Nuclear Theory·nucl-th

Wednesday·June 24, 2020

12 papers—7 primary·5 cross-listed

01
[Submitted on 20 Jun 2020]
Variation of Single-Particle Energies: Scaling Behavior for the Spectrum of $^{48}$ Cr
Castaly Fan · Praveen C. Srivastava · Larry Zamick
We perform shell model calculations for $^{48}$ Cr using GXPF1A and FPD6 interactions by varying single particle energies. We find a scaling behavior which leads to the finding that many different sets of interactions with vastly different single particle energies can give almost identical results for the yrast spectrum of $^{48}$ Cr
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2006.12494 [pdf]
0 citations
02
[Submitted on 22 Jun 2020]
Temperature dependence of $η / s$ of strongly interacting matter: effects of the equation of state and the parametric form of $(η / s) (T)$
Jussi Auvinen🇷🇸 · Kari J. Eskola🇫🇮 · Pasi Huovinen🇷🇸 · Harri Niemi🇫🇮 · Risto Paatelainen🇨🇭 · Peter Petreczky🇺🇸
We investigate the temperature dependence of the shear viscosity to entropy density ratio $η / s$ using a piecewise linear parametrization. To determine the optimal values of the parameters and the associated uncertainties, we perform a global Bayesian model-to-data comparison on Au+Au collisions at $s_{N N} = 200$ GeV and Pb+Pb collisions at $2.76$ TeV and $5.02$ TeV, using a 2+1D hydrodynamical model with the EKRT initial state. We provide three new parametrizations of the equation of state (EoS) based on contemporary lattice results and hadron resonance gas, and use them and the widely used $s 95 p$ parametrization to explore the uncertainty in the analysis due to the choice of the equation of state. We found that $η / s$ is most constrained in the temperature range $T \approx 150$ -- $220$ MeV, where, for all EoSs, $0.08 < η / s < 0.23$ when taking into account the 90% credible intervals. In this temperature range the EoS parametrization has only a small $\approx 10%$ effect on the favored $η / s$ value, which is less than the $\approx 30%$ uncertainty of the analysis using a single EoS parametrization. Our parametrization of $(η / s) (T)$ leads to a slightly larger minimum value of $η / s$ than the previously used parametrizations. When we constrain our parametrization to mimic the previously used parametrizations, our favored value is reduced, and the difference becomes statistically insignificant.
Comments:
19 pages, 12 figures. Published in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2006.12499 [pdf]
PRC(2020)·70 citations
03
[Submitted on 22 Jun 2020]
Two-photon exchange from intermediate state resonances in elastic electron-proton scattering
Jaseer Ahmed🇨🇦 · P. G. Blunden🇨🇦 · W. Melnitchouk🇺🇸
We use a recently developed dispersive approach to compute the two-photon exchange (TPE) correction to elastic electron-proton scattering, including contributions from hadronic $J^{P} = 1/ 2^{\pm}$ and $3/ 2^{\pm}$ resonant intermediate states below~1.8~GeV. For the transition amplitudes from the proton ground state to the resonant excited states we employ new exclusive meson electroproduction data from CLAS at $Q^{2} ≲ 5$ ~GeV $^{2}$ , and we explore the effects of both fixed and dynamic widths for the resonances. Among the resonant states, the $N (1520) 3/ 2^{-}$ becomes dominant for $Q^{2} ≳ 2$ ~GeV $^{2}$ , with a sign opposite to the comparably sized $Δ (1232) 3/ 2^{+}$ contribution, leading to an overall increase in the size of the TPE correction to the cross section relative to the nucleon only contribution at higher $Q^{2}$ values. The results are in good overall agreement with recent $e^{+} p$ to $e^{-} p$ cross section ratio and polarization transfer measurements, and provide compelling evidence for a resolution of the electric to magnetic form factor ratio discrepancy.
Comments:
40 pages, 15 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2006.12543 [pdf]
PRC(2020)·33 citations
04
[Submitted on 23 Jun 2020]
A simple model of the charmed hypertriton
Faisal Etminan🇮🇷
We investigate the three-baryon system with charm +1 in a simple model. Charmed lambda $Λ_{c}$ is assumed to orbit an unperturbed deuteron in a charmed lambda-deuteron potential based on a separable charmed lambda-nucleon potential from chiral effective field theory techniques extrapolations of lattice QCD data for the $Λ_{c} N$ $^{1} S_{0}$ and $^{3} S_{1}$ partial waves. We have estimated the strength and the range of the $Λ_{c}$ d potential. Also, the $Λ_{c}$ particle momentum distribution in $_{Λ_{c}}^{3} H$ is presented and compared by $Λ$ particle in $_{Λ}^{3} H$ . It is found that there is no bound $_{Λ_{c}}^{3} H$ state by solving eigenvalue condition equation.
Comments:
some results is not exact the results is not as good as should be
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2006.12771 [pdf]
0 citations
05
[Submitted on 23 Jun 2020]
Isospin-density dependent pairing from infinite nuclear matter to finite nuclei
Xu Meng · Shisheng Zhang · Lin Guo · Lisheng Geng · Ligang Cao
The effective isospin-density dependent pairing interaction (P1) [S. S. Zhang, U. Lombardo and E. G. Zhao, Sci. Chin. Phys. Mech. Astro. {\bf 54}, 236 (2011)] extracted from neutron pairing gaps for $^{1}$ S $_{0}$ in asymmetric nuclear matter calculations [S. S. Zhang, L. G. Cao, U. Lombardo, et al. Phys. Rev. C {\bf 81}, 044313 (2010)] is employed to study the bulk properties of Ca, Ni, Zr and Sn isotopes. The odd-even mass (OEM) staggering is calculated by the Skyrme Hartree-Fock plus BCS method (SHF + BCS) with the SkP interaction. For comparison, we study two other types of isovector effective pairing interactions. One is also extracted from pairing gaps of infinite nuclear matter by the Brueckner-Hartree-Fock (BHF) method but for free spectrum (P2). The other is obtained by fitting the empirical OEM (P3). An isoscalar effective pairing interaction (P4) is also adopted which is determined by fitting the empirical OEM. We find that interaction P1 can better describe the OEM staggering of Ni, Zr and Sn isotopes by $14.3%, 41%, 30.4%$ compared with interaction P2, in terms of root mean square deviations to the empirical OEM, respectively. On the other hand, the performance of P1 and P2 is comparable for Ca isotopes. For Ca and Ni isotopes, P1 behaves similarly as P3, but for Zr isotopes P1 is better than P3 by $\sim 34%$ . Among the four pairing interactions studied, P4 performs the worst. Therefore, one may conclude that for neutron pairings in finite nuclei, the isovector pairings are preferred than the isoscalar one. It is quite interesting to note that the pairing interaction P1 extracted from nuclear matter calculations can describe pairing gaps of finite nuclei as well as or even better than the interaction P3 directly fitted to finite nuclei.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2006.12914 [pdf]
PRC(2020)·4 citations
06
[Submitted on 23 Jun 2020]
Understanding the energy dependence of $B_{2}$ in heavy ion collisions: Interplay of volume and space-momentum correlations
Vincent Gaebel🇩🇪 · Michel Bonne🇩🇪 · Tom Reichert🇩🇪 · Ajdin Burnic🇧🇦 · Paula Hillmann🇩🇪 · Marcus Bleicher🇩🇪
The deuteron coalescence parameter $B_{2}$ in proton+proton and nucleus+nucleus collisions in the energy range of $s_{N N} =$ 900 - 7000 GeV for proton+proton and $s_{N N} =$ 2 - 2760 GeV for nucleus+nucleus collisions is analyzed with the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) transport model, supplemented by an event-by-event phase space coalescence model for deuteron and anti-deuteron production. The results are compared to data by the E866, E877, PHENIX, STAR and ALICE experiments. The $B_{2}$ values are calculated from the final spectra of protons and deuterons. At lower energies, $s_{N N} \leq 20$ GeV, $B_{2}$ drops drastically with increasing energy. The calculations confirm that this is due to the increasing freeze-out volume reflected in $B_{2} \sim 1/ V$ . At higher energies, $s_{N N} \geq 20$ GeV, $B_{2}$ saturates at a constant level. This qualitative change and the vanishing of the volume suppression is shown to be due to the development of strong radial flow with increasing energy. The flow leads to strong space-momentum correlations which counteract the volume effect.
Comments:
6 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2006.12951 [pdf]
EPJA(2021)·17 citations
07
[Submitted on 23 Jun 2020]
Isobar correlations bearing information on the properties of hot disassembling nuclear sources
S.R. Souza · R. Donangelo
Two-particle correlations based on the multiplicity of selected isobars are found to be sensitive to the parameterization of the fragments' binding energies and the breakup volume assumed in the model calculations. The properties of these correlations have been examined in the framework of the Statistical Multifragmentation Model as a function of the breakup temperature. The model calculations suggest that the maxima of these correlation functions occur at well separated temperatures as the breakup volumes used in the model vary from 3 to 6 times that at normal density. These volumes are within the range assumed in most statistical calculations and supported by experiments. Besides their position, the height and width of the maxima are also found to be sensitive to the parameterization of the fragments' binding energy. The magnitude of all these effects also depends on the isobars considered in the correlations. We found that, due to an interplay between the symmetry energy and the volume dependent terms of the Helmholtz free energy, in the case of nearly symmetric sources, correlations involving light mirror nuclei seem to enhance these effects. We suggest that the proposed correlation functions could be used to extract information on the fragments' energies and on the breakup volume of nuclear sources.
Comments:
6 pages, 3 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2006.13116 [pdf]
PRC(2020)·2 citations
08
[Submitted on 19 Jun 2020] (cross-list from hep-ph)
Revisiting the proton mass decomposition
Andreas Metz🇺🇸 · Barbara Pasquini🇮🇹 · Simone Rodini🇮🇹
Different decompositions (sum rules) for the proton mass have been proposed in the literature. All of them are related to the energy-momentum tensor in quantum chromodynamics. We review and revisit these decompositions by paying special attention to recent developments with regard to the renormalization of the energy-momentum tensor. The connection between the sum rules is discussed as well. We present numerical results for the various terms of the mass decompositions up to 3 loops in the strong coupling, and consider their scheme dependence. We also elaborate on the role played by the trace anomaly and the sigma terms.
Comments:
28 pages; V2: some discussion added, matches PRD version
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2006.11171 [pdf]
PRD(2021)·100 citations
09
[Submitted on 22 Jun 2020] (cross-list from hep-ph)
Charm jets as a probe for strangeness at the future Electron-Ion Collider
Miguel Arratia🇺🇸 · Yulia Furletova🇺🇸 · T. J. Hobbs🇺🇸 · Fredrick Olness🇺🇸 · Stephen J. Sekula🇺🇸
We explore the feasibility of the measurement of charm-jet cross sections in charged-current deep-inelastic scattering at the future Electron-Ion Collider. This channel provides clean sensitivity to the strangeness content of the nucleon in the high- $x$ region. We estimate charm-jet tagging performance with parametrized detector simulations. We show the expected sensitivity to various scenarios for strange parton distribution functions. We argue that this measurement will be key to future QCD global analyses, so it should inform EIC detector designs and luminosity requirements.
Comments:
17 pages, 12 figures, 2 tables; added new plots showing PDF error bands in s(x,Q) and Rs(x,Q) to illustrate range of uncertainty on these quantities
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2006.12520 [pdf]
PRD(2021)·43 citations
10
[Submitted on 22 Jun 2020] (cross-list from cond-mat.stat-mech)
Universal location of the Yang-Lee edge singularity in O(N) theories
Andrew Connelly🇺🇸 · Gregory Johnson🇺🇸 · Fabian Rennecke🇺🇸 · Vladimir Skokov🇺🇸
We determine a previously unknown universal quantity, the location of the Yang-Lee edge singularity for the O( $N$ ) theories in a wide range of $N$ and various dimensions. At large $N$ , we reproduce the $N \to \infty$ analytical result on the location of the singularity and, additionally, we obtain the mean-field result for the location in $d = 4$ dimensions. In order to capture the nonperturbative physics for arbitrary $N$ , $d$ and complex-valued external fields, we use the functional renormalization group approach.
Comments:
6 pages, 2 figures; version accepted for publication in PRL
Subjects:
Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2006.12541 [pdf]
PRL(2020)·64 citations
11
[Submitted on 22 Jun 2020] (cross-list from hep-ph)
A Somewhat Random Walk Through Nuclear and Particle Physics
Thomas D. Cohen🇺🇸 · Nicholas R. Poniatowski🇺🇸
These notes are an outgrowth of an advanced undergraduate course taught at the University of Maryland, College Park. They are intended as an introduction to various aspects of particle and nuclear physics with an emphasis on the role of symmetry. The basic philosophy is to introduce many of the fundamental ideas in nuclear and particle physics using relatively sophisticated mathematical tools -- but to do so in as a simplified a context to explain the underlying ideas. Thus, for example, the Higgs mechanism is discussed in terms of an Abelian Higgs model. The emphasis is largely, but not entirely theoretical in orientation. The goal is for readers to develop an understanding of many of the underlying issues in a relatively sophisticated way.
Comments:
158 pages; submission to SciPost Lecture Notes
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2006.12564 [pdf]
SciPost Phys.Lect.Notes(2021)·0 citations
12
[Submitted on 23 Jun 2020] (cross-list from astro-ph.HE)
Large-scale Simulations of Antihelium Production in Cosmic-ray Interactions
Anirvan Shukla🇺🇸 · Amaresh Datta🇺🇸 · Philip von Doetinchem🇺🇸 · Diego-Mauricio Gomez-Coral🇺🇸 · Carina Kanitz🇩🇪
The possibility of antihelium production in interaction of cosmic rays with the interstellar gas is studied using large-scale Monte Carlo simulations. For this purpose, an energy-dependent coalescence mechanism developed previously is extended to estimate the production of light antinuclei ( $^{3} He$ and $^{4} He$ ). The uncertainty in the coalescence parameter and its effect on the expected antiparticle flux is also investigated. The simulated background antihelium fluxes are found to be lower than the fluxes predicted by simplified models using numerical scaling techniques.
Comments:
16 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2006.12707 [pdf]
PRD(2020)·32 citations

Affiliations

first authorsco-authorsvia INSPIRE