Nuclear Theory·nucl-th

Monday·July 28, 2025

17 papers—6 primary·11 cross-listed

07
Scalar-glueball-mediated scale-anomaly dominance of the confining pressure of the pion in holographic QCD
Daisuke Fujii🇯🇵 · Akihiro Iwanaka🇯🇵 · Mitsuru Tanaka🇯🇵
In this work, we analyze the energy density and the stress distribution inside the pion derived from gravitational form factors in top-down holographic QCD. In particular, we show that the dominance of the scale anomaly in the confining pressure, previously observed in the instant form for the nucleon, also holds for the pion in the light-front form. Furthermore, we find that in large- $N_{c}$ QCD described by this approach, the scalar glueball plays a mediating role in transmitting the confining pressure. These findings support the universal role of the scale anomaly in the stability of hadrons.
↳ hep-phhep-exhep-thnucl-thPRD(2025)·10 citations
08
Color-glass condensate beyond the Gaussian approximation
Jani Penttala🇺🇸
In the high-energy limit, perturbative calculations in QCD are conveniently done using the dipole picture which factorizes the scattering amplitude into a perturbative part and the nonperturbative scattering off the nuclear target, described using correlators of Wilson lines. These correlators can be computed in the color-glass condensate effective field theory by using a Gaussian model for the color density of the target. In this work, we generalize the Gaussian model to a generic function that is local in the transverse coordinates and the light-cone time, and show how to compute physical Wilson-line correlators in this model. We also consider a simple model for the color density based on stable probability distributions and show that the small-dipole behavior of the dipole amplitude is modified from quadratic to a power law, where the power is given by the stability parameter of the distribution. This generalization of the Gaussian model is suitable for numerical applications in the high-energy limit and can be used in future phenomenological studies of the nuclear structure.
↳ hep-phnucl-thJHEP(2026)·3 citations
09
Freezeout at constant energy density and spin polarization in heavy-ion collisions
Andrea Palermo🇺🇸 · Masoud Shokri🇩🇪
Using the local equilibrium density operator, we develop a geometry-informed linear response theory that takes into account the parameterization of the freezeout hypersurface before the gradient expansion is carried out. Assuming local equilibrium on an iso-energy density hypersurface, we study the $Λ$ hyperon spin polarization, and compute corrections to the isothermal case due to finite density. We argue that corrections to isothermal freezeout should be small, and that even in heavy ion collisions with energy as low as $s_{N N} = 11.5$ GeV they constitute at most a $10%$ effect. They may, however, become relevant for local polarization observables.
↳ hep-phnucl-thPRD(2025)·2 citations
10
Particle Correlations in Jets
Wenbin Zhao🇺🇸 · Volker Koch🇺🇸 · Feng Yuan🇺🇸
We study particle correlations in high energy jets by comparing the measured energy-energy correlator (EEC) with that constructed from two individual energy flows with respect to the jet axis. This comparison demonstrates that genuine correlations exists for small angle and moderate/large angle, indicating that they are coming from correlated splitting. This method will provide a unique tool to disentangle different physics, by comparing the genuine correlations in jet EEC between heavy ion collisions and proton-proton collisions. It will help to expose the medium modification of parton splitting in hot QCD medium. On the other hand, the medium responses are expected to be canceled out in the genuine correlations.
↳ hep-phnucl-exnucl-th8 citations
11
Deep Neural Network Driven Simulation Based Inference Method for Pole Position Estimation under Model Misspecification
Daniel Sadasivan🇨🇱 · Isaac Cordero🇨🇱 · Andrew Graham🇨🇱 · Cecilia Marsh🇨🇱 · Daniel Kupcho🇨🇱 · Melana Mourad🇨🇱 · Maxim Mai🇨🇭
Simulation Based Inference (SBI) is shown to yield more accurate resonance parameter estimates than traditional chi-squared minimization in certain cases of model misspecification, demonstrated through a case study of pi-pi scattering and the rho(770) resonance. Models fit to some data sets using chi-squared minimization can predict inaccurate pole positions for the rho(770), while SBI provides more robust predictions across the same models and data. This result is significant both as a proof of concept that SBI can handle model misspecification, and because accurate modeling of pi-pi scattering is essential in the study of many contemporary physical systems (e.g., a1(1260), omega(782)). The method of Simulation Based Inference is shown to lead to a more accurate resonance parameter estimation than traditional chi-squared minimization in certain cases of model misspecification in a case-study of pi-pi scattering and the rho(770)-resonance. Models fit to certain data sets using chi-squared minimization can make inaccurate predictions for the pole position of the rho(770). SBI is shown to make a more robust predictions for the pole positions. This is significant, both as a proof of concept that the SBI method can be used in cases of model misspecification, and because models of pi-pi scattering are a crucial part to many physical systems of contemporary interest (e.g., a1(1260), omega(782)).
↳ hep-phnucl-thstat.APstat.MLPRD(2026)·7 citations
12
Structure of heavy quarkonia in a strong magnetic field
Ahmad Jafar Arifi🇯🇵 · Kei Suzuki🇯🇵
We investigate the structural modifications of heavy quarkonia in the presence of strong magnetic fields using a constituent quark model. By incorporating the effects of spin mixing and quark Landau levels, we employ a nonrelativistic Hamiltonian that captures the essential features of quark dynamics in a magnetic field. The two-body Schrödinger equation is solved using the cylindrical Gaussian expansion method, which respects the cylindrical symmetry induced by a magnetic field. We extract the corresponding light-front wave function (LFWF) densities and analyze their transverse and longitudinal structures, revealing characteristic features such as transverse momentum broadening. While the longitudinal structure is only slightly modified within the nonrelativistic Hamiltonian, we discuss some corrections that can significantly affect its longitudinal structure. Furthermore, we discuss the structure modifications of excited states and find notable changes in the LFWF densities, and state reshuffling near avoided crossings. These results demonstrate the sensitivity of hadron structure to external magnetic fields and help bridge our understanding to relativistic approaches.
↳ hep-phhep-latnucl-thPRD(2025)·6 citations
13
Effect of eigenstates on spectra in coupled-channel scattering with the chiral unitary model
Takuma Nishibuchi · Tetsuo Hyodo
In recent years, as experimental data on the excited $Ξ (1620)$ and $Ξ (1690)$ states have accumulated, theoretical analyses based on chiral dynamics have also been actively pursued. In this study, we construct theoretical models within the chiral unitary approach to reproduce recent experimental data, and perform a model interpolation to examine the relationship between the poles appearing in different models. We then calculate the invariant mass spectra of the $π^{+} Ξ^{-}$ system in the $Ξ_{c} \to π π Ξ$ decay, using the scattering amplitudes obtained from each model, to investigate how the distinct pole structures influence the observable spectrum.
↳ hep-phnucl-thPoS(2026)·0 citations
14
Polarization of the $ϕ$ meson in the hadronic phase with nucleon scatterings and a viscous hydrodynamic background
Eduardo Grossi🇮🇹 · Andrea Palermo🇺🇸 · Ismail Zahed🇺🇸
We extend our previous work on the spin alignment of the $ϕ$ vector meson in the hadronic phase of the Quark Gluon Plasma, by including effects of nucleon scatterings. The emission rates are calculated in a realistic hydrodynamic background simulated with the code Fluid $u$ m, for different beam energies. We find that all the effects taken into account cannot explain the out-of-plane spin alignment of the $ϕ$ meson observed experimentally.
↳ hep-phnucl-thPRC(2025)·4 citations
15
Determination of the $ϕ$ -meson production process and its absorption cross section via directed flow
Jan Steinheimer🇩🇪 · Tom Reichert🇩🇪 · Marcus Bleicher🇩🇪
We show that the directed flow of $ϕ$ -mesons in Au+Au collisions at $s_{N N} = 3$ GeV, is sensitive on production and the absorption cross section of the $ϕ$ in a nuclear medium. This provides a new observable to constrain the in-medium properties of the $ϕ$ which is independent of its absolute production rate. It is shown that the STAR data disfavor any significant $ϕ$ -N absorption in dense nuclear matter and are consistent with a very small cross section of the $ϕ$ comparable to the vacuum cross section. The similarity of the $ϕ$ -meson and proton directed flow also indicates that the $ϕ$ is produced in conjunction with a baryon.
↳ hep-phnucl-thPLB(2025)·6 citations
16
Pushing the hybrid approach to low beam energies with dynamic initial conditions from hadronic transport
Renan Góes-Hirayama🇩🇪 · Joscha Egger🇩🇪 · Zuzana Paulínyová🇩🇪 · Iurii Karpenko🇨🇿 · Hannah Elfner🇩🇪
While hybrid approaches of relativistic hydrodynamics+transport have been well established for the dynamical description of heavy-ion collisions at high beam energies, moving to lower beam energies is challenging. In this work, we propose dynamic initial conditions for the viscous hydrodynamic evolution in heavy-ion collisions at low to intermediate beam energies. They are comprised of core hadrons based on the local energy density during the pre-equilibrium hadronic evolution. The SMASH-vHLLE hybrid approach is then applied to lower beam energies, achieving good agreement with measured bulk observables between $s_{NN} = 3$ and $9.1 GeV$ , thus providing guidance for measurements in STAR-BES and CBM at FAIR.
↳ hep-phhep-exnucl-thPRC(2026)·9 citations
17
Initial conditions and bulk viscosity effects on $Λ$ polarization in high-energy heavy ion collisions
Andrea Palermo🇺🇸
The $Λ$ spin polarization is a crucial probe of the gradients of velocity and temperature in the quark-gluon plasma generated in heavy-ion collisions. However, it is still not systematically used to tune hydrodynamic models. In this work, we investigate the influence of different initial conditions and parametrization of the bulk viscosity on $Λ$ polarization, showing that they affect the local polarization significantly. These results highlight the impact that the use of local polarization can have on refining theoretical models. Finally, we compare our results, including feed-down corrections, with experimental data from high-energy heavy-ion collisions at STAR and ALICE, and demonstrate the crucial role of bulk viscosity in generating the correct sign of longitudinal polarization at LHC energies.
↳ hep-phnucl-thEPJ Web Conf.(2026)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE