Nuclear Theory·nucl-th

Thursday·April 16, 2015

12 papers—7 primary·5 cross-listed

08
Isospin breaking decay $η (1405) \to f_{0} (980) π^{0} \to 3 π$
N.N. Achasov🇷🇺 · A.A. Kozhevnikov🇷🇺 · G.N. Shestakov🇷🇺
There are attempts in the literature to theoretically explain the large breaking of isotopic invariance in the decay $η (1405)$ \, $\to$ \, $f_{0} (980) π^{0}$ \, $\to$ \, $3 π$ by the mechanism containing the logarithmic (triangle) singularity, i.e., as being due to the transition $η (1405) \to (K^{*} K ˉ + K ˉ^{*} K) \to (K^{+} K^{-} + K^{0} K ˉ^{0}) π^{0} \to f_{0} (980) π^{0} \to 3 π$ . The corresponding calculations were fulfilled for a hypothetic case of the stable $K^{*}$ meson. Here, we show that the account of the finite width of the $K^{*}$ ( $Γ_{K^{*} \to K π} \approx 50$ MeV) smoothes the logarithmic singularities in the amplitude and results in the suppression of the calculated decay width $η (1405) \to f_{0} (980) π^{0} \to 3 π$ by the factor of $6 - 8$ as compared with the case of $Γ_{K^{*} \to K π}$ \,=\,0. We also analyze the difficulties related with the assumption of the dominance of the $η (1405) \to (K^{*} K ˉ + K ˉ^{*} K) \to K K ˉ π$ decay mechanism and discuss the possible dynamics of the decay $η (1405) \to η π π$ . The decisive improvement of the experimental data on the $K K ˉ$ , $K π$ , $η π$ , and $π π$ mass spectra in the decay of the resonance structure $η (1405/1475)$ to $K K ˉ π$ and $η π π$ , and on the shape of the resonance peaks themselves in the $K K ˉ π$ and $η π π$ decay channels is necessary for the further establishing the $η (1405) \to 3 π$ decay mechanism.
↳ hep-phhep-exnucl-thPRD(2015)·73 citations
09
Interacting Ensemble of the Instanton-dyons and Deconfinement Phase Transition in the SU(2) Gauge Theory
Rasmus Larsen🇺🇸 · Edward Shuryak🇺🇸
Instanton-dyons, also known as instanton-monopoles or instanton-quarks, are topological constituents of the instantons at nonzero temperature and holonomy. We perform numerical simulations of the ensemble of interacting dyons for the SU(2) pure gauge theory. Unlike previous studies, we focus on back reaction on the holonomy and the issue of confinement. We calculate the free energy as a function of the holonomy and the dyon densities, using standard Metropolis Monte Carlo and integration over parameter methods. We observe that as the temperature decreases and the dyon density grows, its minimum indeed moves from small holonomy to the value corresponding to confinement. We then report various parameters of the self-consistent ensembles as a function of temperature, and investigate the role of inter-particle correlations.
↳ hep-phhep-latnucl-thPRD(2015)·47 citations
10
Empirical description of beta-delayed fission partial half-lives
L. Ghys · AN. Andreyev · S. Antalic · M. Huyse · P. Van Duppen
Background: The process of beta-delayed fission (bDF) provides a versatile tool to study low-energy fission in nuclei far away from the beta-stability line, especially for nuclei which do not fission spontaneously. Purpose: The aim of this paper is to investigate systematic trends in bDF partial half-lives. Method: A semi-phenomenological framework was developed to systematically account for the behavior of bDF partial half-lives. Results: The bDF partial half-life appears to exponentially depend on the difference between the Q value for beta decay of the parent nucleus and the fission-barrier energy of the daughter (after beta decay) product. Such dependence was found to arise naturally from some simple theoretical considerations. Conclusions: This systematic trend was confirmed for experimental bDF partial half-lives spanning over 7 orders of magnitudes when using fission barriers calculated from either the Thomas-Fermi or the liquid-drop fission model. The same dependence was also observed, although less pronounced, when comparing to fission barriers from the finite-range liquid-drop model or the Thomas-Fermi plus Strutinsky Integral method.
↳ nucl-exnucl-thPRC(2015)·18 citations
11
The Vacuum Structure of Vector Mesons in QCD
Fabian Rennecke🇩🇪
We study the chiral dynamics of vector mesons in two-flavor QCD in vacuum by utilizing a functional renormalization group approach. This allows us to capture the dynamical transition from the quark-gluon phase at high energies to the hadronic phase at low energies without the necessity of model parameter tuning. We use this to analyze the scaling of vector meson masses towards the chiral symmetry breaking scale, the decoupling of the mesons at high energies and the validity of vector meson dominance.
↳ hep-phhep-thnucl-thPRD(2015)·114 citations
12
Thermal properties of hot and dense matter with finite range interactions
Constantinos Constantinou🇩🇪 · Brian Muccioli🇺🇸 · Madappa Prakash🇺🇸 · James M. Lattimer🇺🇸
We explore the thermal properties of hot and dense matter using a model that reproduces the empirical properties of isospin symmetric and asymmetric bulk nuclear matter, optical model fits to nucleon-nucleus scattering data, heavy-ion flow data in the energy range 0.5-2 GeV/A, and the largest well-measured neutron star mass of 2 $M_{⊙}$ . Results of this model which incorporates finite range interactions through Yukawa type forces are contrasted with those of a zero-range Skyrme model that yields nearly identical zero-temperature properties at all densities for symmetric and asymmetric nucleonic matter and the maximum neutron star mass, but fails to account for heavy-ion flow data due to the lack of an appropriate momentum dependence in its mean field. Similarities and differences in the thermal state variables and the specific heats between the two models are highlighted. Checks of our exact numerical calculations are performed from formulas derived in the strongly degenerate and non-degenerate limits. Our studies of the thermal and adiabatic indices, and the speed of sound in hot and dense matter for conditions of relevance to core-collapse supernovae, the thermal evolution of neutron stars from their birth and mergers of compact binary stars reveal that substantial variations begin to occur at sub-saturation densities before asymptotic values are reached at supra-nuclear densities.
↳ astro-ph.SRnucl-thPRC(2015)·82 citations

Affiliations

first authorsco-authorsvia INSPIRE

Isospin breaking decay η(1405)→f0​(980)π0→3π

Interacting Ensemble of the Instanton-dyons and Deconfinement Phase Transition in the SU(2) Gauge Theory

Empirical description of beta-delayed fission partial half-lives

The Vacuum Structure of Vector Mesons in QCD

Thermal properties of hot and dense matter with finite range interactions

Affiliations

Isospin breaking decay $η (1405) \to f_{0} (980) π^{0} \to 3 π$