Nuclear Theory·nucl-th

Wednesday·June 8, 2022

8 papers—4 primary·4 cross-listed

01
[Submitted on 6 Jun 2022]
Delta baryons in neutron stars
Kauan D. Marquez🇧🇷 · Helena Pais🇧🇷 · Débora P. Menezes🇵🇹 · Constança Providência🇵🇹
By applying a relativistic mean-field description of neutron star matter with density dependent couplings, we analyse the properties of two different matter compositions: nucleonic matter with delta baryons and nucleonic matter with hyperons and delta baryons. The delta-meson couplings are allowed to vary within a wide range of values obtained by experimental data, while the hyperon-meson couplings are fitted to hypernuclear properties. Neutron star properties with no deconfinement phase transition are studied. It is verified that many models are excluded because the effective nucleon mass becomes zero before the maximum mass configuration is attained. Hyperon-free with delta-dominated composition compact stars are possible, the deltic stars. It is found that with a convenient choice of parameters the existence of deltic stars with 80% of delta baryons at the center of the star is possible. However, the presence of hyperons lowers the delta baryon fraction to values below 20% at the center and below 30% at 2-3 saturation densities. It is discussed that in the presence of delta baryons, the hyperon softening is not so drastic because deltas couple more strongly to the $ω$ -meson, and the stiffness of the equation of state is determined by the $ω$ -dominance at high densities. The speed of sound reflects very well this behavior. The compactness of the pulsar RX J0720.4-3125 imposes $x_{σ Δ} > x_{ω Δ} > 1$ and favors $x_{ρ Δ} > 1$ .
Comments:
14 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2206.02935 [pdf]
PRC(2022)·33 citations
02
[Submitted on 7 Jun 2022]
Triaxiality induced monopole-quadrupole-hexadecupole coupling in the isoscalar giant resonances for $^{86} Ge$
Xuwei Sun · Jie Meng
The isoscalar giant resonances for $^{86} Ge$ are studied by the quasiparticle finite amplitude method based on the covariant density functional theory. In addition to the well-known monopole-quadrupole coupling that splits the isoscalar giant monopole resonance in axially deformed nuclei, a monopole-quadrupole-hexadecupole coupling is identified in the triaxially deformed nucleus $^{86} Ge$ , leading to the emergence of a distinct resonance peak at the low energy side of the isoscalar monopole strength function. The transition density of the triaxiality induced resonance peak shows a strong interplay among monopole, quadrupole, and hexadecupole vibrations. The resonance peak responses to monopole, quadrupole, and hexadecupole perturbations simultaneously, which could be regarded as a fingerprint of the triaxiality in $^{86} Ge$ .
Comments:
15 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2206.03030 [pdf]
PRC(2022)·5 citations
03
[Submitted on 7 Jun 2022]
Combined theoretical analysis of the parity-violating asymmetry for $^{48}$ Ca and $^{208} P b$
Paul-Gerhard Reinhard · Xavier Roca-Maza · Witold Nazarewicz
The recent experimental determination of the parity violating asymmetry $A_{pv}$ in $^{48}$ Ca and $^{208}$ Pb at Jefferson Lab is important for our understanding on how neutrons and protons arrange themselves inside the atomic nucleus. To better understand the impact of these measurements, we present a rigorous theoretical investigation of $A_{pv}$ in $^{48}$ Ca and $^{208}$ Pb and assess the associated uncertainties. We complement our study by inspecting the static electric dipole polarizability in these nuclei. The analysis is carried out within nuclear energy density functional theory with quantified input. We conclude that the simultaneous accurate description of $A_{pv}$ in $^{48}$ Ca and $^{208}$ Pb cannot be achieved by our models that accommodate a pool of global nuclear properties, such as masses and charge radii, throughout the nuclear chart, and describe -- within one standard deviation -- the experimental dipole polarizabilities $α_{D}$ in these nuclei.
Comments:
Published version including supplemental Material in the submission source files
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2206.03134 [pdf]
PRL(2022)·121 citations
04
[Submitted on 7 Jun 2022]
Nuclear $C (e, e^{'} p)$ Transparencies in a Relativistic Glauber Model
Wim Cosyn · Jan Ryckebusch
In light of the recent Jefferson Laboratory (JLab) data for the nuclear $^{12} C (e, e^{'} p)$ transparencies, calculations, obtained in a relativistic multiple scattering Glauber approximation, are discussed. The shell-separated $^{12}$ C transparencies are shown and it is concluded that the $p$ -shell nucleons are 75\% more transparent than the $s$ -shell ones. The presented comparisons between the calculations made here and the current $^{12} C (e, e^{'} p)$ data show no clear indication for the onset of color transparency when implemented within the color diffusion model with standard parameters.
Comments:
5 pages, 2 figures. Matches published version in Special Issue "The Future of Color Transparency, Hadronization and Short-Range Nucleon-Nucleon Correlation Studies". Based on a talk given at the workshop "The Future of Color Transparency and Hadronization Studies at Jefferson Lab and Beyond"
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2206.03374 [pdf]
MDPI Physics(2022)·1 citation
05
[Submitted on 6 Jun 2022] (cross-list from hep-ph)
A unified picture of medium-induced radiation
Johannes Hamre Isaksen🇳🇴 · Adam Takacs🇳🇴 · Konrad Tywoniuk🇳🇴
We revisit the picture of jets propagating in the quark-gluon plasma. In addition to vacuum radiation, partons scatter on the medium constituents resulting in induced emissions. Analytical approaches to including these interactions have traditionally dealt separately with multiple, soft, or rare, hard scatterings. A full description has so far only been available using numerical methods. We achieve full analytical control of the relevant scales and map out the dominant physical processes in the full phase space. To this aim, we extend existing expansion schemes for the medium-induced spectrum to the Bethe--Heitler regime. This covers the whole phase space from early to late times, and from hard splittings to emissions below the thermal scale. Based on the separation of scales, a space-time picture naturally emerges: at early times, induced emissions start to build from rare scatterings with the medium. At a later stage, induced emissions due to multiple soft scatterings result in a turbulent cascade that rapidly degrades energy down to, and including, the Bethe--Heitler regime. We quantify the impact of such an improved picture, compared to the current state-of-the-art factorization that includes only soft scatterings, by both analytical and numerical methods for the medium-induced energy distribution function. Our work serves to improve our understanding of jet quenching from small to large systems and for future upgrades of Monte Carlo generators.
Comments:
published version, 58 pages, 11 figures, if the figures don't load properly try using a different PDF reader
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2206.02811 [pdf]
JHEP(2023)·25 citations
06
[Submitted on 6 Jun 2022] (cross-list from hep-lat)
Heavy quark diffusion coefficient with gradient flow
Nora Brambilla🇩🇪 · Viljami Leino🇩🇪 · Julian Mayer-Steudte🇩🇪 · Peter Petreczky🇺🇸
We calculate chromo-electric and chromo-magnetic correlators in quenched QCD at $1.5 T_{c}$ and $1 0^{4} T_{c}$ with the aim to estimate the heavy quark diffusion coefficient at leading order in the inverse heavy quark mass expansion, $κ_{E}$ , as well as the coefficient of first mass suppressed correction, $κ_{B}$ . We use gradient flow for noise reduction. At $1.5 T_{c}$ we obtain: $1.70 \leq κ_{E} / T^{3} \leq 3.12$ and $1.03 < κ_{B} / T^{3} < 2.61$ . The latter implies that the mass suppressed effects in the heavy quark diffusion coefficient are 20% for bottom quarks and 34% for charm quark at this temperature.
Comments:
18 pages, 20 figures, updated to match the published version
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2206.02861 [pdf]
PRD(2023)·50 citations
07
[Submitted on 6 Jun 2022] (cross-list from hep-lat)
Study of three-flavored heavy dibaryons using lattice QCD
Parikshit Junnarkar🇩🇪 · Nilmani Mathur🇮🇳
We present results of the first lattice QCD calculation of three-flavored heavy dibaryons both in the flavor-symmetric and antisymmetric channels. These dibaryons have spin zero, and are constructed using various possible combinations of quark flavors with at least one of them as the charm or the bottom quark, i.e., namely, $H_{c} (c u d c u d), H_{b} (b u d b u d), H_{b cs} (b cs b cs)$ , $H_{cs l} (cs l cs l), H_{b s l} (b s l b s l)$ and $H_{b c l} (b c l b c l)$ ; $l \in u, d$ . We compute the ground state masses of these dibaryons and the calculations are performed on three $N_{f} = 2 + 1 + 1$ HISQ gauge ensembles of the MILC collaboration, with lattice spacings $a =$ 0.1207, 0.0888 and 0.0582 fm. A relativistic overlap action is employed for the valence light to charm quarks while a non-relativistic-QCD Hamiltonian with improved coefficients is used for the bottom quarks. Unlike the doubly heavy tetraquarks, one and two-flavored heavy dibaryons, for which lattice QCD calculations have predicted deeply bound strong-interactions-stable states, for these $H_{c}, H_{b}, H_{cs l}, H_{b s l}$ dibaryons we do not find any such deeply bound state. However, for $H_{b cs}$ , our results indicate the presence of an energy level $29 \pm 24$ MeV below the lowest two-baryon threshold, which could be relevant for its future experimental searches. Moreover, we find that the energy difference between the ground state of $H_{b c l}$ and its lowest threshold increases when $m_{l} > m_{s}$ . Taken together, our findings indicate the possibility of the existence of the $H_{b cs}$ dibaryon while all other physical three-flavored dibaryons are much closer to their thresholds suggesting either they are weakly bound or unbound, resolving which requires further detail study. Our results also point that the binding of a dibaryon configuration becomes stronger with the increase of its valence quark masses which suggests an interesting aspect of strong interactions at multiple scales.
Comments:
Version published in Phys. Rev. D
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2206.02942 [pdf]
PRD(2022)·24 citations
08
[Submitted on 7 Jun 2022] (cross-list from astro-ph.HE)
Evaluations of uncertainties in simulations of propagation of ultrahigh-energy cosmic-ray nuclei derived from microscopic nuclear models
E. Kido🇯🇵 · T. Inakura🇯🇵 · M. Kimura🇯🇵 · N. Kobayashi🇯🇵 · S. Nagataki🇯🇵 · N. Shimizu🇯🇵 · A. Tamii🇯🇵 · Y. Utsuno🇯🇵
Photodisintegration is a main energy loss process for ultrahigh-energy cosmic-ray (UHECR) nuclei in intergalactic space. Therefore, it is crucial to understand systematic uncertainty in photodisintegration when simulating the propagation of UHECR nuclei. In this work, we calculated the cross sections using the random phase approximation (RPA) of density functional theory (DFT), a microscopic nuclear model. We calculated the $E 1$ strength of 29 nuclei using three different density functionals. We obtained the cross sections of photonuclear reactions, including photodisintegration, with the $E 1$ strength. Then, we implemented the cross sections in the cosmic-ray propagation code CRPropa. We found that assuming certain astrophysical parameter values, the difference between UHECR energy spectrum predictions using the RPA calculation and the default photodisintegration model in CRPropa can be more than the statistical uncertainty of the spectrum. We also found that the differences between the RPA calculations and CRPropa default in certain astrophysical parameters obtained by a combined fit of UHECR energy spectrum and composition data assuming a phenomenological model of UHECR sources can be more than the uncertainty of the data.
Comments:
37 pages, 16 figures
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2206.03447 [pdf]
Astropart.Phys.(2023)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE