Nuclear Theory·nucl-th

Thursday·July 16, 2020

12 papers—6 primary·6 cross-listed

01
[Submitted on 14 Jul 2020]
Effective Field Theory for Two-Body Systems with Shallow S-Wave Resonances
J. Balal Habashi🇺🇸 · S. Sen🇺🇸 · S. Fleming🇺🇸 · U. van Kolck🇫🇷
Resonances are of particular importance to the scattering of composite particles in quantum mechanics. We build an effective field theory for two-body scattering which includes a low-energy $S$ -wave resonance. Our starting point is the most general Lagrangian with short-range interactions. We demonstrate that these interactions can be organized into various orders so as to generate a systematic expansion for an $S$ matrix with two low-energy poles. The pole positions are restricted by renormalization at leading order, where the common feature is a non-positive effective range. We carry out the expansion explicitly to next-to-leading order and illustrate how it systematically accounts for the results of a toy model -- a spherical well with a delta shell at its border.
Comments:
23 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2007.07360 [pdf]
Annals Phys.(2020)·19 citations
02
[Submitted on 15 Jul 2020]
Properties of nuclear pastas
Jorge A. Lopez · Claudio O. Dorso · Guillermo A. Frank
In this Review we study the nuclear pastas as they are expected to be formed in neutron star cores. We start with a study of the pastas formed in nuclear matter (composed of protons and neutrons), we follow with the role of the electron gas on the formation of pastas, and we then investigate the pastas in neutron star matter (nuclear matter embedded in an electron gas).
Comments:
85 pagres, 174 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2007.07417 [pdf]
Front.Phys.(Beijing)(2021)·25 citations
03
[Submitted on 15 Jul 2020]
Nuclear shape evolution and shape coexistence in Zr and Mo isotopes
Pankaj Kumar · Virender Thakur · Smriti Thakur · Vikesh Kumar · Shashi K. Dhiman
The phenomena of shape evolution and shape coexistence in even-even $^{88 - 126}$ Zr and $^{88 - 126}$ Mo isotopes is studied by employing covariant density functional theory (CDFT) with density-dependent point coupling parameter sets DD-PCX and DD-PC1, and with separable pairing interaction. The results for rms deviation in binding energies, two-neutron separation energy, the differential variation of two-neutron separation energy, and rms charge radii, as a function of neutron number, are presented and compared with available experimental data. In addition to the oblate-prolate shape coexistence in $^{96 - 110}$ Zr isotopes, the correlation between shape transition and discontinuity in the observables are also examined. A smooth trend of charge radii in Mo isotopes is found to be due to the manifestation of triaxiality softness. The observed oblate and prolate minima are related to the low single-particle energy level density around the Fermi level of neutron and proton respectively. The present calculations also predict a deformed bubble structure in $^{100}$ Zr isotope.
Comments:
this preprint contains incomplete data and some mistakes
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2007.07479 [pdf]
EPJA(2021)·16 citations
04
[Submitted on 15 Jul 2020]
Bayesian inference of nuclear symmetry energy from measured and imagined neutron skin thickness in $^{116, 118, 120, 122, 124, 130, 132}$ Sn, $^{208}$ Pb, and $^{48}$ Ca
Jun Xu · Wen-Jie Xie · Bao-An Li
The neutron skin thickness $Δ r_{n p}$ in heavy nuclei has been known as one of the most sensitive terrestrial probes of the nuclear symmetry energy around $\frac{2}{3}$ of the saturation density $ρ_{0}$ of nuclear matter. Existing neutron skin data mostly from hadronic observables suffer from large uncertainties and their extraction from experiments are often strongly model dependent. While waiting eagerly for the promised model-independent and high-precision neutron skin data for $^{208}$ Pb and $^{48}$ Ca from the parity-violating electron scattering experiments (PREX-II and CREX at JLab as well as MREX at MESA), within the Bayesian statistical framework using the Skyrme-Hartree-Fock model we infer the posterior probability distribution functions (PDFs) of the slope parameter $L$ of the nuclear symmetry energy at $ρ_{0}$ from imagined $Δ r_{n p} (^{208}$ Pb $) = 0.15$ , 0.20, and 0.30 fm as well as $Δ r_{n p} (^{48}$ Ca $) = 0.12$ , 0.15, and 0.25 fm, with different $1 σ$ error bars. The results are compared with the PDFs of $L$ inferred using the same approach from the available $Δ r_{n p}$ data for Sn isotopes from hadronic probes. They are also compared with results from a recent Bayesian analysis of the radius and tidal deformability data of canonical neutron stars from GW170817 and NICER. The neutron skin data for Sn isotopes gives $L = 45. 5_{- 21.6}^{+ 26.5}$ MeV surrounding its mean value or $L = 53. 4_{- 29.5}^{+ 18.6}$ MeV surrounding its maximum {\it a posteriori} value, respectively, with the latter smaller than but consistent with the $L = 6 6_{- 20}^{+ 12}$ MeV from the neutron star data within their 68\% confidence intervals. In order to provide additionally useful information on $L$ extracted from the $Δ r_{n p}$ of Sn isotopes, the experimental error bar of $Δ r_{n p} (^{208}$ Pb) should be at least smaller than 0.06 fm aimed by some current experiments.
Comments:
11 pages, 6 figures, accepted by Physical Review C
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2007.07669 [pdf]
PRC(2020)·55 citations
05
[Submitted on 14 Jul 2020]
Formation of light nuclei at chemical freezeout: Description within a statistical thermal model
Deeptak Biswas🇮🇳
The thermal description of light nuclei at the chemical freeze-out has been investigated. First, I have verified the equilibration of the light nuclei and then introduced a new method to investigate the light nuclei formation. One can study the proximity between the phase space density of light nuclei ratios and their hadronic constituents e.g $d ˉ / d$ and $(p ˉ n ˉ / p n)$ . I have found that with the exclusion of the decay feed-down from the hadronic yields in the thermal model, the hadronic representations have good agreement with the light nuclei ratios. I have performed a similar analysis with the ratio of $Λ$ -hypernuclei and $^{3} H e$ , which is related to the ratio $Λ/ p$ . In this context, the strangeness population factor $S_{3}$ has been studied also. These results indicate that the nuclei and hypernuclei formation may occur near the standard chemical freeze-out and before the decay of the hadronic resonances. This method will serve as a guideline to discuss the light nuclei formation and the inclusion of decay into their hadronic constituents.
Comments:
Title has been modified, version published in PRC
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2007.07680 [pdf]
PRC(2020)·10 citations
06
[Submitted on 15 Jul 2020]
Extracting the temperature dependence in high- $p_{⊥}$ particle energy loss
Stefan Stojku🇷🇸 · Bojana Ilic🇷🇸 · Marko Djordjevic🇷🇸 · Magdalena Djordjevic🇷🇸
The suppression of high- $p_{⊥}$ particles is one of the main signatures of parton energy loss during its passing through the QGP medium, and is reasonably reproduced by different theoretical models. However, a decisive test of the reliability of a certain energy loss mechanism, apart from its path-length, is its temperature dependence. Despite its importance and comprehensive dedicated studies, this issue is still awaiting for more stringent constraints. To this end, we here propose a novel observable to extract temperature dependence exponent of high- $p_{⊥}$ particle's energy loss, based on $R_{AA}$ . More importantly, by combining analytical arguments, full-fledged numerical calculations and comparison with experimental data, we argue that this observable is highly suited for testing (and rejecting) the long-standing $Δ E / E \propto L^{2} T^{3}$ paradigm. The anticipated significant reduction of experimental errors will allow direct extraction of temperature dependence, by considering different centrality pair in $A + A$ collisions (irrespective of the nucleus size) in high- $p_{⊥}$ region. Overall, our results imply that this observable, which reflects the underlying energy loss mechanism, is very important to distinguish between different theoretical models.
Comments:
19 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2007.07851 [pdf]
PRC(2021)·15 citations

Affiliations

first authorsco-authorsvia INSPIRE

Effective Field Theory for Two-Body Systems with Shallow S-Wave Resonances

Properties of nuclear pastas

Nuclear shape evolution and shape coexistence in Zr and Mo isotopes

Bayesian inference of nuclear symmetry energy from measured and imagined neutron skin thickness in 116,118,120,122,124,130,132Sn, 208Pb, and 48Ca

Formation of light nuclei at chemical freezeout: Description within a statistical thermal model

Extracting the temperature dependence in high-p⊥​ particle energy loss

Affiliations

Bayesian inference of nuclear symmetry energy from measured and imagined neutron skin thickness in $^{116, 118, 120, 122, 124, 130, 132}$ Sn, $^{208}$ Pb, and $^{48}$ Ca

Extracting the temperature dependence in high- $p_{⊥}$ particle energy loss