Nuclear Theory·nucl-th

Friday·October 30, 2020

15 papers—8 primary·7 cross-listed

01
[Submitted on 28 Oct 2020]
A transverse momentum differential global analysis of Heavy Ion Collisions
Govert Nijs🇺🇸 · Wilke van der Schee🇨🇭 · Umut Gürsoy🇳🇱 · Raimond Snellings🇳🇱
The understanding of heavy ion collisions and its quark-gluon plasma formation requires a complicated interplay of rich physics in a wealth of experimental data. In this work we compare for identified particles the transverse momentum dependence of both the yields and the anisotropic flow coefficients for both PbPb and $p$ Pb collisions. We do this in a global model fit including a free streaming prehydrodynamic phase with variable velocity $v_{fs}$ , thereby widening the scope of initial conditions. During the hydrodynamic phase we vary three second order transport coefficients. The free streaming velocity has a preference slightly below the speed of light. In this extended model the bulk viscosity is small and even consistent with zero.
Comments:
6 pages, 6 figures, see also the companion paper "A Bayesian analysis of Heavy Ion Collisions with Trajectum" (2010.15134). v2: added Fig 7
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2010.15130 [pdf]
PRL(2021)·205 citations
02
[Submitted on 28 Oct 2020]
Bayesian analysis of heavy ion collisions with the heavy ion computational framework Trajectum
Govert Nijs🇺🇸 · Wilke van der Schee🇨🇭 · Umut Gürsoy🇳🇱 · Raimond Snellings🇳🇱
We introduce a model for heavy ion collisions named Trajectum, which includes an expanded initial stage with a variable free streaming velocity $v_{fs}$ and a hydrodynamic stage with three varying second order transport coefficients. We describe how to obtain a Gaussian Emulator for this 20-parameter model and show results for key observables. This emulator can be used to obtain Bayesian posterior estimates on the parameters, which we test by an elaborate closure test as well as a convergence study. Lastly, we employ the optimal values of the parameters found in [1] to perform a detailed comparison to experimental data from PbPb and $p$ Pb collisions. This includes both observables that have been used to obtain these values as well as wider transverse momentum ranges and new observables such as correlations of event-plane angles.
Comments:
28 pages, 29 figures, see also the companion paper "A transverse momentum differential global analysis of Heavy Ion Collisions" (2010.15130), v2: matches published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2010.15134 [pdf]
PRC(2021)·295 citations
03
[Submitted on 28 Oct 2020]
Projection on particle number and angular momentum: Example of triaxial Bogoliubov quasiparticle states
Benjamin Bally🇪🇸 · Michael Bender🇫🇷
Many quantal many-body methods that aim at the description of self-bound nuclear or mesoscopic electronic systems make use of auxiliary wave functions that break one or several of the symmetries of the Hamiltonian in order to include correlations associated with the geometrical arrangement of the system's constituents. Such reference states have been used already for a long time within self-consistent methods that are either based on effective valence-space Hamiltonians or energy density functionals, and they are presently also gaining popularity in the design of novel ab-initio methods. A fully quantal treatment of a self-bound many-body system, however, requires the restoration of the broken symmetries through the projection of the many-body wave functions of interest onto good quantum numbers. The goal of this work is three-fold. First, we want to give a general presentation of the formalism of the projection method starting from the underlying principles of group representation theory. Second, we want to investigate formal and practical aspects of the numerical implementation of particle-number and angular-momentum projection of Bogoliubov quasiparticle vacua, in particular with regard of obtaining accurate results at minimal computational cost. Third, we want to analyze the numerical, computational and physical consequences of intrinsic symmetries of the symmetry-breaking states when projecting them.
Comments:
45 pages, 18 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2010.15224 [pdf]
PRC(2021)·57 citations
04
[Submitted on 28 Oct 2020]
Coriolis contribution to excited states of odd-mass nuclei with different deformation-dependent mass coeffcients
A. Ait Ben Hammou · M. Oulne
Within the collective Bohr Hamiltonian, the adoption of a mass tensor as a function of collective coordinates has demonstrated its importance for describing the structure of nuclei. On the other hand, for odd-mass nuclei, the Coriolis interaction between the rotational and single-particle motions affects significantly the structure of nuclear excited states. In the framework of a recently developed extended Bohr Hamiltonian, by considering the Deformation-Dependent Mass Formalism whith different mass parameters for the rotation and the two \betha and \gamma vibrations and taking into account the Coriolis contribution, we investigate the bands structure of the 173Yb, 163Dy, 155Eu and 153Eu nuclei. Excited-state energies and B(E2) transition probabilities are calculated and compared with the available experimental data. Besides, we investigate the effect of DDMF and the Coriolis force on nuclear observables.
Comments:
15 pages, 9 tables, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2010.15262 [pdf]
J.Phys.G(2020)·1 citation
05
[Submitted on 29 Oct 2020]
Hybrid quark-hadron equation of state for multi-messenger astronomy
Michał Marczenko🇵🇱
We present the recent progress of the hybrid quark-meson-nucleon model for multi-messenger astronomy that unifies the thermodynamics of quark and hadronic degrees of freedom. The obtained equation of state is in accordance with nuclear matter properties at saturation density and with the flow constraint from heavy ion collision experiments. The mass-radius relations and tidal deformabilities for compact stars are calculated and compared with the latest astrophysical observations. The phase diagram of the isospin-symmetirc matter is studied as well in terms of the higher-order cumulants of the net-baryon number.
Comments:
prepared for the Criticality in QCD and the Hadron Resonance Gas proceedings
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2010.15420 [pdf]
Acta Phys.Polon.Supp.(2021)·1 citation
06
[Submitted on 29 Oct 2020]
Relativistic rank-one separable kernel for helium-3 charge form factor
Serge Bondarenko · Valery Burov · Sergey Yurev
Elastic electron-helium-3 scattering is studied in the relativistic impulse approximation. The amplitudes for the three-nucleon system are obtained by solving the relativistic generalization of the Faddeev equations with a separable rank-one kernel of the nucleon-nucleon interaction. The contribution of partial-wave states with nonzero orbital moment of a nucleon pair is investigated. The static approximation and additional relativistic corrections for the 3He charge form factor are calculated for the momentum transfer squared up to 100 fm^-2. The contribution of the 3D1 partial-wave state and relativistic corrections are found to be sizable at high energies.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2010.15540 [pdf]
NPA(2020)·6 citations
07
[Submitted on 21 Oct 2020]
Important Influence of Entrance Channel Reorientation Coupling on Proton Stripping
N. Keeley · K.W. Kemper · K. Rusek
While it is well established that the ground state reorientation coupling can have a significant influence on the elastic scattering of deformed nuclei, the effect of such couplings on transfer channels has been much less well investigated. In this letter we demonstrate that the 208Pb(7Li,6He)209Bi proton stripping reaction at an incident energy of 52 MeV can be well described by the inclusion of the 7Li ground state reorientation coupling within the coupled channels Born approximation formalism. Full finite-range distorted wave Born approximation calculations were previously found to be unable to describe these data. Addition of coupling to the 0.478-MeV 1/2- excited state of 7Li, together with the associated two-step transfer path, has little or no influence on the shape of the angular distributions (except that for stripping leading to the 1.61-MeV 13/2+ level of 209Bi which is significantly improved) but does affect appreciably the values of the 209Bi -> 208Pb + p spectroscopic factors. Implications for experiments with weakly-bound light radioactive beams are discussed.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2010.15587 [pdf]
EPJA(2020)·1 citation
08
[Submitted on 29 Oct 2020]
"Tiny galaxies" from "little bang"
Feng Li🇨🇳
We show, by solving the linearized Vlasov equations, that in the presence of an attractive density-dependent vector, or tensor, mean field potential, under a portion of the spinodal unstable phase region where the attractions among the quarks are more dominant, the transverse modes, i.e., the fluctuations of the current densities perpendicular to the wave vector, are activated due to relativity. In particular, the current densities in both the transverse directions oscillate with the same frequency, indicating the existence of the spontaneous rotations of the dense clusters. These rotating clusters would certainly create a local vortical flow field which, according to chiral (or spin) vortical effect, leads to the macroscopic separation of the axial charges or spins due to the spin-orbital interactions. Hence, for the first time, the connection between the axial charge or spin in-homogeneity and the first-order phase transition is proposed.
Comments:
4 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2010.15752 [pdf]
0 citations
09
[Submitted on 28 Oct 2020] (cross-list from astro-ph.HE)
Non-thermal neutrinos created by shock acceleration in successful and failed core-collapse supernova
Hiroki Nagakura🇺🇸 · Kenta Hotokezaka🇯🇵
We present a comprehensive study of neutrino shock acceleration in core-collapse supernova (CCSN). The leading players are heavy leptonic neutrinos, $ν_{μ}$ and $ν_{τ}$ ; the former and latter potentially gain the energy up to $\sim 100$ MeV and $\sim 200$ MeV, respectively, through the shock acceleration. Demonstrating the neutrino shock acceleration by Monte Carlo neutrino transport, we make a statement that it commonly occurs in the early post bounce phase ( $≲ 50$ ms after bounce) for all massive stellar collapse experiencing nuclear bounce and would reoccur in the late phase ( $≳ 100$ ms) for failed CCSNe. This opens up a new possibility to detect high energy neutrinos by terrestrial detectors from Galactic CCSNe; hence, we estimate the event counts for Hyper(Super)-Kamiokande, DUNE, and JUNO. We find that the event count with the energy of $≳ 80$ MeV is a few orders of magnitude higher than that of the thermal neutrinos regardless of the detectors, and muon production may also happen in these detectors by $ν_{μ}$ with the energy of $≳ 100$ MeV. The neutrino signals provide a precious information on deciphering the inner dynamics of CCSN and placing a constraint on the physics of neutrino oscillation; indeed, the detection of the high energy neutrinos through charged current reaction channels will be a smoking gun evidence of neutrino flavor conversion.
Comments:
Accepted to MNRAS
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2010.15136 [pdf]
MNRAS(2021)·17 citations
10
[Submitted on 28 Oct 2020] (cross-list from astro-ph.HE)
Astromers: Nuclear Isomers in Astrophysics
G. Wendell Misch · Surja K. Ghorui · Projjwal Banerjee · Yang Sun · Matthew R. Mumpower
We develop a method to compute thermally-mediated transition rates between the ground state and long-lived isomers in nuclei. We also establish criteria delimiting a thermalization temperature above which a nucleus may be considered a single species and below which it must be treated as two separate species: a ground state species, and an astrophysical isomer ("astromer") species. Below the thermalization temperature, the destruction rates dominate the internal transition rates between the ground state and the isomer. If the destruction rates also differ greatly from one another, the nuclear levels fall out of or fail to reach thermal equilibrium. Without thermal equilibrium, there may not be a safe assumption about the distribution of occupation probability among the nuclear levels when computing nuclear reaction rates. In these conditions, the isomer has astrophysical consequences and should be treated a separate astromer species which evolves separately from the ground state in a nucleosynthesis network. We apply our transition rate methods and perform sensitivity studies on a few well-known astromers. We also study transitions in several other isomers of likely astrophysical interest.
Comments:
Accepted to ApJS, see eventual published article for data. 23 pages, 21 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2010.15238 [pdf]
Astrophys.J.Suppl.(2021)·60 citations
11
[Submitted on 29 Oct 2020] (cross-list from hep-lat)
Higher order cumulants of electric charge and strangeness fluctuations on the crossover line
D. Bollweg🇩🇪 · J. Goswami🇩🇪 · F. Karsch🇩🇪 · S. Mukherjee🇺🇸 · C. Schmidt🇩🇪
We present lattice QCD calculations of higher order cumulants of electric charge distributions for small baryon chemical potentials $μ_{B}$ by using up to NNNLO Taylor expansions. Ratios of these cumulants are evaluated on the pseudo-critical line, $T_{p c} (μ_{B})$ , of the chiral transition and compared to corresponding measurements in heavy ion collision experiments by the STAR and PHENIX Collaborations. We demonstrate that these comparisons give strong constraints on freeze-out parameters. Furthermore, we use strangeness fluctuation observables to compute the ratio $μ_{S} / μ_{B}$ on the crossover line and compare it to $μ_{S} / μ_{B}$ at freeze-out stemming from fits to strange baryon yields measured by the STAR Collaboration.
Comments:
10 pages, 7 figures, Presented at Criticality in QCD and the Hadron Resonance Gas, 29-31 July 2020, Wroclaw Poland
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2010.15501 [pdf]
Acta Phys.Polon.B(2021)·3 citations
12
[Submitted on 29 Oct 2020] (cross-list from physics.ed-ph)
How do I introduce Schrödinger equation during the quantum mechanics course?
T. Mart🇮🇩
In this paper I explain how I usually introduce the Schrödinger equation during the quantum mechanics course. My preferred method is the chronological one. Since the Schrödinger equation belongs to a special case of wave equations I start the course with introducing the wave equation. The Schrödinger equation is derived with the help of the two quantum concepts introduced by Max Planck, Einstein, and de Broglie, i.e., the energy of a photon $E = ℏ ω$ and the wavelength of the de Broglie wave $λ = h / p$ . Finally, the difference between the classical wave equation and the quantum Schrödinger one is explained in order to help the students to grasp the meaning of quantum wavefunction $Ψ (r, t)$ . A comparison of the present method to the approaches given by the authors of quantum mechanics textbooks as well as that of the original Nuffield A level is presented. It is found that the present approach is different from those given by these authors, except by Weinberg or Dicke and Wittke. However, the approach is in line with the original Nuffield A level one.
Comments:
10 pages, 2 figures, submitted to Physics Education
Subjects:
physics.ed-ph (physics.ed-ph); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
arXiv:
2010.15589 [pdf]
Phys.Educ.(2021)·1 citation
13
[Submitted on 29 Oct 2020] (cross-list from hep-lat)
Universal scaling properties of QCD close to the chiral limit
Olaf Kaczmarek🇩🇪 · Frithjof Karsch🇩🇪 · Anirban Lahiri🇩🇪 · Christian Schmidt🇩🇪
We present a lattice QCD based determination of the chiral phase transition temperature in QCD with two massless (up and down) and one strange quark having its physical mass. We propose and calculate two novel estimators for the chiral transition temperature for several values of the light quark masses, corresponding to Goldstone pion masses in the range of $58 MeV ≲ m_{π} ≲ 163 MeV$ . The chiral phase transition temperature is determined by extrapolating to vanishing pion mass using universal scaling relations. After thermodynamic, continuum and chiral extrapolations we find the chiral phase transition temperature $T_{c}^{0} = 13 2_{- 6}^{+ 3}$ MeV. We also show some preliminary calculations that use the conventional estimator for the pseudo-critical temperature and compare with the new estimators for $T_{c}^{0}$ . Furthermore, we show results for the ratio of the chiral order parameter and its susceptibility and argue that this ratio can be used to differentiate between $O (N)$ and $Z_{2}$ universality classes in a non-parametric manner.
Comments:
10 pages, 6 figures, contribution to the proceeding of workshop on Criticality in QCD and the Hadron Resonance Gas; 29-31 July 2020, Wroclaw, Poland
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2010.15593 [pdf]
Acta Phys.Polon.Supp.(2021)·9 citations
14
[Submitted on 24 Oct 2020] (cross-list from physics.data-an)
Independent Normalization for $γ$ -ray Strength Functions: The Shape Method
M. Wiedeking · M. Guttormsen · A.C. Larsen · F. Zeiser · A. Görgen · S. N. Liddick · D. Mücher · S. Siem · A. Spyrou
The Shape method, a novel approach to obtain the functional form of the $γ$ -ray strength function ( $γ$ SF) in the absence of neutron resonance spacing data, is introduced. When used in connection with the Oslo method the slope of the Nuclear Level Density (NLD) is obtained simultaneously. The foundation of the Shape method lies in the primary $γ$ -ray transitions which preserve information on the functional form of the $γ$ SF. The Shape method has been applied to $^{56}$ Fe, $^{92}$ Zr, $^{164}$ Dy, and $^{240}$ Pu, which are representative cases for the variety of situations encountered in typical NLD and $γ$ SF studies. The comparisons of results from the Shape method to those from the Oslo method demonstrate that the functional form of the $γ$ SF is retained regardless of nuclear structure details or $J^{π}$ values of the states fed by the primary transitions.
Comments:
13 pages, 8 figures
Subjects:
Data Analysis, Statistics and Probability (physics.data-an); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2010.15696 [pdf]
PRC(2021)·38 citations
15
[Submitted on 29 Oct 2020] (cross-list from hep-lat)
Sensitivity of the Polyakov loop to chiral symmetry restoration
David Anthony Clarke🇩🇪 · Olaf Kaczmarek🇩🇪 · Anirban Lahiri🇩🇪 · Mugdha Sarkar🇩🇪
In the heavy, static quark mass regime of QCD, the Polyakov loop is well known to be an order parameter of the deconfinement phase transition; however, the sensitivity of the Polyakov loop to the deconfinement of light, dynamical quarks is less clear. On the other hand, from the perspective of an effective Lagrangian written in the vicinity of the chiral transition, the Polyakov loop is an energy-like operator and should hence scale as any energy-like operator would. We show here that the Polyakov loop and heavy-quark free energy are sensitive to the chiral transition, i.e. their scaling is consistent with energy-like observables in 3- $d$ $O (N)$ universality classes.
Comments:
10 pages, 3 figures, presented at the Workshop on Criticality in QCD and the Hadron Resonance Gas
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2010.15825 [pdf]
Acta Phys.Polon.Supp.(2021)·5 citations

Affiliations

first authorsco-authorsvia INSPIRE