Nuclear Theory·nucl-th

Wednesday·June 29, 2022

10 papers—5 primary·5 cross-listed

06
[Submitted on 27 Jun 2022] (cross-list from hep-ph)
Regulator scheme dependence of the chiral phase transition at high densities
Konstantin Otto🇩🇪 · Christopher Busch🇩🇪 · Bernd-Jochen Schaefer🇩🇪
A common feature of recent functional renormalization group investigations of effective low-energy QCD is the appearance of a back-bending behavior of the chiral phase transition line at low temperatures together with a negative entropy density in the symmetric regime. The regulator scheme dependence of this phenomenon and the necessary modifications at finite densities are analyzed within a two-flavor quark-meson model. The flows at finite densities for three different regulators of three- or four-dimensional momenta are confronted to each other. It is found that the back-bending behavior and the negative entropy density can be traced back to the explicit momentum dependence of the regulator shape function. While it persists for the often-used three-dimensional flat regulator, it vanishes for Callan-Symanzik type regulators. This points to truncation artifacts in the lowest order of the derivative expansion. A careful theoretical as well as numerical exploration is given.
Comments:
16 pages, 6 figures, 1 table, to be published in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2206.13067 [pdf]
PRD(2022)·26 citations
07
[Submitted on 26 Jun 2022] (cross-list from physics.atom-ph)
Exchange correction for allowed $β$ -decay
O. Niţescu · S. Stoica · F. Šimkovic
We investigate the exchange effect between the final atom's bound electrons and those emitted in the allowed $β$ -decay of the initial nucleus. The electron wave functions are obtained with the Dirac-Hartree-Fock-Slater self-consistent method, and we ensure the orthogonality between the continuum and bound electron states, in the potential of the final atom, by modifying the last iteration of the self-consistent method. We show that orthogonality plays an essential role in calculating the exchange correction. After imposing the orthogonality, we found considerable differences in magnitude and energy dependence compared to previous results. We argue that our findings can solve the mismatch between the previous predictions and experimental measurements in the low-energy region of the $β$ spectrum. First, we calculate the exchange effect for the low-energy $β$ transitions in $^{14}$ C, $^{45}$ Ca, $^{63}$ Ni, and $^{241}$ Pu, recently investigated in the literature. Next, we compute the total exchange correction for a large number of $β$ emitters, with $Z$ from $1$ to $102$ . From the systematic study, we found that for ultra-low energy, i.e., $5$ eV, the $Z$ dependence of total exchange effect is affected by $s_{1/2}$ and $p_{1/2}$ orbitals closure. We also show that the contributions from orbitals higher than $2 s_{1/2}$ orbital are essential for correctly calculating the total effect, especially for low energies and heavy $β$ emitters. Finally, we provide an analytical expression of the total exchange correction for each atomic number for easy implementation in experimental investigations.
Comments:
13 pages, 10 figures, 3 tables
Subjects:
Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th)
arXiv:
2206.13513 [pdf]
PRC(2023)·23 citations
08
[Submitted on 27 Jun 2022] (cross-list from astro-ph.SR)
Towards solar measurements of nuclear reaction rates
Earl Patrick Bellinger · Jørgen Christensen-Dalsgaard
Nuclear reaction rates are a fundamental yet uncertain ingredient in stellar evolution models. The astrophysical S-factor pertaining to the initial reaction in the proton-proton chain is uncertain at the 1% level, which contributes a systematic but generally unpropagated error of similar order in the theoretical ages of stars. In this work, we study the prospect of improving the measurement of this and other reaction rates in the pp chain and CNO cycle using helioseismology and solar neutrinos. We show that when other aspects of the solar model are improved, then it shall be possible using current solar data to improve the precision of this measurement by nearly an order of magnitude, and hence the corresponding uncertainty on the ages of low-mass stars by a similar amount.
Comments:
8 pages, 11 figures, accepted for publication in MNRAS
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2206.13570 [pdf]
MNRAS(2022)·5 citations
09
[Submitted on 28 Jun 2022] (cross-list from hep-ph)
Understanding the QCD medium by the diffusion of charm quarks using a Color String Percolation Model
Kangkan Goswami🇮🇳 · Dushmanta Sahu🇮🇳 · Raghunath Sahoo🇮🇳
We study the drag and diffusion coefficients of the charm quark in the deconfined matter produced in the ultra-relativistic collisions by taking the Color String Percolation Model (CSPM) approach. CSPM, being a QCD-inspired model, can give us essential information about the hot and dense system produced in ultra-relativistic collisions. With the information on initial percolation temperature and percolation density, we estimate the relaxation time ( $τ_{c}$ ), drag coefficient ( $γ$ ), transverse momentum diffusion coefficient ( $B_{0}$ ), and spatial diffusion coefficient ( $D_{s}$ ) of charm quark inside a deconfined medium. Finally, we compare the obtained results with lattice QCD and with various other theoretical models. A good agreement can be observed between the results obtained from CSPM and lattice QCD.
Comments:
7 pages and 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2206.13786 [pdf]
PRD(2023)·13 citations
10
[Submitted on 28 Jun 2022] (cross-list from hep-ph)
Neutrinos and their interactions with matter
M. Sajjad Athar🇮🇳 · A. Fatima🇮🇳 · S. K. Singh🇮🇳
We have presented a review of the properties of neutrinos and their interactions with matter. The different (anti)neutrino processes like the quasielastic scattering, inelastic production of mesons and hyperons, and the deep inelastic scattering from the free nucleons are discussed and the results for the scattering cross sections are presented. The polarization observables for the leptons and hadrons produced in the final state, in the case of quasielastic scattering, are also studied. The importance of nuclear medium effects in the low, intermediate and high energy regions, in the above processes along with the processes of the coherent neutrino-nucleus scattering, coherent meson production, and trident production, have been highlighted. In some cases the results of the cross sections are also given and compared with the available experimental data as well as with the predictions in the different theoretical models. This study would be helpful in understanding the (anti)neutrino interaction cross section with matter in the few GeV energy region relevant to the next generation experiments like DUNE, Hyper-Kamiokande, and other experiments with accelerator and atmospheric neutrinos. We have emphasized the need of better theoretical models for some of these processes for studying the nuclear medium effects in nuclei.
Comments:
204 pages, 108 figures; Progress in particle and nuclear physics, Elsevier (in Press)
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2206.13792 [pdf]
PPNP(2023)·72 citations

Affiliations

first authorsco-authorsvia INSPIRE

Regulator scheme dependence of the chiral phase transition at high densities

Exchange correction for allowed β-decay

Towards solar measurements of nuclear reaction rates

Understanding the QCD medium by the diffusion of charm quarks using a Color String Percolation Model

Neutrinos and their interactions with matter

Affiliations

Exchange correction for allowed $β$ -decay