Nuclear Theory·nucl-th

Friday·December 22, 2023

17 papers—9 primary·8 cross-listed

01
Impact of tensor interactions and scalar mixing on covariant energy density functionals
Marc Salinas · Jorge Piekarewicz
The recent pioneering campaigns conducted by the Lead Radius Experiment (PREX) and the Calcium Radius Experiment (CREX) collaborations have uncovered major deficiencies in the theoretical description of some fundamental properties of atomic nuclei. Following a recent refinement to the isovector sector of covariant energy density functionals [1], we present here additional improvements to the functional by including both tensor couplings and an isoscalar-isovector mixing term in the scalar sector. Motivated by the distinct surface properties of calcium and lead, we expect that the tensor terms that generate derivative couplings will help break the linear correlation between the neutron skin thickness of these two nuclei. Moreover, the addition of these new terms mitigates most of the problems identified in Ref.[1] in describing the properties of both finite nuclei and neutron stars. While significant progress has been made in reconciling the PREX-CREX results without compromising other observables, the final resolution awaits the completion of a proper calibration for this new class of functionals. We expect that powerful reduced basis methods used recently to create efficient emulators will be essential to accomplish this task.
nucl-thnucl-exPRC(2024)·18 citations
02
Relativistic heat conduction in the large-flux regime
Lorenzo Gavassino
We propose a general procedure for evaluating, directly from microphysics, the constitutive relations of heat-conducting fluids in regimes of large fluxes of heat. Our choice of hydrodynamic formalism is Carter's two-fluid theory, which happens to coincide with Öttinger's GENERIC theory for relativistic heat conduction. This is a natural framework, as it should correctly describe the relativistic ``inertia of heat'' as well as the subtle interplay between reversible and irreversible couplings. We provide two concrete applications of our procedure, where the constitutive relations are evaluated respectively from maximum entropy hydrodynamics and Chapman-Enskog theory.
nucl-thastro-ph.HEgr-qcEntropy(2024)·2 citations
03
Probing configuration of $α$ clusters with spectator particles in relativistic heavy-ion collisions
Lu-Meng Liu🇨🇳 · Song-Jie Li🇨🇳 · Zhen Wang🇨🇳 · Jun Xu🇨🇳 · Zhong-Zhou Ren🇨🇳 · Xu-Guang Huang🇨🇳
We propose to use spectator particle yield ratios to probe the configuration of $α$ clusters in $^{12}$ C and $^{16}$ O by their collisions at RHIC and LHC energies. The idea is illustrated based on initial density distributions with various $α$ -cluster configurations generated by a microscopic cluster model, and without $α$ clusters from mean-field calculations. The multifragmentation of the spectator matter produces more spectator light nuclei including $α$ clusters in collisions of nuclei with chain structure of $α$ clusters, compared to those of nuclei with a more compact structure. The yield ratio of free spectator neutrons to spectator particles with mass-to-charge ratio $A / Z = 2$ scaled by their masses can be practically measured by the zero-degree calorimeter (ZDC) at RHIC and LHC, serving as a clean probe free from modeling the complicated dynamics at midrapidities.
nucl-thhep-exnucl-exPLB(2024)·16 citations
04
Microscopic study of $M$ 1 resonances in Sn isotopes
Shuai Sun · Li-Gang Cao · Feng-Shou Zhang · Hiroyuki Sagawa · Gianluca Colò
The magnetic dipole ( $M$ 1) resonances of even-even $^{112 - 120, 124}$ Sn isotopes are investigated in the framework of the self-consistent Skyrme Hartree-Fock (HF) + BCS and Quasiparticle Random Phase Approximation (QRPA). The Skyrme energy density functionals SLy5 and T11 with and without tensor terms are adopted in our calculations. The mixed type pairing interaction is used to take care of the pairing effect for open-shell nuclei both in the ground and excited states calculations. The calculated magnetic dipole strengths are compared with available experimental data. The QRPA results calculated by SLy5 and T11 with tensor force show a better agreement with the experimental data than those without the tensor force. By analyzing the HF and QRPA strength distributions of $^{112}$ Sn and $^{124}$ Sn, we discuss the effect of tensor force on the $M$ 1 resonances in detail. It is found that the $M$ 1 resonance is sensitive to the tensor interaction, and favors especially a negative triplet-odd tensor one. Depending on the nucleus, a quenching factor of the $M$ 1 operator of about 0.71-0.95 is needed to reproduce the total observed transition strength. In our calculations, we also find some low-lying, pygmy-type magnetic dipole states distributed below 6.0 MeV, and they are formed mainly from the neutron configuration $ν$ 2 $d_{5/2}$ $\to$ $ν$ 2 $d_{3/2}$ .
nucl-thPRC(2024)·3 citations
05
Deuteron production in a combined thermal and coalescence framework for heavy-ion collisions in the few-GeV energy regime
Wojciech Florkowski🇵🇱 · Radoslaw Ryblewski🇵🇱 · Piotr Salabura🇵🇱 · Nikodem Witkowski🇵🇱
A recently formulated thermal model for hadron production in heavy-ion collisions in the few-GeV energy regime is combined with the idea that some part of protons and neutrons present in the original thermal system forms deuterons via the coalescence mechanism. Using realistic parametrizations of the freeze-out conditions, which reproduce well the spectra of protons and pions, we make predictions for deuteron transverse-momentum and rapidity spectra. The best agreement with the experimentally known deuteron yield is obtained if the freeze-out temperature is relatively high and, accordingly, the system size at freeze-out is rather small. In addition, the standard Gaussian distribution of the relative distance between nucleons is replaced by the distribution resulting from their independent and approximately uniform production inside the initial thermal system.
nucl-thhep-phnucl-exActa Phys.Polon.B(2024)·5 citations
06
Effect of the equation of state for dilute neutron matter on the composition of the inner crust of neutron stars
Sunny Kumar Gupta🇮🇳 · Michael Urban🇫🇷
The composition of the inner crust of neutron stars is usually studied using phenomenological interactions such as Skyrme energy-density functionals. But most of these functionals do not agree well with ab-initio calculations of very dilute neutron matter. In this work, we study the inner crust of neutron stars in the model of phase coexistence of dense neutron-rich nuclear clusters and dilute neutron gas, and we investigate how employing a realistic microscopic equation of state to the neutron gas alters the composition. Our results indicate that with a functional that reproduces the correct equation of state of neutron matter at moderate densities, one can obtain a good description of the crust even if the functional does not have the correct behavior at extremely low density.
nucl-thPRC(2024)·3 citations
07
Towards consistent nuclear interactions from chiral Lagrangians II: Symmetry preserving regularization
Hermann Krebs🇩🇪 · Evgeny Epelbaum🇩🇪
Low-energy nuclear structure and reactions can be described in a systematically improvable way using the framework of chiral effective field theory. This requires solving the quantum mechanical many-body problem with regularized nuclear forces and current operators, derived from the most general effective chiral Lagrangian. To maintain the chiral and gauge symmetries, a symmetry preserving cutoff regularization has to be employed when deriving nuclear potentials. Here, we discuss various regularization techniques and show how this task can be accomplished by regularizing the pion field in the effective chiral Lagrangian using the gradient flow method. The actual derivation of the nuclear forces and currents from the regularized effective Lagrangian can be carried out utilizing the novel path-integral approach introduced in our earlier paper.
nucl-thhep-phhep-thPRC(2024)·27 citations
08
Event-by-event Kinetic Description of Pre-Equilibrium Charge Evolution in QCD Plasma
Travis Dore🇩🇪 · Xiaojian Du🇩🇪 · Sören Schlichting🇩🇪
We use QCD effective kinetic theory to calculate far-from-equilibrium dynamics on an event-by-event basis within the Kø{}MPø{}ST framework. We present non-equilibrium charge response functions and the dynamical evolution of the conserved charge current pertinent to the early-time dynamics of heavy-ion collisions at the highest energies. The Kø{}MPø{}ST framework with conserved baryon, strangeness, and electric charges can then be readily implemented into a multistage model allowing for the initialization of a non-equilibrium charge current in hydrodynamic simulations.
nucl-thhep-phEPJ Web Conf.(2024)·3 citations
09
Equation of state at neutron-star densities and beyond from perturbative QCD
Oleg Komoltsev🇳🇴 · Rahul Somasundaram🇺🇸 · Tyler Gorda🇩🇪 · Aleksi Kurkela🇳🇴 · Jérôme Margueron🇫🇷 · Ingo Tews🇺🇸
We explore the consequences of imposing robust thermodynamic constraints arising from perturbative Quantum Chromodynamics (QCD) when inferring the dense-matter equation-of-state (EOS). We find that the termination density, up to which the EOS modeling is performed in an inference setup, strongly affects the constraining power of the QCD input. This sensitivity in the constraining power arises from EOSs that have a specific form, with drastic softening immediately above the termination density followed by a strong stiffening. We also perform explicit modeling of the EOS down from perturbative-QCD densities to construct a new QCD likelihood function that incorporates additional perturbative-QCD calculations of the sound speed and is insensitive to the termination density, which we make publicly available.
nucl-thastro-ph.HEhep-phPRD(2024)·71 citations
10
On the spin period distribution of millisecond pulsars
Xiao-Jin Liu · Zhi-Qiang You · Zu-Cheng Chen · Shen-Shi Du · Ang Li · Xing-Jiang Zhu
Spin period distribution provides important clues to understand the formation of millisecond pulsars (MSPs). To uncover the intrinsic period distribution, we analyze three samples of radio MSPs in the Galactic field and in globular clusters. The selection bias due to pulse broadening has been corrected but turns out to be negligible. We find that all the samples can be well described by a Weibull distribution of spin frequencies. Considering MSPs in the Galactic field or in globular clusters, and in isolation or in binary systems, we find no significant difference in the spin distribution among these subpopulations. Based on the current known population of MSPs, we find that sub-millisecond pulsars are unlikely to be discovered by the Square Kilometer Array, although up to $\sim 10$ discoveries of pulsars that spin faster than the current record holder of $P = 1.4$ ~ms are expected.
↳ astro-ph.HEnucl-thApJ(2024)·11 citations
11
JLab spectral functions of argon in NuWro and their implications for MicroBooNE
Rwik Dharmapal Banerjee🇵🇱 · Artur M. Ankowski🇵🇱 · Krzysztof M. Graczyk🇵🇱 · Beata E. Kowal🇵🇱 · Hemant Prasad🇵🇱 · Jan T. Sobczyk🇵🇱
The Short-Baseline Neutrino program in Fermilab aims to resolve the nature of the low-energy excess events observed in LSND and MiniBooNE, and analyze with unprecedented precision neutrino interactions with argon. These studies require reliable estimate of neutrino cross sections, in particular for charged current quasielastic scattering (CCQE). Here, we report updates of the NuWro Monte Carlo generator that, most notably, bring the state-of-the-art spectral functions to model the ground state properties of the argon nucleus, and improve the accuracy of the cross sections at low energies by accounting for the effects of the nuclear Coulomb potential. We discuss these developments in the context of electron and neutrino interactions, by comparing updated NuWro predictions to experimental data from Jefferson Laboratory Hall A and MicroBooNE. The MicroBooNE CCQE data are described with the $χ^{2}$ per degree of freedom of 0.7, compared with 1.0 in the local Fermi gas model. The largest improvement is observed for the angular distributions of the produced protons, where the $χ^{2}$ reduces nearly by half. Being obtained using the axial form factor parametrization from MINERvA, our results indicate a~consistency between the CCQE measurements in MINERvA and MicroBooNE.
↳ hep-phnucl-thPRD(2024)·16 citations
12
Testing Eigenstate Thermalization Hypothesis for Non-Abelian Gauge Theories
Xiaojun Yao🇺🇸 · Lukas Ebner🇩🇪 · Berndt Müller🇺🇸 · Andreas Schäfer🇩🇪 · Clemens Seidl🇩🇪
We report on progress in full quantum understanding of thermalization in non-Abelian gauge theories. Specifically, we test the eigenstate thermalization hypothesis for (2+1)-dimensional SU(2) lattice gauge theory.
↳ hep-latcond-mat.stat-mechhep-phnucl-th+1EPJ Web Conf.(2024)·4 citations
13
Impact of the MARATHON data on \texorpdfstring{ $F_{2 n} / F_{2 p}$ }{F2n/F2p} and off-shell effects in light nuclei
T. J. Hague (1) · J. Arrington (1) · S. Li (1) · S. N. Santiesteban (2) ((1) Lawrence Berkeley National Laboratory · (2) University of New Hampshire)
The neutron structure function, $F_{2 n}$ , has historically been extracted from measurements of the deuteron structure function, but our understanding of the nuclear effects on the bound proton and neutron limits the extraction of $F_{2 n}$ . The MARATHON collaboration recently extracted $F_{2 n}$ from the comparison of $^{3}$ H and $^{3}$ He targets, where the nuclear effects are larger but nearly identical, yielding a precise extraction of $F_{2 n} / F_{2 p}$ . This precise extraction can then be compared to deuteron extractions, providing important constraints on the nuclear effects in the deuteron. To ensure that this comparison is not biased by the specific model of nuclear effects used by MARATHON, we examine a range of models of the nuclear effects to obtain a more conservative, but more model-independent, extraction of $F_{2 n} / F_{2 p}$ for comparison with deuteron extractions. Even with the more conservative approach, the comparison suggests the need for significant off-shell corrections or other nuclear effects, beyond those include in most calculations, even for the weakly-bound deuteron.
↳ nucl-exnucl-thPRC(2024)·2 citations
14
A Possible Solution to the Difficulty in the Interpretation of Deuteron Compositeness
Zanpeng Yin🇯🇵 · Daisuke Jido🇯🇵
We study the theoretical structure of compositeness with explicit energy dependence, and find a possible explanation for the difficulty in the interpretation of compositeness of deuteron. Compositeness of deuteron is calculated as larger than one in many methods like weak-binding limit. Even though it is widely assumed that the energy dependence in interaction always comes from other states, which we call surjective interpretation, we find that the outcome of deuteron may suggest a violation of surjective interpretation. We directly perform numerical and perturbative calculations of deuteron compositeness. It is concluded that if the energy dependent part of interaction contributes to attraction, compositeness is likely to be enhanced from unity. We discuss the indications of this outcome and the model dependence of compositeness. We propose a straightforward extension and a thorough revise on the formalism of compositeness with field theory considerations.
↳ hep-phnucl-thPRC(2024)·5 citations
15
Quarkonium spectral functions in a bulk-viscous quark-gluon plasma
Lata Thakur🇰🇷 · Yuji Hirono🇰🇷
We study the interplay of non-equilibrium properties of a quark-gluon plasma (QGP) and heavy quarkonia. For this purpose, we compute the quarkonium spectral functions in a bulk-viscous QGP. We take into account the bulk viscous nature of the medium by modifying the distribution functions of thermal quarks and gluons. This modification affects the dielectric permittivity, which is used to calculate the in-medium heavy quark potential. With this modified complex potential, we calculate the quarkonium spectral functions and extract their physical properties. We discuss the impact of bulk viscosity on quarkonia properties such as decay widths and binding energies. We also estimate the relative production yield of $ψ^{'}$ to $J / ψ$ and discuss the bulk viscous effects on it.
↳ hep-phnucl-thNuovo Cim.C(2024)·0 citations
16
Spectrum of the molecular pentaquarks
Bo Wang🇨🇳 · Kan Chen🇨🇳 · Lu Meng🇩🇪 · Shi-Lin Zhu🇨🇳
We investigate the mass spectrum of the molecular pentaquarks composed of a baryon and a meson. We establish the underlying relations among the near-threshold interactions of the molecular tetraquark and pentaquark systems. We find the existence of the molecule candidates in the $Σ_{c} D ˉ^{(*)}$ , $D D^{*}$ , and $D D ˉ^{*}$ systems indicates a substantial presence of the hadronic molecules in the {\it heavy} baryon plus {\it heavy} meson systems ({\it heavy} refers to the hadrons with the $c$ and/or $s$ quarks). We make an exhaustive prediction of the possible bound/virtual molecular states in the systems: $Σ_{c}^{(*)} D ˉ^{(*)}$ , $Σ_{c}^{(*)} D^{(*)}$ , $Ξ_{c}^{(', *)} D ˉ^{(*)}$ , $Ξ_{c}^{(', *)} D^{(*)}$ , $Σ_{c}^{(*)} K^{*}$ , $Σ_{c}^{(*)} K ˉ^{*}$ , $Ξ_{c}^{(', *)} K^{*}$ , $Ξ_{c}^{(', *)} K ˉ^{*}$ , $Ξ_{cc}^{(*)} D ˉ^{(*)}$ , $Ξ_{cc}^{(*)} D^{(*)}$ , $Ξ_{cc}^{(*)} K^{*}$ , $Ξ_{cc}^{(*)} K ˉ^{*}$ , $Σ^{(*)} D ˉ^{(*)}$ , $Σ^{(*)} D^{(*)}$ , $Ξ^{(*)} D ˉ^{(*)}$ , $Ξ^{(*)} D^{(*)}$ , $Σ^{(*)} K^{*}$ , $Σ^{(*)} K ˉ^{*}$ , $Ξ^{(*)} K^{*}$ , $Ξ^{(*)} K ˉ^{*}$ . Hunting for the predicted states in experiments will significantly deepen our understanding of the formation mechanism of the hadronic molecules, and shed light on the manifestation of flavor symmetry in the low-energy residual strong interactions.
↳ hep-phhep-exnucl-thPRD(2024)·31 citations
17
Nucleon to $Δ$ axial and pseudoscalar transition form factors
Chen Chen🇨🇳 · Christian S. Fischer🇩🇪 · Craig D. Roberts🇨🇳
A symmetry-preserving continuum approach to the calculation of baryon properties in relativistic quantum field theory is used to predict all form factors associated with nucleon-to- $Δ$ axial and pseudoscalar transition currents, thereby unifying them with many additional properties of these and other baryons. The new parameter-free predictions can serve as credible benchmarks for use in analysing existing and anticipated data from worldwide efforts focused on elucidation of $ν$ properties.
↳ hep-phhep-exhep-latnucl-ex+1PRL(2024)·20 citations

Affiliations

first authorsco-authorsvia INSPIRE