Nuclear Theory·nucl-th

Monday·August 29, 2022

7 papers—3 primary·4 cross-listed

01
[Submitted on 26 Aug 2022]
The lambda hyperon and the hyperon puzzle
Wazha German🇧🇼 · Dr Jacobus Diener🇧🇼
Neutron stars provide unique conditions to study cold dense nuclear matter at extreme densities. Due to these extreme conditions additional hadronic degrees of freedom are expected to be populated,including hyperons. This talk will focus on the influence of hyperons on the neutron star equation ofstate. In particular the contribution of the lambda hyperon will be discussed, as a first approximation to describing exotic neutron star equations of state. The system under consideration is where the strong nuclear force is described by the exchange of mesons and applying the relativistic mean field theory to study dense nuclear matter. As expected, the inclusion of the lambda hyperon softens the neutron star equation of state (EoS). A softer EoS will reduce the maximum mass attainable by the modeled neutron star with such EoS. While hyperons are certainly not unexpected in high density systems, but there presence seems to be contradicted by observations of high mass neutron stars. This contradiction is known as the "hyperon puzzle". The expected influx of observational data from massive new radio-telescopes like the Square Kilometer Array (SKA) will provide observations that can be supported and evolve theoretical models of nuclear matter. Therefore, the study of hyperonic matter is not only relevant to nuclear theory, but also locally to Botswana as an African partner country of the SKA.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2208.12514 [pdf]
3 citations
02
[Submitted on 26 Aug 2022]
Probing nuclear observables via primordial nucleosynthesis
Ulf-G. Meißner🇩🇪 · Bernard Ch. Metsch🇩🇪
We study the dependence of primordial nuclear abundances on fundamental nuclear observables such as binding energies, scattering lengths, neutron lifetime, \textit{etc.} by varying these quantities. The numerical computations were performed with four publicly available codes, thus facilitating an investigation of the model-dependent (systematic) uncertainties on these dependences. Indeed deviations of the order of a few percent are found. Moreover, accounting for the temperature dependence of the sensitivity of the rates to some relevant parameters leads to a reduction of the sensitivity of the final primordial abundances, which in some cases is appreciable. These effects are considered to be relevant for studies of the dependence of the nuclear abundances on fundamental parameters such as quark masses or couplings underlying the nuclear parameters studied here.
Comments:
13 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
arXiv:
2208.12600 [pdf]
EPJA(2022)·6 citations
03
[Submitted on 26 Aug 2022]
Rescattering effect on the measurement of K* spin alignment in heavy-ion collisions
Ziyang Li🇨🇳 · Wangmei Zha🇨🇳 · Zebo Tang🇨🇳
Spin alignment of vector mesons in noncentral relativistic heavy ion collisions provides a novel probe of the global quark polarization and hadronization mechanism. In this paper, we discuss the spin alignment of a short-lived vector meson, namely K*, arising from the hadronic rescattering process using the UrQMD model. This spin alignment is not related to global quark polarization but cannot be distinguished from those arising from global quark polarization in experiments. The spin alignment parameter $ρ_{00}$ is found to deviate from 1/3 by up to -0.008 (0.03) with respect to the reaction (production) plane. These deviations are much larger than the expected signal from all the theoretical models implementing the conventional global quark polarization mechanism as well as the current experimental precision, and should be considered seriously when comparing measurements with theoretical calculations.
Comments:
13 pages, 9 figures, accepted version
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2208.12750 [pdf]
PRC(2022)·13 citations
04
[Submitted on 22 Aug 2022] (cross-list from quant-ph)
An Alternative Approach to Quantum Imaginary Time Evolution
Pejman Jouzdani🇺🇸 · Calvin W. Johnson🇺🇸 · Eduardo R. Mucciolo🇺🇸 · Ionel Stetcu🇺🇸
There is increasing interest in quantum algorithms that are based on the imaginary-time evolution (ITE), a successful classical numerical approach to obtain ground states. However, most of the proposals so far require heavy post-processing computational steps on a classical computer, such as solving linear equations. Here we provide an alternative approach to implement ITE. A key feature in our approach is the use of an orthogonal basis set: the propagated state is efficiently expressed in terms of orthogonal basis states at every step of the evolution. We argue that the number of basis states needed at those steps to achieve an accurate solution can be kept of the order of $n$ , the number of qubits, by controlling the precision (number of significant digits) and the imaginary-time increment. The number of quantum gates per imaginary-time step is estimated to be polynomial in $n$ . Additionally, while in many QAs the locality of the Hamiltonian is a key assumption, in our algorithm this restriction is not required. This characteristic of our algorithm renders it useful for studying highly nonlocal systems, such as the occupation-representation nuclear shell model. We illustrate our algorithm through numerical implementation on an IBM quantum simulator.
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
arXiv:
2208.10535 [pdf]
PRA(2022)·28 citations
05
[Submitted on 25 Aug 2022] (cross-list from hep-ph)
Wave functions of $(I, J^{P}) = (\frac{1}{2}, \frac{3}{2}^{\mp})$ baryons
Langtian Liu🇨🇳 · Chen Chen🇨🇳 · Craig D. Roberts🇨🇳
Using a Poincaré-covariant quark+diquark Faddeev equation, we provide structural information on the four lightest $(I, J^{P}) = (\frac{1}{2}, \frac{3}{2}^{\mp})$ baryon multiplets. These systems may contain five distinct types of diquarks; but in order to obtain reliable results, it is sufficient to retain only isoscalar-scalar and isovector-axialvector correlations, with the latter being especially important. Viewed with low resolution, the Faddeev equation description of these states bears some resemblance to the associated quark model pictures; namely, they form a set of states related via orbital angular momentum excitation: the negative parity states are primarily $P$ -wave in character, whereas the positive parity states are $D$ wave. However, a closer look reveals far greater structural complexity than is typical of quark model descriptions, with $P$ , $D$ , $S$ , $F$ waves and interferences between them all playing a large role in forming observables. Large momentum transfer resonance electroexcitation measurements can be used to test these predictions and may thereby provide insights into the nature of emergent hadron mass.
Comments:
13 pages, 7 figures, 7 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2208.12353 [pdf]
PRD(2023)·23 citations
06
[Submitted on 26 Aug 2022] (cross-list from hep-ph)
Kinematical higher-twist corrections in $γ^{*} γ \to π π$
Cédric Lorcé🇫🇷 · Bernard Pire🇫🇷 · Qin-Tao Song🇫🇷
We apply the Braun-Manashov technique to improve the description of $γ^{*} (q_{1}) γ (q_{2}) \to M (p_{1}) M (p_{2})$ amplitudes at large $Q^{2} = - q_{1}^{2}$ and small $s = (q_{1} + q_{2})^{2}$ . We derive the kinematical higher-twist contributions of order $s / Q^{2}$ and $m^{2} / Q^{2}$ to the helicity amplitudes and estimate their sizes in the kinematics accessible at Belle and Belle II.Since pion GPDs cannot be directly measured by experiment, $π π$ GDAs are the best way to investigate the energy-momentum tensor form factors for pions.
Comments:
5 pages, 2 figures, Part of Proceedings, XXIX International Workshop on Deep-Inelastic Scattering and Related Subjects, Santiago de Compostela, Spain, May 2-6 2022
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2208.12532 [pdf]
5 citations
07
[Submitted on 26 Aug 2022] (cross-list from gr-qc)
$I -$ Love $- C$ relation for an anisotropic neutron star
H. C. Das🇮🇳
One of the most common assumptions has been made that the pressure inside the star is isotropic in nature. However, the pressure is locally anisotropic in nature which is a more realistic case. In this study, we investigate certain properties of anisotropic neutron stars with the scalar pressure anisotropy model. Different perfect fluid conditions are tested within the star with the relativistic mean-field model equation of states (EOSs). The anisotropic neutron star properties such as mass ( $M$ ), radius ( $R$ ), compactness ( $C$ ), Love number ( $k_{2}$ ), dimensionless tidal deformability ( $Λ$ ), and the moment of inertia ( $I$ ) are calculated. The magnitude of the quantities as mentioned above increases (decreases) with the positive (negative) value of anisotropy except $k_{2}$ and $Λ$ . The Universal relation $I -$ Love $- C$ is calculated with almost 58 EOSs spans from relativistic to non-relativistic cases. We observed that the relations between them get weaker when we include anisotropicity. With the help of the GW170817 tidal deformability limit and radii constraints from different approaches, we find that the anisotropic parameter is less than 1.0 if one uses the BL model. Using the universal relation and the tidal deformability bound given by the GW170817, we put a theoretical limit for the canonical radius, $R_{1.4} = 10.7 4_{- 1.36}^{+ 1.84}$ km, and the moment of inertia, $I_{1.4} = 1.7 7_{- 0.09}^{+ 0.17} \times 1 0^{45}$ g cm $^{2}$ with 90\% confidence limit for isotropic stars. Similarly, for anisotropic stars with $λ_{BL} = 1.0$ , the values are $R_{1.4} = 11.7 4_{- 1.54}^{+ 2.11}$ km, $I_{1.4} = 2.4 0_{- 0.08}^{+ 0.17} \times 1 0^{45}$ g cm $^{2}$ respectively.
Comments:
12 pages, 15 figures, 4 tables, Published in Phys. rev. D
Subjects:
General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2208.12566 [pdf]
PRD(2022)·53 citations

Affiliations

first authorsco-authorsvia INSPIRE

The lambda hyperon and the hyperon puzzle

Probing nuclear observables via primordial nucleosynthesis

Rescattering effect on the measurement of K* spin alignment in heavy-ion collisions

An Alternative Approach to Quantum Imaginary Time Evolution

Wave functions of (I,JP)=(21​,23​∓) baryons

Kinematical higher-twist corrections in γ∗γ→ππ

I−Love−C relation for an anisotropic neutron star

Affiliations

Wave functions of $(I, J^{P}) = (\frac{1}{2}, \frac{3}{2}^{\mp})$ baryons

Kinematical higher-twist corrections in $γ^{*} γ \to π π$

$I -$ Love $- C$ relation for an anisotropic neutron star