phastro-ph.CO1 citation
28
Feasibility study of light sterile neutrino searches with a future NINJA-like detector
Doris Barčot🇭🇷 · Tsutomu Fukuda🇯🇵 · Monojit Ghosh🇭🇷 · Leon Halić🇭🇷 · Mahesh Jakkapu🇭🇷 · Teppei Katori🇬🇧 · Budimir Kliček🇭🇷 · Masahiro Komatsu🇯🇵 · Tomokazu Matsuo🇯🇵 · Osamu Sato🇯🇵 · Atsumu Suzuki🇯🇵
In this paper, we investigate the sensitivity of future NINJA-like experiment at J-PARC to eV-scale sterile neutrinos within the 3+1 framework. We perform a phenomenological feasibility study using the $ν_{μ} \to ν_{e}$ appearance, $ν_{μ} \to ν_{μ}$ and $ν_{e} \to ν_{e}$ disappearance channels, focusing on possible future configurations of the detector located at different floors of the NM building (B2, SS, and GROUND), corresponding to different off-axis angles. Our analysis is based on a simplified and effective detector response, in which events are classified into electron-like and muon-like topologies and constant benchmark selection efficiencies are applied. We explore different exposure scenarios and assess the impact of analysis choices such as upper energy cuts. We include systematic uncertainties corresponding to normalization for signal and background rates and study the robustness of our results with respect to variations in the assumed energy resolution, and vary efficiencies for key backgrounds such as muon misidentification from charge current and neutral current interactions. Finally, we examine the effects of combining data from multiple detector locations. We find that the SS floor provides the strongest constraints on the active-sterile mixing parameters, while the B2 and GROUND configurations offer constraints comparable to the current bounds for probed mass-squared differences. Our results indicate that a NINJA-like detector, optimized for sufficient statistics and benchmark identification performance, has the potential to provide competitive constraints on light sterile neutrino scenarios in its future runs.
hep-phhep-ex0 citations
29
Exclusive Dyon Production in High-Energy Collisions
Luis F. C. Inácio · Werner K. Sauter🇧🇷
In this work, we investigate the exclusive central production of dyons, a particle carrying electric and magnetic charges, in hadronic interactions at LHC energies, assuming the photon fusion mechanism. Motivated by predictions from theoretical physics beyond the Standard Model, we analyze the photoproduction of these particles in the ultraperipheral collision regime, employing the equivalent photon approximation. We estimate the cross-sections for dyons production in spin 0, 1/2, and 1 scenarios, adopting values for electric and magnetic charges from the literature. Our results demonstrate a direct correlation between spin and cross section, predicting a substantially higher probability for the photoproduction of higher-spin dyons.
hep-ph0 citations
30
Doubly charmed baryon-light meson scattering in chiral effective theory with lattice constraints
Peng-Qi Wang🇨🇳 · Zhi-Hui Guo🇨🇳
We study the scattering of the ground states of doubly charmed baryons ( $Ξ_{cc}^{++}, Ξ_{cc}^{+}, Ω_{cc}^{+}$ ) and light-flavor pseudoscalar mesons ( $π, K, η$ ) up to the next-to-leading order within chiral effective theory. We perform the unitarization of the $S$ -wave scattering amplitudes in order to study the excited doubly charmed baryons. The unknown next-to-leading order low energy constants are determined through the fits to recent lattice data in the elastic scattering processes based on the CLQCD ensembles. Following the chiral extrapolation to physical quark masses, we predict resonance, virtual and bound doubly-charmed-baryon states arising from the single- and coupled-channel scattering of $Ξ_{cc}^{++}, Ξ_{cc}^{+}, Ω_{cc}^{+}$ with $π, K, η$ . Furthermore, we also calculate the corresponding scattering lengths, effective ranges, phase shifts and inelasticities at physical quark masses, which could shed light on future experimental searches and lattice simulations.
hep-phhep-lat0 citations
31
Multiparameter Quantum Estimation and Degeneracy Structure in Three-Flavor Neutrino Oscillations
Bhavna Yadav🇮🇳 · Amir Subba🇨🇳 · Yu Shi🇨🇳
Achieving precision measurements of neutrino oscillation parameters and resolving parameter degeneracies remain central challenges in neutrino physics. This work presents a systematic investigation of three-flavor neutrino oscillations within the framework of quantum estimation theory using the quantum Fisher information matrix (QFIM). The behavior of all six independent elements of the QFIM associated with the parameters theta23, deltaCP, and Delta(m31)^2 is analyzed, and the impact of parameter correlations on the quantum Cramér-Rao bound is studied. Furthermore, we demonstrate that parameter degeneracies in neutrino oscillation probabilities do not necessarily imply indistinguishability of the underlying quantum states. By employing quantum fidelity and the QFIM, we show that degenerate parameter sets can exhibit distinct quantum-information characteristics that remain hidden at the probability level, revealing quantum-state differences between probability-degenerate solutions.
hep-phquant-ph2 citations
32
Solution of Canonical Differential Equations for Integrals on Arbitrary Geometries
Michał Czakon🇩🇪 · Lorenzo Tancredi🇩🇪
A highly successful approach to computing multi-loop scattering amplitudes is to reduce the Feynman integrals that arise to a smaller set of master integrals using integration-by-parts identities. These dimensionally-regulated master integrals can often be determined by solving a system of first-order partial differential equations with respect to masses and external invariants. The application of this method to large classes of problems became much more streamlined thanks to the introduction of $ϵ$ -factorized canonical forms. There is increasing evidence that a canonical form can always be achieved, although the required transformation may involve transcendental functions related to the periods of geometrical objects such as elliptic curves or Calabi-Yau manifolds. Until now, obtaining numerical values for the master integrals in such cases has been difficult in practice, also due to the lack of closed-form expressions for the transcendental functions involved. We show that this obstruction is only apparent. Since the original master integrals satisfy linear differential equations with rational coefficients, any functions appearing in the transformation to a canonical basis satisfy, by construction, rational differential equations as well. By solving these auxiliary equations, the numerical evaluation of the canonical system reduces to solving an enlarged rational system. We implement this strategy in a C\texttt{++} package and apply it to the two-loop master integrals that enter di-jet and $γ$ +jet hadro-production via a heavy-quark loop.
hep-ph5 citations
33
Multistage dynamical modeling of heavy-ion collisions
Lipei Du🇺🇸
Relativistic heavy-ion collisions create deconfined QCD matter whose properties must be inferred from final-state observables through dynamical modeling. This contribution discusses recent progress and open issues in multistage simulations, with emphasis on the connection between bulk evolution, conserved charges, strangeness, and heavy flavor. At RHIC Beam Energy Scan energies, the breaking of longitudinal boost invariance makes charge stopping and rapidity-dependent observables essential for constraining the finite-density medium. Strange hadrons are sensitive to the local chemical environment and conserved-charge correlations, while heavy flavor probes microscopic transport and hadronization. Combining these observables within multi-sector inference frameworks provides a path toward more robust constraints on the equation of state and transport properties of QCD matter.
↳ nucl-thhep-phnucl-ex1 citation
34
Meson states in `t Hooft model: Hamiltonian approach
A.V. Smilga🇫🇷
We point out that the masses of the highly excited bound quark-antiquark states in QCD $_{2}$ in the infinite $N$ limit may be determined in the framework of a simple quantum-mechanical model with the potential $V (x) = σ ∣ x ∣$ . In the ultrarelativistic case, the masses follow the pattern $μ_{n}^{2} = \frac{g ^{2} N}{2 π} n,$ which coincides with the law derived by `t Hooft by solving the Bethe--Salpeter equation. In the nonrelativistic case, the energy levels follow the asymptotics $ϵ_{n} = μ_{n} - 2 m = C n^{2/3}$ , where the constant $C$ can be determined by solving the `t Hooft equation or alternatively the nonrelativistic Schrödinger equation.
↳ hep-thhep-ph0 citations
35
Strongest constraints on dark acoustic oscillations from the Lyman-alpha forest
Zhihan Yuan🇨🇦 · Caleb Gemmell🇺🇸 · Keir K. Rogers🇬🇧 · Jared Barron🇺🇸 · Sandip Roy🇺🇸 · David Curtin🇨🇦 · Norman Murray🇨🇦
We set the first constraints on a small-scale dark acoustic oscillation (DAO) in the linear matter power spectrum arising from dark sector interactions, with a full forward model of the Ly- $α$ forest. No more than 30\% of dark matter can form DAOs if they peak at wavenumbers $< 50 h Mpc^{- 1}$ (95\% c.l.), probing scales $25 \times$ smaller than the cosmic microwave background (CMB). Given the complex covariance of DAO and nuisance parameters, we use a deep kernel learning emulator of hydrodynamical simulations to capture imprints of linear oscillations in the Ly- $α$ forest.
↳ astro-ph.COhep-ph3 citations
36
Dark energy from neutrino interactions in Unimodular Gravity
Alejandro Gil-Ocaranza🇲🇽 · Josue De-Santiago🇲🇽 · Mauricio Lopez-Hernandez🇲🇽 · Jorge L. Cervantes-Cota🇲🇽
We investigate a dark energy scenario generated by neutrino interactions mediated by a light scalar field, in which finite-temperature corrections induce an effective neutrino mass that evolves with the thermal history of the Universe. Within the framework of Unimodular Gravity, these interactions give rise to a non-conservation current, leading to dynamical dark energy. We study one- and two-neutrino realizations of the model. In the one-neutrino case, the dark energy density evolves monotonically, whereas in the two-neutrino scenario it can reach a maximum at intermediate redshifts before decreasing at late times. Using late time cosmological datasets, we constrain the effective interaction strength for lightest-neutrino masses in the range $0.05 meV \leq m_{1} \leq 1 meV$ . We find preferred interaction scales of order $G_{s} \sim 1 0^{12} eV^{- 2}$ with a significance of $2 σ$ , with the inferred coupling decreasing as the assumed neutrino mass increases. Assuming neutrino couplings of order unity, this $G_{s}$ value corresponds to an ultralight mediator with mass $m_{ϕ} \sim 1 0^{- 6} eV$ . We further assess the impact of Planck distance-prior, finding a noticeable reduction in parameter degeneracies and a reconstructed dark energy evolution closer to that of a cosmological constant. Our results show that neutrino interactions can generate both monotonic and non-monotonic dark energy evolutions while remaining compatible with current cosmological observations. The inferred interaction strengths remain consistent with non-zero values for part of the explored neutrino-mass range, supporting neutrino-induced dark energy dynamics as a viable phenomenological extension of $Λ$ CDM at the background level.
↳ astro-ph.COgr-qchep-ph1 citation
37
TOA_SP: A Multi-Strategy Framework for Single-Pulse Timing
Songbo Zhang🇨🇳 · Xuan Yang🇨🇳
Precision pulsar timing typically relies on the stability of average pulse profiles, enabling time-of-arrival (TOA) estimation through template cross-correlation. This assumption breaks down for highly variable radio sources such as Rotating Radio Transients (RRATs) and fast radio bursts (FRBs), where individual pulses could exhibit strong variability in morphology and amplitude, and no single averaged profile may represent the underlying emission process. We present toa_sp, an open-source Python package for extracting TOAs directly from PSRFITS search-mode data without requiring profile folding into a stable template. The framework implements a suite of complementary single-pulse timing strategies, including parametric profile fitting, non-parametric estimators, and adaptive sub-band and time-resolution optimisation, together with empirical diagnostics for assessing model consistency. We apply toa_sp to 688 single pulses from a 3-hour FAST observation of RRAT~J1913+1330. The resulting TOAs residual achieve a weighted RMS residual of 1.33\,ms, a 24\% improvement over a standard template-based PSRCHIVE pipeline, while retaining all pulses without statistical outlier rejection. A set of bright FRB 20220529 bursts provides a controlled test of the framework across regimes of increasing pulse complexity, revealing frequency-dependent substructure not captured by band-integrated profiles. We introduce an empirical convergence diagnostic that identifies well-constrained pulses and guides the transition between parametric and non-parametric regimes. Full multi-strategy processing of 688 pulses requires approximately 7.6\,s per pulse on a 10-thread CPU. The package is publicly available via pip install toa_sp.
↳ astro-ph.IMastro-ph.HEhep-ph0 citations
38
Investigating forward-backward asymmetry in D-meson production and anisotropic flow in p-Pb collisions at the LHC
Siyu Tang🇨🇳 · Chao Zhang🇨🇳 · Liang Zheng🇨🇳 · Renzhuo Wan🇨🇳 · Zi-Wei Lin🇺🇸 · Guo-Liang Ma🇨🇳
We investigate the forward--backward asymmetry in the production and elliptic flow of prompt D0 mesons in proton--lead (p--Pb) collisions at $s_{NN} = 8.16$ TeV using the heavy-flavor improved string-melting version of the AMPT model. The model calculations provide a simultaneous description of nuclear modification factor $R_{pPb}$ and $v_{2}$ in forward and backward rapidities. We find that the observed asymmetry arises from the interplay of initial-state cold nuclear matter effects and final-state partonic interactions, with the competition between coalescence and fragmentation playing a critical role in shaping the transverse momentum and rapidity dependence of both observables. This work suggests that a partonic medium is formed in high-multiplicity p-Pb collisions at LHC energies.
↳ nucl-thhep-ph0 citations
39
Quantifying Quantum Correlations in Annihilation Photon Pairs under Compton Scattering
Z. AskariPour Ravari · Z. Riazi
We present a theoretical study of the evolution of polarization entanglement and quantum coherence in 511 keV photon pairs produced by para-positronium decay during successive Compton scattering events. We start with a maximally entangled Bell state and employ the generalized Stokes-Mueller formalism to derive the two-photon density matrix following single-, double-, and triple-Compton scattering, explicitly considering both polar and azimuthal scattering geometries. Using this framework, we quantify the degradation of quantum correlations through concurrence (as a measure of entanglement) and the $l_{1}$ -norm (as a measure of coherence). Our results demonstrate that entanglement is highly sensitive to the scattering geometry and disappears near right-angle scattering, while quantum coherence remains finite even in regimes where entanglement vanishes completely. These findings provide a unified description of polarization-dependent decoherence in annihilation photon pairs and clarify the distinct roles of entanglement and coherence in realistic two-photon interactions. These results are relevant for quantum-enhanced positron emission tomography and highlight the persistence of quantum resources in scattering-dominated media.
↳ quant-phhep-phEur.Phys.J.Plus(2026)·0 citations
40
Evolution of Compact Stellar Systems in Ultralight Dark Matter Halos: Dependence on Stellar and Dark Matter Parameters
Yu-Ming Yang🇨🇳 · Xiao-Jun Bi🇨🇳 · Long Wang🇨🇳 · Peng-Fei Yin🇨🇳
Compact stellar systems are often used to place stringent constraints on the particle mass of ultralight dark matter (ULDM), as the heating effect induced by wave interference can drive system expansion, potentially bringing them into tension with observations. In a recent study, we pointed out that internal two-body relaxation in these stellar systems may have a significant impact on their evolution in ULDM halos, an effect overlooked in previous studies. Here, we further investigate the influence of stellar metallicity, the Milky Way's tidal field, and the ULDM particle mass on the long-term fate of compact stellar populations. We find that metal-richer systems are generally more resistant to disruption. The tidal field of the Milky Way, by altering the orbital motion of the stellar systems within host ULDM halos, can significantly affect their stability. Furthermore, we find in our simulations that the heating effect becomes stronger with increasing ULDM particle mass when the system size is much smaller than the ULDM de Broglie wavelength $R_{h} ≪ λ_{dB}$ , in contrast to the $λ_{dB} ≲ R_{h}$ case. These results highlight the complexity of the evolution of compact stellar systems in ULDM halos, and suggest that existing constraints derived from the systems, such as ultrafaint dwarf galaxies, may require careful revision.
↳ astro-ph.GAastro-ph.COhep-ph0 citations
41
Revisiting identified-particle $p_{T}$ spectra using the Boltzmann-Gibbs blast-wave model in a Bayesian inference framework
Z. Xie🇨🇳 · W.Z. Li🇨🇳 · J.Q. Tao🇨🇳 · H. Zheng🇨🇳 · W.C. Zhang🇨🇳 · W. Dai🇨🇳 · L.L. Zhu🇨🇳 · X.Q. Liu🇨🇳 · D.M. Zhou🇨🇳 · B.H. Sa🇨🇳
We perform a Bayesian analysis of transverse momentum ( $p_{T}$ ) spectra of identified particles, i.e., pions, kaons, and protons, at midrapidity in Au+Au collisions and Pb+Pb collisions using the Boltzmann-Gibbs blast-wave (BGBW) model. We investigate whether it is possible to simultaneously describe the $p_{T}$ spectra of identified particles without imposing the particle species-dependent $p_{T}$ fit ranges -- a practice that was followed in conventional blast-wave model studies to achieve reasonable simultaneous fits. Using Bayesian analysis, our results indicate that a simultaneous description of the $p_{T}$ spectra of pions, kaons, and protons is feasible without imposing the particle species-dependent $p_{T}$ fit ranges, for Au+Au collisions up to the available data ( $\sim$ 2 GeV/c) and for Pb+Pb collisions up to 3 GeV/c. The extracted parameters remain broadly consistent with those obtained from conventional BGBW simultaneous fits, while the extension of the fit range leads to moderate changes in some parameters. Furthermore, Bayesian analysis yields well-constrained posterior distributions for the kinetic freeze-out temperature $T_{k in}$ , the average transverse flow velocity $⟨ β_{T} ⟩$ , and the exponent of the velocity profile $n$ and shows their correlations transparently. We suggest that the BGBW model in a Bayesian inference framework proposed can be applied in future data analyses to simultaneously describe the $p_{T}$ spectra of identified particles and extract the relevant information about the collision system.
↳ nucl-thhep-ph0 citations
42
Gluon mass and small-x dynamics in hadrons
Stanisław D. Głazek🇵🇱
Precise derivation of the logarithmically scale-dependent Hamiltonian eigenstate picture for hadrons in the space of virtual quark and gluon states of the canonical front form of QCD requires addressing first the problem of divergences stronger than logarithmic, and especially the small-x divergences in the dynamics of gluons. We propose to facilitate the regularization and cancellation of these divergences using a gluon mass parameter and an auxiliary color-octet scalar field corresponding to the longitudinally polarized gluons. The auxiliary field decouples from the hadronic constituent dynamics when the mass parameter tends to zero, as required in the gauge theory. The same method applies in the cancellation of the quadratic ultraviolet transverse divergences in the self-interactions. After explaining how the method works in computations of the scattering amplitudes, we describe its application to the bound-state eigenvalue problems. We focus on the results it leads to already in the second-order weak-coupling expansion for effective Hamiltonians of heavy quarks. They include the concept of confinement in an effective theory with the gluon mass parameter sent to zero and a heuristic scenario concerning extension of the Hamiltonian approach to the dynamics of light quarks.
↳ hep-thhep-ph0 citations
43
Quark and hybrid stars with renormalization group improvement of NNLO perturbative QCD
Loïc Fernandez🇫🇮 · Jean-Loïc Kneur🇫🇷 · Marcus Benghi Pinto🇧🇷 · Constança Providência🇵🇹 · Claudia Ratti🇺🇸 · Tulio E. Restrepo🇺🇸
Recently, the NNLO perturbative QCD pressure of cold and dense symmetric matter, with arbitrary quark masses, has been resummed within the renormalization-group-optimized perturbation theory (RGOPT) framework. By being imbued with renormalization group properties, the resulting pressure is less sensitive to renormalization scale ( $Λ \equiv X μ_{B} /3$ ) variations than the NNLO perturbative QCD pressure. Here, we extend this by considering $β$ -equilibrium and charge neutrality to evaluate the corresponding equation of state (EoS). We provide a compact ``pocket" fitting formula for the EoS for $N_{f} = 2 + 1$ massive quarks at different renormalization scale parameter ( $X$ ) values. We describe pure quark stars as well as hybrid stars with quark-cores. Pure quark stars compatible with astrophysical observations were obtained with $X = 3.08 - 3.58$ , whereas a larger value (4.10) is needed if the low mass object of the observation GW190814 represents a neutron star. Hybrid stars were built considering three representative hadron models based on a relativistic mean-field description, and chosen to produce soft and stiff EoSs. Stable hybrid stars with masses compatible with the massive pulsar PSR J0740+6620 were obtained considering $X$ of the order of 2 to 2.60-2.98, the largest scale giving rise to hybrid stars with a large quark core with a radius of 5 to 8 km, and the smallest to a small quark core at the center of the star.
↳ nucl-thastro-ph.HEhep-phhep-th0 citations
44
Complete Access to Leading-Twist $Λ$ -Baryon Light-Cone Distribution Amplitudes from Lattice QCD
Mu-Hua Zhang🇨🇳 · Haoyang Bai🇨🇳 · Min-Huan Chu🇵🇱 · Jun Hua🇨🇳 · Xiangdong Ji🇨🇳 · Xiangyu Jiang🇨🇳 · Jian Liang🇨🇳 · Cai-Dian Lü🇨🇳 · Andreas Schäfer🇩🇪 · Wei Wang🇨🇳 · Yi-Bo Yang🇨🇳 · Jian-Hui Zhang🇨🇳 · Jia-Lu Zhang🇨🇳 · Qi-An Zhang🇨🇳
We report the first complete lattice-QCD determination of the leading-twist light-cone distribution amplitudes (LCDAs) of the $Λ$ baryon, obtained as full two-dimensional functions of the valence-quark momentum fractions. The calculation employs large-momentum effective theory to relate the light-cone amplitudes to equal-time nonlocal three-quark matrix elements of boosted $Λ$ baryons. Controlled physical extrapolations to the continuum, physical pion mass, and infinite momentum, together with hybrid renormalization, large- $λ$ extrapolation, and perturbative matching, yield the three leading-twist LCDAs $V$ , $A$ , and $T$ . Using the lattice-determined LCDAs in place of the asymptotic form, we find an $O (10%)$ shift in the $Λ$ electromagnetic form factor at perturbative scales, demonstrating that the full two-dimensional LCDAs, rather than only their asymptotic shapes or lowest moments, are required for precision baryonic phenomenology. This work, together with the companion paper [1] detailing the baryon-LaMET framework, provides the first complete multi-dimensional $x$ -dependent baryon LCDAs from first principles and establishes a benchmark for lattice access to multi-dimensional baryon structure.
↳ hep-lathep-ph3 citations
45
Landau's Leviathans
Vsevolod Chestnov🇬🇧 · Giulio Crisanti🇬🇧 · Mathieu Giroux🇺🇸
We present a new method together with a proof-of-concept implementation for determining the Landau singularities of Feynman integrals, read off directly from where the Euler characteristic of the associated integral drops. Working over finite fields makes the requisite elimination tractable for multi-scale integrals at the multi-loop frontier. The algorithm returns the genuine and complete set of singularities, subject to a set of conditions which are practically testable. We apply these methods to classes of Feynman integrals beyond the reach of current methods, including non-planar six-point diagrams at two loops, as well as a fully massive three-loop envelope graph. Several of the newly found singularities, both in $d$ - and 4-dimensional external kinematics, are of unexpected complexity when compared to previously known singularities for these examples.
↳ hep-thhep-ph1 citation
46
What Naturalness Measures: Fine-Tuning and Informational Invariants in Cosmology and Dark Matter
Stefano Profumo🇺🇸
Naturalness is commonly presented as an objective constraint on physical theories: a model requiring fine-tuning is judged implausible. This presentation conflates a representation-dependent quantity with an invariant one. A fine-tuning verdict depends on the choice of fundamental parameters, the prior, and the measure convention, so it does not by itself fix a feature of the world. Here, I argue that what is objective is structural: the universality class of the map from parameters to observables, invariant under admissible changes of parametrization and measure convention, and independent of any prior over parameter space; it constitutes an informational invariant. On this account naturalness is neither an aesthetic preference nor an objective probability, but a statement about the distinguishability geometry of the representations through which physics encodes observation. I trace the certainty of naturalness verdicts to a tradition, from Ockham through Dirac and Weinberg, in which parsimony and beauty are taken as guides to truth; modern naturalness inherits that tradition's authority without its successive justifications. The argument is developed in the gravitational and cosmological sector, where naturalness reasoning is sharpest and its effective-field-theory grounding is weakest. A uniform analysis across gravitational and particle dark matter candidates shows that fine-tuning tracks the analytic structure of the abundance map, not the nature of the candidate; that the resulting classification is invariant across measure conventions while the tuning number is not; and that this decomposition instantiates informational structural realism. I situate the position against the autonomy-of-scales account, which the argument largely accepts, and against the deflationary reading, which identifies the borrowed authority but discards the structural residue.
↳ physics.hist-phastro-ph.COhep-phhep-th2 citations
47
Krylov Complexity in Non-Inertial Quantum Systems
Ming-Qi Ma🇨🇳 · Shi-Cheng Liu🇨🇳 · Lei-Hua Liu🇨🇳 · Hai-Qing Zhang🇨🇳
This study formulates observer-dependent Krylov spreading for non-inertial quantum systems driven by linear Bogoliubov transformations. Starting with the closed single Rindler-pair $S U (1, 1)$ sector, we show that its Lanczos basis is identical to the Rindler pair-number basis. As a result, the Krylov spread complexity reduces exactly to the mean number of correlated Rindler pairs, $C_{k} = ∣ β_{k} ∣^{2}$ . Within this framework, we demonstrate that Krylov spreading dynamics are governed by the competition between the detuning parameter and the coupling constant, naturally dividing the dynamics into three distinct regimes. Notably, Krylov complexity becomes localized in the detuning-dominated regime. By extending this to a multimode, strictly quadratic Bogoliubov Hamiltonian, we find that inequivalent Rindler wave-packet pairs violate the $C_{k} = ∣ β_{k} ∣^{2}$ correspondence, thereby highlighting the single-pair $S U (1, 1)$ model as an exactly solvable, observer-adapted benchmark. In such multimode scenarios, the mean pair-number eigenstates no longer dictate Krylov complexity. Overall, our work provides a new perspective for analyzing Krylov complexity in non-inertial quantum systems.
↳ quant-phgr-qchep-phhep-th2 citations
48
Superhorizon curvature perturbations in hybrid inflation revisited
Shi Pi🇨🇳 · Anxianyi Xiong🇨🇳
We revisit cosmological perturbations in multi-field inflation using the $δ N$ formalism. By extending the analysis to directions transverse to the inflationary trajectory, we explicitly account for the geometry of the final hypersurface. Applying this framework to hybrid inflation, we identify an enhancement mechanism of the curvature perturbation driven by the growing isocurvature perturbation due to the tachyonic instability of the waterfall field. This amplification occurs during the trajectory's turn in field space, a process qualitatively distinct from the non-attractor solution in single-field inflation models such as ultra-slow-roll. The resulting power spectrum features a broad peak with a characteristic $k^{3}$ infrared growth and a ultraviolet spectral tilt that uniquely determines the nonlinear parameter $f_{NL}$ of a logarithmic non-Gaussianity, all of which are primarily governed by the waterfall dynamics. We found that in hybrid inflation, the sign of $f_{NL}$ is fixed by tachyonic waterfall geometry and is always positive, leading to a generic enhancement of primordial black hole formation. The enhanced curvature perturbation can simultaneously account for primordial black hole dark matter and a stochastic gravitational wave background detectable by LISA, Taiji, and TianQin.
↳ astro-ph.COgr-qchep-ph1 citation
49
The topological susceptibility slope $χ^{'}$ in the large- $N$ limit
Claudio Bonanno🇪🇸
This paper presents the first non-perturbative lattice determination of the Yang--Mills topological susceptibility slope $χ^{'}$ in the large- $N$ limit. This quantity represents the $O (p^{2})$ term of the momentum expansion of the topological charge density two-point correlator, and has important theoretical and phenomenological implications for strong interactions. This calculation is based on a novel algorithm that avoids topological freezing at large $N$ on fine lattices, and on a novel method to reliably compute $χ^{'}$ on the lattice. The results of this study are relevant for the description of the proton spin in deep inelastic scattering experiments via the Shore--Veneziano formula.
↳ hep-lathep-phhep-th0 citations
50
Quantum (non)equivalence of dual massive $p$ -form gauge theories
Christian Canete🇦🇺 · Elden Loomes
Gauge theories of massive $p$ -forms are connected by various dualities, which hold classically but may be broken at the quantum level. One example is the $B F$ theory of topologically coupled $p$ - and $(d - p - 1)$ -forms in $d$ dimensions, where the coupling between forms results in a manifestly gauge invariant mass term for either form when the other is integrated out classically. We perform the path integral quantisation of this theory; by integrating out one of the forms, the resulting determinants are sensitive to the topology of spacetime, and counterterms must be introduced to renormalise their divergences. We compute these determinants in terms of the topological numbers of spacetime, showing explicitly how the quantum duality of the massive theories is broken on topologically non-trivial backgrounds. This is directly related to the quantum breaking of the massless duality between the form that was integrated out and the longitudinal modes of its partner. In particular, the difference of counterterms is proportional to the Euler characteristic of spacetime. The existence of gravitational instantons suggests that these dualities may be broken even in Minkowski space in the presence of topological fluctuations.
↳ hep-thhep-ph0 citations
51
Influence of the KK graviton decay into hh on the triple Higgs measurement at LHC
Alain Le Yaouanc🇫🇷 · François Richard🇫🇷
Evidence for two KK graviton candidates has been previously reported at 380 GeV and 700 GeV. Following a Randall Sundrum interpretation, two extra resonances should appear at 1000 GeV and 1300 GeV. Recently ATLAS, in its search for triple Higgs coupling, has reported an excess in that mass region in conformity with this prediction. Local cross sections are therefore clearly in excess of the standard predictions even for large values of kl. While still marginally significant, this effect appears in a mass region with low background which allows to expect good prospects of discovery with RUN3 data. Such a result could therefore allow to interpret an excess in the measurement of kl and confirm the existence of a series of KK graviton resonances observable at LHC. Other opportunities seem to appear in searches for heavy resonances decaying into ZZ/WW in semi-leptonic and fully hadronic modes. Indirect evidences for the RS model coming from precision measurements are also presented.
↳ hep-exhep-ph0 citations
52
Anisotropic hadronic rescattering and its impact on $K^{* 0}$ yield, and polarization observable
Kadambini Menduli🇮🇳 · Md. Nasim🇮🇳
In this work, we investigate the anisotropic suppression of reconstructed $K^{* 0}$ resonances arising from hadronic rescattering using the A Multi-Phase Transport (AMPT) model for Au+Au collisions at $s_{N N} = 200$ GeV. We demonstrate that the rescattering probability of the decay daughters depends strongly on the decay angle $θ^{*}$ due to Lorentz boost effects, which lead to smaller laboratory-frame momenta for daughters emitted opposite to the parent particle motion. This anisotropic suppression influences several experimentally measured observables. We show that the reconstructed $K^{* 0}$ yield exhibits a strong $θ^{*}$ dependence. Furthermore, the anisotropic loss of resonances modifies the angular distributions used to extract the spin alignment parameter $ρ_{00}$ in the production-plane and helicity frames. Even in the absence of intrinsic polarization in the model, the reconstructed $K^{* 0}$ sample shows deviations of $ρ_{00}$ from the unpolarized value of $1/3$ , with opposite trends in the two reference frames. These results demonstrate that hadronic rescattering can generate apparent polarization signals and must be carefully considered in experimental measurements of vector-meson spin alignment using production plane and helicity frame.
↳ nucl-thhep-phPRC(2026)·0 citations
53
Isospin-Driven Splitting of Chemical Potentials in Isobar Collisions from Lattice QCD
Heng-Tong Ding🇨🇳 · Jin-Biao Gu🇨🇳 · Arpith Kumar🇨🇳 · Jia Ni🇨🇳
Strong magnetic fields produced in relativistic heavy-ion collisions can modify fluctuations of conserved charges and, consequently, their associated chemical potentials. We present first-principles $(2 + 1)$ -flavor lattice-QCD results for isospin-driven splittings of conserved-charge chemical potentials between the isobar systems $_{44}^{96} Ru +_{44}^{96} Ru$ and $_{40}^{96} Zr +_{40}^{96} Zr$ in the QCD crossover region, both at vanishing and nonzero magnetic fields along the pseudo-critical line $T_{p c} (e B)$ . We outline a framework that, under strangeness neutrality and charge-to-baryon ratio $r \equiv n_{Q} / n_{B}$ , maps the isospin difference between two nuclei, as encoded in $r_{Zr}$ and $r_{Ru}$ , onto splitting ratios $Δ μ_{Q} /Δ μ_{B}$ , $Δ μ_{S} /Δ μ_{B}$ , and $Δ μ_{S} /Δ μ_{Q}$ as functions of $μ_{B} (r_{Ru}) /Δ μ_{B}$ . Using continuum-estimated lattice results for the leading-order coefficients $q_{1} \equiv (μ_{Q} / μ_{B})_{LO}$ and $s_{1} \equiv (μ_{S} / μ_{B})_{LO}$ , we find that, at vanishing magnetic field, the splitting ratios are of similar magnitude to recent Bayesian extractions from STAR isobar data and yield $Δ μ_{Q} < 0$ and $Δ μ_{S} > 0$ , with the electric-charge sector dominating. At nonzero magnetic fields, the splitting ratios show only moderate $e B$ dependence. We therefore further examine Ru--Zr differences in the normalized magnetic-field response of chemical-potential ratios, particularly those involving $μ_{Q} / μ_{B}$ , which display a pronounced enhancement in lattice QCD. We also present hadron resonance gas (HRG) results and experimentally motivated proxy observables with kinematic cuts to facilitate contact with experiment.
↳ hep-lathep-phnucl-exnucl-th1 citation
54
Systematic study of the morphology and length of slow stable hybrid star branches
Mauro Mariani🇦🇷 · Milva G. Orsaria🇦🇷 · Germán Lugones🇧🇷 · Ignacio F. Ranea-Sandoval🇦🇷
We introduce and systematically study the length of the slow stable hybrid star branch as a quantitative measure of the extended stability region that arises in hybrid neutron stars when the hadron-quark phase conversion is slow compared to the radial oscillation timescale. Combining generalized piecewise-polytropic hadronic equations of state of varying stiffness with a constant-speed-of-sound quark-matter model, we construct a large set of hybrid equations of state spanning a broad range of transition pressures, energy-density jumps, and quark-matter speeds of sound. We identify four morphological types for the slow stable branch in the mass-radius plane: waterfall branches that descend monotonically from the hadronic maximum mass, bridges that connect the hadronic branch to a second unconditionally stable hybrid branch, tails that extend briefly beyond the maximum mass of an unconditionally stable hybrid branch, and tail-bridges that combine features of the latter two. Their prevalence is governed primarily by the transition pressure and the energy-density jump, while the branch length is also significantly influenced by the stiffness of the hadronic sector and the quark-matter speed of sound. Imposing current astrophysical and microphysical constraints shows that viable long branches are predominantly of waterfall type, and that stiff hadronic equations of state -- strongly disfavored under the rapid-conversion assumption -- remain compatible with all current constraints within the slow-conversion framework. In the plane of transition baryon density versus density jump, slow stable configurations open a new region of viable parameter space inaccessible under rapid conversions.
↳ astro-ph.HEhep-phPRD(2026)·1 citation
55
Baryon Light-Cone Distribution Amplitudes from Lattice QCD: Formalism, Renormalization, Extrapolation, and Matching
Mu-Hua Zhang🇨🇳 · Haoyang Bai🇨🇳 · Min-Huan Chu🇵🇱 · Jun Hua🇨🇳 · Xiangdong Ji🇨🇳 · Xiangyu Jiang🇨🇳 · Jian Liang🇨🇳 · Cai-Dian Lü🇨🇳 · Andreas Schäfer🇩🇪 · Wei Wang🇨🇳 · Yi-Bo Yang🇨🇳 · Jian-Hui Zhang🇨🇳 · Jia-Lu Zhang · Qi-An Zhang🇨🇳
Baryon light-cone distribution amplitudes (LCDAs) are inherently multidimensional objects parametrized by two independent longitudinal momentum fractions, making their first-principles determination substantially more challenging than that of meson LCDAs. We present a systematic large-momentum effective theory (LaMET) framework for determining baryon leading-twist LCDAs from lattice QCD. The framework covers the complete path from equal-time three-quark quasi-distribution amplitudes to physical baryon LCDAs. We formulate the leading-twist $V$ , $A$ , and $T$ quasi-DAs and analyze their spin-flavor and coordinate-space symmetries, including antisymmetric amplitudes with vanishing local limits. We develop a hybrid renormalization prescription on the $(z_{1}, z_{2})$ plane, introduce a newly developed large- $λ$ extrapolation strategy based on the asymptotic large-distance behavior of Euclidean correlators, and derive the corresponding one-loop LaMET matching relation in the hybrid renormalization scheme. As a demonstration, we apply the complete analysis pipeline to the $Λ$ -baryon $A$ -structure quasi-DAs using seven $2 + 1$ --flavor lattice ensembles, and use this amplitude to examine the impact of large-distance extrapolation, perturbative matching, and extrapolation to the continuum, physical-pion-mass, and infinite-momentum limits, together with the associated systematic uncertainties. This work provides the formalism, renormalization, extrapolation, and matching infrastructure for first-principles determinations of $x$ -dependent baryon LCDAs.
↳ hep-lathep-ph3 citations

Affiliations

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