HEP Phenomenology·hep-ph

Wed·Jun 24, 2026Wednesday·June 24, 2026

43 papers—34 primary·9 cross-listed

01
Analysis of Fully-Heavy and Hidden-Heavy Tetraquarks in Anisotropic Plasma Using the Generalized Fractional Derivatives
H. M. Fath-Allah🇪🇬 · M. Abu-Shady🇪🇬 · E. M. Khokha🇪🇬
Investigating the spectroscopy and thermal stability of exotic multiquark states provides crucial insights into the fundamental confinement mechanisms of quantum chromodynamics (QCD) under extreme regimes. This work presents an innovative study of the spectroscopy and dissociation of fully-heavy tetraquarks in an anisotropic plasma via the generalized fractional derivative (GFD) structure. The radial Schrödinger equation (SE) with an extended Cornell potential that includes Debye screening and plasma anisotropy into account is solved by applying the parametric generalised fractional Nikiforov-Uvarov (PGFNU) technique. The analysis of systems consisting of $cc c ˉ c ˉ$ and $bb b ˉ b ˉ$ shows that the binding potential of the systems and the dissociation energy increase with the anisotropy parameter and decrease with temperature. The fractional paradigm also shows that when the fractional orders are lower, the systems will be more strongly bound than in classical quantum mechanics. Furthermore, the mass spectra for all considered tetraquark configurations, including the $cc c ˉ c ˉ$ , $bb b ˉ b ˉ$ , $c q ˉ c q ˉ$ , and $b q ˉ b q ˉ$ systems, are calculated for both ground and excited states. These calculations were performed across both the fractional and classical regimes. The findings indicate that the GFD framework provides an effective mathematical basis for modelling hadronic systems in complex contexts, and they demonstrate significant agreement with earlier theoretical studies.
hep-phnucl-th0 citations
02
From Magnetic to Inverse Magnetic Catalysis: The Interplay of Quark and Gluon Mass Generation in Magnetic Fields
Fei Gao🇨🇳 · Kairen Huang🇨🇳 · Yi Lu🇨🇳 · Yuxin Liu🇨🇳
We analyze the effects of the magnetic field on the quark and gluon propagators within the functional QCD framework. By solving the coupled Dyson-Schwinger equations for the quark and gluon propagators, we find that the quark mass is generally enhanced in the presence of a magnetic field, leading to magnetic catalysis of the chiral condensate. Meanwhile, the magnetic field also induces an increase in the gluon screening mass. The enhancement of the gluon screening mass suppresses the quark-gluon interaction and thereby weakens the strength of dynamical chiral symmetry breaking, establishing a competing mechanism against magnetic catalysis. In particular, this enhancement of the gluon screening mass becomes dominant near the chiral phase transition, which in turn gives rise to inverse magnetic catalysis.
hep-phhep-lathep-thnucl-ex+11 citation
03
axionbloch: an Open-Source Python Package for Simulating Axion-Induced Spin Dynamics
Yuzhe Zhang🇨🇳
The interaction of ultralight bosonic dark matter with spins can be interpreted as a pseudomagnetic field acting on normal matter. Such interactions can be modeled as usual magnetic interactions using spin-evolution (Bloch) equations. axionbloch, an open-source Python package for simulating spin dynamics induced by both usual and exotic interactions, is presented. The numerical simulations serve as a tool for deriving axion signal signatures, which are crucial for designing experimental searches and data analysis. Simulations are calibrated against theoretical expectations, ensuring the accuracy of the simulated signals. axionbloch is available at https://github.com/Yuzhe98/AxionBloch, allowing researchers to simulate pseudomagnetic signals under specific configurations of the axion models and experimental setups. The package is documented at http://axionbloch.readthedocs.io/ and includes example scripts for application.
hep-ph0 citations
04
SN1987A Constraints of Light $Z^{'}$ with Non-Mixing Polarisations
Debottam Das🇮🇳 · Purusottam Ghosh🇮🇳 · Rahul Puri🇮🇳
The observation of supernova 1987A (SN1987A) provides a unique opportunity to explore new physics beyond the Standard Model (BSM). The production of new particles in the supernova core could accelerate the cooling process, leading to additional energy loss and consequently reducing the duration of the observed neutrino burst at detectors. Therefore, any BSM interactions that affect supernova cooling are subject to stringent constraints from SN1987A observations. In this paper, we revisit the constraints on light gauge bosons (LGBs) by reassessing the validity of underlying assumptions about the polarisation intermixing. We argue that the intermixing between different polarisation modes is suppressed in the low coupling regime. Using the light gauge boson in the $L_{μ} - L_{τ}$ model as an example, we find that considering the independent energy transport of longitudinal and transverse polarisations can lead to significant modifications of the SN1987A bounds on the parameter space.
hep-phastro-ph.HE0 citations
05
Scalar diquarks in the QCD vacuum
Hosein Gholami🇩🇪 · Ugo Mire🇩🇪 · Fabian Rennecke🇩🇪 · Bernd-Jochen Schaefer🇩🇪 · Shi Yin🇩🇪
While QCD fundamentally only depends on the values of the strong coupling and the quark masses, it exhibits a rich nonperturbative structure at low energies, where composite fields emerge as the relevant degrees of freedom. In this work, we present a first-principles framework that captures the transition from fundamental QCD to its low-energy sector in vacuum. It builds on the dynamical hadronization technique within the functional renormalization group approach to two-flavor QCD. In this framework, the low-energy constants relevant for effective models, including effective masses and coupling strengths, naturally emerge from the underlying renormalization group flow without introducing free parameters beyond those of QCD itself. We investigate the dynamical emergence of the pion, the $σ$ -meson and the scalar diquark in both imaginary and real time, and determine a set of QCD low-energy constants which can be used to fix the free parameters of models of dense quark matter with a two-flavor color superconducting phase. In particular, this includes previously unknown properties of the scalar diquark. Our results provide important microscopic input for constraining color superconducting phases, which are expected to play a key role in our understanding of dense neutron star matter.
hep-phhep-thnucl-th3 citations
06
Multi-peaked high-frequency gravitational waves from PBH-assisted leptogenesis
Debasish Borah🇮🇳 · Nayan Das🇮🇳
We study the possibility of probing non-thermal leptogenesis with multi-peaked high-frequency gravitational waves (GW) by considering heavy right-handed neutrino (RHN) produced from primordial black hole (PBH) evaporation to be responsible for generating the required lepton asymmetry. The decay of RHN also produces a GW spectrum due to graviton bremsstrahlung with the corresponding amplitude being enhanced for heavier RHN. The presence of an ultra-light PBH dominated epoch not only ensures sufficient production of RHNs, but also keeps the leptogenesis scenario free from strong washout problem of thermal leptogenesis at very high scale. In addition, the PBH dominated epoch also helps in generating a gravitational bremsstrahlung spectrum distinct from the stochastic GW background from the thermal bath. Finally, PBH evaporation also brings two separate sources of GW via density perturbation and graviton emission via Hawking evaporation. For the most optimistic scenario with very high scale seesaw consistent with neutrino mass and leptogenesis, this leads to a multi-peaked GW spectrum with peak frequencies lying in the MHz-EHz range.
hep-phastro-ph.CO2 citations
07
One Generator, Any Process: LLM-Conditioning for the LHC
Henning Bahl🇩🇪 · Tilman Plehn🇩🇪 · Daniel Schiller🇩🇪 · Thanush Sivagnanalingam🇩🇪
Neural network training for LHC event generation should, ideally, benefit from common high-level patterns in different processes. We propose novel conditioning schemes for continuous parameters, process labels, and Feynman diagrams. We employ pre-trained LLMs as multi-modal foundation models to provide descriptive embeddings for an autoregressive transformer. With such high-level physics-inductive bias the generative networks converge faster, provide better result, and generalize to unseen processes.
hep-ph2 citations
08
Nuclei in high-energy neutrino sources: A multimessenger study of in-source propagation
AmirFarzan Esmaeili🇧🇷 · Arman Esmaili🇧🇷 · Pasquale Dario Serpico🇫🇷
The joint observation of astrophysical sources in gamma rays and neutrinos can provide invaluable insight into the physical conditions of the source, including its size, particle densities, and acceleration and production mechanisms. In this work, we investigate the role of nuclear composition in high-energy astrophysical environments. Using NGC 1068 as a representative example, we perform detailed Monte Carlo simulations of nuclear and electromagnetic cascades within the source and study the imprints of the injected nuclear composition on the resulting neutrino and gamma-ray emissions. We further discuss the importance of MeV-GeV gamma-ray observations for constraining the source composition in the context of future gamma-ray experiments. A dedicated re-analysis of archival COMPTEL observations is also presented.
hep-phastro-ph.HE0 citations
09
PDF evolution in alternative factorisation schemes
Stéphane Delorme🇵🇱 · Aleksander Kusina🇵🇱 · Andrzej Siódmok🇵🇱 · James Whitehead🇵🇱
Beyond leading order, parton distribution functions (PDFs) require a choice of factorisation scheme to be defined unambiguously. Different choices of factorisation scheme lead to PDFs that satisfy modified DGLAP evolution equations, relative to the conventional $MS$ scheme. In this paper we derive the NLO DGLAP splitting functions for PDFs in alternative factorisation schemes, including for a parametrised scheme spanning a subspace of the general factorisation-scheme space. We plot their Mellin-space counterparts, the anomalous dimensions, and study the leading large- and small- $x$ behaviour, relevant to resummation. We find that the leading behaviour admits a natural interpretation as a modified effective evolution scale. This is an essential step towards being able to evolve and fit PDFs in alternative schemes for use within QCD calculations.
hep-ph3 citations
10
Polarized Deep-Inelastic Scattering with Spin Correlations in Herwig 7
M.R. Masouminia🇬🇧 · A. Papaefstathiou🇺🇸 · P. Richardson🇬🇧
We investigate polarized deep-inelastic scattering (DIS) in the context of fully exclusive Monte Carlo simulations for the Electron-Ion Collider (EIC). We present a next-to-leading-order (NLO) treatment of polarized DIS in HERWIG 7 using the POWHEG matching scheme, including neutral-current $γ / Z$ exchange and charged-current scattering. We also construct a spin-correlation treatment for NLO-matched events, first by initializing the shower from the spin-density matrix of the polarized DIS Born process and then by propagating the spin-density matrix of the accepted real-emission configuration without changing the POWHEG event weight or hardest-emission choice. We validate the integrated cross sections against fixed-order calculations, use parton-level comparisons without subsequent shower evolution to isolate the accepted POWHEG real-emission kinematics, and employ shower-level observables to test the numerical importance of the Born-level and real-emission spin information. We find that the Born-level spin-density initialization can have a visible impact on shower-sensitive observables, while the additional spin information from the accepted real-emission configuration is not resolved as a robust separate effect within the independent-sample Monte Carlo precision for the longitudinally polarized observables considered here.
hep-phhep-exnucl-exnucl-th0 citations
11
Event isotropy in perturbative QCD
Daniele Atzori🇫🇷 · Matteo Cacciari🇫🇷 · Simone Marzani🇮🇹 · Gregory Soyez🇫🇷
It has recently been proposed that collider events can be equipped with a metric, the Energy Mover's Distance (EMD), which allows one to rephrase multiple aspects of collider physics in a geometric language. Further, the EMD can be exploited to define new observables. In this context, event isotropy quantifies the resemblance of an event to a uniform energy distribution. We present the first theoretical study of event isotropy within the framework of perturbative QCD. In particular, we first obtain the isotropy distribution in $e^{+} e^{-}$ collisions semi-analytically at $O (α_{s})$ (leading-order) and numerically at $O (α_{s}^{2})$ (next-to-leading order, NLO). Furthermore, we obtain all-order theoretical predictions by resumming the contributions of soft and collinear emissions, at next-to-leading logarithmic (NLL) accuracy. By matching resummed and fixed-order predictions we reach NLL+NLO accuracy.
hep-ph0 citations
12
Mapping jet substructure in heavy-ion collisions with track functions
João Barata🇨🇭 · Yeonju Go🇺🇸 · Daniel Pablos🇪🇸
We investigate the dynamics of high-energy QCD cascades in heavy-ion collisions, focusing on modifications to jets' substructure induced by the presence of a quark-gluon plasma (QGP). To this end, we study the properties and scale evolution of track functions, non-perturbative objects encoding the flow of energy from an initiating parton to all charged hadrons. In contrast to the more standard fragmentation functions, these objects have a non-linear renormalization group (RG) evolution, being sensitive to the entire jet fragmentation process. Using the JEWEL and HYBRID Monte-Carlo models of jet quenching, we find that in both frameworks the higher moments and cumulants of the track functions' distributions exhibit sizable deviations from their vacuum baselines, demonstrating that medium-induced energy loss imprints itself in the in-medium jet fragmentation pattern. We find that the quantitative magnitude of these modifications differs significantly between the two models. This identifies track functions as a class of observables capable of discriminating between competing microscopic pictures of jet-medium interactions. We further examined the (in-medium) RG flows for the leading moments, which remain in qualitative agreement with the in-vacuum evolution. This provides an avenue to directly test the RG flows inside a QGP, linking heavy-ion jet measurements to basic QFT understanding of partonic branching. Finally, we comment on the feasibility and challenges associated with extracting track functions from experimental data.
hep-phhep-exnucl-exnucl-th0 citations
13
Non-Standard Interactions and Light Z' Bosons from CEvNS Data at CONUS+: A Statistical Analysis
Ch. M. Benavides🇨🇴 · C. S. Muñoz🇨🇴 · B. C. Canas🇨🇴 · Eduardo Rojas🇨🇴
Motivated by the recent results reported by the CONUS $+$ collaboration, in which coherent elastic neutrino-nucleus scattering (CE $ν N$ S) with reactor antineutrinos was observed for the first time, we perform a statistical analysis to constrain possible low-energy scenarios of physics beyond the Standard Model (BSM). The models considered include effective non-standard vector interactions of neutrinos (NSI) and generalized neutrino interactions (NGI) by light vector bosons within the $E_{6}$ and $U (1)_{L_{e} - L_{μ}}$ frameworks.
hep-phhep-th0 citations
14
From the Great Wave of Translation to the Force between Quarks
Chris Quigg🇺🇸
The chance observation of a novel traveling wave in a canal led over time to the formulation of a nonlinear wave equation -- the Korteweg--de Vries equation -- that describes strikingly robust disturbances now called solitons. The figure of an isolated soliton corresponds to a reflectionless potential that supports a single bound state in the one-dimensional Schrödinger equation. An appropriate combination of individual solitons yields a symmetric reflectionless potential that supports multiple bound states. Thus, the KdV equation opens the path to solving the inverse scattering problem for a collection of bound states. Applied to the quarkonium spectra, this formalism allows the construction of reflectionless approximations to the confining potentials that account for the force between quarks, and to tests of the flavor-independence of the interquark interaction.
hep-phhep-thInt.J.Mod.Phys.A(2026)·0 citations
15
Neutrinoless double $β$ decay and leptogenesis in seesaw model
Kazuo Fujikawa🇯🇵
The fermion $ν_{R} + C ν_{R}^{T}$ in the Type I seesaw model, which is commonly identified with a Majorana fermion, is not a Majorana fermion and thus no neutrinoless double $β$ decay (in the case of $ν_{L} - C ν_{L}^{T}$ ) due to the theorem on the absence of a Majorana-Weyl fermion in the representation of the d=4 Lorentz group. The leptogenesis is realized naturally together with the neutrinoless double $β$ decay by first defining C symmetric Majorana fermions in the seesaw model using an analogue of the Bogoliubov transformation.
hep-phhep-th0 citations
16
Rare Radiative Decays of Z boson into S- and P-wave Charmonium within the Bethe-Salpeter Model
Asif Ali🇨🇳 · Yi-Jie Li🇨🇳 · Guang-Zhi Xu🇨🇳 · Kui-Yong Liu🇨🇳
We employ the Bethe-Salpeter (BS) model to investigate radiative decays of the Z boson into charmonium. Within the instantaneous approximation of the BS equation, we analyze the relevant decay channels for S-wave charmonium states ( $ψ (n S)$ , $η_{c} (n S)$ , $n = 1, 2, 3$ ) and P-wave charmonium states ( $χ_{c 0} (m P)$ , $χ_{c 1} (m P)$ , $h_{c} (m P)$ , $m = 1, 2$ ). We compute all branching fractions using leading-order Feynman diagrams. For the $J / ψ$ channel, our BS calculations suggest that prior theoretical results were likely underestimated, making our prediction more promising for future experimental measurements.
hep-ph0 citations
17
Addressing the lightest $S$ -wave strange $K_{0}^{*} (700) / κ$ resonance in four-body semileptonic $B ˉ_{s}^{0} \to K^{0} π^{+} ℓ^{-} ν ˉ_{ℓ}$ decays
Dong Huang🇨🇳 · Sheng-Bo Wu🇨🇳 · Fang-Ping Peng🇨🇳 · Long Zeng🇨🇳 · Hai-Bing Fu🇨🇳
As the lightest strange scalar resonance, $K_{0}^{*} (700)$ (also called $κ$ ) has a large width and resides close to the $K π$ threshold, leading to a longstanding debate about its internal structure. Within the framework of the conventional quark-antiquark ( $q q ˉ$ ) picture, this paper attempts to research the behaviors of $K_{0}^{*} (700)$ resonance in the four-body final state decays. Firstly, we investigates the $K_{0}^{*} (700)$ resonance one twist-2 and two twist-3 light-cone distribution amplitudes (LCDAs), {\it i.e.} $ϕ_{2; K_{0}^{*} (700)} (x, μ)$ and $ϕ_{3; K_{0}^{*} (700)}^{p; σ} (x, μ)$ by constructing light-cone harmonic oscillator model. For the longitudinal distribution characteristics of the twist-2 LCDA, two typical parametrization schemes, {\it i.e.} $φ_{2; K_{0}^{*} (700)}^{(S1)} (x)$ and $φ_{2; K_{0}^{*} (700)}^{(S2)} (x)$ , are adopted in this paper. Meanwhile, it has enriched theoretical predictions for the first ten-order LCDAs $ξ$ -moments. Subsequently, we apply the QCD light-cone sum rules approach to compute the $B ˉ_{s}^{0} \to K_{0}^{*} (700)$ transition form factors (TFFs) $f_{\pm}^{B ˉ_{s}^{0} K_{0}^{*} (700)} (q^{2})$ and $f_{T}^{B ˉ_{s}^{0} K_{0}^{*} (700)} (q^{2})$ by taking into account the perturbative $O (α_{s})$ corrections to the twist-2 LCDAs terms. By using the simplified series expansion parameterization, these TFFs are extrapolated over the full physical region. Then, we calculate the differential decay widths and branching fractions for four-body semileptonic decay $B ˉ_{s}^{0} \to K^{0} π^{+} ℓ^{-} ν ˉ_{ℓ}$ with $ℓ = (e, μ, τ)$ via the $S$ -wave $K_{0}^{*} (700)$ resonance, respectively. We expect that the obtained prediction results will provide valuable insights for future experiments and theoretical research.
hep-ph0 citations
18
Non-holomorphic $S_{4}^{'}$ modular symmetry for leptons and leptogenesis
Cai-Chang Li🇨🇳 · Jun-Nan Lu🇨🇳 · Xiang-Yan Gao🇨🇳 · Ming-Hua Weng🇨🇳 · Gui-Jun Ding🇨🇳
We perform a comprehensive and systematic investigation of lepton models based on the non-holomorphic $S_{4}^{'}$ modular symmetry, by using level 4 polyharmonic Maaß forms spanning integer weights from $- 4$ to $6$ . The light neutrino masses are generated by the type-I seesaw mechanism with two right-handed neutrinos, no flavon fields other than the modulus $τ$ is introduced, and the generalized CP symmetry is not imposed. An exhaustive numerical analysis yields 36 viable models with only four real couplings besides the modulus $τ$ when neutrino masses are normal ordering. They are classified into three categories, each containing twelve models which yield quite similar predictions for lepton observables and are distinguished by the assignment of $E_{1}^{c}$ . Furthermore, we perform a detailed numerical analysis for one representative model from each category. These representative models are found to yield very sharp predictions for neutrino masses and mixing parameters, and they are distinguished by the predictions for the atmospheric mixing angle $θ_{23}$ , the Dirac CP phase $δ_{C P}$ and the Majorana CP phase $α_{21}$ . Furthermore, we find that only two of these three representative models accommodate successful thermal leptogenesis in the unflavored regime, reproducing the observed baryon asymmetry with the identical parameter values that satisfy neutrino oscillation data. In these models, the real part of the modulus $τ$ is the unique source of CP violation in both lepton mixing and leptogenesis.
hep-ph0 citations
19
Fully-heavy multiquarks in neural-network quantum states
Wen-min Li🇨🇳 · Zhenyu Zhang🇨🇳 · Qian Wang🇨🇳
Exotic hadrons beyond the conventional quark model provide a direct window into the dynamics of strong interaction. However, extracting the multiquark spectroscopy has to face the quantum many-body problem, which is still a theoretical challenge. In this case, diquark-antidiquark model is proposed as an approximation. Although this model can describe the spectroscopy roughly, it cannot describe the detailed dynamics. Furthermore, the methods aiming at dealing with many-body problem, e.g. the Gaussian expansion method and Diffusion Monte Carlo, are proposed, but face severe computational bottlenecks. In this work, we introduce the neural-network quantum state (NNQS) approach to investigate the spectra of fully-heavy multiquark states within the non-relativistic potential quark model. By employing deep neural networks to represent the complex many-body spatial wave function, and constructing the color-spin part exactly from group theory to enforce fermionic antisymmetry, our approach effectively overcomes the dimensionality obstacles inherent in traditional methods. The results are compared with various model calculations, demonstrating that NNQS offers superior accuracy and flexibility, particularly in treating high-dimensional correlations. This work establishes NNQS as a promising tool for exploring the spectroscopy of exotic hadrons.
hep-ph0 citations
20
Bottom quark electroweak dipole moments at a high-energy $μ -$ collider
D. Barducci🇮🇹
We study the sensitivity of a high-energy $μ -$ collider with center of mass energy in the multi--TeV range in testing electroweak dipole interactions of the $b -$ quark. We parametrize the relevant deformations in the language of the Standard Model effective field theory, where the dominant modifications arise at the $d = 6$ level. We analyse $μ^{+} μ^{-} \to b b ˉ$ and $μ^{+} μ^{-} \to b b ˉ h$ scatterings, performing a study at the level of a fast detector simulation. Owing the chiral structure of the dipole interaction, the study of the $μ^{+} μ^{-} \to b b ˉ h$ process allows to enforce the stronger bounds on the Wilson coefficients of the $d = 6$ operators. The limits that can be obtained surpass present and future bounds from EW precision measurements also improving upon the ones arising from the measurement of the $Δ F = 1$ transitions $B \to X_{s} γ$ .
hep-phhep-ex0 citations
21
NNLO QCD Corrections to $D$ -Wave Spin-Singlet Heavy Quarkonia Decay $η_{Q 2} \to γ γ$ via the Principle of Maximum Conformality
Hua Zhou🇨🇳 · Xing-Gang Wu🇨🇳 · Qing Yu🇨🇳 · Sheng-Quan Wang🇨🇳
In this paper, we perform a comprehensive study of the decay process $η_{Q 2} \to γ γ$ for $D$ -wave spin-singlet heavy quarkonia up to next-to-next-to-leading-order (NNLO) QCD corrections within the nonrelativistic QCD effective theory. Following its factorization formalism, the total decay width is decomposed into perturbatively calculable short-distance coefficients (SDCs) and nonperturbative $D$ -wave long-distance matrix elements (LDMEs). The original NNLO series of SDCs suffers from sizable renormalization and factorization scale uncertainties. To eliminate such inherent scale ambiguities, we adopt the Principle of Maximum Conformality (PMC). We show that recursively applying the renormalization group equations for the running of $α_{s}$ and $D$ -wave LDMEs within the PMC framework yields an effective strong coupling $α_{s} (Q_{*})$ consistent with the expansion coefficients, resulting in a scale-invariant perturbative series. The determined PMC scales are $Q_{*} = 1.483$ GeV for $η_{c 2}$ and $Q_{*} = 4.246$ GeV for $η_{b 2}$ . By removing divergent renormalon contributions, the PMC naturally improves the convergence of the perturbative series for SDCs. Our PMC predictions for the total decay widths are $Γ_{η_{c 2} \to γ γ}^{PMC} = 3.32 2_{- 0.828}^{+ 0.899} eV$ and $Γ_{η_{b 2} \to γ γ}^{PMC} = 0.018 8_{- 0.0013}^{+ 0.0014} eV$ . The uncertainties arise from variations of the charm and bottom quark masses $Δ m_{c} = \pm 0.07$ GeV, $Δ m_{b} = \pm 0.06$ GeV, as well as systematic errors from uncalculated higher-order corrections. The corresponding branching ratios are $Br (η_{c 2} \to γ γ) = (7.46 3_{- 1.860}^{+ 2.020}) \times 1 0^{- 6}$ and $Br (η_{b 2} \to γ γ) = (6.46 0_{- 0.447}^{+ 0.481}) \times 1 0^{- 7}$ .
hep-phEPJC(2026)·0 citations
22
Entanglement and non-separability of momenta and coordinates at colliders
Marco Fabbrichesi🇮🇹 · Roberto Floreanini🇮🇹 · Luca Marzola🇪🇪
We explore the possibility of testing in collider experiments whether phase-space variables are separable. We first study phase-space non-separability by means of EPR-like correlations. The original EPR setting is realized in an actual experiment, specifically in terms of coordinates and momenta, as per the original formulation, rather than spins or polarizations. We then show how to quantify the entanglement in the momenta of particle pairs by reducing the continuous variables to a two-qubit system through hemispherical projections. We discuss in detail the production of $τ$ -leptons at an electron collider, reconstructing the momenta of the former from their decays into pions and neutrinos, and demonstrate through a Monte Carlo simulation that phase-space non-separability can be experimentally assessed.
hep-phhep-exquant-ph2 citations
23
Reinterpretation of ATLAS and CMS searches in monojet and mono- $V$ final states: prospects of limits on excited neutrinos
Gabriela Karkosova Martinovicova🇨🇿 · Vojtech Pleskot🇨🇿
Searches for final states with large missing transverse momentum recoiling against a jet or a hadronically decaying vector boson provide strong constraints on a wide class of physics scenarios beyond the Standard Model. In this work, we reinterpret existing ATLAS and CMS monojet and mono- $V$ searches at $s =$ 13 TeV in the context of excited-neutrino production. Published signal-region selections, post-fit background estimates, and observed event yields are used with simulated excited-neutrino signals to derive upper limits on the production cross-section as a function of the excited-neutrino mass. The monojet searches allow excited-neutrino masses of up to approximately 4 TeV to be excluded for representative benchmark scenarios. Mono- $V$ searches provide constraints on the parameter space region with large couplings to the SM electroweak gauge bosons and low excited-neutrino masses compared to the compositeness scale. This is complementary to the region probed by the monojet searches.
hep-ph1 citation
24
Disentangle RG Running Parameters with Medium-Baseline Reactor Experiments
Shao-Feng Ge🇨🇳 · João Paulo Pinheiro🇨🇳 · Shaoyang Qin🇨🇳
We study how the renormalization group running beta functions of mixing angles and leptonic CP phases affect the slow and fast oscillation modes at JUNO. While the slow mode is modulated by the solar parameters, its amplitude can also be affected by the solar angle beta function $β_{s}$ and its phase by the Majorana CP phase counterpart $β_{M1}$ . On the other hand, the fast mode also receives corrections from the beta functions of the Dirac CP phase $δ_{D}$ and the Majorana CP phase $δ_{M3}$ . Since the fast mode is essentially the one measuring the neutrino mass ordering, the RG running effect can then interfere to deteriorate the sensitivity. Fortunately, the JUNO-TAO near detector can provide supplementary measurements of the RG running parameters to restore the mass ordering sensitivity. Since the rephasing phases $δ_{M1}$ and $δ_{M3}$ can be shifted by a vector-like rephasing for Dirac neutrinos, their running is physical only in the Majorana case. In consolidated, the mild preference for a nonzero $β_{M1}$ by the current JUNO data thus hints the Majorana nature of neutrinos.
hep-phhep-ex2 citations
25
Universal two-zero texture in SO(10): implications of JUNO and realization from non-invertible symmetries
Zi-Qiang Chen🇨🇳 · Wen-Hao Jiang🇨🇳 · Ye-Ling Zhou🇨🇳
We apply the universal two-zero texture (UTZT) to all quark and lepton mass matrices in the SO(10) grand unified framework. With charged fermion masses fixed at their best-fit values, this texture contains only seven free parameters to account for nine flavor observables, rendering it highly predictive. Motivated by the recent JUNO indication in favor of the normal ordering of light neutrino masses, we perform an updated analysis of the UTZT in SO(10). The texture remains fully compatible with all current flavor data and exhibits an enhanced preference for normal ordering. The Dirac phase is predicted mainly in two regions, one of which matches very well with current data. A meV-scale $m_{β β}$ is predicted, beyond the sensitivity bound of future neutrinoless double beta decay measurements. We further explore the origin of the UTZT from non-invertible symmetries, without introducing additional low-energy degrees of freedom. We show that the UTZT can be realized through non-invertible selection rules arising from the $Z_{3}$ gauging of $Z_{N}$ , with a minimal realization corresponding to $N = 7$ .
hep-ph3 citations
26
Analytic electromagnetic signatures of compact pentaquark structure: A multi-current QCD light-cone sum rules analysis of the $P_{ψ s}^{Λ}$ states
Ulaş Özdem🇹🇷
Probing the internal organization of hidden-charm pentaquarks -- including the spin-color correlations that distinguish compact diquark-diquark-antiquark configurations from loosely bound hadronic molecules -- requires observables beyond mass spectroscopy. We argue that multi-current QCD light-cone sum rules (LCSR) provide a diagnostic framework through exact analytic relations among flavor-sector contributions enforced by the algebra of the interpolating currents. We identify two such signatures: (i) the light-quark contributions satisfy $μ_{u} / μ_{d} = e_{u} / e_{d} = - 2$ in all four currents considered, reflecting a common Lorentz-color kernel; and (ii) for the $J_{3} (x)$ current the charm contribution vanishes identically, $μ_{c} = 0$ , from the Dirac structure of the anti-charm coupling rather than the pseudoscalar charm-diquark embedding alone. Using four diquark-diquark-antiquark currents $J_{1} (x)$ - $J_{4} (x)$ with $J^{P} = \frac{1}{2}^{-}$ , we obtain $μ_{J_{1}} = - 1.3 5_{- 0.28}^{+ 0.35} μ_{N}$ , $μ_{J_{2}} = 3.1 4_{- 0.50}^{+ 0.65} μ_{N}$ , $μ_{J_{3}} = 1.0 1_{- 0.20}^{+ 0.25} μ_{N}$ , $μ_{J_{4}} = - 1.7 9_{- 0.34}^{+ 0.41} μ_{N}$ . These predictions are paired with the $P_{ψ s}^{Λ} (4338)$ and $P_{ψ s}^{Λ} (4459)$ on mass grounds as a working hypothesis, since the $\pm 0.11 GeV$ uncertainties accommodate either state within $1 σ$ of all four currents. The magnitudes $∣ μ ∣ \sim 1$ - $3 μ_{N}$ lie above quark-model and heavy pentaquark chiral perturbation theory expectations ( $∣ μ ∣ ≲ 0.5 μ_{N}$ ). Applying the same procedure to two previous molecular LCSR analyses yields $μ_{u} / μ_{d} = - 1/2$ rather than $- 2$ , providing an LCSR-internal contrast at the flavor-decomposed level even when total magnitudes are comparable. The two signatures are immune to the state-to-current pairing and offer falsifiable tests of the compact picture.
hep-phhep-exhep-latPRD(2026)·0 citations
27
Application of Deep Learning to Jet Charge Discrimination
Meisam Ghasemi Bostanabad🇮🇷 · Mojtaba Mohammadi Najafabadi🇮🇷
The Large Hadron Collider (LHC) produces an enormous volume of data in which the identification and characterization of hadronic jets is a central challenge. Determining the electric charge of the parton initiating a light-quark jet; a task known as jet-charge discrimination; is highly valuable for both precision tests of the Standard Model (SM) and searches for physics beyond it. In this work, we benchmark a range of classical and quantum machine-learning models for the task of distinguishing up-quark from anti-up-quark jets in a controlled QCD environment. Among the approaches tested, a Graph Neural Network achieved the best performance, with an AUC of 0.883. Jet-charge tagging of this kind has broad phenomenological applications, from improving measurements of charge asymmetries to enhancing sensitivity in searches for new particles from beyond the SM where quark versus antiquark discrimination is essential. Our study provides a methodological foundation for deploying modern machine-learning techniques in jet-charge analyses at the LHC experiments.
hep-phJINST(2026)·0 citations
28
Second-order effective renormalized Hamiltonian of Quantum Chromodynamics
Kamil Serafin🇺🇸 · Carter M. Gustin🇺🇸 · Peter J. Love🇺🇸
The effective Hamiltonian of quantum chromodynamics in the front form of Hamiltonian dynamics is calculated and renormalized. The renormalization group procedure for effective particles up to the second order in the coupling constant is used. Small gluon mass is used to regulate infrared singularities of the theory. The counterterms necessary to renormalize the theory are determined by computing matrix elements of the effective Hamiltonian. The effective Hamiltonians are well-defined symmetric forms on a dense subspace of the Fock space. The zero modes are cut off but, once ultraviolet renormalization is performed, no divergences are found in the color singlet subspace in the limit of the gluon mass approaching zero. A major result is that the interplay between self-energy terms and gluon exchange effective terms generates a term proportional to the quadratic SU(3) Casimir operator times the logarithm of the gluon mass. Therefore, the matrix elements are logarithmically divergent in the color nonsinglet subspace, but finite in the color singlet subspace, because the Casimir operator vanishes in the color singlet subspace. The effective Hamiltonians are suitable for nonperturbative numerical calculations using either classical or quantum computers.
hep-phhep-th1 citation
29
Reweighting Underlying Event and Colour Reconnection parameter variations in Sherpa
Moritz Pabst🇩🇪 · Max Knobbe🇺🇸 · Frank Krauss🇬🇧 · Steffen Schumann🇩🇪
We propose and validate a new method to trace the impact of parameter variations in the simulation of multi-parton interactions and colour reconnections in the Sherpa event generator. They are reflected, at an event-by-event basis, through relative weights with respect to the central production parameters that give rise to the generated events and distributions. Our method facilitates the tuning of the Monte Carlo event generator at a dramatically reduced computational cost, alleviates parameter sensitivity studies, and enables robust quantification of parametric uncertainties on-the-fly, one of the missing ingredients for future simulations of high-energy particle collisions. The method can easily be adapted to and implemented in other event generators. To illustrate its potential, we here consider combined tunes of the multi-parton-interaction and colour-reconnection models in Sherpa using LHC proton-proton collision data at $s = 7 TeV$ . We furthermore calibrate the energy-scaling behaviour of dimensionful model parameters based on $s = 13 TeV$ LHC data and Tevatron data taken at $s = 1.96 TeV$ .
hep-ph0 citations
30
The $a_{1} (1420)$ in a Unitary Coupled-Channel Three-Body Approach
Ajay S. Sakthivasan🇩🇪 · Yuchuan Feng🇺🇸 · Michael Döring🇺🇸 · Maxim Mai🇺🇸
An enhancement in the three-pion energy at around $s \approx 1.42 GeV$ with $a_{1}$ quantum numbers was observed at the COMPASS experiment. This was later attributed to the triangle singularity mechanism involving an on-shell $K^{*} (892)$ , $K$ and $K ˉ$ intermediate states. The alignment of the decay $K$ with the spectator $K ˉ$ produces an $f_{0} (980)$ , resulting in a kinematic enhancement, which is classically explained by the Landau equations. However, this one-loop process forms only part of a non-diagonal transition in a much larger coupled-channel framework. This study demonstrates the feasibility of embedding one-loop triangle-singularity calculations into a unitary three-body amplitude allowing one to consistently incorporate final-state interactions and their potentially substantial effect. For this, up to $P$ -wave isobars and all sub-channel isospins are combined in a nine-channel production amplitude that is fitted to COMPASS lineshapes at different momentum transfers. The fitted amplitude reproduces the narrow enhancement in the $(π f_{0})_{P}$ channel near $s \approx 1.42$ GeV. This implies that the triangle singularity mechanism sufficiently explains the observed enhancement, and an additional genuine $a_{1} (1420)$ pole is not required. Incidentally, the parameters of the ground state axial vector resonance (the $a_{1} (1260)$ ) are also extracted from that data.
hep-phnucl-th2 citations
31
Radiative decays of dynamically generated pentaquarks in the chiral unitary approach: the $P_{c} (4457) \to P_{c} (4312) γ$ transition
Ratirat Suntharawirat🇹🇭 · Nongnaphat Ponkhuha🇹🇭 · Daris Samart🇹🇭
We study the radiative decay of dynamically generated pentaquarks and apply the formalism to the transition $P_{c} (4457) (3/ 2^{-}) \to P_{c} (4312) (1/ 2^{-}) γ$ . Both states are treated as $S$ -wave hadronic molecules generated in the chiral unitary approach with heavy-quark spin symmetry and the local hidden gauge interaction. The photon therefore couples to the meson-baryon components of the two poles. The calculation combines the strong coupling residues of the coupled-channel solution, heavy-quark spin symmetry for the electromagnetic vertices, and a transverse assembly of the $M 1$ triangle loops. A complete calculation gives nineteen triangle loops. We reduce each loop to a single numerical quadrature and give the closed analytic form. The electromagnetic vertices that are not fixed by data are estimated with the naive-quark model and heavy-quark spin symmetry. We normalize the main $D^{*} D γ$ coupling to $D ˉ^{* 0} \to D ˉ^{0} γ$ and test the same convention with $J / ψ \to η_{c} γ$ . The central width is $6.7 \keV$ , with a conservative range of about $2$ to $9 \keV$ . This radiative decay process is a pure $M 1$ transition with photon energy $143 \MeV$ . The $D ˉ^{* 0} \to D ˉ^{0} γ$ loop gives the leading contribution. The near-threshold $D ˉ^{*} Λ_{c}$ loop gives the main correction. A soft Gaussian form-factor on the leading diagram reduces the width to about $2 \keV$ , compatible with earlier molecular results, and decreases the full width to about $4 \keV$ . The coherent result is sensitive to the relative residue phases in the coupled-channel convention. We also estimate the cascade rate for $Λ_{b}^{0} \to J / ψ p K^{-} γ$ and discuss how the line can be searched for. The pure $M 1$ content, the ratio to the $P_{c} (4440)$ radiative decay, and the binding-energy dependence of the width are proposed as tests of the molecular nature.
hep-phnucl-th0 citations
32
Radiative Signature of New Scalar Boson Decays in the $m_{ℓℓ γ}$ Spectrum at the LHC
Pramod Sharma🇿🇦 · Arnav Chauhan🇿🇦 · Mukesh Kumar🇿🇦 · Andreas Crivellin🇪🇸 · Sukanta Dutta🇮🇳 · Rachid Mazini🇿🇦 · Bruce Mellado🇿🇦
We investigate the radiative decay $S \to W^{+} W^{-} γ$ in the context of the multi-lepton anomalies and recent indications of a narrow scalar resonance near $m_{S} = 152 \pm 1 GeV$ in the $γ γ$ , $Z γ$ , and $W^{+} W^{-}$ channels at the Large Hadron Collider. These excesses arise in final states containing leptons, missing transverse momentum, and associated $b$ -jets, and motivate a search for a corresponding localized excess in the invariant-mass spectrum of the dilepton--photon system, $m_{ℓℓ γ}$ , in events with associated $b$ -jets. We use recent CMS measurements of the $t t ˉ γ$ differential cross sections~\cite{CMS:2025zbe} to study the $m_{ℓℓ γ}$ spectrum and perform a search for a scalar-resonance contribution. A localized excess is observed, compatible with the scalar-resonance hypothesis, with a global significance of $2.7 σ$ at $m_{S} = 152 GeV$ . This result provides additional support for the hypothesis of a narrow resonance. The ratio $σ (S \to W^{+} W^{-} γ) / σ (S \to W^{+} W^{-}) = (2.14 \pm 0.77)$ \% is extracted. This value is compatible with an enhanced radiative contribution that could arise in scenarios beyond the Standard Model.
hep-ph0 citations
33
Hyperon-pair spin tomography beyond scalar spin correlations
Lei Wang🇨🇳
Spin correlations measured after hadronization probe how quantum information is transported through confinement. We formulate a process-independent spin-tomography framework for $Λ Λ ˉ$ pairs in which the weak-decay angles determine the full two-spin tensor rather than only its scalar trace. Applied to the short-range STAR correlation in unpolarized $pp \to Λ Λ ˉ X$ , the framework shows that the published scalar $P_{Λ Λ ˉ}$ leaves a continuous density-matrix degeneracy: separable tensor completions and completions that violate the positive-partial-transpose (PPT) criterion can have the same trace. The missing observables are the transverse and longitudinal tensor components and their anisotropy $A_{C} = C_{⊥} - C_{∥}$ . A local $^{3} P_{0}$ string-breaking benchmark turns the STAR trace into the falsifiable pattern $C_{⊥} > 0$ , $C_{∥} < 0$ , and $A_{C} > 0$ . We further show that feed-down must be treated as a tensor response rather than as a universal scalar dilution. In the complementary $e^{+} e^{-}$ calibration channel, the same benchmark predicts a centrally enhanced $A_{C}$ of order $0.3$ in Belle II kinematics, measurable with about $1 0^{4}$ selected pairs for nominal spin-transfer parameters. A claim of entanglement requires the reconstructed two-spin density matrix, not the scalar trace alone, to violate the PPT bound.
hep-ph2 citations
34
Probing Invisible Fermions in $B \to D^{*} ℓ X_{inv}$ via Angular Observables
Lipika Kolay🇮🇳 · Soumitra Nandi🇮🇳 · Shantanu Sahoo🇮🇳
Semileptonic decays $B \to D^{*} ℓ X_{inv}$ provide a sensitive probe of light invisible particles, such as sterile neutrinos or dark-sector fermions. Within a general weak effective theory framework, we show that a massive invisible fermion induces distinctive modifications in the angular distributions. We identify observables with enhanced sensitivity to the invisible particle mass, allowing a clear discrimination of such scenarios, and highlight angular structures that differentiate left- and right-handed lepton-dark-sector currents.
hep-ph0 citations
35
EGUP effects on the thermodynamic properties of the Kerr-Newman black hole surrounded by quintessence
Aheibam Boycha Meitei🇮🇳 · Yenshembam Priyobarta Singh🇮🇳 · T. Ibungochouba Singh🇮🇳 · Irom Ablu Meitei🇮🇳 · Kangujam Yugindro Singh🇮🇳
In this paper, we investigate the effects of the Extended Generalized Uncertainty Principle (EGUP) on the thermodynamic quantities of the Kerr-Newman black hole surrounded by quintessence (KNBHQ). Additionally, we conduct a comparative analysis of the outcomes derived from the Generalized Uncertainty Principle (GUP) and the Extended Uncertainty Principle (EUP). The GUP is crucial in the context of the early universe, whereas the EUP is significant in the framework of the later universe. This analysis illustrates the variations in thermodynamic quantities, including Hawking temperature, heat capacity, Gibbs free energy, entropy and pressure of the Kerr-Newman black hole, as they evolve from the early universe to the latter universe under the influence of the dark energy model known as quintessence. The remnant mass, temperature and the stability of the KNBHQ are also studied.
↳ gr-qchep-phInt.J.Mod.Phys.A(2026)·0 citations
36
A thorough investigation of cross-correlation estimators for stochastic gravitational-wave background searches in ground-based detector data
Haowen Zhong🇺🇸 · Joseph D. Romano🇺🇸 · Vuk Mandic🇺🇸 · Shivaraj Kandhasamy🇮🇳 · Arianna I. Renzini🇨🇭
Detecting a stochastic gravitational-wave background represents a crucial yet challenging objective within the field of gravitational-wave astronomy. Ground-based detectors currently rely almost exclusively on cross-correlation methods to detect stochastic gravitational-wave background signals. Traditionally, these methods define and optimize a broadband estimator initially constructed in the time domain. However, a growing number of analyses require precise narrowband estimators to accurately characterize the energy density of the underlying signal in specific frequency bins. Transitioning from time-domain broadband estimators to frequency-domain narrowband estimators introduces significant complexities that have not yet been fully explored in the existing literature. In this study, we systematically revisit and rigorously reformulate the cross-correlation method in the frequency domain, explicitly addressing and resolving issues related to non-zero covariances induced by windowing and overlapping of data in the time domain. We provide new expressions for the narrowband estimators and their covariances, which differ from those used in past searches. Fortunately, we show that the expressions that have been widely used in the field nonetheless lead to correct posterior distributions for parameter estimation and correct log-Bayes factors for model selection. By establishing a robust theoretical framework, our work facilitates more accurate and physically insightful interpretations of stochastic gravitational-wave background observations, laying an essential foundation for current and future research in this field.
↳ gr-qcastro-ph.HEastro-ph.IMhep-ph2 citations
37
Primordial Black Holes: A Review of Formation and Evolution
S. Shankaranarayanan🇮🇳 · Soumya Bhattacharya🇮🇳 · Archit Vidyarthi🇮🇳
Primordial Black Holes (PBHs) have emerged as a leading non-particulate candidate for dark matter and a unique cosmological probe, a paradigm shift accelerated by the detection of anomalous binary mergers by the LIGO-Virgo-KAGRA (LVK) collaboration. While the literature is rich with phenomenological constraints, the fundamental quantum and relativistic underpinnings governing PBH genesis and evolution often receive comparatively less emphasis. This review aims to bridge that gap by systematically detailing the physics of PBH formation and their subsequent evolutionary trajectory. We critically examine the hydrodynamic complexity of the early universe, establishing the relativistic thresholds for collapse, the non-linear \emph{race against sound} in the primordial plasma, and the rigorous mathematical utility of the compaction function. Furthermore, by incorporating the dynamic nature of FLRW backgrounds, higher curvature corrections, and quantum backreaction via the memory burden effect, we challenge the standard hawking evaporation and show that extreme-curvature environments halt evaporation entirely, leaving Planck-scale relics that evade current extragalactic bounds. Finally, we map the multimessenger observational landscape, highlighting how the imminent search for sub-solar mass inspirals by next-generation gravitational wave observatories such as the Einstein Telescope and Cosmic Explorer could yield smoking-gun evidence for the PBH paradigm, ultimately transforming these primordial relics into unparalleled laboratories for high-energy physics.
↳ gr-qcastro-ph.COhep-phhep-thIndian J Phys (2026)·7 citations
38
Minimal Extensions of the $α$ -Starobinsky Model: Reconciling ACT DR6 and Reheating Constraints
Nehla Shobcha🇮🇩 · Norma Sidik Risdianto🇮🇩 · Romy Hanang Setya Budhi🇮🇩
The latest combined data from the Atacama Cosmology Telescope (ACT) DR6, Planck, and DESI yields a scalar spectral index $n_{s} = 0.9743 \pm 0.0034$ , which lies approximately $2 σ$ above the prediction of the standard $α$ -Starobinsky inflation model. To address this tension, we propose two minimal extensions that preserve the model's plateau structure and attractor properties: a multiplicative exponential modification and an additive polynomial deformation, both governed by a single small perturbative parameter $δ > 0$ . We analytically derive the slow-roll parameters and inflationary observables up to second order in $δ$ and integrate them with reheating dynamics via the consistency equation. It is shown that the $δ$ term effectively shifts $n_{s}$ into the $1 σ$ confidence region of the joint P-ACT-LB-BK18 dataset without violating the tensor-to-scalar ratio bound ( $r < 0.038$ ). The viable parameter space at $1 σ$ requires $α ≲ 35$ with $δ \sim O (1 0^{- 2})$ for the exponential model, while the additive model requires $δ \sim O (1 0^{- 3})$ for $p = 1$ and $δ \sim O (1 0^{- 4})$ for $p = 2$ . For the e-folding range $N_{k} \in [50, 65]$ , the relevant reheating equation of state is $0 < ω_{re} \leq 1$ . All viable scenarios yield a reheating temperature $T_{re} \sim 1 0^{9}$ GeV, which is safely above the Big Bang Nucleosynthesis (BBN) bound and below the gravitino overproduction limit.
↳ astro-ph.COgr-qchep-ph2 citations
39
Non-adiabatic transitions in the density matrix formalism
Pasquale Di Bari🇬🇧 · Shreya Pandit · Ye-Ling Zhou🇨🇳
We show that a density matrix formalism provides a useful description of non-adiabatic transitions in two-state quantum systems. Compared to a traditional Hamiltonian formalism, even in the absence of decoherence when there is full equivalence between the two, the density matrix formalism provides a convenient change of variables that yields a powerful general analytical solution. This solution nicely describes a transition regime between the well known Landau-Zener-Stuckelberg-Majorana (LZSM) approximation and the extremely non-adiabatic limit. Our results have very general applications, within a large variety of problems in quantum physics, neutrino physics, cosmology.
↳ quant-phhep-ph0 citations
40
Understanding the Intermittency Signal in RHIC-STAR Data through Modeling
Jin Wu🇨🇳 · Zhiming Li🇨🇳 · Mingmei Xu🇨🇳 · Shuyun Yang🇨🇳 · Ranran Guo🇨🇳 · Yuanfang Wu🇨🇳
Intermittency analysis provides a promising probe of scale-invariant density fluctuations near the QCD critical point. The intermittency measurements reported in the STAR BES-I data call for a quantitative assessment of the signal strength and a clearer physical understanding of its collision-energy dependence. In this work, we perform such a study for the STAR measurements using an improved hybrid UrQMD+CMC model, in which critical-like fluctuations are embedded into a realistic non-critical background through event-level, particle-level, and combined replacement schemes. By directly comparing the second-order factorial moment $Δ F_{2} (M)$ between model calculations and experimental data on a point-by-point basis, we constrain the effective critical-like contribution compatible with the STAR measurements without relying on scaling exponents. The STAR data at $s_{NN} = 7.7$ -- $27 GeV$ used for model comparison can be consistently described only by small and nearly energy-independent effective critical-like fractions. These results indicate that the current BES-I intermittency signal is weak and exhibits little collision-energy dependence, thereby favoring only a limited critical-like contribution rather than a strong critical-point-induced enhancement localized near a specific collision energy.
↳ nucl-thhep-ph0 citations
41
The $ω$ -Effect from a Multimode Squeezed Graviton State
Nick E. Mavromatos🇬🇷 · Sarben Sarkar🇬🇧
The $ω$ -effect in entangled neutral-meson systems provides a sensitive probe of CPT violation induced by quantum-gravitational environments. In open quantum systems, interactions with inaccessible gravitational degrees of freedom can render the reduced meson dynamics non-unitary, causing the CPT operator to become ill-defined, even when the underlying microscopic Hamiltonian is CPT invariant. We present a microscopic derivation of the $ω$ -effect arising from a multimode squeezed gravitational environment generated by an axion cloud around a Kerr black hole. Using the Takagi decomposition of the associated complex symmetric squeezing kernel, the graviton field is expressed in terms of independent squeezed supermodes possessing anomalous correlators. These correlators provide a microscopic quantum counterpart of the stochastic fluctuations that appear in earlier D-particle foam descriptions of the $ω$ -effect, replacing phenomenological variances of flavour-changing D-particle recoil by calculable graviton correlation functions. After tracing over the graviton bath, the anomalous correlators and the weak-interactions-induced mixing combine to generate transitions between the antisymmetric and symmetric two-meson sectors. This results in a small exchange-symmetric admixture, parametrised by $ω$ , in the otherwise antisymmetric EPR state. We obtain an explicit expression for $ω$ in terms of a sum over Takagi supermodes weighted by their squeezing amplitudes and phases together with the weak-interaction flavour-mixing matrix element. The resulting framework suggests that the $ω$ -effect may be a generic signature of non-classical states of gravitational environments, extending beyond the specific axion-cloud scenario considered here. The observability of the $ω$ -effect from other astrophysical and microscopic black-hole sources is discussed.
↳ gr-qchep-phhep-thquant-ph1 citation
42
When Black Holes Can Wear Pants
Giacomo Cacciapaglia🇫🇷 · Manuel Del Piano🇩🇰 · Francesco Sannino🇩🇰 · Vania Vellucci🇩🇰
We investigate the conditions under which black hole fragmentation, the splitting of a black hole horizon into multiple smaller ones, may occur. The simplest realization is that of a single black hole horizon splitting into two, giving rise to the eponymous pants topology. In classical general relativity, the Bekenstein-Hawking area law forbids such processes for Schwarzschild black holes. For spinning Kerr black holes, purely kinematic analyses impose constraints that prevent fragmentation, even in regimes where entropy considerations might allow it, except possibly in near-extremal cases. We then hunt for scenarios where black holes can wear pants: from the well-known Gregory-Laflamme instability in higher dimensions, to the potential effect of superradiant instabilities in non-axisymmetric radiation trapping, to finally gravitational models that modify the relations between entropy and/or horizon radius and the black hole mass in four dimensions. In all such cases, emission of small fragments can be entropically favored, however its occurrence still depends on the kinematic configuration of the initial state. Our analysis clarifies the theoretical landscape where black holes may fragment, which is particularly relevant for primordial black holes and catastrophic events such as black hole mergers.
↳ gr-qchep-ph0 citations
43
Radial Mirror Scattering and the QNM Convergence Region
Alex Kehagias🇬🇷 · Antonio Riotto🇨🇭
We revisit the convergence region of the quasinormal modes expansion of Schwarzschild retarded Green functions from a radial scattering viewpoint. The tortoise coordinate admits a natural reflection about a distinguished point, which maps the original Regge-Wheeler problem to a mirror radial problem with the same quasinormal mode spectrum. Although this reflection is not a spacetime symmetry and does not leave the potential invariant, it gives a simple image interpretation of the second lightcone distance that controls convergence. Equivalently, after folding the radial line at the reflection point, the direct and mirror contributions arise as diagonal and off-diagonal propagation channels of a two-component half-line problem. We also relate this structure to the AdS $_{2}$ Green function, where the same direct-plus-image lightcone structure arises from a genuine boundary-bouncing null geodesic. This provides a spectral interpretation of the convergence condition and clarifies the role of the reflection point in the Schwarzschild radial Green function.
↳ gr-qchep-phhep-th0 citations

Affiliations

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