Nuclear Theory·nucl-th

Friday·October 6, 2023

8 papers—6 primary·2 cross-listed

01
[Submitted on 4 Oct 2023]
Hypertriton lifetime
D. Gazda🇨🇿 · A. Pérez-Obiol🇪🇸 · A. Gal🇮🇱 · E. Friedman🇮🇱
Over the last decade, conflicting values of the hypertriton $_{Λ}^{3} H$ lifetime $τ (_{Λ}^{3} H)$ were extracted from relativistic heavy-ion (RHI) collision experiments, ranging from values compatible with the free- $Λ$ lifetime $τ_{Λ}$ -as expected naively for a very weakly bound $Λ$ in $_{Λ}^{3} H$ -to lifetimes as short as $τ (_{Λ}^{3} H) \approx (0.4 - 0.7) τ_{Λ}$ . In a recent work [Phys. Lett. B 811, 135916 (2020)] we studied this $_{Λ}^{3} H$ lifetime puzzle theoretically using realistic three-body $_{Λ}^{3} H$ and $^{3} He$ wave functions computed within the ab initio no-core shell model approach with interactions derived from chiral effective field theory. In particular, $τ (_{Λ}^{3} H)$ was found to be strongly correlated with the $Λ$ separation energy $B_{Λ}$ in $_{Λ}^{3} H$ , the value of which is rather poorly known experimentally and, in addition, is known to suffer from sizable theoretical uncertainties inherent in the employed nuclear and hypernuclear interaction models. In the present work we find that these uncertainties propagate into $τ (_{Λ}^{3} H)$ , and thus limit considerably the theoretical precision of its computed value. Although none of the conflicting RHI measured $τ (_{Λ}^{3} H)$ values can be excluded, but rather can be attributed to a poor knowledge of $B_{Λ}$ , we note the good agreement between the lifetime value $τ (_{Λ}^{3} H) = 238 (27)$ ps computed at the lowest value $B_{Λ} = 66$ keV reached by us and the very recent ALICE measured lifetime value $τ^{ALICE} (_{Λ}^{3} H) = 253 (11) (6)$ ps associated with the ALICE measured $B_{Λ}$ value $B_{Λ}^{ALICE} = 102 (63) (67)$ keV [Phys. Rev. Lett. 131, 102302 (2023)].
Comments:
15 pages, 6 figures, 3 tables; minor changes, matches published version
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2310.03087 [pdf]
PRC(2024)·5 citations
02
[Submitted on 4 Oct 2023]
$^{40}$ Ca transverse response function from coupled-cluster theory
Joanna Sobczyk🇩🇪 · Bijaya Acharya🇺🇸 · Sonia Bacca🇩🇪 · Gaute Hagen🇺🇸
We present calculations of the $^{40}$ Ca transverse response function obtained from coupled-cluster theory used in conjunction with the Lorentz integral transform method. We employ nuclear forces derived at next-to-next-to leading order in chiral effective field theory with and without $Δ$ degrees of freedom. We first benchmark this approach on the $^{4}$ He nucleus and compare both the transverse sum rule and the response function to earlier calculations based on different methods. As expected from the power counting of the chiral expansion of electromagnetic currents and from previous studies, our results retaining only one-body term underestimate the experimental data for $^{4}$ He by about $20%$ . However, when the method is applied to $^{40}$ Ca at the same order of the expansion, response functions do not lack strength and agree well with the world electron scattering data. We discuss various sources of theoretical uncertainties and comment on the comparison of our results with the available experiments.
Comments:
9 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2310.03109 [pdf]
PRC(2024)·27 citations
03
[Submitted on 5 Oct 2023]
Effects of imaginary and real rotations on QCD matters
Gaoqing Cao🇨🇳
Inspired from perturbative calculations, this work introduces imaginary ( $Ω_{I}$ ) and real ( $Ω$ ) rotation effects to the pure $S U (3)$ gauge potentials simply through variable transformations: The empirical Polyakov loop (PL) potentials can be rewritten as functions of the imaginary chemical potentials of gluons and ghosts $(q_{ij})$ , and the transformations are taken as $q_{ij} \to q_{ij} \pm Ω_{I} / T$ and $q_{ij} \to q_{ij} \pm i Ω/ T$ , respectively. For the PL potential of Fukushima $(V_{1})$ , a smaller imaginary rotation $Ω_{I}$ tends to suppress PL at all temperature and the deconfinement transition keeps of first order. However, for the PL potential of Munich group $(V_{2})$ , $Ω_{I}$ tends to enhance PL at low temperature $T$ , consistent with lattice simulations; but suppress PL at high $T$ , consistent with perturbative calculations. Moreover, the deconfinement alters from first order to crossover with increasing $Ω_{I}$ as is expected from lattice simulations. On the other hand, the real rotation $Ω$ tends to enhance PL at relatively low $T$ for both potentials, and the (pseudo-)critical temperature decreases with $Ω$ as expected. Therefore, we find that analytic continuation of the phase diagram from imaginary to real rotation is not necessarily valid in the non-perturbative region. Finally, we apply the more successful PL potential $V_{2}$ to the Polyakov--Nambu-Jona-Lasinio (PNJL) model and discover that $Ω_{I}$ tends to break chiral symmetry while $Ω$ tends to restore it. Especially, the modified model is even able to qualitatively explain the lattice result that a larger $T$ would catalyze chiral symmetry breaking for a large $Ω_{I}$ .
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2310.03310 [pdf]
PRD(2024)·17 citations
04
[Submitted on 5 Oct 2023]
Open Strange and Open Heavy Flavour mesons in Asymmetric Nuclear Matter within Quark Meson Coupling model
Arpita Mondal🇮🇳 · Amruta Mishra🇮🇳
The in-medium properties of open strange ( $K$ , $K ˉ$ ), open charm ( $D$ , $D ˉ$ ), and open bottom ( $B$ , $B ˉ$ ) mesons are investigated in asymmetric nuclear matter using Quark Meson Coupling (QMC) model. A direct coupling of scalar ( $σ$ , $δ$ ) and vector ( $ω$ , $ρ$ ) mesons to the light quarks and anti-quarks of these mesons give rise to the in-medium modification of the properties of the corresponding meson within the model. The inclusion of the $δ$ (scalar iso-vector) meson breaks the isospin symmetry for the masses of the light quark and antiquark doublets, causing mass splitting between ( $u, d$ ) as well as ( $d ˉ, u ˉ$ ). Consequently, the considered mesons exhibit mass splittings within the isodoublets of $K$ , $K ˉ$ , $D$ , $D ˉ$ , $B$ and $B ˉ$ mesons when embedded in asymmetric nuclear matter. In the current study, the interactions of the pseudoscalar meson with the scalar, as well as vector mesons, are considered, which lead to significant medium modifications of the excitation energies of the open strange (charm and bottom) mesons. In asymmetric nuclear matter, due to the interaction of the pseudoscalar meson with the vector iso-vector $ρ$ meson, there is a splitting in the excitation energies of the mesons within the isospin doublets. The isospin effects are seen to be large for high baryon densities. This study can have significant observable consequences, such as in the production ratios, e.g., $K^{+} / K^{0}$ , $K^{-} / K^{0} ˉ$ , $D^{+} / D^{0}$ , $D^{-} / D ˉ^{0}$ , $B^{+} / B^{0}$ and $B^{-} / B ˉ^{0}$ in the upcoming heavy ion collision experiments at FAIR project at GSI, where the experiments are planned to be performed using neutron-rich beams to study the compressed baryonic matter.
Comments:
27 pages, 5 figures, version to be published in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2310.03336 [pdf]
PRC(2024)·8 citations
05
[Submitted on 5 Oct 2023]
Electromagnetic interaction models for Monte Carlo simulation of protons and alpha particles
Francesc Salvat · Carlos Heredia
Electromagnetic interactions of protons and alpha particles are modeled in a form that is suitable for Monte Carlo simulation of the transport of charged particles. The differential cross section (DCS) for elastic collisions with neutral atoms is expressed as the product of the DCS for collisions with the bare nucleus and a correction factor that accounts for the screening of the nuclear charge by the atomic electrons. The screening factor is obtained as the ratio of the DCS for scattering of the projectile by an atom with a point nucleus and the parameterized Dirac-Hartree-Fock-Slater (DHFS) electron density, calculated from the eikonal approximation, and the Rutherford DCS for collisions with the bare point nucleus. Inelastic collisions, which cause electronic excitations of the material, are described by means of the plane-wave Born approximation, with an empirical simple model of the generalized oscillator strength (GOS) that combines several extended oscillators with resonance energies and strengths determined from the atomic configurations and from the empirical mean excitation energy of the material. The contributions from inner subshells are renormalized to agree with realistic ionization cross sections calculated numerically from the DHFS self-consistent model of atoms by means of the plane-wave Born approximation. The resulting DCS allows analytical random sampling of individual hard inelastic interactions.
Comments:
48 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th); physics.app-ph (physics.app-ph); Atomic Physics (physics.atom-ph)
arXiv:
2310.03357 [pdf]
Nucl.Instrum.Meth.B(2024)·0 citations
06
[Submitted on 5 Oct 2023]
On inclusion of the long-range proton-proton Coulomb force in the three-nucleon scattering Faddeev calculations
H. Witała · J. Golak · R. Skibiński
We propose a simplified approach to incorporate the long-range proton-proton (pp) Coulomb force in the three-nucleon (3N) scattering calculations, based on exact formulation presented in Eur. Phys. Journal A {\bf{41}}, 369 (2009) and {\bf{41}}, 385 (2009). It permits us to get elastic proton-deuteron (pd) scattering and breakup observables relatively simply by performing standard Faddeev calculations as known for the neutron-deuteron (nd) system. The basic ingredient in that approach is a 3-dimensional screened pp Coulomb t-matrix obtained by numerical solution of the 3-dimensional Lippmann-Schwinger (LS) equation. Based on this t-matrix pure Coulomb transition terms contributing to elastic scattering and breakup are calculated without any need for partial wave decomposition. For elastic scattering such a term removes the Rutherford amplitude for point deuteron proton-deuteron (pd) scattering. For breakup it has never been applied in spite of the fact that its contributions could become important in some regions of the breakup phase space. We demonstrate numerically that the pd elastic observables can be determined directly from the resulting 3N amplitudes without any renormalization, simply by increasing the screening radius in order to reach the existing screening limit. However,for pd breakup the renormalization of the contributing on-shell amplitudes is required. We apply our approach in a wide energy range of the incoming proton for pd elastic scattering as well as for pd breakup reaction.
Comments:
50 pages, 21 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2310.03433 [pdf]
PRC(2024)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE

Hypertriton lifetime

40Ca transverse response function from coupled-cluster theory

Effects of imaginary and real rotations on QCD matters

Open Strange and Open Heavy Flavour mesons in Asymmetric Nuclear Matter within Quark Meson Coupling model

Electromagnetic interaction models for Monte Carlo simulation of protons and alpha particles

On inclusion of the long-range proton-proton Coulomb force in the three-nucleon scattering Faddeev calculations

Affiliations

$^{40}$ Ca transverse response function from coupled-cluster theory