Nuclear Theory·nucl-th

Thursday·December 10, 2020

13 papers—9 primary·4 cross-listed

10
[Submitted on 8 Dec 2020] (cross-list from hep-ph)
Dispersive analysis of the Primakoff reaction $γ K \to K π$
Maximilian Dax🇩🇪 · Dominik Stamen🇩🇪 · Bastian Kubis🇩🇪
We provide a dispersion-theoretical representation of the reaction amplitudes $γ K \to K π$ in all charge channels, based on modern pion-kaon $P$ -wave phase shift input. Crossed-channel singularities are fixed from phenomenology as far as possible. We demonstrate how the subtraction constants can be matched to a low-energy theorem and radiative couplings of the $K^{*} (892)$ resonances, thereby providing a model-independent framework for future analyses of high-precision kaon Primakoff data.
Comments:
17 pages, 8 figures; version published in EPJC
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2012.04655 [pdf]
EPJC(2021)·20 citations
11
[Submitted on 9 Dec 2020] (cross-list from nucl-ex)
Evidence for the reduction of nuclear level density away from the $β$ -stability line
Pratap Roy · K. Banerjee · T. K. Rana · S. Kundu · S. Manna · A. Sen · D. Mondal · J. Sadhukhan · M. T. Senthil Kannan · T. K. Ghosh · S. Mukhopadhyay · Deepak Pandit and 5 other authors
The isospin dependence of nuclear level density has been investigated by analyzing the spectra of evaporated neutrons from excited $^{116}$ Sn and $^{116}$ Te nuclei. These nuclei are populated via $p$ + $^{115}$ In and $^{4}$ He + $^{112}$ Sn reactions in the excitation energy range of 18 - 26 MeV. Because of low excitation energy, the neutron spectra are predominantly contributed by the first-chance decay leading to the $β$ -stable $^{115}$ Sn and neutron-deficient $^{115}$ Te as residues for the two cases. Theoretical analysis of the experimental spectra have been performed within the Hauser-Feshbach formalism by employing different models of the level density parameter. It is observed that the data could only be explained by the level density parameter that decreases monotonically when the proton number deviates from the $β$ -stable value. This is also confirmed by performing a microscopic shell-model calculation with the Wood-Saxon mean field. The results have strong implication on the estimation of the level density of unstable nuclei, and calculation of astrophysical reaction rates relevant to $r$ - and $r p$ -processes.
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2012.04869 [pdf]
PRC·14 citations
12
[Submitted on 9 Dec 2020] (cross-list from hep-ph)
Insights into $Z_{b} (10610)$ and $Z_{b} (10650)$ from dipion transitions from $Υ (10860)$
V. Baru🇩🇪 · E. Epelbaum🇩🇪 · A.A. Filin🇩🇪 · C. Hanhart🇩🇪 · R.V. Mizuk🇷🇺 · A.V. Nefediev🇷🇺 · S. Ropertz🇩🇪
The dipion transitions $Υ (10860) \to π^{+} π^{-} Υ (n S)$ ( $n = 1, 2, 3$ ) are studied in the framework of a unitary and analytic coupled-channel formalism previously developed for analysing experimental data on the bottomoniumlike states $Z_{b} (10610)$ and $Z_{b} (10650)$ [Phys. Rev. D 98, 074023 (2018)] and predicting the properties of their spin partners [Phys. Rev. D 99, 094013 (2019)]. In this work we use a relatively simple but realistic version of this approach, where the scattering and production amplitudes are constructed employing only short-ranged interactions between the open- and hidden-flavour channels consistent with the constraints from heavy quark spin symmetry, for an extended analysis of the experimental line shapes. In particular, the transitions from the $Υ (10860)$ to the final states $π π h_{b} (m P)$ ( $m = 1, 2$ ) and $π B^{(*)} B ˉ^{*}$ already studied before, are now augmented by the $Υ (10860) \to π^{+} π^{-} Υ (n S)$ final states ( $n = 1, 2, 3$ ). This is achieved by employing dispersion theory to account for the final state interaction of the $π π$ subsystem including its coupling to the $K K ˉ$ channel. Fits to the two-dimensional Dalitz plots for the $π^{+} π^{-} Υ$ final states were performed. Two real subtraction constants are adjusted to achieve the best description of the Dalitz plot for each $Υ (n S)$ $(n = 1, 2, 3)$ while all the parameters related to the properties of the $Z_{b}$ 's are kept fixed from the previous study. A good overall description of the data for all $Υ (10860) \to π^{+} π^{-} Υ (n S)$ channels achieved in this work provides additional strong support for the molecular interpretation of the $Z_{b}$ states.
Comments:
16 pages, 7 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2012.05034 [pdf]
PRD(2021)·26 citations
13
[Submitted on 9 Dec 2020] (cross-list from hep-ph)
N $^{3}$ LO extraction of the Sivers function from SIDIS, Drell-Yan, and $W^{\pm} / Z$ data
Marcin Bury🇩🇪 · Alexei Prokudin🇺🇸 · Alexey Vladimirov🇩🇪
We perform the global analysis of polarized Semi-Inclusive Deep Inelastic Scattering (SIDIS), pion-induced polarized Drell-Yan (DY), and $W^{\pm} / Z$ boson production data and extract the Sivers function for $u$ , $d$ , $s$ and for sea-quarks. We use the framework of transverse momentum dependent factorization at N $^{3}$ LO accuracy. The Qiu-Sterman function is determined in a model-independent way from the extracted Sivers function. We also evaluate the significance of the predicted sign change of Sivers function in DY with respect to SIDIS.
Comments:
6 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2012.05135 [pdf]
PRL(2021)·59 citations

Affiliations

first authorsco-authorsvia INSPIRE

Dispersive analysis of the Primakoff reaction γK→Kπ

Evidence for the reduction of nuclear level density away from the β-stability line

Insights into Zb​(10610) and Zb​(10650) from dipion transitions from Υ(10860)

N3LO extraction of the Sivers function from SIDIS, Drell-Yan, and W±/Z data

Affiliations

Dispersive analysis of the Primakoff reaction $γ K \to K π$

Evidence for the reduction of nuclear level density away from the $β$ -stability line

Insights into $Z_{b} (10610)$ and $Z_{b} (10650)$ from dipion transitions from $Υ (10860)$

N $^{3}$ LO extraction of the Sivers function from SIDIS, Drell-Yan, and $W^{\pm} / Z$ data