Nuclear Theory·nucl-th

Monday·June 24, 2019

8 papers—6 primary·2 cross-listed

01
Non-relativistic expansion of single-nucleon Dirac equation: Comparison between Foldy-Wouthuysen transformation and similarity renormalization group
Yixin Guo🇨🇳 · Haozhao Liang🇯🇵
By following the Foldy-Wouthuysen (FW) transformation of the Dirac equation, we work out the exact analytic expressions up to the $1/ M^{4}$ order for the general cases in the covariant density functional theory. These results are further compared with the corresponding ones derived from another novel non-relativistic expansion method, the similarity renormalization group (SRG). Based on that, the origin of the difference between the results obtained by the FW transformation and SRG method is explored.
nucl-thmath-phmath.MPquant-phCPC(2019)·12 citations
02
Measuring Momentum-Dependent Flow Fluctuations in Heavy-Ion Collisions
Mauricio Hippert🇧🇷 · David Dobrigkeit Chinellato🇧🇷 · Matthew Luzum🇧🇷 · Jorge Noronha🇧🇷 · Tiago Nunes da Silva🇧🇷 · Jun Takahashi🇧🇷
In heavy-ion collisions, momentum-dependent pair correlations can be characterized by a principal component analysis (PCA), in which subleading modes are expected to reveal new information on flow fluctuations. However, we find that, as currently measured, these modes can be dominated by multiplicity fluctuations, which serve as an unwanted background. Here, we propose new PCA observables that are robust against multiplicity fluctuations and isolate novel sources of flow fluctuations, thus being suited to provide fresh insight into the initial stages of the system at small length scales.
nucl-thhep-phnucl-exPRC(2020)·15 citations
03
Irregularities in nuclear radii at magic numbers
H. Nakada
Influence of magic numbers on nuclear radii is investigated via the Hartree-Fock-Bogolyubov calculations and available experimental data. With the $ℓ s$ potential including additional density-dependence suggested from the chiral effective field theory, kinks are universally predicted at the $j j$ -closed magic numbers and anti-kinks (\textit{i.e.} inverted kinks) are newly predicted at the $ℓ s$ -closed magic numbers, both in the charge radii and in the matter radii along the isotopic and isotonic chains where nuclei stay spherical. These results seem consistent with the kinks of the charge radii observed in Ca, Sn and Pb and the anti-kink in Ca. The kinks and the anti-kinks could be a peculiar indicator for magic numbers, discriminating $j j$ -closure and $ℓ s$ -closure.
nucl-thPRC(2019)·42 citations
04
Time Reversal Violation in Light Nuclei
A. Gnech🇮🇹 · M. Viviani🇮🇹
Time Reversal Violation (TRV) interactions between quarks which appear in Standard Model (SM) and beyond-SM theories can induce TRV components in the nucleon-nucleon potential. The effects of these components can be studied by measuring the electric dipole moment (EDM) of light nuclei. In this work we present a complete derivation of the TRV nucleon-nucleon and three-nucleon potential up to next-to-next-to leading order (N2LO) in a chiral effective field theory (chiEFT) framework. The TRV interaction is then used to evaluate the EDM of 2H, 3H and 3he focusing in particular on the effects of the TRV three-body force and on the calculation of the theoretical errors. In case of a measurement of the EDM of these nuclei, the result of present work would permit to determine the values of the low energy constants and to identify the source of TRV.
nucl-thhep-phPRC(2020)·20 citations
05
Elliptic flow in ultra-relativistic collisions with light polarized nuclei
Wojciech Broniowski🇵🇱 · Piotr Bozek🇵🇱
Estimates for elliptic flow in collisions of polarized light nuclei with spin $j \geq 1$ with a heavy nucleus are presented. In such collisions the azimuthal symmetry is broken via polarization of the wave function of the light nucleus, resulting in nonzero one-body elliptic flow coefficient evaluated relative to the polarization axis. Our estimates involve experimentally well known features of light nuclei, such as their quadrupole moment and the charge radius, yielding the one-body elliptic flow coefficient in the range from 1\% for collisions with the deuteron to 5\% for for collisions with $^{10}$ B nucleus. Prospects of addressing the issue in the upcoming fixed-target experiment at the Large Hadron Collider are discussed.
nucl-thnucl-exPRC(2020)·15 citations
06
$^{7}$ Be and $^{7}$ Li nuclei within the no-core shell model with continuum
Matteo Vorabbi🇨🇦 · Petr Navrátil🇨🇦 · Sofia Quaglioni🇺🇸 · Guillaume Hupin🇫🇷
The production of $^{7}$ Be and $^{7}$ Li nuclei plays an important role in primordial nucleosynthesis, nuclear astrophysics, and fusion energy generation. The $^{3} He (α, γ)^{7} Be$ and $^{3} H (α, γ)^{7} Li$ radiative-capture processes are important to determine the $^{7}$ Li abundance in the early universe and to predict the correct fraction of pp-chain branches resulting in $^{7}$ Be versus $^{8}$ B neutrinos. In this work we study the properties of $^{7}$ Be and $^{7}$ Li within the no-core shell model with continuum (NCSMC) method, using chiral nucleon-nucleon interactions as the only input, and analyze all the binary mass partitions involved in the formation of these systems. The NCSMC is an ab initio method applicable to light nuclei that provides a unified description of bound and scattering states and thus is well suited to investigate systems with many resonances and pronounced clustering like $^{7}$ Be and $^{7}$ Li. Our calculations reproduce all the experimentally known states of the two systems and provide predictions for several new resonances of both parities. Some of these new possible resonances are built on the ground states of $^{6}$ Li and $^{6}$ He, and thus represent a robust prediction. We do not find any resonance in the p $+^{6}$ Li mass partition near the threshold. On the other hand, in the p $+^{6}$ He mass partition of $^{7}$ Li we observe an $S$ -wave resonance near the threshold producing a very pronounced peak in the calculated S factor of the $^{6} He (p, γ)^{7} Li$ radiative-capture reaction, which could be relevant for astrophysics and its implications should be investigated.
nucl-thnucl-exPRC(2019)·42 citations
07
Effects of a dense medium on parameters of doubly heavy baryons
K. Azizi🇮🇷 · N. Er🇹🇷
The spectroscopic properties of the doubly heavy spin- $1/2$ baryons $Ξ_{Q Q^{'}}$ , $Ξ_{Q Q^{'}}^{'}$ , $Ω_{Q Q^{'}}$ and $Ω_{Q Q^{'}}^{'}$ , with heavy quarks $Q$ and $Q^{'}$ being $b$ or/and $c$ , are investigated in cold nuclear matter. In particular, the behavior of the mass of these particles with respect to the density of the medium in the range $ρ \in [0, 1.4] ρ_{s a t}$ , with $ρ_{s a t} = 0.1 1^{3} G e V^{3}$ being the saturation density of nuclear matter, is investigated. From the shifts in the mass and vector self energy of the states under consideration, it is obtained that $Ξ_{Q Q^{'}}$ and $Ξ_{Q Q^{'}}^{'}$ baryons with two heavy quarks and one $u$ or $d$ quark are affected by the medium, considerably. It is also seen that the $Ω_{Q Q^{'}}$ and $Ω_{Q Q^{'}}^{'}$ states, containing two heavy quarks and one $s$ quark do not see the dense medium, at all. The value of mass for the $Ξ_{cc}$ state obtained at $ρ \to 0$ limit is nicely consistent with the experimental data. Our results on parameters of other members can be useful in the search for these states. The obtained results may also shed light on the future in-medium experiments aiming to search for the behavior of the doubly heavy baryons under extreme conditions.
↳ hep-phhep-exnucl-thPRD(2019)·8 citations
08
Quantum chromodynamics axion in a hot and magnetized medium
Aritra Bandyopadhyay🇧🇷 · Ricardo L. S. Farias🇧🇷 · Bruno S. Lopes🇧🇷 · Rudnei O. Ramos🇧🇷
It is analyzed the effects of a hot and magnetized medium on the axion mass, self-coupling and topological susceptibility when in presence of an anisotropic external magnetic field along the $z$ -direction, within the Nambu--Jona-Lasinio effective model for quantum chromodynamics. The effects of both Magnetic Catalysis and Inverse Magnetic Catalysis are explicitly taken into account through appropriate matching of parameters with those from lattice Monte-Carlo numerical simulations. It is also analyzed the dependence of the results with respect to different model parametrizations in the context of the Nambu--Jona-Lasinio model.
↳ hep-phhep-thnucl-thPRD(2019)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE