Nuclear Theory·nucl-th

Thursday·September 19, 2024

6 papers—3 primary·3 cross-listed

04
[Submitted on 17 Sept 2024] (cross-list from hep-ph)
Pion Boer-Mulders function using a contact interaction
Dan-Dan Cheng🇨🇳 · Zhu-Fang Cui🇨🇳 · Minghui Ding🇨🇳 · Craig D. Roberts🇨🇳 · Sebastian M. Schmidt🇩🇪
A symmetry preserving treatment of a vector $\otimes$ vector contact interaction (SCI) is used as the basis for calculations of the two pion transverse momentum dependent parton distribution functions (TMDs); namely, that for unpolarised valence degrees-of-freedom and the analogous Boer-Mulders (BM) function. Amongst other things, the analysis enables the following themes to be addressed: the quark current mass dependence of pion TMDs; the impact of the gauge link model on the positivity constraint that bounds the BM function relative to the unpolarised TMD; the equivalence of direct diagrammatic and light-front wave function TMD calculations; and the size of the BM shift. Interpreted astutely, these SCI results enable one to draw insightful pictures of pion TMDs.
Comments:
14 pages, 9 figures, 1 table
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2409.11568 [pdf]
EPJC(2025)·11 citations
05
[Submitted on 18 Sept 2024] (cross-list from astro-ph.SR)
Photo-nuclear reaction rates of $^{157, 159}$ Ho and $^{163, 165}$ Tm and their impact in the $γ$ --process
Hao Cheng · Bao-Hua Sun · Li-Hua Zhu · Motohiko Kusakabe · Yudong Luo · Toshitaka Kajino · Chang-Jian Wang · Xing-Qun Yao · Chuang-Ye He · Fu-Long Liu · Bing Guo
Reliable photo-nuclear reaction rates at the stellar conditions are essential to understand the origin of the heavy stable neutron-deficient isotopes between $^{74}$ Se and $^{196}$ Hg-p-nuclei, however, many reaction rates of relevance still have to rely on the Hauser-Feshbach model due to rare experimental progress. One such case is in the mass range of 160 for Dy, Er, Ho and Tm isotopes. In this work we attempt to constrain the Hauser-Feshbach model in the TALYS package by reproducing the available experimental data of $^{160}$ Dy( $p, γ$ ) $^{161}$ Ho and $^{162}$ Er( $p, γ$ ) $^{163}$ Tm in the $A \sim 160$ mass region, and examine the effects of level density, gamma strength function and the optical model potential. The constrained model then allows us to calculate the reaction rates of $^{157, 159}$ Ho( $γ$ , $p$ ) and $^{163, 165}$ Tm( $γ$ , $p$ ) for the $γ$ -process nucleosynthesis in carbon-deflagration SNe Ia model. Our recommended rates differ from the JINA REACLIB by more than 1 order of magnitude in the temperature range of 2-3 GK. This results in the changes of final abundance of $p$ -nuclei in the $A \sim 160$ mass range by -5.5-3\% from those with JINA, which means that the ( $γ$ , $p$ ) reactions uncertainty is not predominant for the synthesis of these nuclei.
Comments:
12 pages,7 figures
Subjects:
Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2409.11710 [pdf]
ApJ(2024)·1 citation
06
[Submitted on 18 Sept 2024] (cross-list from hep-ph)
Far-from-equilibrium attractors with Full Relativistic Boltzmann approach in 3+1 D: moments of distribution function and anisotropic flows $v_{n}$
Vincenzo Nugara (1 and 2)🇮🇹 · Vincenzo Greco (1 and 2)🇮🇹 · Salvatore Plumari (1 and 2) ((1) Department of Physics and Astronomy, University of Catania, Catania, (2) INFN-Laboratori Nazionali del Sud, Catania, Italy)🇮🇹
We employ the Full Relativistic Boltzmann Transport approach for a conformal system in 3+1D to study the universal behaviour in moments of the distribution function and anisotropic flows. We investigate different transverse system sizes $R$ and interaction strength $η / s$ and identify universality classes based upon the interplay between $R$ and the mean free path; we show that each of this classes can be identified by a particular value of the opacity $γ^$ , which has been previously introduced in literature. Our results highlight that, at early times, the inverse Reynolds number and momentum moments of the distribution function display universal behaviour, converging to a 1D attractor driven by longitudinal expansion. This indicates that systems of different sizes and interaction strengths tend to approach equilibrium in a similar manner. We provide a detailed analysis of how the onset of transverse flow affects these moments at later times. Moreover, we investigate the system size and $η / s$ dependence for the harmonic flows $v_{2}$ , $v_{3}$ , $v_{4}$ and their response functions, along with the impact of the $η / s$ and the system transverse size on the dissipation of initial azimuthal correlations in momentum space. Finally, we introduce the normalised elliptic flow $v_{2} / v_{2, e q}$ , showing the emergence of attractor behaviour in the regime of large opacity. These results offer new insights into how different systems evolve towards equilibrium and the role that system size and interaction play in this process.
Comments:
14 pages, 14 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2409.12123 [pdf]
EPJC(2025)·19 citations

Affiliations

first authorsco-authorsvia INSPIRE

Pion Boer-Mulders function using a contact interaction

Photo-nuclear reaction rates of 157,159Ho and 163,165Tm and their impact in the γ--process

Far-from-equilibrium attractors with Full Relativistic Boltzmann approach in 3+1 D: moments of distribution function and anisotropic flows vn​

Affiliations

Photo-nuclear reaction rates of $^{157, 159}$ Ho and $^{163, 165}$ Tm and their impact in the $γ$ --process

Far-from-equilibrium attractors with Full Relativistic Boltzmann approach in 3+1 D: moments of distribution function and anisotropic flows $v_{n}$