Nuclear Theory·nucl-th

Friday·April 3, 2020

10 papers—3 primary·7 cross-listed

01
[Submitted on 1 Apr 2020]
Transverse momentum fluctuations and their correlation with elliptic flow in nuclear collision
Björn Schenke🇺🇸 · Chun Shen🇺🇸 · Derek Teaney🇺🇸
We propose observables $v_{0}$ and $v_{0} (p_{T})$ which quantify the relative fluctuations in the total transverse momentum at fixed multiplicity. We first study the factorization of the fixed multiplicity momentum dependent two particle correlation function into a product of $v_{0} (p_{T}^{a})$ and $v_{0} (p_{T}^{b})$ within realistic hydrodynamic simulations. Then we present computations of $v_{0} (p_{T})$ for different particle types. We determine the relation between the integrated $v_{0}$ and previously measured observables, and compare results from a hybrid hydrodynamics based model to experimental data. The effects of bulk viscosity and an initial pre-equilibrium stage on the results are quantified. We find that $v_{0}$ is strongly correlated with the initial state entropy per elliptic area, $S / A$ . Using this result, we explain how the observed correlations between the elliptic flow and the transverse momentum (both in simulations and experiment) reflect the initial state correlations between $1/ A$ and ellipticity $ε_{2}$ at fixed multiplicity. We argue that the systematic experimental study of $v_{0}$ , with the same sophistication as used for the other $v_{n}$ , can contribute significantly to our understanding of quark gluon plasma properties.
Comments:
14 pages, 11 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2004.00690 [pdf]
PRC(2020)·131 citations
02
[Submitted on 2 Apr 2020]
$α$ Decay Half-life Estimation and Uncertainty Analysis
Boshuai Cai · Guangshang Chen · Jiongyu Xu · Cenxi Yuan · Chong Qi · Yuan Yao
The non-parametric bootstrap method is used to evaluate the uncertainties of two $α$ decay formulas, the universal decay law (UDL) and the new Geiger-Nuttall law (NGNL). Such a method can simultaneously obtain the uncertainty of each parameter, the correlation between each pair of parameters, and the total, statistical, and systematic uncertainties of each formula. Both even-even (ee) nuclei and odd-A (oA) nuclei are used in the analysis. The collected data are separated into three parts: ee nuclei, oA nuclei without spin or parity change (oA\_nc), and oA nuclei with spin and/or parity change (oA\_c). Based on the residues between observed data and corresponding calculations, the statistical and systematic uncertainties are decomposed from the total uncertainty, from which one can clarify the effects from the shell structure, pairing, and angular momentum change on describing $α$ decay half-life. If $N > 126$ and $N ⩽ 126$ nuclei are considered together, the systematic uncertainty of residues between observed and predicted half-lives are larger than if those groups are considered separately. Without shell correction term, a much larger systematic uncertainty is found if parameters obtained for $N ⩽ 126$ nuclei are used to describe the half-lives of $N > 126$ nuclei. A global hindrance on the $α$ decay process is found in oA\_nc (oA\_c) nuclei comparing with ee (oA\_nc) nuclei. If parameters obtained from ee (oA\_nc) nuclei are used, the half-lives of oA\_nc (oA\_c) nuclei are generally underestimated with large systematic uncertainties, which can be related to the contribution of pairing effect and angular momentum. The recently observed superallowed decay from $^{104}$ Te to $^{100}$ Sn is also discussed based on uncertainty analysis. (Abstract is not fully presented because of length limitation)
Comments:
To be published in Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2004.00964 [pdf]
PRC(2020)·20 citations
03
[Submitted on 2 Apr 2020]
Masses and Decay widths of Charmonium states in presence of strong magnetic fields
Amruta Mishra🇮🇳 · S.P. Misra🇮🇳
The masses and decay widths of charmonium states are studied in the presence of strong magnetic fields. The mixing between the pseudoscalar and vector charmonium states at rest is observed to lead to appreciable negative (positive) shifts in the masses of the pseudoscalar (longitudinal component of the vector) charmonium states in vacuum/hadronic medium in the presence of high magnetic fields. The pseudoscalar and vector charmonium masses in the hadronic medium, calculated in an effective chiral model from the medium changes of a scalar dilaton field, have additional significant modifications due to the mixing effects. The masses of the $D$ and $D ˉ$ mesons in the magnetized hadronic matter are calculated within the chiral effective model. The partial decay widths of the vector charmonium state to $D D ˉ$ are computed using a field theoretical model for composite hadrons with quark/antiquark constituents, and are compared to the decay widths calculated using an effective hadronic Lagrangian. The effects of the mixing are observed to lead to significant contributions to the masses of the pseusoscalar and vector charmonium states, and an appreciable increase in the decay width $ψ (3770) \to D D ˉ$ at large values of the magnetic fields. These studies of the charmonium states in strong magnetic fields should have observable consequences on the dilepton spectra, as well as on the production of the open charm mesons and the charmonium states in ultra relativistic heavy ion collision experiments.
Comments:
31 pages, 5 figures,to be published in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2004.01007 [pdf]
PRC(2020)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE

Transverse momentum fluctuations and their correlation with elliptic flow in nuclear collision

α Decay Half-life Estimation and Uncertainty Analysis

Masses and Decay widths of Charmonium states in presence of strong magnetic fields

Affiliations

$α$ Decay Half-life Estimation and Uncertainty Analysis