Nuclear Theory·nucl-th

Wednesday·October 13, 2021

10 papers—5 primary·5 cross-listed

01
[Submitted on 11 Oct 2021]
Anisotropic flow decorrelation in heavy-ion collisions at RHIC-BES energies with 3D event-by-event viscous hydrodynamics
Jakub Cimerman🇨🇿 · Iurii Karpenko🇨🇿 · Boris Tomasik🇨🇿 · Barbara Antonina Trzeciak🇨🇿
In the RHIC Beam Energy Scan program, gold nuclei are collided with different collision energies in the range from few to 62.4 GeV. The goals of the program are to explore the onset of QGP creation, locate the critical point of QCD and study dense baryon matter. We report on the first application of Monte Carlo Glauber (GLISSANDO2) and T $_{R}$ ENTo $p = 0$ initial states extended to 3D for event-by-event viscous fluid dynamic (vHLLE) with hadronic cascade modelling of Au+Au collisions at $s_{_{NN}} = 27$ and 62.4 GeV, which is the upper region of RHIC BES energies. The initial states are extended into both the longitudinal direction and for finite baryon density using simple ansätze. The full energy and baryon charge counting in the initial states is implemented. We show the reproduction of elliptic flow, at both collision energies and with both initial states. We compare it also to the results obtained with UrQMD initial state. Furthermore, we show the results for rapidity decorrelation of elliptic flow $r_{2}$ at $s_{_{NN}} = 27$ and 200 GeV from the same setup of hydrodynamic calculations with the 3D Monte Carlo Glauber and UrQMD initial states. We discuss the features of the initial states responsible for the magnitude of the observed flow decorrelation.
Comments:
Proceedings of EPS-HEP 2021, July 26-30 (online conference). 6 pages
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2110.05578 [pdf]
PoS(2022)·0 citations
02
[Submitted on 12 Oct 2021]
The mean square radius of the neutron distribution in the relativistic and non-relativistic mean field models
Haruki Kurasawa · Toshio Suzuki
It is investigated why the root mean square radius of the point neutron distribution is smaller by about 0.1 fm in non-relativistic mean field models than in relativistic ones. The difference is shown to stem from the different values of the product of the effective mass and the strength of the one-body potential in the two frameworks. The values of those quantities are constrained by the Hugenholtz-Van Hove theorem. The neutron skin is not a simple function of the symmetry potential, but depends on the nucleon effective mass.
Comments:
31 pages, 15 figures; to appear in Prog. Theor. Exp. Phys
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2110.05656 [pdf]
PTEP(2022)·5 citations
03
[Submitted on 12 Oct 2021]
Nuclear Shell Structure in a Finite-Temperature Relativistic Framework
Herlik Wibowo🇹🇼 · Elena Litvinova🇺🇸
The shell evolution of neutron-rich nuclei with temperature is studied in a beyond-mean-field framework rooted in the meson-nucleon Lagrangian. The temperature-dependent Dyson equation with the dynamical kernel taking into account the particle-vibration coupling (PVC) is solved for the fermionic propagators in the basis of the thermal relativistic mean-field Dirac spinors. The calculations are performed for $^{68 - 78}$ Ni in a broad range of temperatures $0 \leq T \leq 4$ MeV. The special focus is put on the fragmentation pattern of the single-particle states, which is further investigated within toy models in strongly truncated model spaces. Such models allow for quantifying the sensitivity of the fragmentation to the phonon frequencies, the PVC strength and to the mean-field level density. The model studies provide insights into the temperature evolution of the PVC mechanism in real nuclear systems under the conditions which may occur in astrophysical environments.
Comments:
Article: 17 pages, 19 figures
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); cond-mat.other (cond-mat.other); Nuclear Experiment (nucl-ex)
arXiv:
2110.05749 [pdf]
PRC(2022)·9 citations
04
[Submitted on 12 Oct 2021]
Hydrodynamic analyses of nuclear collisions in Landau and Eckart frames
Akihiko Monnai🇯🇵
Relativistic dissipative hydrodynamic model at finite density is a promising tool for analyzing the dense QCD matter created in the beam energy scan experiments. The hydrodynamic frame can be chosen in the direction of energy flow, which is called the Landau frame, or conserved charge flow, which is called the Eckart frame. In this study, I investigate the stability and causality of full second-order relativistic hydrodynamic equations in the two frames. Then the effects of frame choice on hydrodynamic variables and experimental observables are estimated numerically and are found to be visible on the flow but limited on the rapidity distributions.
Comments:
4 pages, 2 figures - To appear in the conference proceedings for PANIC 2021, September 5-11, Lisbon, Portugal
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2110.05867 [pdf]
PoS(2022)·0 citations
05
[Submitted on 12 Oct 2021]
Variational approaches to constructing the many-body nuclear ground state for quantum computing
I. Stetcu · A. Baroni · J. Carlson
We explore the preparation of specific nuclear states on gate-based quantum hardware using variational algorithms. Large scale classical diagonalization of the nuclear shell model have reached sizes of $1 0^{9} - 1 0^{10}$ basis states, but are still severely limited by computational resources. Quantum computing can, in principle, solve such systems exactly with exponentially fewer resources than classical computing. Exact solutions for large systems require many qubits and large gate depth, but variational approaches can effectively limit the required gate depth. We use the unitary coupled cluster approach to construct approximations of the ground-state vectors, later to be used in dynamics calculations. The testing ground is the phenomenological shell model space, which allows us to mimic the complexity of the inter-nucleon interactions. We find that often one needs to minimize over a large number of parameters, using a large number of entanglements that makes challenging the application on existing hardware. Prospects for rapid improvements with more capable hardware are, however, very encouraging.
Comments:
10 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2110.06098 [pdf]
PRC(2022)·77 citations
06
[Submitted on 11 Oct 2021] (cross-list from hep-ph)
Chiral extrapolation of hadronic vacuum polarization
Gilberto Colangelo🇨🇭 · Martin Hoferichter🇨🇭 · Bastian Kubis🇩🇪 · Malwin Niehus🇩🇪 · Jacobo Ruiz de Elvira🇨🇭
We study the pion-mass dependence of the two-pion channel in the hadronic-vacuum-polarization (HVP) contribution to the anomalous magnetic moment of the muon $a_{μ}^{HVP}$ , by using an Omnès representation for the pion vector form factor with the phase shift derived from the inverse-amplitude method (IAM). Our results constrain the dominant isospin- $1$ part of the isospin-symmetric light-quark contribution, and should thus allow one to better control the chiral extrapolation of $a_{μ}^{HVP}$ , required for lattice-QCD calculations performed at larger-than-physical pion masses. In particular, the comparison of the one- and two-loop IAM allows us to estimate the associated systematic uncertainties and show that these are under good control.
Comments:
9 pages, 4 figures; journal version; Mathematica implementation included as supplemental material
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2110.05493 [pdf]
PLB(2022)·41 citations
07
[Submitted on 11 Oct 2021] (cross-list from astro-ph.HE)
Effect of the Nuclear Equation of State on Relativistic-Turbulence Induced Core-Collapse Supernovae
Luca Boccioli · Grant J. Mathews · In-Saeng Suh · Evan P. O'Connor
The nuclear equation of state is an important component in the evolution of core collapse supernovae. In this paper we make a survey of various equations of state in the literature and analyze their effect on spherical core-collapse models in which the effects of three-dimensional turbulence is modeled by a general relativistic formulation of Supernova Turbulence in Reduced dimensionality (STIR). We show that the viability of the explosion is quite EOS dependent and that it best correlates with the early-time interior entropy density of the proto-neutron star. We check that this result is not progenitor dependent, although low-mass progenitors show different explosion properties, due to the different pre-collapse nuclear composition. Larger central entropies also induce more vigorous proto-neutron-star convection in our one-dimensional turbulence model, as well as a wider convective layer.
Comments:
Accepted to ApJ
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2110.05544 [pdf]
ApJ(2022)·34 citations
08
[Submitted on 11 Oct 2021] (cross-list from gr-qc)
Extending Israel and Stewart hydrodynamics to relativistic superfluids via Carter's multifluid approach
Lorenzo Gavassino🇵🇱 · Marco Antonelli🇵🇱 · Brynmor Haskell🇵🇱
We construct a relativistic model for bulk viscosity and heat conduction in a superfluid. Building on the principles of Unified Extended Irreversible Thermodynamics, the model is derived from Carter's multifluid approach for a theory with 3 four-currents: particles, entropy, and quasi-particles. Dissipation arises directly from the fact that the quasi-particle four-current is an independent degree of freedom that does not necessarily comove with the entropy. For small deviations from local thermodynamic equilibrium, the model provides an extension of the Israel-Stewart theory to superfluid systems. It can, therefore, be made hyperbolic, causal and stable if the microscopic input is accurate. The non-dissipative limit of the model is the relativistic two-fluid model of Carter, Khalatnikov and Gusakov. The Newtonian limit of the model is an Extended-Irreversible-Thermodynamic extension of Landau's two-fluid model. The model predicts the existence of four bulk viscosity coefficients and accounts for their microscopic origin, providing their exact formulas in terms of the quasi-particle creation rate. Furthermore, when fast oscillations of small amplitude around the equilibrium are considered, the relaxation-time term in the telegraph-type equations for the bulk viscosities accounts directly for their expected dependence on the frequency.
Comments:
34 pages, 1 figure
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
arXiv:
2110.05546 [pdf]
PRD(2022)·17 citations
09
[Submitted on 12 Oct 2021] (cross-list from hep-ph)
Pion GPDs: A path toward phenomenology
José Manuel Morgado Chavez🇪🇸 · Valerio Bertone🇫🇷 · Feliciano De Soto Borrero🇪🇸 · Maxime Defurne🇫🇷 · Cédric Mezrag🇫🇷 · Hervé Moutarde🇫🇷 · José Rodríguez-Quintero🇪🇸 · Jorge Segovia🇪🇸
We introduce a new family of Generalised Parton Distribution models able to fulfil by construction all the theoretical properties imposed by QCD. These models are built on standard Parton Distribution Functions and extended to off-forward kinematics through a well-defined procedure. We apply this strategy on the pion, first handling a simple but insightful algebraic model, and then exploiting state-of-the-art computations obtained in continuum QCD. We compare these models with a more standard one relying on an xFitter extraction of the pion Parton Distribution Functions. The results for both quark and gluon Generalised Parton Distributions are presented and exploited for calculation of Electromagnetic, Gravitational and Compton Form Factors. Results on the latter highlight the relevance of next-to-leading order corrections, even in the so-called valence region.
Comments:
20 pages, 12 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2110.06052 [pdf]
PRD(2022)·59 citations
10
[Submitted on 12 Oct 2021] (cross-list from hep-ph)
X17 discovery potential in the $γ N \to e^{+} e^{-} N$ process at electron scattering facilities
Johannes Backens🇩🇪 · Marc Vanderhaeghen🇩🇪
We propose a direct search for the X17 particle, which was conjectured to explain the ATOMKI $^{8}$ Be and $^{4}$ He anomalies, through the dilepton photoproduction process on a nucleon in the photon energy range below or around the pion production threshold. For the scenarios of either pseudoscalar, vector, or axial-vector quantum numbers of the conjectured X17, we use existing constraints to estimate the X17 signal process. For dilepton resolutions which have been achieved in previous experiments, a signal-to-background ratio of up to an order of magnitude is found for a neutron target, and in particular for the pseudoscalar and vector X17 scenarios.
Comments:
5 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2110.06055 [pdf]
PRL(2022)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE