Nuclear Theory·nucl-th

Thursday·January 20, 2022

9 papers—4 primary·5 cross-listed

01
[Submitted on 18 Jan 2022]
Angular-momentum projection in coupled-cluster theory: structure of $^{34}$ Mg
G. Hagen · S. J. Novario🇺🇸 · Z. H. Sun🇺🇸 · T. Papenbrock🇺🇸 · G. R. Jansen🇺🇸 · J. G. Lietz🇺🇸 · T. Duguet🇫🇷 · A. Tichai🇩🇪
Single-reference coupled-cluster theory is an accurate and affordable computational method for the nuclear many-body problem. For open-shell nuclei, the reference state typically breaks rotational invariance and angular momentum must be restored as a good quantum number. We perform angular-momentum projection after variation and employ the disentangled coupled-cluster formalism and a Hermitian approach. We compare our results with benchmarks for $^{8}$ Be and $^{20}$ Ne using a two-nucleon interaction from chiral effective field theory and for $p f$ -shell nuclei within the traditional shell model. We compute the rotational band in the exotic nucleus $^{34}$ Mg and find agreement with data.
Comments:
23 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2201.07298 [pdf]
PRC(2022)·91 citations
02
[Submitted on 18 Jan 2022]
Efficient emulation of relativistic heavy ion collisions with transfer learning
Dananjaya Liyanage🇺🇸 · Yi Ji🇺🇸 · Derek Everett🇺🇸 · Matthew Heffernan🇨🇦 · Ulrich Heinz🇺🇸 · Simon Mak🇺🇸 · Jean-Francois Paquet🇺🇸
Measurements from the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC) can be used to study the properties of quark-gluon plasma. Systematic constraints on these properties must combine measurements from different collision systems and methodically account for experimental and theoretical uncertainties. Such studies require a vast number of costly numerical simulations. While computationally inexpensive surrogate models ("emulators") can be used to efficiently approximate the predictions of heavy ion simulations across a broad range of model parameters, training a reliable emulator remains a computationally expensive task. We use transfer learning to map the parameter dependencies of one model emulator onto another, leveraging similarities between different simulations of heavy ion collisions. By limiting the need for large numbers of simulations to only one of the emulators, this technique reduces the numerical cost of comprehensive uncertainty quantification when studying multiple collision systems and exploring different models.
Comments:
15 pages, 6 figures, journal article
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2201.07302 [pdf]
PRC(2022)·25 citations
03
[Submitted on 19 Jan 2022]
Competition between weak and alpha-decay modes in superheavy nuclei
Pedro Sarriguren
The competition between alpha- and beta+/EC-decay modes is studied systematically in nuclei along the alpha-decay chains following the synthesis of superheavy nuclei with Z = 119 and Z = 120. A microscopic approach based on deformed self-consistent Hartree-Fock mean-field calculations with Skyrme forces and pairing correlations is used to describe the beta+ and electron capture weak decays, whereas the alpha-decay is estimated from existing phenomenological expressions. It is shown that alpha-decay is in most cases the dominant decay mode, but interesting instances are identified where the half-lives are comparable, opening the possibility of new pathways towards more neutron-rich nuclei in this region.
Comments:
9 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2201.07476 [pdf]
PRC(2022)·7 citations
04
[Submitted on 19 Jan 2022]
S-wave pion condensation in symmetric nuclear matter
D. N. Voskresensky (JINR, Dubna, Russia)🇷🇺
S-wave pion-nucleon interactions in the linear sigma model, and in Manohar-Georgi and Gasser-Sainio-Svarc models with finite number of terms in Lagrangians, as well as in a general phenomenological approach are reviewed. Subtleties associated with the current algebra theorems and field redefinitions are discussed. In the first and third models most likely the s-wave pion condensation in the isospin-symmetric matter does not occur at least up to high densities, whereas within the second model it may appear already at moderate densities. In the phenomenological approach two parameterizations of the s-wave pion-nucleon scattering amplitude and the pion polarization operator used in the literature are considered. The first parameterization employs the off-mass-shell amplitude and allows to fulfil the current algebra theorems. Using it the s-wave pion polarization operator in the isospin-symmetric matter is reconstructed within the gas approximation. With this pion polarization operator the s-wave pion condensation in the isospin-symmetric matter does not occur at least up to high densities. Second parameterization uses the on-mass-shell pion-nucleon scattering amplitude and does not satisfy the Adler and Weinberg conditions. With such a parameterization most likely the s-wave pion condensation in the isospin-symmetric matter may occur already at the nucleon density $n ≃ (1.4 - 2.5) n_{0}$ , where $n_{0}$ is the density of the atomic nucleus, that should result in observable effects. Both parameterizations allow to successfully describe the pion atom data.
Comments:
15 pages, 2 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2201.07536 [pdf]
PRD(2022)·12 citations
05
[Submitted on 18 Jan 2022] (cross-list from hep-ph)
Empirical capture cross sections for cosmic neutrino detection with $^{151} Sm$ and $^{171} Tm$
Vedran Brdar🇺🇸 · Ryan Plestid🇺🇸 · Noemi Rocco🇺🇸
The nuclei $^{151}$ Sm and $^{171}$ Tm have been identified as attractive candidates for the detection of the cosmic neutrino background. Both isotopes undergo first-forbidden non-unique beta decays which inhibits a prediction of their spectral shape using symmetries alone and this has, so far, obstructed a definitive prediction of their neutrino capture cross sections. In this work we point out that for both elements the so-called " $ξ$ -approximation" is applicable and this effectively reduces the spectral shape to deviate by at most $1%$ from the one that would arise if beta decays were of the allowed type. Using measured half-lives we extract the relevant nuclear matrix element and predict the neutrino capture cross sections for both isotopes at $1%$ level, accounting for a number of relevant effects including radiative corrections and the finite size of the nuclei. We obtained $(1.12 \pm 0.01) \times 1 0^{- 46} cm^{2}$ for $^{171}$ Tm and $(4.77 \pm 0.01) \times 1 0^{- 48} cm^{2}$ for $^{151}$ Sm. This method is robust as it does not rely on the data points near the end-point of the beta spectrum which may be contaminated by atomic physics effects, namely shake-up and shake-off. Finally, we calculate the target mass which is necessary for cosmic neutrino discovery and discuss several bottlenecks and respective solutions associated to the experimental program. We conclude that the detection of cosmic neutrino background by neutrino capture on $^{151}$ Sm and $^{171}$ Tm is achievable and free from theoretical limitations but still subject to technical issues that should be further investigated by the experimentalists in the context of the proposed PTOLEMY project.
Comments:
published version; 10 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2201.07251 [pdf]
PRC(2022)·14 citations
06
[Submitted on 19 Jan 2022] (cross-list from hep-ph)
Final-state interaction in the process $e^{+} e^{-} \to Λ_{c} Λ ˉ_{c}$
A.I. Milstein🇷🇺 · S.G. Salnikov🇷🇺
We show that the final-state interaction explains the nontrivial near-threshold energy dependence of the cross section of the process $e^{+} e^{-} \to Λ_{c} Λ ˉ_{c}$ observed by the Belle and BESIII collaborations. This energy dependence is the result of the mixture of $S$ -wave and $D$ -wave components of the $Λ_{c} Λ ˉ_{c}$ wave function due to a tensor interaction. The Coulomb potential is important only in the narrow energy region about a few MeV above the threshold of the process. It is shown that the widely used assumption that the impact of the Coulomb interaction on the cross sections of hadron production is reduced to the Sommerfeld-Gamow-Sakharov factor is not correct.
Comments:
9 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2201.07450 [pdf]
PRD(2022)·15 citations
07
[Submitted on 19 Jan 2022] (cross-list from hep-ph)
Planck Formula for the Gluon Parton Distribution in the Proton
Loredana Bellantuono🇮🇹 · Roberto Bellotti🇮🇹 · Franco Buccella🇮🇹
We describe the gluon parton distribution function (PDF) in the proton, deduced by data from the ATLAS and HERA experiments, in the framework of the parton statistical model. The best fit parameters involved in the Planck formula that describes the gluon distribution are consistent with the results obtained from analysis of deep inelastic scattering processes. Remarkably, the agreement between the statistical model and the experimental gluon distributions is found with the same value of the "temperature" parameter $x ˉ$ found by fitting the valence parton distributions from deep inelastic scattering. This result corroborates the validity of the statistical approach in the gluon sector.
Comments:
4 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2201.07640 [pdf]
Mod.Phys.Lett.A(2023)·7 citations
08
[Submitted on 19 Jan 2022] (cross-list from hep-ph)
Foundations and Applications of Quantum Kinetic Theory
Yoshimasa Hidaka🇯🇵 · Shi Pu🇨🇳 · Qun Wang🇨🇳 · Di-Lun Yang🇹🇼
Many novel quantum phenomena emerge in non-equilibrium relativistic quantum matter under extreme conditions such as strong magnetic fields and rotations. The quantum kinetic theory based on Wigner functions in quantum field theory provides a powerful and effective microscopic description of these quantum phenomena. In this article we review some of recent advances in the quantum kinetic theory and its applications in describing these quantum phenomena.
Comments:
114 pages, 3 figures; List of acronyms and symbols are added
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2201.07644 [pdf]
PPNP(2022)·108 citations
09
[Submitted on 19 Jan 2022] (cross-list from hep-ph)
Quarkonium Suppression in the Open Quantum System Approach
Xiaojun Yao🇺🇸
Quarkonium suppression in relativistic heavy ion collisions has been studied experimentally for decades to probe the properties of the quark-gluon plasma. For this purpose, complete theoretical understanding of the time evolution of quarkonium inside the quark-gluon plasma is needed but challenging. Here I review recent progress in applying the open quantum system framework to describe the real-time dynamics of quarkonium, with a focus on the gauge-invariant chromoelectric field correlators of the plasma that control the dynamics.
Comments:
4 pages, leading parallel contribution to the proceedings of the 19th International Conference on Hadron Spectroscopy and Structure (Hadron 2021)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2201.07702 [pdf]
Rev.Mex.Fis.Suppl.(2022)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE