Nuclear Theory·nucl-th

Tuesday·July 21, 2026

14 papers—11 primary·3 cross-listed

01
Lorentz-Covariant Spectral Bounds from Thermal Quantum Field Theory
Alisher Sanetullaev🇺🇿 · Sarbinaz Bazarbaeva🇺🇿 · Marhabo Beymamatova🇺🇿 · Shokir Tursunov (New Uzbekistan University)🇺🇿
We derive rigorous Lorentz-covariant bounds on relaxation spectra directly from the analytic structure of retarded Green's functions in thermal quantum field theory, using only causality, unitarity, the Kubo-Martin-Schwinger condition, and Lorentz covariance, without reference to any specific dynamical model. A single rest-frame quasinormal pole is generically smeared into a continuum of excitations in boosted frames, with width set by the maximal signal velocity. We prove that the non-hydrodynamic gap $Γ_{gap}$ transforms as $Γ ~_{gap} \geq Γ_{gap} / [γ (1 + v v_{max})]$ , and that the convergence radius of the hydrodynamic gradient expansion satisfies $k ~_{c} \in [k_{c} / γ (1 + v v_{s}), k_{c} / γ (1 - v v_{s})]$ under a boost of velocity $v$ . We verify the bounds by a numerical quasinormal-mode computation in the $N = 4$ super-Yang-Mills plasma: the leading boosted pole moves deeper into the complex plane -- the observed relaxation rate increases with boost velocity, in sharp contrast to naive time dilation -- while respecting the bound throughout. The results apply non-perturbatively to the quark-gluon plasma, neutron star merger dynamics, and quantum critical systems.
nucl-th1 citation
02
Wounded parton scaling of multiplicities in ultra-relativistic light- and heavy-ion collisions
Rupam Samanta🇵🇱 · Piotr Bozek🇵🇱 · Wojciech Broniowski🇵🇱
Multiplicities of charged particles produced in O+O, Ne+Ne, Xe+Xe, and Pb+Pb collisions at $s_{N N} \sim 5$ ~TeV are studied in a uniform way within a wounded parton Glauber framework with overlaid negative binomial fluctuations. In this model, the nucleon's inelastic interaction is modeled via its constituent partons, whose number is a parameter, with best description obtained with four partons per nucleon. We fit directly the experimental multiplicity distributions (histograms), using {\it the same model parameters} for each reaction. The fit is performed in the c=1--80 $%$ centrality range. Avoiding the most peripheral events makes the method insensitive to the normalization issues caused by the difficulty in separating the Coulomb interactions, whereas the most central collisions may involve a different particle production mechanism. We find a proper model description of multiplicity distributions across all the studied systems for $c ≲ 1%$ .
nucl-thhep-phnucl-ex0 citations
03
Finite-nucleus-protected high-density extension of covariant density functionals constrained by multimessenger data
Wen-Jie Xie🇨🇳 · Jun-Hua Guo🇨🇳
We construct a finite-nucleus-protected high-density extension of covariant density functionals by modifying only the isoscalar-vector channel outside the finite-nucleus calibration domain. The extension introduces three parameters controlling the strength, onset, and width of the high-density deformation, while the scalar and isovector channels are kept unchanged. A Bayesian analysis using heavy-ion flow constraints, massive-pulsar information, NICER mass-radius measurements, and the GW170817 tidal constraint shows that the original \ddme interaction is strongly disfavored relative to its protected high-density extension, with $\ln K=\ln(Z_{\rm ext}/Z_{\rm base})=26.67$, where $Z$ denotes the Bayesian evidence, after imposing a causal/stability filter on the reshaped EOS. In contrast, \ddpc serves as a reference functional for which the same extension is not required by the present data, giving $\ln K=-0.44$. The result supports the interpretation that the proposed extension is not an unconstrained phenomenological patch: Bayesian evidence selects it only when demanded by the combined high-density data, while finite-nucleus observables remain unchanged within numerical precision.
nucl-th0 citations
04
The equation of state for neutron stars
Veronica Dexheimer
This chapter is intended as an introduction to dense matter and the equation of state of neutron stars and their mergers. It begins with a brief description of neutron star interiors, followed by a historical overview of the theoretical frameworks used to describe them focusing on relativistic formalisms, including different degrees of freedom, models, symmetries, and phases. It also provides an overview of our current understanding of dense matter (including theory, experiments, and observations) and discusses the advances we expect to see in the field over the next decade.
nucl-thastro-ph.HEastro-ph.SRhep-th1 citation
05
Kaon-induced $ϕ Σ$ production off the proton
Sang-Ho Kim🇰🇷 · Myung-Ki Cheoun🇰🇷
We investigate the reaction mechanism of $K^{-} p \to ϕ Σ^{0}$ within a hybrid Regge approach based on effective Lagrangians. The nonresonant background includes Reggeized $t$ -channel $K$ and $K^{*}$ exchanges, together with ground-state $Σ$ and nucleon exchanges in the $s$ and $u$ channels, respectively. To describe the structures observed at $3.0 ⩽ P_{Lab} ⩽ 4.5$ GeV, we include the high-mass $Σ (2620)$ and $Σ (3000)$ resonances and examine the spin-parity assignments $J^{P} = 1/ 2^{\pm}$ , $3/ 2^{\pm}$ , and $5/ 2^{\pm}$ . The $K^{*}$ -Reggeon exchange dominates the forward-angle cross sections, whereas the smaller $K$ -Reggeon contribution is important for the total cross section at low energies and for the spin-density matrix elements. The nonresonant background alone is not sufficient to reproduce the local structures in the total cross section or the differential cross sections at large $- t^{'}$ . Including the two resonances, particularly the $Σ (3000)$ , substantially improves the agreement with the available data. The $J^{P} = 5/ 2^{-}$ assignment for the $Σ (3000)$ provides a reasonable overall description, although the present data do not permit a definitive determination.
nucl-thhep-ph0 citations
06
Coulomb interaction in the diffraction description of the $^{12}$ C(d,p)X reaction
Yaroslav D. Krivenko-Emetov · Boris I. Sydorenko
Within the Glauber-Sitenko diffraction multiple-scattering theory, we calculate Coulomb corrections to the invariant cross section for inclusive deuteron breakup in the $^{12}$ C(d,p)X reaction at small proton emission angles. Extending our previous analysis of the longitudinal momentum transfer $Q_{z}$ and the transverse relative momentum of the final $p n$ pair, we include the proton--nucleus electromagnetic interaction, Coulomb-nuclear interference, and the Coulomb correction to double $p n$ rescattering. For a finite nuclear charge distribution, we derive the Coulomb phase and relate its spatial scale to the measured charge radius. Closed and Yukawa-screened expressions for the proton Coulomb term are obtained. The two-dimensional correction to $p n$ rescattering is reduced to a one-dimensional integral without an independent Gaussian approximation to the full transition form factor. Calculations with the $S$ -wave components of the K2 and Nijm-I deuteron wave functions show that the Coulomb effect is concentrated near the quasifree peak. Its interference with the strong amplitude increases the peak height but decreases rapidly with relative momentum. It therefore cannot explain the experimental enhancement at $0.3$ -- $0.5$ GeV/ $c$ , where final-state interactions, relativistic corrections, and nonnucleonic components may be important.
nucl-thhep-ph0 citations
07
Chemonuclear Transmutation and Noble Metal Synthesis
Hidetsugu Ikegami · Masako Ikegami
In the system of metallike hydride-electron donor mixtures, adsorbed hydrogen atoms are transformed into metallic states and alloyed. Dense itinerary s-electrons supplied by the electron donor cause a drop in the melting point of metallic hydrogen. As a result, this system reveals thermodynamical liquid activity. The coherent D2-D2 fusion and the D3-D3 chemonuclear fusion are enhanced with factors of 20 to 30 and 30 to 46 figures of magnitude respectively at T=460 K, hence the production of intense He ions of 23.8 MeV kinetic energy. The ions or alpha-particles induce enhanced cascade chemonuclear reactions towards diverse and useful element synthesis. This phenomenon is in the nature of the Big Bang nucleosynthesis that takes place in an inhomogeneous universe. An application of the alpha-induced chemonuclear reaction - i.e., the transmutation of 90Sr and 137Cs - is prescribed in this chapter. This system of metallike hydride-electron donor mixtures raises the possibility of radioactive waste vanishment. Stimulated by alpha-particle irradiation, trans-gold nuclei undergo exothermic alpha-cluster emissions, producing coherently line-up alpha-clusters. In the chemonuclear D-D fusion, the 4alpha-cluster reveals the thermodynamical activity of oxygen atoms. In the hydrogen-Ni nanopowder-Li mixtures, dispersively charged trans-gold atoms undergo enhanced chemonuclear alpha-cluster emissions, hence the mass synthesis of noble metals. The case of chemonuclear pion production is presented at the end of this chapter.
nucl-thcond-mat.mtrl-sci0 citations
08
Rapidity-even Dipolar Flow in Relativistic Heavy-Ion Collisions
Niseem Magdy🇺🇸
Rapidity-even directed flow, ( $v_{1}^{e v e n}$ ), provides a sensitive probe of fluctuation-driven dipolar asymmetry in the initial state of relativistic heavy-ion collisions. Its extraction is complicated by large first-harmonic non-flow correlations, particularly those induced by global momentum conservation (GMC). In this work, we study ( $v_{1}^{e v e n}$ ) and its multi-particle correlations in Au+Au collisions at ( $s_{N N} = 200$ ) GeV using the AMPT and HIJING models. An ( $η$ )-dependent weighting procedure is employed to suppress the leading GMC contribution. HIJING is used as a non-collective baseline, while AMPT is used to investigate sensitivity to final-state partonic transport. The GMC-corrected HIJING results are strongly reduced for most ( $v_{1}$ )-related observables, indicating that the leading HIJING-like recoil contribution is effectively mitigated. The AMPT calculations reproduce the characteristic sign-changing ( $p_{T}$ ) dependence of ( $v_{1}^{e v e n}$ ) and show sensitivity to the partonic scattering strength. Mixed-harmonic and normalized correlations involving ( $v_{1}$ ), ( $v_{2}$ ), and ( $v_{3}$ ) suggest that the dipolar mode is correlated with both the elliptic geometry and fluctuation-driven triangular structure. These results demonstrate that GMC-suppressed rapidity-even dipolar-flow correlations provide a promising framework for constraining initial-state fluctuations and final-state transport in heavy-ion collisions.
nucl-thhep-ph0 citations
09
Trace anomaly and isospin splitting in inverse-mapped relativistic mean-field theory
Wen-Jie Xie🇨🇳 · Jun-Hua Guo🇨🇳
Trace anomaly and sound speed provide EOS-level probes of dense-matter nonconformality, but do not by themselves identify the microscopic channels responsible for the response. We study this question with a uniform-matter inverse-mapped relativistic mean-field ensemble constrained by chiral effective field theory, heavy-ion flow information, and neutron-star mass-radius data. The ensemble reproduces the flow-based trace trend in symmetric nuclear matter, while beta-equilibrated matter approaches the neutron-star trace bands more slowly. The resulting splitting, $\Delta_{\SNM}-\Delta_{\betaeq}$, remains positive over $2--5\nzero$ and is most strongly correlated with the density derivative of the isovector-vector coupling, with bootstrap-stable Spearman coefficients $r_s\simeq0.91--0.92$ at $2--3\nzero$. Its correlation with the beta-equilibrium proton fraction is much weaker. The sound-speed splitting changes sign near $3.38\nzero$, and the derivative term $-\dd\Delta/\dd\ln\varepsilon$ becomes sensitive to both scalar-vector and isovector responses above $4\nzero$. Data-combination and controlled-isovector tests show that this channel separation is resolved only when laboratory and astrophysical projections are combined. Thus, within the present inverse-mapped RMF space, the SNM--beta trace splitting acts as a thermodynamic probe of the high-density symmetry sector rather than as a unique signal of exotic degrees of freedom. A finite-nucleus-calibrated extension will be needed to test how much of this channel diagnostic survives in predictive covariant density functionals.
nucl-th0 citations
10
Dissipative properties of a Fermi system within the diffusion approximation of kinetic theory
Sergiy V. Lukyanov
The dissipative properties of a Fermi system are studied within the diffusion approximation of kinetic theory for a model of a spherical atomic nucleus. An analytical solution of the nonlinear diffusion equation in energy space with constant kinetic coefficients is used to show that the distribution function asymptotically approaches the equilibrium Fermi distribution. It is found that the deviation from equilibrium at finite times decays with an effective relaxation time of $τ_{eff} \approx 1.0 \times 1 0^{- 23}$ s, whereas the asymptotic regime is characterized by an exponential decay with a relaxation time of $τ_{eq} \approx 3 τ_{eff}$ . These results explain the difference between the relaxation times extracted from integral characteristics of the relaxation process and from the asymptotic long-time evolution.
nucl-th0 citations
11
Sensitivity of p_T Fluctuations to the QCD Equation of State
Rutik Manikandhan🇺🇸 · Rohit Gupta🇮🇳 · Rene Bellwied🇺🇸
We construct a novel theoretical baseline for dynamical transverse momentum correlations, $C_{pT}$ , across a wide range of collision energies spanning the RHIC Beam Energy Scan (BES) program. For the first time, a unified framework is developed to describe the energy and centrality dependence of $C_{p_{T}}$ from $s_{NN} = 3.0$ to $200$ ~GeV. A central feature of this study is the implementation of Equation of State (EOS) inputs derived from Lattice QCD results at finite baryochemical potential $μ_{B}$ , representing the first such application to the measured transverse momentum correlations. Despite the minimalist nature of the fluid-dynamic evolution employed, the model effectively captures the characteristic centrality scaling of the experimental data. Our results indicate that while the bulk evolution is largely governed by the EOS and system lifetime at lower energies, significant deviations in peripheral collisions at top energies highlight the onset of non-thermal correlation mechanisms. This baseline provides a necessary benchmark for interpreting transverse momentum fluctuations in heavy-ion collisions and can aid in the search for the QCD critical point.
nucl-thhep-ex0 citations

Affiliations

first authorsco-authorsvia INSPIRE