Nuclear Theory·nucl-th

Tuesday·June 6, 2023

11 papers—4 primary·7 cross-listed

05
[Submitted on 2 Jun 2023] (cross-list from quant-ph)
Missing levels in intermediate spectra
María Hita-Pérez · Laura Muñoz · Rafael A. Molina
We derive an expression for the nearest-neighbor spacing distribution $P (s)$ of the energy levels of quantum systems with intermediate dynamics between regularity and chaos and missing levels due to random experimental errors. The expression is based on the Brody distribution, the most widely used for fitting mixed spectra as a function of one parameter. By using Monte Carlo simulations of intermediate spectra based on the $β$ -Hermite ensemble of Random Matrix Theory, we evaluate the quality of the formula and its suitability for fitting purposes. Estimations of the Brody parameter and the fraction of missing levels can be obtained by a least-square two-parameter fitting of the experimental $P (s)$ . The results should be important to distinguish the origins of deviations from RMT in experimental spectra.
Subjects:
Quantum Physics (quant-ph); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); nlin.CD (nlin.CD); Nuclear Theory (nucl-th); Data Analysis, Statistics and Probability (physics.data-an)
arXiv:
2306.01821 [pdf]
J.Phys.A(2023)·0 citations
06
[Submitted on 2 Jun 2023] (cross-list from nucl-ex)
133In: A Rosetta Stone for decays of r-process nuclei
Z. Y. Xu🇺🇸 · M. Madurga🇺🇸 · R. Grzywacz🇺🇸 · T. T. King🇺🇸 · A. Algora🇪🇸 · A. N. Andreyev🇬🇧 · J. Benito🇪🇸 · T. Berry🇬🇧 · M. J. G. Borge🇪🇸 · C. Costache🇷🇴 · H. De Witte🇧🇪 · A. Fijalkowska🇺🇸 and 37 other authors
The $β$ decays from both the ground state and a long-lived isomer of $^{133}$ In were studied at the ISOLDE Decay Station (IDS). With a hybrid detection system sensitive to $β$ , $γ$ , and neutron spectroscopy, the comparative partial half-lives (logft) have been measured for all their dominant $β$ -decay channels for the first time, including a low-energy Gamow-Teller transition and several First-Forbidden (FF) transitions. Uniquely for such a heavy neutron-rich nucleus, their $β$ decays selectively populate only a few isolated neutron unbound states in $^{133}$ Sn. Precise energy and branching-ratio measurements of those resonances allow us to benchmark $β$ -decay theories at an unprecedented level in this region of the nuclear chart. The results show good agreement with the newly developed large-scale shell model (LSSM) calculations. The experimental findings establish an archetype for the $β$ decay of neutron-rich nuclei southeast of $^{132}$ Sn and will serve as a guide for future theoretical development aiming to describe accurately the key $β$ decays in the rapid-neutron capture (r-) process.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2306.01842 [pdf]
PRL(2023)·12 citations
07
[Submitted on 3 Jun 2023] (cross-list from nucl-ex)
Isomeric excitation energy for $^{99}$ In $^{m}$ from mass spectrometry reveals constant trend next to doubly magic $^{100}$ Sn
L. Nies (1 and 2)🇨🇭 · D. Atanasov (1 and 3)🇨🇭 · M. Athanasakis-Kaklamanakis (1 and 4)🇨🇭 · M. Au (1 and 5)🇨🇭 · K. Blaum (6)🇩🇪 · J. Dobaczewski (7 and 8)🇵🇱 · B. S. Hu (9)🇨🇦 · J. D. Holt (9 and 10)🇨🇦 · J. Karthein (11)🇺🇸 · I. Kulikov (12)🇩🇪 · Yu. A. Litvinov (12 and 13)🇩🇪 · D. Lunney (14)🇫🇷 and 7 other authors
The excitation energy of the 1/2 $^{-}$ isomer in $^{99}$ In at $N = 50$ is measured to be 671(37) keV and the mass uncertainty of the 9/2 $^{+}$ ground state is significantly reduced using the ISOLTRAP mass spectrometer at ISOLDE/CERN. The measurements exploit a major improvement in the resolution of the multi-reflection time-of-flight mass spectrometer. The results reveal an intriguing constancy of the $1/ 2^{-}$ isomer excitation energies in neutron-deficient indium that persists down to the $N = 50$ shell closure, even when all neutrons are removed from the valence shell. This trend is used to test large-scale shell model, \textit{ab initio}, and density functional theory calculations. The models have difficulties describing both the isomer excitation energies and ground-state electromagnetic moments along the indium chain.
Comments:
13 pages, 4 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2306.02033 [pdf]
PRL(2023)·22 citations
08
[Submitted on 3 Jun 2023] (cross-list from hep-ph)
Heavy-flavor transport and hadronization in pp collisions
Andrea Beraudo🇮🇹 · Arturo De Pace🇮🇹 · Daniel Pablos🇮🇹 · Francesco Prino🇮🇹 · Marco Monteno🇮🇹 · Marzia Nardi🇮🇹
Recent experimental results on the Lambda_c/D^0 ratio in proton-proton collisions have revealed a significant enhancement compared to expectations based on universal fragmentation fractions/functions across different colliding systems, from e+e- to pp. This unexpected enhancement has sparked speculation about the potential effects of a deconfined medium impacting hadronization, previously considered exclusive to heavy-ion collisions. In this study, we propose a novel approach that assumes the formation of a small, deconfined, and expanding fireball even in pp collisions, where charm quarks can undergo rescattering and hadronization. We make use of the same in-medium hadronization mechanism developed for heavy-ion collisions, which involves local color-neutralization through recombination of charm quarks with nearby opposite color charges from the background fireball. Our model incorporates the presence of diquark excitations in the hot medium, which promotes the formation of charmed baryons. Moreover, the recombination process, involving closely aligned partons from the same fluid cell, effectively transfers the collective flow of the system to the final charmed hadrons. We show that this framework can qualitatively reproduce the observed experimental findings in heavy-flavor particle-yield ratios, $p_{T}$ -spectra and elliptic-flow coefficients. Our results provide new, complementary supporting evidence that the collective phenomena observed in small systems naturally have the same origin as those observed in heavy-ion collisions
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2306.02152 [pdf]
PRD(2024)·43 citations
09
[Submitted on 4 Jun 2023] (cross-list from hep-ph)
Perturbative QCD concerning light and heavy flavor in the EPOS4 framework
K. Werner🇫🇷 · B. Guiot🇨🇱
We recently introduced new concepts, implemented in EPOS4, which allow to consistently accommodate factorization and saturation in high energy proton-proton and nucleus-nucleus collisions, in a rigorous parallel scattering framework. EPOS4 has a modular structure and in this paper, we present in detail how the "single scattering module" (the main EPOS4 building block) is related to perturbative QCD, and how these calculations are performed, with particular care being devoted to heavy flavor contributions. We discuss similarities and differences compared to the usual pQCD approach based on factorization.
Comments:
36 pages, 39 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2306.02396 [pdf]
PRC(2023)·56 citations
10
[Submitted on 5 Jun 2023] (cross-list from hep-ph)
Heavy quark drag and diffusion coefficients in the pre-hydrodynamic QCD plasma
Xiaojian Du🇪🇸
Kinetic and chemical equilibrations play important roles in the formation of the quark-gluon plasma (QGP) in relativistic heavy-ion collisions (HICs). These processes further influence the production of hard and electromagnetic probes in HICs, in particular, the thermalization of heavy quarks, which are produced at an extremely early time before the formation of the QGP. We calculate the drag and diffusion coefficients of heavy quarks in the pre-hydrodynamic quantum chromodynamic (QCD) plasma with the state-of-the-art QCD effective kinetic theory (EKT) solver. We present the time, momentum, and angular dependencies of these coefficients for gluon and quark contributions separately, showing the effects of isotropization and chemical equilibration from the QCD plasma. We also provide a simple formula to estimate the heavy quark drag and diffusion coefficients, as well as its energy loss, within the pre-hydrodynamic plasma at different coupling strengths based on the attractor theory. We then discuss the validity of these estimations with leading-order calculations and leading-logarithmic rescaling factors.
Comments:
9 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2306.02530 [pdf]
PRC(2024)·19 citations
11
[Submitted on 5 Jun 2023] (cross-list from hep-ph)
Normal single-spin asymmetries in electron-proton scattering: two-photon exchange with intermediate state resonances
Jaseer Ahmed🇧🇩 · P. G. Blunden🇨🇦 · W. Melnitchouk🇺🇸
We calculate the beam ( $B_{n}$ ) and target ( $A_{n}$ ) normal single-spin asymmetries in electron-proton elastic scattering from two-photon exchange amplitudes with resonance intermediate states of spin-parity $1/ 2^{\pm}$ and $3/ 2^{\pm}$ and mass $W ≲ 1.8$ GeV. The latest CLAS exclusive meson electroproduction data are used as input for the transition amplitudes from the proton to the excited resonance states. For $B_{n}$ , the spin 3/2 resonances dominate by an order of magnitude over the spin 1/2 states. In general we observe cancellations between the negative contributions of the $Δ (1232)$ and $N (1520)$ across both beam energy and scattering angle, and the positive contributions of the $Δ (1700)$ and $N (1720)$ , leading to a rather large overall uncertainty band in the total $B_{n}$ . At forward angles and beam energies $E_{lab} < 1$ GeV, where the $Δ (1232)$ dominates, the calculated $B_{n}$ tend to overshoot the A4 and SAMPLE data. The calculated $B_{n}$ compare well with the measured values from the A4 and $Q_{weak}$ experiments with $E_{lab} > 1$ GeV.
Comments:
31 pages, 7 figures, 3 tables
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2306.02540 [pdf]
PRC(2023)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE

Missing levels in intermediate spectra

133In: A Rosetta Stone for decays of r-process nuclei

Isomeric excitation energy for 99Inm from mass spectrometry reveals constant trend next to doubly magic 100Sn

Heavy-flavor transport and hadronization in pp collisions

Perturbative QCD concerning light and heavy flavor in the EPOS4 framework

Heavy quark drag and diffusion coefficients in the pre-hydrodynamic QCD plasma

Normal single-spin asymmetries in electron-proton scattering: two-photon exchange with intermediate state resonances

Affiliations

Isomeric excitation energy for $^{99}$ In $^{m}$ from mass spectrometry reveals constant trend next to doubly magic $^{100}$ Sn