Nuclear Theory·nucl-th

Tuesday·March 7, 2023

15 papers—7 primary·8 cross-listed

01
Dynamical mechanisms for deuteron production at mid-rapidity in relativistic heavy-ion collisions from SIS to RHIC energies
Gabriele Coci🇩🇪 · Susanne Gläßel🇩🇪 · Viktar Kireyeu🇩🇪 · Jörg Aichelin🇫🇷 · Christoph Blume🇩🇪 · Elena Bratkovskaya🇩🇪 · Vadim Kolesnikov🇷🇺 · Vadim Voronyuk🇩🇪
The understanding of the mechanisms for the production of weakly bound clusters, such as a deuteron $d$ , in heavy-ion reactions at mid-rapidity is presently one of the challenging problems which is also known as the "ice in a fire" puzzle. In this study we investigate the dynamical formation of deuterons within the Parton-Hadron-Quantum-Molecular Dynamics (PHQMD) microscopic transport approach and advance two microscopic production mechanisms to describe deuterons in heavy-ion collisions from SIS to RHIC energies: kinetic production by hadronic reactions and potential production by the attractive potential between nucleons. Differently to other studies, for the "kinetic" deuterons we employ the full isospin decomposition of the various $π N N \leftrightarrow π d$ , $N N N \leftrightarrow N d$ channels and take into account the finite size properties of the deuteron by means of an excluded volume condition in coordinate space and by the projection onto the deuteron wave function in momentum space. We find that considering the quantum nature of the deuteron in coordinate and momentum space reduces substantially the kinetic deuteron production in a dense medium as encountered in heavy-ion collisions. If we add the "potential" deuterons by applying an advanced Minimum Spanning Tree (aMST) procedure, we obtain good agreement with the available experimental data from SIS energies up to the top RHIC energy.
nucl-thPRC(2023)·43 citations
02
Octupole deformation of nuclei near the spherical closed-shell configurations
Ken-ichiro Arita
The origin of octupole deformation for even-even nuclei near the doubly-closed shell configurations are investigated by means of the semiclassical periodic orbit theory. In order to focus on the change of shell structure due to deformation, a simple infinite-well potential model is employed with octupole shape parametrized by merging a sphere and a paraboloid. Attention is paid to the contributions of the degenerate families of periodic orbits (POs) confined in the spherical portion of the potential, that are expected to partially preserve the spherical shell effect up to considerably large value of the octupole parameter. The contribution of those POs to the semiclassical trace formula plays an important role in bringing about shell energy gain due to octupole deformation in the system with a few particles added to spherical closed-shell configurations.
nucl-thPRC(2023)·2 citations
03
Fourier-over-Spheroid shape parametrization applied to nuclear fission dynamics
K. Pomorski🇵🇱 · B. Nerlo-Pomorska🇵🇱 · C. Schmitt🇫🇷 · Z.G. Xiao🇨🇳 · Y. J. Chen🇨🇳 · L.L. Liu🇨🇳
We propose a new, rapidly convergent, the so-called Fourier over Spheroid (FoS), shape parametrization to model fission of heavy nuclei. Four collective coordinates are used to characterize the shape of the fissioning system, being its elongation, left-right asymmetry, neck size, and non-axiality. The potential energy landscape is computed within the macroscopic-microscopic approach, on the top of which the multi-dimensional Langevin equation is solved to describe the dynamics. Charge equilibration at scission and de-excitation of the primary fragments after scission are further considered. The model gives access to a wide variety of observables, including fission fragments mass, charge, and kinetic energy yields, fragment mean N/Z and post-scission neutron multiplicities, and importantly, their correlations. The latter are crucial to unravel the complexity of the fission process. The parameters of the model were tuned to reproduce experimental observation from thermal neutron-induced fission of 235U, and next used to discuss the transition from the asymmetric to symmetric fission along the Fm isotopic chain.
nucl-thnucl-exPRC(2023)·20 citations
04
Description of inclusive $(d, d^{'} x)$ reaction with the semiclassical distorted wave model
Hibiki Nakada · Kazuki Yoshida · Kazuyuki Ogata
The description of deuteron-induced inclusive reactions has been an important subject in direct nuclear reaction studies and nuclear data science. For proton-induced inclusive processes, the semiclassical distorted wave model (SCDW) is one of the most successful models based on quantum mechanics. We improve SCDW for deuteron-induced inclusive processes and clarify the importance of the proper treatment of the kinematics of the deuteron inside a nucleus. The double differential cross section (DDX) of the inclusive deuteron-emission process $(d, d^{'} x)$ is described by one-step SCDW. The changes in the kinematics due to the distortion effect, the refraction effect, is taken into account by the local semiclassical approximation (LSCA). The calculated DDXs of $(d, d^{'} x)$ reasonably reproduce experimental data in the small energy-transfer region and at forward and middle angles with some exceptions. The angular distributions of $(d, d^{'} x)$ are improved by including the refraction effect. The proper treatment of the changes in the kinematics of the deuteron inside a nucleus is necessary in describing the ( $d$ , $d^{'} x$ ) reaction. The effect of the changes on the DDX of $(d, d^{'} x)$ is significant compared to on the proton-induced inclusive process $(p, p^{'} x)$ because of the stronger distortion effect on the deuteron.
nucl-thnucl-exPRC(2023)·4 citations
05
A Crossover phase transition based on the phenomenology of hadronic matter and quark matter
Mahboubeh Shahrbaf🇵🇱
The phase transition calculations are utilized for an in-depth understanding of the thermodynamics of the deconfinement transition to perform the best analysis of the QCD phase diagram. The phenomenological justifications for a mathematical approach to constructing the phase transition are found based on the properties of hadronic matter at low densities as well as quark matter at high densities. We modify both the quark matter equation of state by confining effects at low densities and the hadronic matter equation of state by excluded volume effects at higher densities. Over the intermediate densities, the transition from the hadronic phase to the quark phase is modified by the surface tension between to phases. The results are in agreement with the observational constraints of neutron stars.
nucl-thhep-ph0 citations
06
Excitation functions of related temperatures of {\eta} and {\eta}0 emission sources from squared momentum transfer spectra in high-energy collisions
Qi Wang🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿
The squared momentum transfer spectra of $η$ and $η^{0}$ , produced in high-energy photon-proton ( $γ p$ ) $\to η (η^{0}) + p$ processes in electron-proton ( $e p$ ) collisions performed at CEBAF, NINA, CEA, SLAC, DESY, and WLS are analyzed. The Monte Carlo calculations are used in the analysis of the squared momentum transfer spectra, where the transfer undergoes from the incident $γ$ to emitted $η (η^{0})$ or equivalently from the target proton to emitted proton. In the calculations, the Erlang distribution and Tsallis-Levy function are used to describe the transverse momentum ( $p_{T}$ ) spectra of emitted particles. Our results show that the average transverse momentum ( $⟨ p_{T} ⟩$ ), the initial-state temperature ( $T_{i}$ ), and the final-state temperature ( $T_{0}$ ) roughly decrease from the lower center-of-mass energy ( $W$ ) to the higher one in the concerned energy range of a few GeV, which is different from the excitation function from heavy-ion collisions in the similar energy range.
hep-phnucl-thUniverse(2023)·4 citations
07
Quasielastic (p, n) reactions described by a microscopic optical model based on the Gogny force
Juan López Moraña · Xavier Viñas
In this work we want to study quasielastic (p, n) exchange reactions using a semi-microscopic optical model derived in a previous work [1] based on a nuclear matter approach where the real and imaginary parts are given by the first and second order terms, respectively, of the mass operator obtained by a Brueckner-Hartree-Fock calculation using a G-matrix built up with an effective Gogny interaction. The study of these quasielastic reactions is performed within a Distorted Wave Born Approximation (DWBA) to evaluate the wave functions in the entrance and exit channels, which in turn are used to compute the transition matrix elements. This model, which is free of adjustable parameters, provide a reasonable good agreement with the considered experimental data, namely differential cross sections, analyzing powers and total cross sections, of different reactions spanned along the periodic table at several energies.
nucl-thJ.Phys.G(2023)·2 citations
08
Investigating the impact of spin effects at the high-energy neutrino-nucleon interactions while it crosses the Earth's core
R. Francener🇧🇷 · D.R. Gratieri🇧🇷 · G. Torrieri🇧🇷
In this work, we investigate the impact of assuming the polarization of the Earth's outer core on the propagation of neutrinos that cross the all the Earth. We taking into account the spin-dependent structure functions to describe the polarized neutrino-nucleon cross-section, and also on the neutrino absorption while it crosses all of the Earth. We found that adding spin information and simultaneously assuming polarization of Earth's outer core impacts the probability of neutrino absorption in the energy range of 10 - 100 TeV and for upward neutrino direction. However, the magnitude of the effect is small and should be comparable with the magnitude of the errors associated with the IceCube neutrino data.
↳ hep-phnucl-th1 citation
09
Bayesian uncertainty quantification of perturbative QCD input to the neutron-star equation of state
Tyler Gorda🇩🇪 · Oleg Komoltsev🇳🇴 · Aleksi Kurkela🇳🇴 · Aleksas Mazeliauskas🇩🇪
The equation of state of neutron-star cores can be constrained by requiring a consistent connection to the perturbative Quantum Chromodynamics (QCD) calculations at high densities. The constraining power of the QCD input depends on uncertainties from missing higher-order terms, the choice of the unphysical renormalization scale, and the reference density where QCD calculations are performed. Within a Bayesian approach, we discuss the convergence of the perturbative QCD series, quantify its uncertainties at high densities, and present a framework to systematically propagate the uncertainties down to neutron-star densities. We find that the effect of the QCD input on the neutron-star inference is insensitive to the various unphysical choices made in the uncertainty estimation.
↳ hep-phastro-ph.HEnucl-thJHEP(2023)·50 citations
10
Quantum Computation of Phase Transition in Interacting Scalar Quantum Field Theory
Shane Thompson🇺🇸 · George Siopsis🇺🇸
It has been demonstrated that the critical point of the phase transition in scalar quantum field theory with a quartic interaction in one space dimension can be approximated via a Gaussian Effective Potential (GEP). We discuss how this critical point can be estimated using quantum hardware. We perform quantum computations with various lattice sizes and obtain evidence of a transition from a symmetric to a symmetry-broken phase. We use both discrete- and continuous-variable quantum computation. We implement the ten-site case on IBM quantum hardware using the Variational Quantum Eigensolver (VQE) algorithm to minimize the GEP and identify lattice level-crossings. These are extrapolated via simulations to find the continuum critical point.
↳ quant-phhep-thnucl-thQuant.Inf.Proc.(2023)·7 citations
11
The Present and Future of QCD
P. Achenbach · D. Adhikari · A. Afanasev · F. Afzal · C.A. Aidala · A. Al-bataineh · D.K. Almaalol · M. Amaryan · D. Androić · W.R. Armstrong · M. Arratia · J. Arrington and 391 other authors
This White Paper presents the community inputs and scientific conclusions from the Hot and Cold QCD Town Meeting that took place September 23-25, 2022 at MIT, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 424 physicists registered for the meeting. The meeting highlighted progress in Quantum Chromodynamics (QCD) nuclear physics since the 2015 LRP (LRP15) and identified key questions and plausible paths to obtaining answers to those questions, defining priorities for our research over the coming decade. In defining the priority of outstanding physics opportunities for the future, both prospects for the short (~ 5 years) and longer term (5-10 years and beyond) are identified together with the facilities, personnel and other resources needed to maximize the discovery potential and maintain United States leadership in QCD physics worldwide. This White Paper is organized as follows: In the Executive Summary, we detail the Recommendations and Initiatives that were presented and discussed at the Town Meeting, and their supporting rationales. Section 2 highlights major progress and accomplishments of the past seven years. It is followed, in Section 3, by an overview of the physics opportunities for the immediate future, and in relation with the next QCD frontier: the EIC. Section 4 provides an overview of the physics motivations and goals associated with the EIC. Section 5 is devoted to the workforce development and support of diversity, equity and inclusion. This is followed by a dedicated section on computing in Section 6. Section 7 describes the national need for nuclear data science and the relevance to QCD research.
↳ hep-phhep-exnucl-exnucl-thNPA(2024)·135 citations
12
On-shell approximation for the s-wave scattering theory
F. Lorenzi · A. Bardin · L. Salasnich
We investigate the scattering theory of two particles in a generic $D$ -dimensional space. For the s-wave problem, by adopting an on-shell approximation for the $T$ -matrix equation, we derive analytical formulas which connect the Fourier transform $V ~ (k)$ of the interaction potential to the s-wave phase shift. In this way we obtain explicit expressions of the low-momentum parameters $g ~_{0}$ and $g ~_{2}$ of $V ~ (k) = g ~_{0} + g ~_{2} k^{2} + ...$ in terms of the s-wave scattering length $a_{s}$ and the s-wave effective range $r_{s}$ for $D = 3$ , $D = 2$ , and $D = 1$ . Our results, which are strongly dependent on the spatial dimension $D$ , are a useful benchmark for few-body and many-body calculations. As a specific application, we derive the zero-temperature pressure of a 2D uniform interacting Bose gas with a beyond-mean-field correction which includes both scattering length and effective range.
↳ cond-mat.quant-gasnucl-thPRA(2023)·8 citations
13
Gluons, light and heavy quarks and their interactions in the instanton vacuum
Mirzayusuf Musakhanov🇺🇿
The instanton size $ρ$ and inter-instanton distance $R$ are the main parameters of Instanton Liquid Model (ILM) of the QCD vacuum. Various estimates show that $ρ \approx 1/3$ fm and $R \approx 1$ fm, and the corresponding packing parameter $κ = ρ^{4} / R^{4} \approx 0.01$ . The strength of the light quark-instanton interaction is sizable and close to that of the gluon-instanton one since the dynamical light quark mass $M_{q}$ and dynamical gluon mass $M_{g}$ are given by $M_{q} \approx M_{g} \approx 360$ MeV $\sim κ^{1/2} ρ^{- 1}$ . On the other hand, the strength of the heavy quark-instanton interaction is weak - the direct instanton contribution to the heavy quark mass $Δ M_{Q}^{dir} \approx 70$ MeV $\sim κ ρ^{- 1} .$ The instantons are responsible for mutual interactions among colored particles which are crossing the field of the same instanton, like t'Hooft-like interactions of $N_{f}$ light quarks ( $N_{f}$ is the light quark flavors number). The light quark propagators in the instanton field have zero modes, which give dominant contributions. Within ILM we are able to derive the light quarks determinants and the light quarks partition function. These tools perfectly describe the light quark physics and its most important and basic phenomena - the spontaneous breaking of the chiral symmetry (SBChS) in details. These one allows us to find the properties of light and heavy quarks interactions and get SBChS traces in light-heavy and heavy-heavy quarks systems. So, we need to find heavy $Q Q ˉ$ quarkonia spectra and their wave functions. Here we have interplay of two scales: short ( $\sim (M_{Q} v)^{- 1} \leq 0.15$ fm) perturbative QCD and large ( $\sim (M_{Q} v^{2})^{- 1} \sim 0.5$ fm) nonperturbative QCD scales, where $v$ is the velocity in $Q Q ˉ$ . We calculate the heavy quarks correlators with perturbative corrections within ILM.
↳ hep-phhep-thnucl-th2 citations
14
Impact of nonextensivity on the transport coefficients of a magnetized hot and dense QCD matter
Shubhalaxmi Rath🇮🇳 · Sadhana Dash🇮🇳
We have studied the impact of the nonextensivity on the transport coefficients related to charge and heat in thermal QCD. For this purpose, the electrical ( $σ_{el}$ ), Hall ( $σ_{H}$ ), thermal ( $κ$ ) and Hall-type thermal ( $κ_{H}$ ) conductivities are determined using the kinetic theory approach in association with the nonextensive Tsallis statistical mechanism. The effect of nonextensivity is encoded in the nonextensive Tsallis distribution function, where the deviation of the parameter $q$ from 1 signifies the degree of nonextensivity in the concerned system. The thermal and electrical conductivities are found to increase with the introduction of nonextensivity, which means that the deviation of the medium from thermal equilibrium enhances both charge and heat transports. With the magnetic field, the deviations of $σ_{el}$ , $σ_{H}$ , $κ$ and $κ_{H}$ from their respective equilibrated values increase, whereas these deviations decrease with the chemical potential. We have also studied how the extent of the nonextensivity modulates the longevity of magnetic field. Present work is further extended to the study of some observables associated with the aforesaid transport phenomena, such as the Knudsen number and the elliptic flow within the nonextensive Tsallis framework.
↳ hep-phhep-thnucl-thEPJC(2023)·12 citations
15
Neutron star mass-radius constraints using the high-frequency QPOs of GRB 200415A
H. Sotani · K. D. Kokkotas · N. Stergioulas
Quasi-periodic oscillations (QPOs) observed in a giant flare of a strongly magnetized neutron star (magnetar), are carrying crucial information for extracting the neutron star properties. The aim of the study is to constrain the mass and radius of the neutron star model for GRB 200415A, by identifying the observed QPOs with the crustal torsional oscillations together with the experimental constraints on the nuclear matter properties. The frequencies of the crustal torsional oscillations are determined by solving the eigenvalue problem with the Cowling approximation, assuming a magnetic field of about $1 0^{15}$ G. We find that the observed QPOs can be identified with several overtones of crustal oscillations, for carefully selected combinations of the nuclear saturation parameters. Thus, we can inversely constrain the neutron star mass and radius for GRB 200415A by comparing them to the values of nuclear saturation parameters obtained from terrestrial experiments. We impose further constraints on the neutron star mass and radius while the candidate neutron star models are consistent with the constraints obtained from other available astronomical and experimental observations.
↳ astro-ph.HEnucl-thAstron.Astrophys.(2023)·24 citations

Affiliations

first authorsco-authorsvia INSPIRE