Nuclear Theory·nucl-th

Tuesday·May 6, 2025

18 papers—13 primary·5 cross-listed

01
Higher order flow coefficients -- A Messenger of QCD medium formed in heavy-ion collisions at the Large Hadron Collider
Suraj Prasad🇮🇳 · Aswathy Menon K R🇮🇳 · Raghunath Sahoo🇮🇳 · Neelkamal Mallick🇫🇮
Anisotropic flow and fluctuations are sensitive observables of the initial state effects in heavy ion collisions and are characterized by the medium properties and final state interactions. Using event-shape observables, one can constrain the probability distributions of anisotropic flow coefficients, thus reducing the linear and nonlinear contributions in the measured higher-order harmonics. In this paper, we use transverse spherocity as an event shape observable to study the flow coefficients and elliptic flow fluctuations. Transverse spherocity is found to have a strong correlation with elliptic flow and its fluctuations. We exploit this feature of transverse spherocity to remove the contribution to elliptic flow from higher-order harmonics. The study is performed in Pb--Pb collisions at $s_{NN} = 5.02$ TeV using a multi-phase transport model. The multi-particle Q-cumulant method estimates the anisotropic flow coefficients, which reduces the non-flow contributions. We observe a stronger system response to the flow coefficients for the events with smaller values of elliptic flow.
nucl-thhep-exhep-phnucl-exPLB(2025)·7 citations
02
Effects of a background magnetic field on dilepton radiation
Han Gao🇨🇦 · Xiang-Yu Wu🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
We explore the feasibility of using dilepton radiations as a QGP magnetometer. We calculate the dilepton production rate in the presence of a time-dependent magnetic field typically found in heavy-ion collisions. We compute the thermal dilepton spectra from Au+Au collisions at $s$ = 19.6 GeV BES energy -- using a realistic (3+1)-dimensional multistage hydrodynamic simulation. We find the thermal dilepton elliptic flow to be very sensitive to the strength of the magnetic field.
nucl-thEPJ Web Conf.(2025)·4 citations
03
Generalized relativistic second-order spin hydrodynamics from Zubarev's non-equilibrium statistical operator
Duan She🇨🇳 · Yi-Wei Qiu🇨🇳 · Ze-Fang Jiang🇨🇳 · Defu Hou🇨🇳
Inspired by the work in Ref.[1], which considers the additional second-order contributions arising from nonlocal corrections due to two-point correlation functions of tensors of different ranks at distinct spacetime points, we similarly employ the nonequilibrium statistical operator method to extend this framework to include spin degrees of freedom. In addition to obtaining analogous extra second-order terms in the shear stress tensor, bulk viscous pressure, and charge diffusion currents resulting from such contributions, we further derive additional second-order terms originating from the same mechanism in the charge diffusion currents, rotational stress tensor and the boost heat vector. Furthermore, we express all transport coefficients represented by two-point or three-point correlations in terms of retarded Green's functions.
nucl-thPRD(2025)·5 citations
04
Chiral $3 π$ -exchange potential using the method of unitary transformation
Victor Springer🇩🇪 · Hermann Krebs🇩🇪 · Evgeny Epelbaum🇩🇪
Nuclear potentials are known to exhibit a considerable degree of scheme dependence. For one- and two-pion exchange nucleon-nucleon (NN) potentials, unitary ambiguities start showing up at the level of the leading relativistic corrections to the dominant static contributions. However, for the three-pion exchange potential, scheme-dependent contributions are expected to appear already at the static level. Here, we analyze the leading and subleading chiral $3 π$ -exchange NN potentials using the method of unitary transformation. In line with the expectations, our results for selected classes of contributions differ from those obtained by Kaiser using S-matrix matching. We present analytical expressions for the $3 π$ -exchange potential, which are off-shell consistent with the interactions used by the Bochum group, and discuss the numerical importance of the observed differences.
nucl-thPRC(2025)·4 citations
05
Tilted-axis-cranking covariant density functional theory for the high-spin spectroscopy in $^{69}$ Ga
Y. P. Wang · Y. K. Wang · P. W. Zhao
The tilted-axis-cranking covariant density functional theory is applied to investigate the three newly-observed positive-parity bands SI, SII, and SIII in $^{69}$ Ga. The energy spectra and angular momenta are calculated and compared with the experimental data. For the yrast band SI, pairing correlations play a crucial role for the states with spin $I \leq 23/2ℏ$ . The bands SII and SIII are suggested to be signature partner bands with positive and negative signatures, respectively. The transition probabilities $B (E 2)$ for these bands are predicted, and await further experimental verification. By analyzing the angular momentum alignments microscopicly, it is revealed that the $g_{9/2}$ protons and neutrons play an important role in the description of the collective structure of $^{69}$ Ga.
nucl-thnucl-exCPC(2026)·1 citation
06
Dynamics of light nuclei produced in the massive transfer reactions
Zi-Han Wang · Zhao-Qing Feng
Within the framework of the dinuclear system (DNS) model by implementing the cluster transfer into the dissipation process, we systematically investigated the energy spectra and the angular distribution of the preequilibrium clusters (n, p, d, t, $^{3}$ He, $α$ , $^{6, 7}$ Li, $^{8, 9}$ Be) in the massive transfer reactions of $^{12}$ C+ $^{209}$ Bi, $^{14}$ N+ $^{159}$ Tb, $^{14}$ N+ $^{169}$ Tm, $^{14}$ N+ $^{181}$ Ta, $^{14}$ N+ $^{197}$ Au, $^{14}$ N+ $^{209}$ Bi, $^{58, 64, 72}$ Ni+ $^{198}$ Pt near the Coulomb barrier energies. It is found that the neutron emission is the most probable in comparison with the charged particles and the $α$ yields are comparable with the hydrogen isotopes in magnitude. The preequilibrium clusters are mainly produced from the projectile-like and target-like fragments in the evolution of dinuclear system. The kinetic energy spectra manifest the Boltzmann distribution and the Coulomb potential influences the structure. The preequilibrium clusters follows the angular distribution of multinucleon transfer fragments.
nucl-thNucl.Sci.Tech.(2025)·3 citations
07
Probing the neutron-skin thickness via the double-charge exchange reactions in pion-nucleus collisions
Ban Zhang🇨🇳 · Zhao-Qing Feng🇨🇳
Within the framework of Lanzhou quantum molecular dynamics (LQMD) transport model, we investigate the influence of the neutron-skin thickness of neutron-rich nuclei on the pion emission in the double-charge exchange reactions near the $△$ -resonance energy, in particular, the rapidity and transverse momentum spectra, charged pion ratios et al. The reactions induced by pions are associated with the multiple processes of pions, nucleons and $△$ -resonances, correlated with the neutron-skin thickness. It is found that the kinetic energy spectra of $π^{-}$ / $π^{+}$ ratio are sensitive to the neutron-skin thickness of neutron-rich nuclei for extracting the subsaturation-density symmetry energy. The double-charge exchange reactions are influenced by the neutron-skin thickness, in-medium properties of resonances, pion-nucleon potential and pion-nucleon scattering.
nucl-thPRC(2026)·1 citation
08
Exploring the role of low-lying intrinsic degrees of freedom and their impact on fusion cross-sections
Nishu Jain · M. Bhuyan · Raj Kumar
The present work focuses on examining the low-lying intrinsic degrees of freedom and their impact on fusion dynamics. Fusion cross-sections were calculated using the coupled-channel code CCFULL for four specific reactions: $^{18}$ O+ $^{74}$ Ge, $^{18}$ O+ $^{148}$ Nd, $^{18}$ O+ $^{182}$ W, and $^{18}$ O+ $^{186}$ W, all conducted at energies below the Coulomb barrier across various energy levels. Vibrational and rotational features were studied concerning energy to distinguish their respective effects on fusion properties. The results indicate that the theoretical calculations for the nuclei $^{74}$ Ge, $^{148}$ Nd, $^{182}$ W and $^{186}$ W closely match the experimental data, particularly for the $2^{+}$ excited states. While slight discrepancies are observed for other excited states ( $4^{+}$ and $6^{+}$ ), overall agreement remains significant. Additionally, the study reveals that hexadecapole deformation with different magnitudes have significant influences on the fusion cross-section. In cases where $β_{4}$ has a positive value, rotational levels beyond $6^{+}$ have minimal impact on the cross-section, resulting in a notable difference in the contribution of sequential channels. In contrast, for negative $β_{4}$ values, rotational energy levels up to the $2^{+}$ state substantially affect the fusion characteristics. Furthermore, the analysis extends to the estimation of the relative change ( $Δ σ_{f u s}$ ) between the excited states and the ground state, both with and without considering coupling terms.
nucl-thMod.Phys.Lett.A(2025)·0 citations
09
Jet shape modification in a transport calculation
Monideepa Maity🇮🇳 · Subrata Pal🇮🇳
A precise quantification of the medium-modification of the high transverse momenta jets in relativistic heavy ion collisions rely on consistent modelling of elastic and inelastic energy loss suffered by the jet and the concurrent underlying medium evolution. We have developed a unified framework for jet and bulk medium evolution within a multiphase transport approach where the jets and medium share energy and momentum via multiple elastic scatterings and medium-induced gluon radiation during the parton transport. The formulation enables realistic predictions of jet based observables extended to a large radius of the jet cone in central Pb-Pb collisions at 5.02 TeV. The model provides reasonable quantitative agreement with the experimental data from inclusive jet suppression and the full jet shape function up to large radial distances induced by both the collisional and radiative jet energy loss and migration of the lost $p_{T}$ in the medium. We find that gradual degradation of jet energy through gluon emissions alters the energy-momentum evolution in the jet, essential to describe the entire range of jet shape ratio relative to proton-proton collisions. Pure collisional energy loss injects appreciable $p_{T}$ broadening and migration of the medium partons, resulting in an enhanced population at large angular distances in the jet-shape ratio.
nucl-thhep-phPLB(2025)·0 citations
10
Probing $Λ$ potential via its $v_{2}$ flow in hypernuclei-induced reaction
Gao-Chan Yong🇨🇳
The hyperon potential, particularly its behavior at high densities, is crucial for resolving the ``hyperon puzzle'' in neutron stars and for advancing our understanding of the strong interactions between strange and non-strange particles in high baryon density environments. Using the hadronic transport model AMPT-HC, hypernucleus-nucleus collision is studied. It is found that at beam energies below the threshold for hyperon production, the hyperon elliptic flow exhibits noticeable asymmetry between the positive and negative rapidity regions and is sensitive to the strength of the hyperon potential, especially in the large negative rapidity region. One can extract the hyperon potential approximately twice the saturation density based on the hyperon elliptic flow in the negative rapidity region, and the hyperon potential around the saturation density based on the hyperon elliptic flow in the positive rapidity region.
nucl-thnucl-exPLB(2025)·2 citations
11
Constraining the neutron star equation of state by including the isoscalar-vector and isovector-vector coupling using the Bayesian analysis
Deepak Kumar🇮🇳 · Pradip Kumar Sahu🇮🇳
We constrain the nuclear matter equation of state within the relativistic mean field model by including the isoscalar-vector and isovector-vector coupling term at a fundamental level using the Bayesian analysis. We used the nuclear saturation properties and recent astrophysical observations to constrain the dense matter equation of state. We obtained about 20000 sets of equations of states out of sampling about 60 millions sets of equations of states. All 20000 equations of states satisfy nuclear matter saturation properties at saturation densities and produces high mass neutron stars. In our findings, we find that the non-zero value of isoscalar-vector and isovector-vector coupling parameter and negative value of sigma meson self-coupling stiffen the equation of state. Our sets of equations of state produces neutron stars of mass larger than 2.5 M $_{⊙}$ to include the recent gravitational waves observation GW190419.
nucl-thastro-ph.HEhep-phhep-th2 citations
12
Transverse momentum fluctuations as a probe of thermalization and collective dynamics of QGP
Rupam Samanta🇵🇱 · Tribhuban Parida🇮🇳
We study fluctuations of mean transverse momentum per particle ( $[p_{T}]$ ) in ultrarelativistic heavy-ion collisions. We show that the steep fall in the variance of transverse momentum fluctuation in ultracentral Pb+Pb collision serves as a natural consequence of the thermalization of the QGP medium. We study the correlation between the spectra and $[p_{T}]$ which maps these fluctuations differentially and dubbed as $v_{0} (p_{T})$ . We highlight the importance of $v_{0} (p_{T})$ showing that it plays similar role as anisotropic flow when probing the collective nature of QGP.
nucl-thnucl-exJ.Subatomic Part.Cosmol.(2025)·1 citation
13
Dynamical coupled-channel models for hadron dynamics
Michael Döring🇺🇸 · Johann Haidenbauer🇩🇪 · Maxim Mai🇺🇸 · Toru Sato🇯🇵
Dynamical coupled-channel (DCC) approaches parametrize the interactions and dynamics of two and more hadrons and their response to different electroweak probes. The inclusion of unitarity, three-body channels, and other properties from scattering theory allows for a reliable extraction of resonance spectra and their properties from data. We review the formalism and application of the ANL-Osaka, the Juelich-Bonn-Washington, and other DCC approaches in the context of light baryon resonances from meson, (virtual) photon, and neutrino-induced reactions, as well as production reactions, strange baryons, light mesons, heavy meson systems, exotics, and baryon-baryon interactions. Finally, we also provide a connection of the formalism to study finite-volume spectra obtained in Lattice QCD, and review applications involving modern statistical and machine learning tools.
nucl-thhep-lathep-phnucl-exPPNP(2026)·45 citations
14
Connecting afterglow light curves to the GRB central engine
Muhammed Diyaddin Ilhan · Kai Schwenzer
Gamma ray burst (GRB) afterglow light curves have the potential to inform us about presently unobserved stages in the aftermath of a neutron star merger. Using numerical simulations of short GRB afterglows we obtain an approximate quantitative connection between key aspects of the emission mechanism and the shapes of the resulting light curves. Employing simple, but efficient, parameterizations of the light curve based on a broken power law in terms of physical parameters, fitted to a large dataset of synthetic light curves, we apply basic machine learning techniques to determine the approximate connection between key input parameters of the forward shock model and the light curve parameters. Solving then the inverse problem, we find that the strength of the central engine can be reasonably accurately estimated even with very limited information. In particular, merely the position of jet-break in the on-axis, respectively the maximum in the off-axis light curve determines the kinetic energy at the tens of percent level.
↳ astro-ph.HEgr-qcnucl-th0 citations
15
Realization of all-to-all fermion propagator for the first principle high accuracy strong interaction prediction
Zhi-Cheng Hu🇨🇳 · Ji-Hao Wang🇨🇳 · Xiangyu Jiang🇨🇳 · Liuming Liu🇨🇳 · Shi-Hao Su🇨🇳 · Peng Sun🇨🇳 · Yi-Bo Yang🇨🇳
We propose a ``blending" algorithm that projects the all-to-all fermion propagator onto spatial low-frequency modes (LFM) combined with a stochastic estimate of spatial high-frequency modes (SHFM) at each time slice. This approach enables the calculation of arbitrary-point correlation functions for arbitrary hadron states in strongly interacting quantum field theories (QFT) with fermions, such as quantum chromodynamics (QCD). Specifically, LFM allows the construction of spatially extended hadron states below a certain energy threshold by diagonalizing multi-fermion interpolation fields. Meanwhile, the local interactions required for N-point correlation functions in QFT can be approximated in an unbiased manner through a reweighted summation of both LFM and SHFM contributions. To demonstrate the efficiency of this algorithm, we obtained {\color{black} $g_{A}^{u} = 0.895 (15)$ , $g_{A}^{d} = - 0.338 (15)$ , $g_{A}^{s} = - 0.0245 (72)$ , $g_{A}^{u + d + s} = 0.533 (28)$ and $g_{A}^{u - d} = 1.2339 (43)$ } for nucleon at $m_{π} = 300$ MeV and $a = 0.077$ fm using 40 configurations. The consistency check of the pion electric form factor and charge radius derived from 3-point and 4-point correlation functions is also provided.
↳ hep-lathep-phnucl-th3 citations
16
Chiral anomaly from (anomalous) spin hydrodynamics
Jay Armas🇳🇱 · Giorgos Batzios🇳🇱
We show that the low energy fluctuations of spinning black Dp branes are described by a theory of spin hydrodynamics on a spacetime $M_{p + 1} \times T^{n + 2}$ in which the fluid is flowing on $M_{p + 1}$ and spinning on $T^{n + 2}$ . Focusing on the hydrodynamic regime of $N = 4$ supersymmetric Yang-Mills theory, we provide a geometric interpretation of the R-current anomaly in terms of a gravitational anomaly from the ten-dimensional point of view. This follows from the holographic duality between a spinning fluid in ten dimensions and an anomalous chiral fluid in four dimensions. We comment on the relations between the theory of spin hydrodynamics introduced here and other theories of spin hydrodynamics in the context of heavy-ion collisions.
↳ hep-thhep-phnucl-thPRD(2026)·3 citations
17
Unified exact WKB framework for resonance -- Zel'dovich/complex-scaling regularization and rigged Hilbert space
Okuto Morikawa🇯🇵 · Shoya Ogawa🇯🇵
We develop a unified framework for analyzing quantum mechanical resonances using the exact WKB method. The non-perturbative formulation based on the exact WKB method works for incorporating the Zel'dovich regularization, the complex scaling method, and the rigged Hilbert space. While previous studies have demonstrated the exact WKB analysis in bound state problems, our work extends its application to quasi-stationary states. By examining the inverted Rosen--Morse potential, we illustrate how the exact WKB analysis captures resonant phenomena in a rigorous manner. We explore the equivalence and complementarity of different well-established regularizations à la Zel'dovich and complex scaling within this framework. Also, we find the most essential regulator of functional analyticity and construct a modified Hilbert space of the exact WKB framework for resonance, which is called the rigged Hilbert space. This offers a deeper understanding of resonant states and their analytic structures. Our results provide a concrete demonstration of the non-perturbative accuracy of exact WKB methods in unstable quantum systems.
↳ hep-thnucl-thquant-phJHEP(2025)·7 citations
18
Local equilibrium Wigner function for spin-1/2 particles
Samapan Bhadury🇵🇱 · Zbigniew Drogosz🇵🇱 · Wojciech Florkowski🇵🇱 · Sudip Kumar Kar🇵🇱 · Valeriya Mykhaylova🇵🇱
Formal connections between the spin density matrix and the Wigner function for spin-1/2 particles forming a relativistic gas are explored to determine their general structures. They suggest that the commonly used form of the local equilibrium Wigner function should be replaced by a new expression. The latter fulfills the necessary condition for the normalization of the mean spin polarization, which the former fails to reproduce. The new definition of the Wigner function leads to generalized thermodynamic relations for perfect spin hydrodynamics, identical to those obtained earlier using the classical concept of spin. Moreover, one can prove that the perfect spin hydrodynamics based on the new equilibrium Wigner function is nonlinearly causal and stable. Finally, the selection rule for the Lagrange multipliers, which is satisfied by real systems, is discussed.
↳ hep-phnucl-th13 citations

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