Nuclear Theory·nucl-th

Tuesday·May 5, 2026

16 papers—8 primary·8 cross-listed

09
Bounds on massive graviton-like particles from searches for axion-like particles coupling to photons
Jordan Gué🇪🇸 · David d'Enterria🇨🇭
Limits on spin-0 axion-like-particles (ALPs) coupling to photons are reinterpreted as constraints on massive spin-2 graviton-like-particles (GLPs) with universal coupling $α_{G} / M_{P}$ (where $M_{P}$ is the reduced Planck mass) to the Standard Model fields. A minimally model-dependent recasting is performed, exploiting the formally analogous production and detection mechanisms for both particle types, based on the Primakoff and Gertsenshtein effects, i.e., photon-axion/graviton conversion. Constraints originally derived in the ALP mass vs. photon-coupling plane ( $m_{a}, g_{a γ}$ ) are translated into the corresponding bounds in the GLP ( $m_{G}, α_{G} / M_{P}$ ) parameter space over the full mass range, $m_{a,G} \approx 1 0^{- 20}$ -- $1 0^{14}$ eV probed in current and future experimental setups including cavity-based detectors (haloscopes and resonant upconversion devices), helioscopes, magnetometers, optical interferometers, beam dumps, fixed-target, and collider experiments, as well as astrophysical and cosmological constraints. Generic scenarios are considered in which GLPs are a dark matter candidate and not. Whereas current ALP searches do not set stronger bounds on massive spin-2 particles than fifth-force tests, future magnetometers, two-beam interferometers, and upconversion experiments have the potential to provide very strong sensitivity, down to $α_{G} / M_{P} \approx 1 0^{- 32} GeV^{- 1}$ , for light graviton-like particles with $m_{G} ≲ 1 0^{- 8}$ eV. These future detectors exhibit comparatively greater sensitivity to massive gravitons than to axions. For massive gravitons at the TeV scale, exclusive diphoton decay searches, employed in ALP studies, offer a complementary approach to standard searches for spin-2 resonances in other inclusive final states.
↳ hep-phastro-ph.HEhep-exnucl-ex+11 citation
10
Nuclear geometry driven symmetry plane correlations in OO and Ne--Ne collisions at the Large Hadron Collider
Suraj Prasad🇭🇺 · Raghunath Sahoo🇮🇳
Symmetry-plane correlations (SPCs) are key observables sensitive to the medium's transport properties and are driven by participant-plane correlations (PPCs) in the nuclear overlap region. This study explores the possibility of nuclear-geometry-driven SPCs in Oxygen--Oxygen (OO) and Neon--Neon (Ne--Ne) collisions at $s_{NN} = 5.36$ TeV using nuclear geometry simulations based on Nuclear Lattice Effective Field Theory (NLEFT) and Projected Generator Coordinate Method (PGCM) configurations. We investigate $⟨ cos [4 (ψ_{2} - ψ_{4})] ⟩_{GE}$ and $⟨ cos [6 (ψ_{3} - ψ_{6})] ⟩_{GE}$ in OO and Ne--Ne collisions at $s_{NN} = 5.36$ TeV using the A Multi-Phase Transport (AMPT) model. We find that Ne--Ne collisions exhibit larger $⟨ cos [4 (ψ_{2} - ψ_{4})] ⟩_{GE}$ values than OO collisions, whereas $⟨ cos [6 (ψ_{3} - ψ_{6})] ⟩_{GE}$ is larger in OO than in Ne--Ne collisions. This behavior indicates a strongly deformed shape of the $^{20}$ Ne nucleus and a tetrahedral structure of the $^{16}$ O nucleus. We also explore SPCs for events with tip-tip and body-body collision configurations, which further support these findings.
↳ hep-phhep-exhep-thnucl-ex+11 citation
11
Probing Saturation Effect in Heavy Meson Pair Correlation in Forward $p A$ Collisions
Zhan Gao🇨🇳 · Cyrille Marquet🇫🇷 · Yu Shi🇫🇷 · Bo-Wen Xiao🇨🇳
Forward two-particle angular correlations in $p A$ collisions have long been recognized as a particularly sensitive observable for exploring gluon saturation effects. In the back-to-back regime, two-particle correlations receive substantial contributions from both soft-gluon radiation and saturation effects. In this work, we study heavy meson pair correlation in forward proton-nucleus collisions by incorporating a unified Sudakov resummation for heavy meson pair correlations in the Color Glass Condensate effect theory. Our results are in good agreement with the $Δ ϕ$ data measured by the LHCb Collaboration for $D^{0} D ˉ^{0}$ pairs in forward $pp$ and $p A$ collisions, as well as $J / ψ$ pairs from $b b ˉ$ decays in forward $pp$ collisions. Furthermore, we present predictions for $D D ˉ$ and $B B ˉ$ correlations in the forward rapidity regions at the Large Hadron Collider. A pronounced mass-hierarchy is observed in the nuclear modification factor, $R_{p A}_{m_{b}} < R_{p A}_{m_{c}}$ , indicating stronger sensitivity to saturation effects at small $x$ . As the rapidity increases, the suppression becomes more pronounced while the mass hierarchy remains robust. This study will help us to search for the saturation signal via heavy-meson pair correlations in forward $p A$ collisions.
↳ hep-phhep-exhep-thnucl-th4 citations
12
Multimodal Fragmentation of All-Heavy Pentaquarks: Uncertainty-Aware Predictions for Hadron Colliders
Francesco Giovanni Celiberto🇪🇸
We present an uncertainty-aware description of leading-power fragmentation for all-charm pentaquark states ( $S$ -wave $∣ cccc c ˉ ⟩$ ) at hadron colliders. We construct a multimodal set of collinear fragmentation functions, PQ5Q1.1, incorporating both perturbative and nonperturbative uncertainties. Perturbative effects are estimated via missing higher-order variations (F-MHOUs), while the nonperturbative wave function is modeled through controlled modifications of its transverse-momentum structure (F-NPWF), consistently combined within a replica-like framework. The initial-scale input for constituent charm fragmentation is refined to describe both compact multiquark and diquark-driven production mechanisms. We employ the (sym)JETHAD interface to study NLL/NLO $^{+}$ semi-inclusive pentaquark-plus-jet production at the HL-LHC and future FCC. The bottom sector is left to future dedicated studies due to its enhanced sensitivity to nonperturbative modeling. Our results provide a flexible framework for uncertainty-controlled predictions, bridging exotic-hadron structure, heavy-flavor fragmentation, and high-energy QCD.
↳ hep-phhep-exhep-thnucl-ex+1PRD(2026)·2 citations
13
Equation of State of Dense Matter: Pauli Degeneracy, Pairing Correlations, and Implications for Neutron Stars
Yaroslav D. Krivenko-Emetov🇦🇹 · Gleb Shabal🇦🇹
We develop a unified description of dense fermionic matter that consistently incorporates Pauli degeneracy, interaction effects, and pairing correlations. The condition that the temperature is much smaller than the Fermi energy leads to a natural separation among the Sommerfeld, Fermi-liquid, and pairing regimes. We show how these contributions enter the equation of state. The resulting EOS is applied to the Tolman-Oppenheimer-Volkoff equations to analyze neutron-star structure. We demonstrate that Pauli degeneracy provides the dominant pressure, interactions determine the stiffness of the EOS, and pairing correlations produce subleading but potentially significant corrections, especially in quark matter. Implications for mass-radius constraints and modern observations are discussed. The quasiparticle interaction in the normal Fermi-liquid phase is parameterized by the isotropic Landau parameter F_0^s and linked explicitly to the compressibility and sound speed. The theoretical mass-radius curves are compared with four recent NICER measurements.
↳ hep-phnucl-th0 citations
14
Boost-invariant and cylindrically symmetric perfect spin hydrodynamics
Zbigniew Drogosz🇵🇱 · Wojciech Florkowski🇵🇱 · Jakub Witkowski🇵🇱
Equations of a boost-invariant and cylindrically symmetric perfect hydrodynamics are solved numerically for initial conditions inspired by the wounded nucleon model. The energy-momentum and spin tensors are used in the form that describes a relativistic massive gas governed by Boltzmann statistics. In contrast to one dimensional boost-invariant expansion, we find a coupling between the azimuthal and longitudinal components of the electric and magnetic components of the spin polarization tensor. This feature is similar to that found earlier for the Gubser symmetry, however, our treatment allows for a more general form of initial conditions and expansion geometry. Defining the freeze-out hypersurface by the constant temperature condition, we evaluate the Pauli-Lubański four-vector and find that for the assumed geometry the only nonzero total polarization may be induced by the longitudinal component of the magnetic part of the spin polarization tensor coupled with the azimuthal electric component. The obtained results may serve as a reference point for more realistic models of hydrodynamic expansion.
↳ hep-phnucl-th0 citations
15
$K_{S}^{0} - K_{S}^{0}$ femtoscopy in Pb $-$ Pb collisions at $s_{NN} = 5.02$ TeV at the LHC
ALICE Collaboration
Results from a one-dimensional femtoscopic analysis of $K_{S}^{0} - K_{S}^{0}$ correlations in Pb $-$ Pb collisions at the center-of-mass energy $s_{NN} = 5.02$ TeV using data collected by the ALICE experiment at the LHC are presented. The source radius $R$ and correlation strength $λ$ are studied as a function of centrality and pair-transverse momentum ( $k_{T}$ ) to provide insight into the space-time structure and composition of the particle-emitting source. The observed trends of radii as a function of $k_{T}$ and centrality are consistent with the collective expansion of the system. Comparisons with measurements at $s_{NN} = 2.76$ TeV by the ALICE Collaboration show agreement across multiplicities and $k_{T}$ . Hydrokinetic model predictions match the most central collision results but deviate in peripheral events, potentially reflecting limitations in the model's description of peripheral collisions. A comparison with recent measurements at the same energy by the CMS Collaboration shows compatibility in both $R$ and $λ$ within 1.3 $σ$ . These results extend previous $K_{S}^{0} - K_{S}^{0}$ femtoscopy to a higher energy, providing a consistent baseline for future comparisons.
↳ nucl-exnucl-th1 citation
16
Measurement of isolated-prompt photon $-$ hadron correlations in Pb $-$ Pb collisions at $s_{NN} = 5.02$ TeV
ALICE Collaboration
The ALICE Collaboration has measured the azimuthal correlation between trigger isolated-prompt photons and associated charged hadrons in Pb $-$ Pb collisions at the CERN LHC, at a centre-of-mass energy per nucleon pair of \snnfive. The trigger isolated-prompt photons are measured in the transverse-momentum range $18 < p_{T}^{γ} < 40$ GeV/ $c$ and pseudorapidity range $∣ η^{γ} ∣ < 0.67$ . The isolation selection is based on a charged particle isolation momentum threshold $p_{T}^{iso, ch} = 1.5$ GeV/ $c$ within a cone of radius $R = 0.2$ . The associated charged particles are measured in the transverse-momentum ranges $p_{T}^{h} > 1.8$ GeV/ $c$ and pseudorapidity $∣ η^{h} ∣ < 0.9$ . The yield D $(z_{T})$ of associated hadrons per trigger, with $z_{T} = p_{T}^{h} / p_{T}^{γ}$ , is measured in three Pb $-$ Pb collision centrality classes: central (0 $-$ 30%), semicentral (30 $-$ 50%), and peripheral (50 $-$ 90%). An approximation to the standard $I_{AA}$ is computed from the D $(z_{T})$ conditional yields, using NLO pQCD predictions as pp reference. A strong suppression of this ratio is observed in central collisions compared to peripheral collisions. The result extends to a lower $p_{T}^{γ}$ relative to those reported in previously published Pb $-$ Pb collisions measurements at $s_{NN} = 5.02$ TeV. The measurement is compared to NLO pQCD calculations that include energy loss, and to the CoLBT-hydro model. The results from central collisions are also compared with measurements of jets correlated with isolated-prompt photons and of hadrons correlated with Z $^{0}$ bosons, both reported by the CMS Collaboration at the LHC, as well as with direct photon $-$ hadron correlation measurements reported by the PHENIX and STAR Collaborations at RHIC.
↳ nucl-exnucl-th2 citations

Affiliations

first authorsco-authorsvia INSPIRE