Nuclear Theory·nucl-th

Tuesday·August 22, 2023

15 papers—7 primary·8 cross-listed

01
[Submitted on 18 Aug 2023]
Comparisons and Predictions for Collisions of deformed $^{238}$ U nuclei at $s_{N N} = 193$ GeV
Nicolas Fortier🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
We present comparisons to experimental data along with predictions of observables for U+U collisions at 193 GeV using a multistage theoretical and computational framework consisting of boost-invariant IP-Glasma initial state, MUSIC hydrodynamics, and a hadronic transport cascade generated by iS3D \& SMASH. Our results show great agreement with existing anisotropic flow measurements from RHIC [ arXiv:1505.07812 ; arXiv:1901.08155 ] . We provide predictions for differential flow observables as well as multiparticle correlations and transverse-momentum-flow correlations. When possible, we compare our predictions to results from Au+Au collisions at 200 GeV to properly outline the effects of deformation in the initial state on final state observables.
Comments:
21 pages, 18 figures, 1 Table
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2308.09816 [pdf]
PRC(2025)·18 citations
02
[Submitted on 18 Aug 2023]
Modified Urca neutrino emissivity at finite temperature
Lami Suleiman🇫🇷 · Micaela Oertel🇫🇷 · Marco Mancini🇫🇷
Charged current neutrino-nucleon reactions, generally called Urca processes, are crucial actors of a neutron star's thermal evolution. The so-called direct processes show a pronounced threshold under which the reaction is kinematically suppressed. This suppression does not apply to "modified" Urca processes which involve interaction with an additional nucleon. Calculations of the modified Urca neutrino rates were established for cold neutron star matter and for dilute hot matter, in both cases under strong assumptions. In this paper, we revise the calculations of the modified Urca neutrino rates for dense and hot matter, and for different compositions. We study the influence of different approximations used in previous computations. We derive expressions for the rates of modified Urca neutrino emissivity within thermal field theory and perform the phase space integration numerically using mainly importance sampling Monte-Carlo techniques. The neutrino emissivity of modified and direct processes are established and compared. We find in particular that the modified Urca process is not necessarily suppressed with respect to the direct process above the threshold of the latter at moderate densities and temperatures, in contrast to what is generally assumed. Numerical results are confirmed by an estimation of the ratio of modified to direct Urca rates with a simple analytic approximation, thereby showing the regimes of suppression for the modified processes depending on temperature and density. These results show that modified Urca rates have to be considered carefully upon evaluating neutrino opacities in dense and warm matter.
Comments:
17 pages, 8 figures, accepted for publication in PRC
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2308.09819 [pdf]
PRC(2023)·15 citations
03
[Submitted on 19 Aug 2023]
Microscopic triaxial cranking model: preliminary predictions for oscillator potential and light nuclei
Parviz Gulshani · Alaaddine Lahbas
The conventional cranking model for uniaxial and triaxial rotation (CCRM3) is frequently used to study rotational features in deformed nuclei. However, CCRM3 is semi-classical and phenomenological because it uses a constant angular velocity, resulting in a number of Hamiltonian symmetry breakings. To investigate the effect of a dynamic angular velocity, a quantal, microscopic, D2, signature, and time-reversal invariant cranking model for triaxial rotation (MSCRM3) is derived exactly from a unitary rigid-flow-velocity-field rotation transformation of the nuclear Schrodinger equation and Hartree-Fock method. Except for a microscopically-determined angular velocity and normally-small residual terms, the MSCRM3 and CCRM3 Schrodinger equations are identical in form. The microscopic angular velocity emerges from the HF variation, and the residual terms may become significant for triaxial rotation at high spins and in back-bending regions where and undergo large changes. A preliminary application of MSCRM3 and CCRM3 to the light nuclei 20Ne, 24Mg, and 28Si using the simple self-consistent deformed harmonic oscillator potential predicts some interesting differences between the rotational features and phenomena predicted by the two models. These differences are attributable to the impact of the dynamic angular velocity. It is important to investigate and understand these differences for the simple and realistic nuclear interactions.
Comments:
13 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2308.10026 [pdf]
0 citations
04
[Submitted on 20 Aug 2023]
Nuclear level density in the statistical semiclassical micro-macroscopic approach
A.G. Magner · A.I. Sanzhur · S.N. Fedotkin · A.I. Levon · U.V. Grygoriev · S. Shlomo
Level density $ρ$ is derived for a finite system with strongly interacting nucleons at a given energy E, neutron N and proton Z particle numbers, projection of the angular momentum M, and other integrals of motion, within the semiclassical periodic-orbit theory (POT) beyond the standard Fermi-gas saddle-point method. For large particle numbers, one obtains an analytical expression for the level density which is extended to low excitation energies U in the statistical micro-macroscopic approach (MMA).The interparticle interaction averaged over particle numbers is taken into account in terms of the extended Thomas-Fermi component of the POT. The shell structure of spherical and deformed nuclei is taken into account in the level density. The MMA expressions for the level density $ρ$ reaches the well-known macroscopic Fermi-gas asymptote for large excitation energies U and the finite combinatoric power-expansion limit for low energies U. We compare our MMA results for the averaged level density with the experimental data obtained from the known excitation energy spectra by using the sample method under statistical and plateau conditions. Fitting the MMA $ρ$ to these experimental data on the averaged level density by using only one free physical parameter - inverse level density parameter K - for several nuclei and their long isotope chain at low excitation energies U, one obtains the results for K. These values of K might be much larger than those deduced from neutron resonances. The shell, isotopic asymmetry, and pairing effects are significant for low excitation energies.
Comments:
31 pages, 7 figures, 1 table
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2308.10350 [pdf]
Nucl.Phys.Atom.Energy(2023)·1 citation
05
[Submitted on 20 Aug 2023]
Transverse and non-boost longitudinal expansion of (2+1)dimensional relativistic ideal-hydrodynamics flow in heavy ion collisions
M. Karimabadi🇮🇷 · A.F. Kord🇮🇷 · B. Azadegan🇮🇷
This study investigates the evolution of quark gluon plasma (QGP) within a generalized Bjorken flow framework. The medium under consideration is assumed to possess a finite transverse size and to expand both radially and along the beam axis. However, we assume that the boost invariance of longitudinal expansion is broken. To be more specific, we generalize the Bjorken solution to include the acceleration and transverse expansion of the fluid. We analytically study the (2 + 1) dimensional longitudinal acceleration expansion of hot and dense quark matter, applying a perturbation approach to solve the relativistic hydrodynamics equations. This procedure enables us to obtain exact algebraic expressions for fluid velocities and energy densities in both transverse and longitudinal directions. To simplify our calculations, we assume that the fluid is produced in central collisions, and therefore, we consider azimuthal symmetry. We compare the radial velocity and correction energy density with those obtained from the Gubser model. Furthermore, we determine the fluid's acceleration parameter and longitudinal correction energy density, which exhibits a Gaussian distribution.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
2308.10367 [pdf]
0 citations
06
[Submitted on 21 Aug 2023]
Strangeness production in neutron star matter
Gao-Chan Yong🇨🇳
Based on a dynamical model on particle production, the production and fraction of exotic components in neutron star matter are analyzed. It is found that there exists a small fraction of strangeness in twice saturation density matter. For five times saturation density matter, the fraction of strange baryons can be as high as 25-50\%, depending on the equation of state used. The neutron-proton asymmetry of dense matter does not significantly impact the strangeness fraction in neutron star matter. This research provides new insights into the strange components in neutron stars.
Comments:
Physical Review D - Letter, in production
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2308.10628 [pdf]
PRD(2023)·4 citations
07
[Submitted on 21 Aug 2023]
A novel method for calculating Bose-Einstein correlation functions with Coulomb final-state interaction
Márton Nagy🇭🇺 · Aletta Purzsa🇭🇺 · Máté Csanád🇭🇺 · Dániel Kincses🇭🇺
Measurements of Bose-Einstein correlations played a crucial role in the discovery and the subsequent detailed exploration of the Quark-Gluon-Plasma (QGP) created in high-energy collisions of heavy nuclei. Such measurements gave rise to femtoscopy, a flourishing sub-field of high-energy physics, and there are important new directions to explore and discoveries to be made in the near future. One of these important current topics is the precise investigation of the shape of the correlation functions utilizing Lévy-stable sources. In this paper, we present a novel method of calculating the shape of the two-particle correlation functions, including the Coulomb final-state interaction. This method relies on an exact calculation of a large part of the necessary integrals of the Coulomb wave function and can be utilized to calculate the correlation function for any source function with an easily accessible Fourier transform. In this way, it is eminently applicable to Lévy-stable source functions. In this particular case, we find that the new method is more robust and allows the investigation of a wider parameter range than the previously utilized techniques. We present an easily applicable software package that is ready to use in experimental studies.
Comments:
20 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2308.10745 [pdf]
EPJC(2023)·17 citations
08
[Submitted on 18 Aug 2023] (cross-list from hep-ph)
Pre-equilibrium photons from the early stages of heavy-ion collisions
Oscar Garcia-Montero🇩🇪 · Aleksas Mazeliauskas🇩🇪 · Philip Plaschke🇩🇪 · Sören Schlichting🇩🇪
We use QCD kinetic theory to compute photon production in the chemically equilibrating Quark-Gluon Plasma created in the early stages of high-energy heavy-ion collisions. We do a detailed comparison of pre-equilibrium photon rates to the thermal photon production. We show that the photon spectrum radiated from a hydrodynamic attractor evolution satisfies a simple scaling form in terms of the specific shear viscosity $η / s$ and entropy density $d S / d ζ \sim (T τ^{1/3})^{3/2}_{\infty}$ . We confirm the analytical predictions with numerical kinetic theory simulations. We use the extracted scaling function to compute the pre-equilibrium photon contribution in $s_{N N} = 2.76 TeV$ 0-20\% PbPb collisions. We demonstrate that our matching procedure allows for a smooth switching from pre-equilibrium kinetic to thermal hydrodynamic photon production. Finally, our publicly available implementation can be straightforwardly added to existing heavy ion models.
Comments:
19 pages, 12 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2308.09747 [pdf]
JHEP(2024)·37 citations
09
[Submitted on 18 Aug 2023] (cross-list from math.AP)
Recent developments in mathematical aspects of relativistic fluids
Marcelo M. Disconzi
We review some recent developments in mathematical aspects of relativistic fluids. The goal is to provide a quick entry point to some research topics of current interest that is accessible to graduate students and researchers from adjacent fields, as well as to researches working on broader aspects of relativistic fluid dynamics interested in its mathematical formalism. Instead of complete proofs, which can be found in the published literature, here we focus on the proofs' main ideas and key concepts. After an introduction to the relativistic Euler equations, we cover the following topics: a new wave-transport formulation of the relativistic Euler equations tailored to applications; the problem of shock formation for relativistic Euler; rough (i.e., low-regularity) solutions to the relativistic Euler equations; the relativistic Euler equations with a physical vacuum boundary; relativistic fluids with viscosity. We finish with a discussion of open problems and future directions of research.
Subjects:
math.AP (math.AP); General Relativity and Quantum Cosmology (gr-qc); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
arXiv:
2308.09844 [pdf]
Living Rev.Rel.(2024)·29 citations
10
[Submitted on 18 Aug 2023] (cross-list from math.AP)
Strongly hyperbolic quasilinear systems revisited, with applications to relativistic fluid dynamics
Marcelo M. Disconzi · Yuanzhen Shao
We revisit the theory of first-order quasilinear systems with diagonalizable principal part and only real eigenvalues, what is commonly referred to as strongly hyperbolic systems. We provide a self-contained and simple proof of local well-posedness, in the Hadamard sense, of the Cauchy problem. Our regularity assumptions are very minimal. As an application, we apply our results to systems of ideal and viscous relativistic fluids, where the theory of strongly hyperbolic equations has been systematically used to study several systems of physical interest.
Subjects:
math.AP (math.AP); General Relativity and Quantum Cosmology (gr-qc); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th)
arXiv:
2308.09851 [pdf]
Asymptotic Anal.(2024)·8 citations
11
[Submitted on 19 Aug 2023] (cross-list from hep-ph)
Overview: Jet quenching with machine learning
Yi-Lun Du🇨🇳
Jets are suppressed and modified in heavy ion collisions, which serve as powerful probes to the properties of the quark-gluon plasma (QGP). Attributed to the abundant information carried by the jet constituents and reconstructed substructures, plenty of interesting applications of machine learning techniques have been made on a jet-by-jet basis to study the jet quenching phenomena. Here we review recent proceedings on this topic including the tasks of reconstructing jet momentum in heavy ion collisions, classifying quenched jets and unquenched jets, identifying jet energy loss, locating the jet creation points as well as distinguishing between quark- and gluon-initiated jets in the QGP. Such jet-by-jet analyses will allow us to have a better handle on the jet reconstruction and selections to investigate the effects of jet modifications and push forward the long-standing goal of jet tomographic probes of the QGP.
Comments:
11 pages, 11th International Conference on Hard and Electromagnetic Probes of High-Energy Nuclear Collisions (Hard Probes 2023)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2308.10035 [pdf]
6 citations
12
[Submitted on 20 Aug 2023] (cross-list from hep-ph)
Nature of $X (3872)$ from its radiative decay
Shuo-Ying Yu🇨🇳 · Xian-Wei Kang🇨🇳
We study the radiative decay of $X (3872)$ based on the assumption that $X (3872)$ is regarded as a $c c$ charmonium with quantum number $J^{P C} = 1^{++}$ ( $J, P, C$ represent the spin, parity and charge conjugation, respectively). The form factors of $X (3872)$ transitions to $J / ψ γ$ and $ψ^{'} γ$ ( $ψ^{'}$ denotes $ψ (2 S)$ throughout the paper) are calculated in the framework of the covariant light-front quark model. The phenomenological wave function of a meson depends on the parameter $β$ , whose inverse essentially describes the confinement scale. In the present work, the parameters $β$ for the vector $J / ψ$ and $ψ^{'}$ mesons will be determined through their decay constants, which are obtained from the experimental values of their partial decay widths to the electron-positron pair. For $X (3872)$ , we determined the value of $β$ by the decay width of $X (3872) \to ψ^{'} γ$ . Then, we examined the width of $X (3872) \to J / ψ γ$ in a manner of parameter-free prediction and compared it with the experimental value. As a result, an inconsistency or contradiction occurs between the widths of $X (3872) \to J / ψ γ$ and $X (3872) \to ψ^{'} γ$ . We thus conclude that $X (3872)$ cannot be a pure $c c$ resonance and that other components are necessary in its wave function.
Comments:
two columu, 8 pages, more clarifications and references added, accepted for publication in Phys. Letts. B
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2308.10219 [pdf]
PLB(2024)·16 citations
13
[Submitted on 20 Aug 2023] (cross-list from hep-ph)
Electromagnetic radiation at extreme angular velocity
Matteo Buzzegoli🇺🇸 · Kirill Tuchin🇺🇸
We consider a system rotating at extremely high angular velocity, so that its matter is found mostly at the light-cylinder. We posit that it can be described by quantum fields confined to the two-dimensional cylindrical surface rotating about its symmetry axis. We apply this model to study the electromagnetic radiation. In particular, we compute the photon spectrum emitted by the quark-gluon plasma.
Comments:
15 pages, 6 figures. v2: typos and minor errors fixed
Subjects:
High Energy Physics — Phenomenology (hep-ph); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2308.10349 [pdf]
JHEP(2023)·12 citations
14
[Submitted on 21 Aug 2023] (cross-list from hep-ph)
Modeling Backward-Angle ( $u$ -channel) Virtual Compton Scattering at an Electron-Ion Collider
Zachary Sweger🇺🇸 · Spencer R. Klein🇺🇸 · Yuanjing Ji🇺🇸 · Minjung Kim🇺🇸 · Saeahram Yoo🇺🇸 · Ziyuan Zeng🇺🇸 · Daniel Cebra🇺🇸 · Xin Dong🇺🇸
High-energy backward ( $u$ -channel) reactions can involve very large momentum transfers to the target baryons, shifting them by many units of rapidity. These reactions are difficult to understand in conventional models in which baryon number is carried by the valence quarks. Backward Compton scattering is an especially attractive experimental target, because of its simple final state. There is currently limited data on this process, and that data is at low center-of-mass energies. In this paper, we examine the prospects for studying backward Compton scattering at the future Electron-Ion Collider (EIC). We model the cross-section and kinematics using the limited data on backward Compton scattering and backward meson production, and then simulate Compton scattering at EIC energies, in a simple model of the ePIC detector. Generally, the proton is scattered toward mid-rapidity, while the produced photon is in the far-forward region, visible in a Zero Degree Calorimeter (ZDC). We show that the background from backward $π^{0}$ production can be rejected using a high-resolution, well-segmented ZDC.
Comments:
12 pages, 9 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2308.10478 [pdf]
PRC(2023)·6 citations
15
[Submitted on 21 Aug 2023] (cross-list from hep-ph)
Diffractive Processes at Next-to-Leading Order in the Dipole Picture
Jani Penttala🇫🇮
In this thesis, we calculate diffractive processes at next-to-leading order (NLO) in the high-energy limit, with an emphasis on exclusive vector meson production and inclusive diffraction in deep inelastic scattering (DIS). Calculations in the high-energy limit can be done using the dipole picture, the basics of which are briefly reviewed. This includes using the color-glass condensate effective field theory to describe the nonperturbative dipole-target scattering amplitude which appears in practically all calculations in the dipole picture. The universality of the dipole-target scattering amplitude at NLO is shown numerically, in the sense that the same dipole-target scattering amplitude can be used to describe the data in both massless and massive quark production in inclusive DIS, and also in diffractive processes where exclusive vector meson production is considered. The analytical NLO calculations of exclusive vector meson production and inclusive diffraction in DIS are also explained. Exclusive vector meson production is calculated in the nonrelativistic limit for heavy mesons and the limit of large photon virtuality for light mesons. Also, the importance of including relativistic corrections to the heavy vector meson wave function in exclusive vector meson production is considered. For inclusive diffraction in DIS, we focus on the NLO corrections to the final state and show how the divergences cancel.
Comments:
PhD thesis, introductory part
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2308.10690 [pdf]
JYU Dissertations 668, 2023, ISBN:978-951…·3 citations

Affiliations

first authorsco-authorsvia INSPIRE