Nuclear Theory·nucl-th

Wednesday·March 3, 2021

13 papers—6 primary·7 cross-listed

01
Exploring Origins for Correlations between Flow Harmonics and Transverse Momentum in Small Collision Systems (Unambiguous Ambiguity)
S.H. Lim🇰🇷 · J.L. Nagle🇺🇸
High statistics data sets from experiments at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) with small and large collision species have enabled a wealth of new flow measurements, including the event-by-event correlation between observables. One exciting such observable $ρ (v_{n}^{2}, [p_{T}])$ gauges the correlation between the mean transverse momentum of particles in an event and the various flow coefficients ( $v_{n}$ ) in the same event [1]. Recently it has been proposed that very low multiplicity events may be sensitive to initial-state glasma correlations [2] rather than flow-related dynamics. We find utilizing the IP-JAZMA framework that the color domain explanation for the glasma results are incomplete. We then explore predictions from PYTHIA-8, and the version for including nuclear collisions called PYTHIA-ANGANTYR, which have only non-flow correlations and the AMPT model which has both non-flow and flow-type correlations. We find that PYTHIA-ANGANTYR has non-flow contributions to $ρ (v_{n}^{2}, [p_{T}])$ in p+O, p+Pb, O+O collisions that are positive at low multiplicity and comparable to the glasma correlations. It is striking that in PYTHIA-8 in p+p collisions there is actually a sign-change from positive to negative $ρ (v_{n}^{2}, [p_{T}])$ as a function of multiplicity. The AMPT results match the experimental data general trends in Pb+Pb collisions at the LHC, except at low multiplicity where AMPT has the opposite sign. In p+Pb collisions, AMPT has the opposite sign from experimental data and we explore this within the context of parton geometry. Predictions for p+O, O+O, and Xe+Xe are also presented.
nucl-thnucl-exPRC(2021)·22 citations
02
Unbound spectra of neutron-rich oxygen isotopes predicted by the Gamow shell model
J. G. Li🇨🇳 · N. Michel🇨🇳 · W. Zuo🇨🇳 · F. R. Xu🇨🇳
The Gamow shell model has shown to efficiently describe weakly bound and unbound nuclear systems, as internucleon correlations and continuum coupling are both taken into account in this model. In the present work, we study neutron-dripline oxygen isotopes. It is hereby demonstrated that the presence of continuum coupling is important for the description of oxygen isotopes at dripline, and especially to assess the eventual bound or unbound character of $^{28}$ O. Our results suggest that the ground state of $^{28}$ O is weakly unbound and is similar to the narrow resonant $^{26}$ O ground state. Predictions of weakly bound and resonance excited states in $^{24 - 26}$ O are also provided. The asymptotes of the studied many-body states are analyzed via one-body densities, whereby the different radial properties of well bound, loosely bound, resonance states are clearly depicted.
nucl-thPRC(2021)·35 citations
03
A Relativistic Quantum Approach to Neutrino and Antineutrino Emissions via the Direct Urca Process in Strongly Magnetized Neutron-Star Matter
Tomoyuki Maruyama🇯🇵 · A. Baha Balantekind🇺🇸 · Myung-Ki Cheoung🇰🇷 · Toshitaka Kajino🇯🇵 · Motohiko Kusakabef🇨🇳 · Grant J. Mathewsh🇺🇸
We study neutrino and antineutrino emission from the direct Urca process in neutron-star matter in the presence of strong magnetic fields. We calculate the neutrino emissivity of the direct Urca process, whereby a neutron converts to a proton, an electron and an antineutrino, or a proton-electron pair converts to a neutron-neutrino pair. We solve exact wave functions for protons and electrons in the states described with Landau levels. We find that the direct Urca process can satisfy the kinematic constraints even in density regions where this process could not normally occur in the absence of a magnetic field.
nucl-thastro-ph.HEPLB(2022)·16 citations
04
Triangle singularity mechanism for the $pp \to π^{+} d$ fusion reaction
Natsumi Ikeno🇯🇵 · Raquel Molina🇪🇸 · Eulogio Oset🇪🇸
We develop a model for the $pp \to π^{+} d$ reaction based on the $pp \to Δ (1232) N$ transition followed by $Δ (1232) \to π N^{'}$ decay and posterior fusion of $N N^{'}$ to give the deuteron. We show that the triangle diagram depicting this process develops a triangle singularity leading to a large cross section of this reaction compared to ordinary fusion reactions. The results of the calculation also show that the process is largely dominated by the $pp$ system in $L = 2, S = 0$ , which transfers $J = 2$ to the final $π^{+} d$ system. This feature is shown to be well suited to provide $L = 2, S = 1$ , $J^{tot} = 3$ for $n p$ in the $n p (I = 0) \to π^{-} pp$ followed by $pp \to π^{+} d$ reaction, which has been proposed recently, as a means of describing the so far assumed dibaryon $d^{*} (2380)$ peak.
nucl-thhep-phPRC(2021)·35 citations
05
Mapping topology to nuclear dilaton-HLS effective field theory for dense baryonic matter
Yong-Liang Ma🇨🇳 · Mannque Rho🇫🇷
We describe the on-going effort to formulate the baryon-quark continuity in terms of a topology change in the equation of state (EoS) of dense baryonic matter in analogy to -- and inspired by -- the mapping of the characteristics of Chern-Simon topological field theory to Kohn-Sham density functional theory in the fractional quantized Hall effect (FQHE). This is done by translating the density-dependent characteristics of the skyrmion-half-skyrmion transition formulated in the presence of hidden local symmetry and (hidden) scale symmetry to the density-dependent parameters of a renormalization-group approach to Fermi-liquid fixed point theory. Predictions made in finite nuclei and infinite compact-star matter are presented.
nucl-thhep-ph3 citations
06
Investigation of important weak interaction nuclei in presupernova evolution
Jameel-Un Nabi🇵🇰 · Asim Ullah🇵🇰 · Ali Abas Khan🇵🇰
The project aims to investigate most important weak interaction nuclei in the presupernova evolution of massive stars. To achieve the goal, an ensemble containing 728 nuclei in the mass range A = 1--100 was considered. We computed the mass fractions of these nuclei using Saha's equation for predetermined values of \textit{ $T$ }, \textit{ $ρ$ } and \textit{ $Y_{e}$ } and assuming nuclear statistical equilibrium. The nuclear partition functions were obtained using a newly introduced recipe where excited states, up to 10 $M e V$ , were treated as discrete. The weak interaction rates (electron capture (\textit{ec}) and $β$ -decay (\textit{bd})) were calculated in a \textit{totally} microscopic fashion using the proton-neutron quasiparticle random phase approximation (pn-QRPA) model and without assuming the Brink-Axel hypothesis. The calculated rates were coupled with the computed mass fractions to investigate the time rate of change of lepton to baryon fraction of the stellar matter. We compare our results with the previous calculations reported in the literature. Noticeable differences up to orders of magnitude are reported with previous calculations. These differences may influence the evolution of the star in the later stages of presupernova. We present a list of top 50 \textit{ec} and \textit{bd} nuclei which have the largest effect on $Y_{e}$ for conditions after silicon core burning. The competition between the \textit{ec} and \textit{bd} rates in stellar core was investigated and it was found that $Y_{e}$ = 0.424--0.455 is the interval where the \textit{bd} results are bigger than the \textit{ec} rates.
nucl-thastro-ph.SRApJ(2021)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE

Exploring Origins for Correlations between Flow Harmonics and Transverse Momentum in Small Collision Systems (Unambiguous Ambiguity)

Unbound spectra of neutron-rich oxygen isotopes predicted by the Gamow shell model

A Relativistic Quantum Approach to Neutrino and Antineutrino Emissions via the Direct Urca Process in Strongly Magnetized Neutron-Star Matter

Triangle singularity mechanism for the pp→π+d fusion reaction

Mapping topology to nuclear dilaton-HLS effective field theory for dense baryonic matter

Investigation of important weak interaction nuclei in presupernova evolution

Affiliations

Triangle singularity mechanism for the $pp \to π^{+} d$ fusion reaction