Nuclear Theory·nucl-th

Friday·March 10, 2023

12 papers—7 primary·5 cross-listed

01
[Submitted on 8 Mar 2023]
Multi-scale Imaging of Nuclear Deformation at the Electron Ion Collider
Heikki Mäntysaari🇫🇮 · Björn Schenke🇺🇸 · Chun Shen🇺🇸 · Wenbin Zhao🇺🇸
We show within the Color Glass Condensate framework that exclusive vector meson production at high energy is sensitive to the geometric deformation of the target nucleus at multiple length scales. Studying $e +$ U collisions and varying the deformation of the uranium target, we demonstrate that larger deformations result in enhanced incoherent vector meson production cross sections. Further, different multipole deformation parameters affect different regions of transverse momentum transfer. Employing JIMWLK evolution to study the Bjorken- $x$ dependence of our results, we find that the ratio of incoherent to coherent cross sections decreases with decreasing $x$ , largely independently of the quadrupole deformation of the target. Comparing results for the same process using $^{20} Ne$ targets with $^{16} O$ targets, we find that differences in deformation are clearly visible in the incoherent cross section. These findings show that certain observables at the Electron-Ion Collider are very sensitive to nuclear structure. Consequently, deformations need to be taken into account when interpreting experimental results. More importantly, this also means that $∣ t ∣$ -differential diffractive vector meson production could become a powerful tool, enabling the most direct measurements of nuclear structure at different length scales, ranging from nuclear deformation at low $∣ t ∣$ to nucleon- and subnucleon-size scales at higher $∣ t ∣$ .
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2303.04866 [pdf]
PRL(2023)·43 citations
02
[Submitted on 8 Mar 2023]
Strong Interaction Dynamics and Fermi $β$ decay in the nucleon and the nucleus
Gerald A. Miller🇺🇸
Nuclear super-allowed $β$ decay has been used to obtain tight limits on the value of the CKM matrix element $V_{u d}$ that is important for unitarity tests, and therefore important for tests of the standard model. Current requirements on precision are so intense that effects formerly thought too small to matter are now relevant. This article is a brief review of personal efforts to include the effects of strong interactions on Fermi $β$ decay. First I examine the role of isospin violation in the decay of the neutron. The size of the necessary correction depends upon detailed strong-interaction dynamics. The isospin violating parts of the nucleon wave function, important at the low energy of $β$ decay, can be constrained by data taken at much higher energies, via measurements, for example, of $e d \to e^{'} π^{\pm} + X$ reactions at Jefferson Laboratory. The next focus is on the role of nuclear short-ranged correlations, which affect the value of the correction needed to account for isospin violation in extracting the value of $V_{u d}$ . The net result is that effects previously considered as irrelevant have become relevant for both neutron and nuclear $β$ decay.
Comments:
7 pages, no figures, Prepared for a Special Issue of the journal Universe on the general subject of neutron lifetime determination. arXiv admin note: text overlap with arXiv:2201.10651
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2303.04917 [pdf]
Universe(2023)·2 citations
03
[Submitted on 9 Mar 2023]
Unified mechanism behind the even-parity ground state and neutron halo of $^{11}$ Be
Jing Geng · Yi Fei Niu · Wen Hui Long
Using the axially deformed relativistic Hartree-Fock-Bogoliubov (D-RHFB) model, we explore the mechanism behind the parity inversion and halo occurrence in $^{11}$ Be, which are well reproduced by the RHF Lagrangian PKA1. It is illustrated that evidently enhanced deformation effects by the $π$ -pseudo-vector and $ρ$ -tensor couplings in PKA1 are crucial for correctly describing both even-parity ground state (GS) and neutron halo of $^{11}$ Be. Coupling with the deformation, the intrude $1 d_{5/2}$ component largely enhances the couplings between the even-parity orbit $1/ 2_{2}^{+}$ and the nuclear core to promise the even-parity GS, whereas the $2 s_{1/2}$ component therein dominates the halo formation in $^{11}$ Be. Moreover, the deformed halo in $^{11}$ Be is found to be stabilized by the attractive inherent correlations between the $1 d_{5/2}$ and $2 s_{1/2}$ components of the halo orbit $1/ 2_{2}^{+}$ , instead of pairing correlations, which paves a new way to understand the halo pictures in deformed unstable nuclei.
Comments:
4 figures, 1 table, 9 pages
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.04987 [pdf]
CPC(2023)·11 citations
04
[Submitted on 9 Mar 2023]
Deformed ground state of $^{32}$ Mg and breaking of pseudo-spin symmetry
Yong Peng · Jing Geng · Yi Fei Niu · Wen Hui Long
Deformed ground state of $^{32}$ Mg is investigated using the axially deformed relativistic Hartree-Fock-Bogoliubov (D-RHFB) model with the effective Lagrangian PKA1, which provides coincident description with the experimental measurements. It is illustrated that obvious breaking of the pseudo-spin symmetry (PSS) given by PKA1, being consistent with the experimental observation in nearby isotone $^{40}$ Ca, is crucial for describing correctly the deformed ground state by producing unique shape evolution of neutron orbit $1/ 2_{4}^{+}$ in $^{32}$ Mg. The PSS breaking is essentially determined by characteristic in-medium balance between nuclear attractions and repulsions that is manifested as unparalleled density dependent behaviors for coupling strengths $g_{σ}$ and $g_{ω}$ in dominant $σ$ -scalar and $ω$ -vector channels.
Comments:
10 pages, 6 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2303.04990 [pdf]
0 citations
05
[Submitted on 9 Mar 2023]
$Λ Λ ˉ$ final-state interaction in the reactions $e^{+} e^{-} \to ϕ Λ Λ ˉ$ and $e^{+} e^{-} \to η Λ Λ ˉ$
Johann Haidenbauer🇩🇪 · Ulf-G. Meißner🇩🇪
Near-threshold $Λ Λ ˉ$ mass spectra for the reactions $e^{+} e^{-} \to η Λ Λ ˉ$ and $e^{+} e^{-} \to ϕ Λ Λ ˉ$ are investigated with an emphasis on the role played by the interaction in the $Λ Λ ˉ$ system. A variety of $Λ Λ ˉ$ potential models is employed that have been established in the analysis of data on $p p ˉ \to Λ Λ ˉ$ in the past. It is shown that the near-threshold enhancement observed for the two $e^{+} e^{-}$ reactions can be reproduced by considering the $Λ Λ ˉ$ final-state interaction in the partial waves suggested by the helicity-angle analysis of the experiments. For $e^{+} e^{-} \to η Λ Λ ˉ$ the same $Λ Λ ˉ$ $S$ -wave interaction as in $e^{+} e^{-} \to Λ Λ ˉ$ is relevant and with it a consistent description of the pertinent measurements can be achieved. It is pointed out that a nonzero threshold cross section as observed for the latter reaction is not supported by the new $η Λ Λ ˉ$ data.
Comments:
8 pages, 5, figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2303.05128 [pdf]
EPJA(2023)·6 citations
06
[Submitted on 9 Mar 2023]
P-even and -odd asymmetries on $^{117}$ Sn at the vicinity of the p-resonance E $_{p}$ =1.33 eV
L. E. Charón-García · J. Curole · L. Barrón-Palos · V. Gudkov · W. M. Snow
A self consistent description of angular correlations in neutron induced reactions is required for quantitative analysis of parity violating (PV) and time reversal invariance violating (TRIV) effects in neutron nucleus scattering. The 1.33 eV p-wave compound resonance in $^{117}$ Sn is one of the few p-wave resonances where enough measurements have been performed to allow a nontrivial test of the internal consistency of the theory. We present the results of a global analysis of the several different asymmetries and angular distribution measurements in ( $n, γ$ ) reactions on the 1.33 eV p-wave resonance in $^{117}$ Sn conducted over the last few decades. We show that the compound resonance mixing theory can give an internally consistent description of all observations made in this system to date within the experimental measurement errors. We also confirm the conclusions of previous analyses that a subthreshold resonance in $^{117}$ Sn dominates correlations related to s-p mixing, and discuss the implications of these results for future searches for TRIV in this system.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2303.05425 [pdf]
0 citations
07
[Submitted on 9 Mar 2023]
Probing spherical outbursts of neutron star mergers from an equation of state with composite nucleons
Vikram Soni
We consider a variational 'crystalline' equation of state (EOS) that follows from nucleons that are chiral solitons with deep relativistic quark bound states. In this model conventional quark matter does not occur till a high density threshold at which the quark bound states in the nucleons get compressed and merge with the continuum. Once the barrier at this threshold is overcome, roughly when, $n_{B} \sim 1/ f m^{3}$ , we expect the 'crystalline' nuclear matter to make a sudden transition into quark matter when the EOS becomes soft through a decompression. The sudden increase in density triggers a collapse releasing large amount of gravitational potential energy that can generate a spherical outburst (or kilonova) of ejected matter.
Comments:
3 pages. Substantially revised. arXiv admin note: text overlap with arXiv:1912.08096
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
2303.05452 [pdf]
0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Multi-scale Imaging of Nuclear Deformation at the Electron Ion Collider

Strong Interaction Dynamics and Fermi β decay in the nucleon and the nucleus

Unified mechanism behind the even-parity ground state and neutron halo of 11Be

Deformed ground state of 32Mg and breaking of pseudo-spin symmetry

ΛΛˉ final-state interaction in the reactions e+e−→ϕΛΛˉ and e+e−→ηΛΛˉ

P-even and -odd asymmetries on 117Sn at the vicinity of the p-resonance Ep​=1.33 eV

Probing spherical outbursts of neutron star mergers from an equation of state with composite nucleons

Affiliations

Strong Interaction Dynamics and Fermi $β$ decay in the nucleon and the nucleus

Unified mechanism behind the even-parity ground state and neutron halo of $^{11}$ Be

Deformed ground state of $^{32}$ Mg and breaking of pseudo-spin symmetry

$Λ Λ ˉ$ final-state interaction in the reactions $e^{+} e^{-} \to ϕ Λ Λ ˉ$ and $e^{+} e^{-} \to η Λ Λ ˉ$

P-even and -odd asymmetries on $^{117}$ Sn at the vicinity of the p-resonance E $_{p}$ =1.33 eV