Nuclear Theory·nucl-th

Thursday·May 27, 2021

4 papers—3 primary·1 cross-listed

01
[Submitted on 26 May 2021]
Role of Quarks in Nuclear Structure
Anthony W Thomas🇦🇺
The strong force that binds atomic nuclei is governed by the rules of Quantum Chromodynamics. Here we consider the suggestion the internal quark structure of a nucleon will adjust self-consistently to the local mean scalar field in a nuclear medium and that this may play a profound role in nuclear structure. We show that one can derive an energy density functional based on this idea, which successfully describes the properties of atomic nuclei across the periodic table in terms of a small number of physically motivated parameters. Because this approach amounts to a new paradigm for nuclear theory, it is vital to find ways to test it experimentally and we review a number of the most promising possibilities.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2105.12327 [pdf]
Oxford Encyclopedia of Science July 2020·2 citations
02
[Submitted on 26 May 2021]
From Cosmic Matter to the Laboratory
Anton Motornenko🇩🇪 · Jan Steinheimer🇩🇪 · Horst Stoecker🇩🇪
The recent discovery of binary neutron star mergers has opened a new and exciting venue of research into hot and dense strongly interacting matter. For the first time this elusive state of matter, described by the theory of quantum chromo dynamics, can be studied in two very different environments. On the macroscopic scale in the collisions of neutron stars and on the microscopic scale in collisions of heavy ions at particle collider facilities. We will discuss the conditions that are created in these mergers and the corresponding high energy nuclear collisions. This includes the properties of QCD matter, i.e. the expected equation of state as well as expected chemical and thermodynamic properties of this exotic matter. To explore this matter in the laboratory - a new research prospect is available at the Facility for Antiproton and Ion Research, FAIR. The new facility is being constructed adjacent to the existing accelerator complex of the GSI Helmholtz Center for Heavy Ion Research at Darmstadt/Germany, expanding the research goals and technical possibilities substantially. The worldwide unique accelerator and experimental facilities of FAIR will open the way for a broad spectrum of unprecedented research supplying a variety of experiments in hadron, nuclear, atomic and plasma physics as well as biomedical and material science which will be briefly described.
Comments:
10 pages, 8 figures, accepted contribution to a 'special issue' of the Astronomische Nachrichten
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2105.12475 [pdf]
Astron.Nachr.(2021)·1 citation
03
[Submitted on 26 May 2021]
Isospin symmetry breaking in double-pion production in the region of $d^{*} (2380)$ and the scalar $σ$ meson
M.N. Platonova🇷🇺 · V.I. Kukulin🇷🇺
The first attempt is made to provide a quantitative theoretical interpretation of the WASA-at-COSY experimental data on the basic double-pion production reactions $p n \to d π^{0} π^{0}$ and $p n \to d π^{+} π^{-}$ in the energy region $T_{p} = 1$ - $1.3$ GeV [P. Adlarson et al., Phys. Lett. B 721, 229 (2013)]. The data are analyzed within a model based on production and decay of an intermediate $I (J^{P}) = 0 (3^{+})$ dibaryon resonance $D_{03}$ (denoted also as $d^{*} (2380)$ ). The observed decrease of the near-threshold enhancement (the so-called ABC effect) in the reaction $p n \to d π^{+} π^{-}$ in comparison to that in the reaction $p n \to d π^{0} π^{0}$ is explained (at least partially) to be due to isospin symmetry violation in the two-pion decay of an intermediate near-threshold scalar $σ$ meson emitted from the $D_{03}$ dibaryon resonance under conditions of the partial chiral symmetry restoration.
Comments:
16 pages, 9 figures; version accepted for publication in Phys. Rev. D
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2105.12482 [pdf]
PRD(2021)·4 citations
04
[Submitted on 25 May 2021] (cross-list from quant-ph)
Transition-state dynamics in complex quantum systems
G.F. Bertsch · K. Hagino
A model is proposed for studying the reaction dynamics in complex quantum systems in which the complete mixing of states is hindered by an internal barrier. Such systems are often treated by the transition-state theory, also known in chemistry as RRKM theory, but the validity of the theory is questionable when there is no identifiable coordinate associated with the barrier. The model consists of two Gaussian Orthogonal Ensembles (GOE) of internal levels coupled to each other and to the wave functions in the entrance and decay channels. We find that the transition-state formula can be derived from the model under some easily justifiable approximations. In particular, the assumption in transition-state theory that the reaction rates are insensitive to the decay widths of the internal states on the far side of the barrier is fulfilled for broad range of Hamiltonian parameters. More doubtful is the common assumption that the transmission factor $T$ across the barrier is unity or can be modeled by a one-dimensional Hamiltonian giving $T$ close to unity above the barrier. This is not the case in the model; we find that the transmission factor only approaches one under special conditions that are not likely to be fulfilled without a strong collective component in the Hamiltonian.
Comments:
8 pages and 6 figures
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th); physics.chem-ph (physics.chem-ph)
arXiv:
2105.12073 [pdf]
J.Phys.Soc.Jap.(2021)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE

Role of Quarks in Nuclear Structure

From Cosmic Matter to the Laboratory

Isospin symmetry breaking in double-pion production in the region of d∗(2380) and the scalar σ meson

Transition-state dynamics in complex quantum systems

Affiliations

Isospin symmetry breaking in double-pion production in the region of $d^{*} (2380)$ and the scalar $σ$ meson