Nuclear Theory·nucl-th

Thursday·December 20, 2018

14 papers—7 primary·7 cross-listed

01
Linking nuclear reactions and nuclear structure to study exotic nuclei using the dispersive optical model
W. H. Dickhoff
The dispersive optical model (DOM) is employed to simultaneously describe elastic nucleon scattering data for $^{40}$ Ca, $^{48}$ Ca, and $^{208}$ Pb as well as observables related to the ground state of these nuclei, with emphasis on the charge density. Such an analysis requires a fully non-local implementation of the DOM including its imaginary component. Illustrations are provided how ingredients thus generated provide critical components for the description of the $(d, p)$ and $(e, e^{'} p)$ reaction. For the nuclei with $N > Z$ the neutron distribution is constrained by available elastic scattering and ground-state data thereby generating a prediction for the neutron skin. We identify ongoing developments including a non-local DOM analysis for $^{208}$ Pb and point out possible extensions of the method to secure a successful extension of the DOM to rare isotopes.
nucl-thSpringer Proc.Phys.(2020)·1 citation
02
Electromagnetic currents for dressed hadrons
Helmut Haberzettl🇺🇸
We propose an extension of the minimal-substitution prescription for coupling the electromagnetic field to hadronic systems with internal structure. The resulting rules of extended substitution necessarily distinguish between couplings to scalar and Dirac particles. Moreover, they allow for the incorporation of electromagnetic form factors for virtual photons in an effective phenomenological framework. Applied to pions and nucleons, assumed to be fully dressed to all orders, the resulting dressed currents are shown to be locally gauge invariant. Moreover, half-on-shell expressions of (hadron propagator) $\times$ (electromagnetic current) needed in all descriptions of physical processes will lose \textit{all} information about hadronic dressing for real photons. The Ball-Chiu ansatz for the spin-1/2 current is seen to suffer from an incomplete coupling procedure where some essential aspects of the Dirac particle are effectively treated as those of a scalar particle. Applied to real Compton scattering on pions and nucleons, we find that \emph{all} dressing information cancels exactly when external hadrons are on shell, leaving only gauge-invariant bare Born-type contributions with physical masses. Hence, nontrivial descriptions necessarily require contact-type two-photon processes obtained by hadrons looping around two photon insertion points.
nucl-thhep-phPRD(2019)·3 citations
03
Clusterization and deformation of multi- $Λ$ hypernuclei within relativistic mean-field model
Yusuke Tanimura🇯🇵
Deformed multi- $Λ$ hypernuclei are studied within a relativistic mean-field model. In this paper, we take some $N = Z$ "hyper isotope" chains, i.e., $_{n Λ}^{8 + n} Be$ , $_{n Λ}^{20 + n} Ne$ , and $_{n Λ}^{28 + n} Si$ systems where $n = 2$ , $4$ for Be, and $n = 2$ , $8$ for Ne and Si. A sign of two- $_{2Λ}^{6}$ He cluster structure is observed in the two-body correlation in $_{4Λ}^{12}$ Be. In the Ne hyper isotopes, the deformation is slightly reduced by addition of $Λ$ hyperons whereas it is significantly reduced or even disappears in the Si hyper isotopes.
nucl-thPRC(2019)·26 citations
04
Electromagnetic Excitations and Responses in Nuclei from First Principles
R. B. Baker · K. D. Launey · N. Nevo Dinur · S. Bacca · J. P. Draayer · T. Dytrych
We discuss the role of clustering on monopole, dipole, and quadrupole excitations in nuclei in the framework of the ab initio symmetry-adapted no-core shell model (SA-NCSM). The SA-NCSM starts from nucleon-nucleon potentials and, by exploring symmetries known to dominate the nuclear dynamics, can reach nuclei up through the calcium region by accommodating ultra-large model spaces critical to descriptions of clustering and collectivity. The results are based on calculations of electromagnetic sum rules and discretized responses using the Lanczos algorithm, that can be used to determine response functions, and for 4He are benchmarked against exact solutions of the hyperspherical harmonics method. In particular, we focus on He, Be, and O isotopes, including giant resonances and monopole sum rules.
nucl-thAIP Conf.Proc.(2018)·1 citation
05
Heavy-flavor dynamics in event-by-event viscous hydrodynamic backgrounds
Roland Katz🇧🇷 · Caio A. G. Prado🇨🇳 · Jacquelyn Noronha-Hostler🇺🇸 · Alexandre A. P. Suaide🇧🇷 · Jorge Noronha🇧🇷 · Marcelo G. Munhoz🇧🇷
We investigate the effects of (2+1)d event-by-event fluctuating hydrodynamic backgrounds on the nuclear modification factor and momentum anisotropies of heavy-flavor mesons. Using the state-of-the-art D and B mesons modular simulation code (the so-called DAB-mod), updated recently with heavy-light quark coalescence, we perform a systematic comparison of different transport equations, including two energy loss models and a relativistic Langevin model with two drag parametrizations. We present the resulting D $^{0}$ meson $R_{AA}$ , $v_{2}$ and $v_{3}$ , using the multiparticle cumulant method, in Pb-Pb collisions at $s_{NN} = 5.02$ TeV and compare them to the latest experimental data. We investigate the $v_{2} {4} / v_{2} {2}$ ratio as a function of centrality for different initial conditions (MCKLN vs. Trento) and different system geometries and sizes (coming from Pb-Pb collisions at $s_{NN} = 5.02$ TeV, spherical and prolate Xe-Xe collisions at $s_{NN} = 5.44$ TeV).
nucl-thPoS(2018)·3 citations
06
Exploring New Small System Geometries in Heavy Ion Collisions
S.H. Lim🇺🇸 · J. Carlson🇺🇸 · C. Loizides🇺🇸 · D. Lonardoni🇺🇸 · J.E. Lynn🇩🇪 · J.L. Nagle🇺🇸 · J.D. Orjuela Koop🇺🇸 · J. Ouellette🇺🇸
Relativistic heavy ion collisions produce nuclei-sized droplets of quark-gluon plasma whose expansion is well described by viscous hydrodynamic calculations. Over the past half decade, this formalism was also found to apply to smaller droplets closer to the size of individual nucleons, as produced in $p$ $+$ $p$ and $p$ $+$ $A$ collisions. The hydrodynamic paradigm was further tested with a variety of collision species, including $p$ $+$ Au, $d$ $+$ Au, and $^{3}$ He $+$ Au producing droplets with different geometries. Nevertheless, questions remain regarding the importance of pre-hydrodynamic evolution and the exact medium properties during the hydrodynamic evolution phase, as well as the applicability of alternative theories that argue the agreement with hydrodynamics is accidental. In this work we explore options for new collision geometries including $p$ $+$ O and O $+$ O proposed for running at the Large Hadron Collider, as well as, $^{4}$ He $+$ Au, C $+$ Au, O $+$ Au, and $^{7, 9}$ Be $+$ Au at the Relativistic Heavy Ion Collider.
nucl-thnucl-exPRC(2019)·67 citations
07
Physics perspectives with heavy ions in the HL-LHC phase and beyond
Stefan Floerchinger🇩🇪
The current state of research on high-energy heavy ion physics, including its motivations and purpose is reviewed from a theorist's perspective. Possible future directions are discussed, in particular the possibility of investigating the regime of small transverse momenta in more detail and an improved interplay between experiments and dedicated theory development.
nucl-thhep-phPoS(2018)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Linking nuclear reactions and nuclear structure to study exotic nuclei using the dispersive optical model

Electromagnetic currents for dressed hadrons

Clusterization and deformation of multi-Λ hypernuclei within relativistic mean-field model

Electromagnetic Excitations and Responses in Nuclei from First Principles

Heavy-flavor dynamics in event-by-event viscous hydrodynamic backgrounds

Exploring New Small System Geometries in Heavy Ion Collisions

Physics perspectives with heavy ions in the HL-LHC phase and beyond

Affiliations

Clusterization and deformation of multi- $Λ$ hypernuclei within relativistic mean-field model