Nuclear Theory·nucl-th

Thursday·October 29, 2015

10 papers—6 primary·4 cross-listed

07
[Submitted on 27 Oct 2015] (cross-list from nucl-ex)
A Scaling Phenomenon in Shannon Information Uncertainty Difference of fragments in Heavy-ion Collisions
Chun-Wang Ma · Yi-Dan Song · Chun-Yuan Qiao · Shan-Shan Wang · Hui-Ling Wei · Yu-Gang Ma · Xi-Guang Cao
The Shannon information-entropy uncertainty (in brief as "information uncertainty") is used to analyze the fragments in the measured 140 $A$ MeV $^{40, 48}$ Ca + $^{9}$ Be and $^{58, 64}$ Ni + $^{9}$ Be reactions. A scaling phenomenon is found in the information-uncertainty difference of fragments between the reactions. The scaling phenomenon is explained in a manner of canonical ensemble theory, and is reproduced in the simulated reactions by the antisymmetric molecular dynamics (AMD) and AMD + GEMINI models. The probes based on information uncertainty, requiring no equilibrium state of reaction, can be used in the non-equilibrium system, and bridge the results of the static thermodynamics models and the evolving dynamical transport models.
Comments:
11 pages, 7 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1510.08095 [pdf]
J.Phys.G(2016)·17 citations
08
[Submitted on 27 Oct 2015] (cross-list from nucl-ex)
Isobaric yield ratio difference between the 140 $A$ MeV $^{58, 64}$ Ni + $^{9}$ Be reactions studied by antisymmetric molecular dynamics model
C. Y. Qiao🇨🇳 · H. L. Wei🇨🇳 · C. W. Ma🇨🇳 · Y. L. Zhang🇨🇳 · S. S. Wang🇨🇳
\item[Background] The isobaric yield ratio difference (IBD) method is found to be sensitive to the density difference of neutron-rich nucleus induced reaction around the Fermi energy. \item[Purpose] An investigation is performed to study the IBD results in the transport model. \item[Methods] The antisymmetric molecular dynamics (AMD) model plus the sequential decay model GEMINI are adopted to simulate the 140 $A$ MeV $^{58, 64}$ Ni + $^{9}$ Be reactions. A relative small coalescence radius R $_{c} =$ 2.5 fm is used for the phase space at $t =$ 500 fm/c to form the hot fragment. Two limitations on the impact parameter ( $b 1 = 0 - 2$ fm and $b 2 = 0 - 9$ fm) are used to study the effect of central collisions in IBD. \item[Results] The isobaric yield ratios (IYRs) for the large-- $A$ fragments are found to be suppressed in the symmetric reaction. The IBD results for fragments with neutron-excess $I =$ 0 and 1 are obtained. A small difference is found in the IBDs with the $b 1$ and $b 2$ limitations in the AMD simulated reactions. The IBD with $b 1$ and $b 2$ are quite similar in the AMD + GEMINI simulated reactions. \item[Conclusions] The IBDs for the $I =$ 0 and 1 chains are mainly determined by the central collisions, which reflects the nuclear density in the core region of the reaction system. The increasing part of the IBD distribution is found due to the difference between the densities in the peripheral collisions of the reactions. The sequential decay process influences the IBD results. The AMD + GEMINI simulation can better reproduce the experimental IBDs than the AMD simulation.
Comments:
6 pages, 5 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1510.08105 [pdf]
PRC(2015)·12 citations
09
[Submitted on 28 Oct 2015] (cross-list from hep-ph)
Radiative transitions of charmonium states in a constituent quark model
Wei-Jun Deng🇨🇳 · Li-Ye Xiao🇨🇳 · Long-Cheng Gui🇨🇳 · Xian-Hui Zhong🇨🇳
We study the electromagnetic (EM) transitions of the $n S$ , $n P$ ( $n \leq 3$ ), and $n D$ ( $n \leq 2$ ) charmonium states with a constituent quark model. We obtain a reasonable description of the EM transitions of the well-established charmonium states $J / ψ$ , $ψ (2 S)$ , $χ_{c J} (1 P)$ , $h_{c} (1 P)$ and $ψ (3770)$ . We find that the M2 transitions give notable corrections to some E1 dominant processes by interfering with the E1 transitions. Our predictions of EM decay properties for the higher charmonium states are also presented and compared with other model predictions. In particular, we discuss the EM decay properties of some $" X Y Z "$ states, such as $X (3823)$ , $X (3872)$ , $X (3915)$ , $X (3940)$ and $X (4350)$ as conventional charmonium states. Assuming $X (3872)$ as the $χ_{c 1} (2 P)$ state, our predicted ratio $Γ [X (3872) \to ψ (2 S) γ] /Γ [X (3872) \to J / ψ γ] ≃ 4.0$ is consistent with BaBar's measurement.
Comments:
17 pages, 6 figures and five tables. EM multipole transitions are defined and text is improved
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
1510.08269 [pdf]
13 citations
10
[Submitted on 28 Oct 2015] (cross-list from hep-lat)
Direct calculation of hadronic light-by-light scattering
Jeremy Green🇩🇪 · Nils Asmussen🇩🇪 · Oleksii Gryniuk🇩🇪 · Georg von Hippel🇩🇪 · Harvey B. Meyer🇩🇪 · Andreas Nyffeler🇩🇪 · Vladimir Pascalutsa🇩🇪
We report calculations of hadronic light-by-light scattering amplitudes via lattice QCD evaluation of Euclidean four-point functions of vector currents. These initial results include only the fully quark-connected contribution. Particular attention is given to the case of forward scattering, which can be related via dispersion relations to the $γ^{*} γ^{*} \to$ hadrons cross section, and thus allows lattice data to be compared with phenomenology. We also present a strategy for computing the hadronic light-by-light contribution to the muon anomalous magnetic moment.
Comments:
7 pages, 4 figures. Talk presented at the 33rd International Symposium on Lattice Field Theory (Lattice 2015), 14-18 July 2015, Kobe International Conference Center, Kobe, Japan
Subjects:
High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1510.08384 [pdf]
PoS(2016)·42 citations

Affiliations

first authorsco-authorsvia INSPIRE

A Scaling Phenomenon in Shannon Information Uncertainty Difference of fragments in Heavy-ion Collisions

Isobaric yield ratio difference between the 140 A MeV 58,64Ni + 9Be reactions studied by antisymmetric molecular dynamics model

Radiative transitions of charmonium states in a constituent quark model

Direct calculation of hadronic light-by-light scattering

Affiliations

Isobaric yield ratio difference between the 140 $A$ MeV $^{58, 64}$ Ni + $^{9}$ Be reactions studied by antisymmetric molecular dynamics model