Nuclear Theory·nucl-th

Monday·April 27, 2015

10 papers—3 primary·7 cross-listed

01
[Submitted on 24 Apr 2015]
Effect of in-medium parameters of rho meson in its photoproduction reactions on nuclei
Swapan Das🇮🇳
There exist model calculations showing the modification of the hadronic parameters of $ρ$ meson in the nuclear environment. From these parameters, we extract the $ρ$ meson nucleus optical potential and show the medium effect due to this potential on the $ρ$ meson mass distribution spectra in the photonuclear reaction. The calculated results reproduced reasonably the measured $e^{+} e^{-}$ invariant mass, i.e., $ρ$ meson mass, distribution spectra in the $(γ, ρ^{0} \to e^{+} e^{-})$ reaction on nuclei.
Comments:
14 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1504.06479 [pdf]
Phys.Atom.Nucl.(2015)·2 citations
02
[Submitted on 24 Apr 2015]
Skyrme Random-Phase-Approximation description of lowest $K^{π} = 2_{γ}^{+}$ states in axially deformed nuclei
V.O. Nesterenko · V. G. Kartavenko · W. Kleinig · R.V. Jolos · J. Kvasil · P.-G. Reinhard
The lowest quadrupole $γ$ -vibrational $K^{π} = 2^{+}$ states in axially deformed rare-earth (Nd, Sm, Gd, Dy, Er, Yb, Hf, W) and actinide (U) nuclei are systematically investigated within the separable random-phase-approximation (SRPA) based on the Skyrme functional. The energies $E_{γ}$ and reduced transition probabilities $B (E 2)$ of $2_{γ}^{+}$ -states are calculated with the Skyrme forces SV-bas and SkM $^{*}$ . The energies of two-quasiparticle configurations forming the SRPA basis are corrected by using the pairing blocking effect. This results in a systematic downshift of $E_{γ}$ by 0.3-0.5 MeV and thus in a better agreement with the experiment, especially in Sm, Gd, Dy, Hf, and W regions. For other isotopic chains, a noticeable overestimation of $E_{γ}$ and too weak collectivity of $2_{γ}^{+}$ -states still persist. It is shown that domains of nuclei with a low and high $2_{γ}^{+}$ -collectivity are related with the structure of the lowest 2-quasiparticle states and conservation of the Nilsson selection rules. The description of $2_{γ}^{+}$ states with SV-bas and SkM $^{*}$ is similar in light rare-earth nuclei but deviates in heavier nuclei. However SV-bas much better reproduces the quadrupole deformation and energy of the isoscalar giant quadrupole resonance. The accuracy of SRPA is justified by comparison with exact RPA. The calculations suggest that a further development of the self-consistent calculation schemes is needed for a systematic satisfactory description of the $2_{γ}^{+}$ states.
Comments:
16 pages, 10 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1504.06492 [pdf]
PRC(2016)·13 citations
03
[Submitted on 24 Apr 2015]
Systematic Coarse-Graining in Nucleation Theory
Marco Schweizer · Leonard Sagis
In this work we show that the standard method to obtain nucleation rate-predictions with the aid of atomistic Monte-Carlo simulations leads to nucleation rate predictions that deviate $3 - 5$ orders of magnitude from the recent brute-force molecular dynamics simulations [J. Diemand, R. Angélil, K. K. Tanaka, and H. Tanaka, J. Chem. Phys. \textbf{139}, 074309 (2013)] conducted in the experimental accessible supersaturation regime for Lennard-Jones argon. We argue that this is due to the truncated state space literature mostly relies on, where the number of atoms in a nucleus is considered the only relevant order parameter. We here formulate the nonequilibrium statistical mechanics of nucleation in an extended state space, where the internal energy and momentum of the nuclei is additionally incorporated. We show that the extended model explains the lack in agreement between the molecular dynamics simulations by Diemand et al.\ and the truncated state space. We demonstrate additional benefits of using the extended state space; in particular, the definition of a nucleus temperature arrises very naturally and can be shown without further approximation to obey the fluctuation law of McGraw and Laviolette. In addition, we illustrate that our theory conveniently allows to extend existing theories to richer sets of order parameters.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1504.06495 [pdf]
J.Chem.Phys.(2015)·0 citations

Affiliations

first authorsco-authorsvia INSPIRE

Effect of in-medium parameters of rho meson in its photoproduction reactions on nuclei

Skyrme Random-Phase-Approximation description of lowest Kπ=2γ+​ states in axially deformed nuclei

Systematic Coarse-Graining in Nucleation Theory

Affiliations

Skyrme Random-Phase-Approximation description of lowest $K^{π} = 2_{γ}^{+}$ states in axially deformed nuclei