Nuclear Theory·nucl-th

Friday·December 11, 2020

5 papers—2 primary·3 cross-listed

01
[Submitted on 9 Dec 2020]
Partial decay widths of baryons in the spin-momentum operator expansion method
A.V. Sarantsev🇩🇪
The covariant operator expansion method used by the Bonn-Gatchina group for the analysis of the meson photoproduction data is extended on the case of meson electro-production reactions. The angular dependence of the partial waves is deduced and the obtained amplitudes are compared with those used in other analyses of the electro-production reactions
Comments:
8 pages. arXiv admin note: text overlap with arXiv:hep-ph/0605135
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2012.05305 [pdf]
0 citations
02
[Submitted on 10 Dec 2020]
In-medium effects in strangeness production in heavy-ion collisions at (sub-)threshold energies
Taesoo Song🇩🇪 · Laura Tolos🇪🇸 · Joana Wirth🇩🇪 · Joerg Aichelin🇫🇷 · Elena Bratkovskaya🇩🇪
We study the in-medium effects in strangeness production in heavy-ion collisions at (sub-)\-threshold energies of 1 - 2 A GeV based on the microscopic Parton-Hadron-String Dynamics (PHSD) transport approach. The in-medium modifications of the antikaon $(K ˉ = K^{-}, K ˉ^{0})$ properties are described via the self-consistent coupled-channel unitarized scheme based on a SU(3) chiral Lagrangian which incorporates explicitly the $s -$ and $p -$ waves of the kaon-nucleon interaction. This scheme provides the antikaon potential, spectral functions and reaction cross sections as well as their dependence on baryon density, temperature and antikaon momentum in the nuclear medium, which are incorporated in the off-shell dynamics of the PHSD. The in-medium modification of kaons $(K = K^{+}, K^{0})$ are accounted via the kaon-nuclear potential, which is assumed to be proportional to the local baryon density. The manifestation of the medium effects in observables is investigated for the $K$ and $K ˉ$ rapidity distributions, $p_{T}$ -spectra as well as the polar and azimuthal angular distributions, direct ( $v_{1}$ ) and elliptic ( $v_{2}$ ) flow in C+C, Ni+Ni, and Au+Au collisions. We find - by comparison to experimental data from the KaoS, FOPI and HADES Collaborations - that the modifications of (anti)kaon properties in nuclear matter are necessary to explain the data in a consistent manner. Moreover, we demonstrate the sensitivity of kaon observables to the equation-of-state of nuclear matter.
Comments:
38 pages, 26 figures, to be published in PRC
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2012.05589 [pdf]
PRC(2021)·51 citations
03
[Submitted on 9 Dec 2020] (cross-list from hep-ph)
The neutron star inner crust: an empirical essay
Luiz L. Lopes🇧🇷
In this work we study how the small contribution of the inner crust to the total equation of state (EoS) of a neutron star affects its mass-radius relation, focusing on the canonical mass of 1.4 $M_{⊙}$ . We build empirical EoS of the kind - $p = K ϵ^{γ} + b$ - in the range of 0.003 fm $^{- 3} < n <$ 0.08 fm $^{- 3}$ and also calculate the speed of sound in this region. We see that different behaviours of the speed of sound can affect the radius of the canonical star by more than 1.1 km. This result can help us understand extreme results as GW170817, where some studies indicate that the radius of the canonical star cannot exceed 11.9 km.
Comments:
letter, Published version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2012.05277 [pdf]
EPL(2021)·14 citations
04
[Submitted on 10 Dec 2020] (cross-list from hep-ph)
Quantum fluctuations of energy in subsystems of a hot relativistic gas
Arpan Das🇵🇱 · Wojciech Florkowski🇵🇱 · Radoslaw Ryblewski🇵🇱 · Rajeev Singh🇵🇱
We derive a formula that defines quantum fluctuations of energy in subsystems of a hot relativistic gas. For small subsystem sizes we find substantial increase of fluctuations compared to those known from standard thermodynamic considerations. However, if the size of the subsystem is sufficiently large, we reproduce the result for energy fluctuations in the canonical ensemble. Our results are subsequently used in the context of relativistic heavy-ion collisions to introduce limitations of the concepts such as classical energy density or fluid element. In the straightforward way, our formula can be applied in other fields of physics, wherever one deals with hot and relativistic matter.
Comments:
11 pages, 4 figures, Matches with the published version, Published in Acta Physica Polonica B, Vol. 52 (2021), page no: 1395-1404
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2012.05662 [pdf]
Acta Phys.Polon.B(2021)·10 citations
05
[Submitted on 10 Dec 2020] (cross-list from hep-ph)
Finite Size Effects on the Chiral Phase Transition of Quantum Chromodynamics
Shen-Song Wan🇨🇳 · Daize Li🇨🇳 · Bonan Zhang🇨🇳 · Marco Ruggieri🇨🇳
We study the effect of periodic boundary conditions on chiral symmetry breaking and its restoration in Quantum Chromodynamics. As an effective model of the effective potential for the quark condensate, we use the quark-meson model, while the theory is quantized in a cubic box of size $L$ . After specifying a renormalization prescription for the vacuum quark loop, we study the condensate at finite temperature, $T$ , and quark chemical potential, $μ$ . We find that lowering $L$ leads to a catalysis of chiral symmetry breaking. The excitation of the zero mode leads to a jump in the condensate at low temperature and high density, that we suggest to interpret as a gas-liquid phase transition that takes place between the chiral symmetry broken phase (hadron gas) and chiral symmetry restored phase (quark matter). We characterize this intermediate phase in terms of the increase of the baryon density, and of the correlation length of the fluctuations of the order parameter: for small enough $L$ the correlation domains occupy a substantial portion of the volume of the system, and the fluctuations are comparable to those in the critical region. For these reasons, we dub this phase as the {\it subcritical liquid}. The qualitative picture that we draw is in agreement with previous studies based on similar effective models. We also clarify the discrepancy on the behavior of the critical temperature versus $L$ found in different models.
Comments:
11 pages, 9 figures. A short discussion about the critical temperature versus L, including a comparison with the NJL model, has been added in the V2, in Section IV.B
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2012.05734 [pdf]
7 citations

Affiliations

first authorsco-authorsvia INSPIRE

Partial decay widths of baryons in the spin-momentum operator expansion method

In-medium effects in strangeness production in heavy-ion collisions at (sub-)threshold energies

The neutron star inner crust: an empirical essay

Quantum fluctuations of energy in subsystems of a hot relativistic gas

Finite Size Effects on the Chiral Phase Transition of Quantum Chromodynamics

Affiliations