Nuclear Theory·nucl-th

Tuesday·April 7, 2015

8 papers—4 primary·4 cross-listed

01
Electric Dipole Polarizability in $^{208}$ Pb as a Probe of the Symmetry Energy and Neutron Matter around $ρ_{0} /3$
Zhen Zhang · Lie-Wen Chen
It is currently a big challenge to accurately determine the symmetry energy $E_{sym} (ρ)$ and the pure neutron matter equation of state $E_{PNM} (ρ)$ , even their values around saturation density $ρ_{0}$ . We find that the electric dipole polarizability $α_{D}$ in $^{208}$ Pb can be determined uniquely by the magnitude of the $E_{sym} (ρ)$ or almost equivalently the $E_{PNM} (ρ)$ at subsaturation densities around $ρ_{0} /3$ , shedding a light upon the genuine correlation between the $α_{D}$ and the $E_{sym} (ρ)$ . By analyzing the experimental data of the $α_{D}$ in $^{208}$ Pb from RCNP using a number of non-relativistic and relativistic mean-field models, we obtain very stringent constraints on $E_{sym} (ρ)$ and $E_{PNM} (ρ)$ around $ρ_{0} /3$ . The obtained constraints are found to be in good agreement with the results extracted in other analyses. In particular, our results provide for the first time the experimental constraints on $E_{PNM} (ρ)$ around $ρ_{0} /3$ , which are in harmony with the recent determination of $E_{PNM} (ρ)$ from microscopic theoretical studies and potentially useful in constraining the largely uncertain many-nucleon interactions in microscopic calculations of neutron matter.
nucl-thastro-ph.SRnucl-exPRC(2015)·107 citations
02
Effects of thermal shape fluctuations and pairing fluctuations on the giant dipole resonance in warm nuclei
A. K. Rhine Kumar · P. Arumugam · N. Dinh Dang
Apart from the higher limits of isospin and temperature, the properties of atomic nuclei are intriguing and less explored at the limits of lowest but finite temperatures. At very low temperatures there is a strong interplay between the shell (quantal fluctuations), statistical (thermal fluctuations), and residual pairing effects as evidenced from the studies on giant dipole resonance (GDR). In our recent work [Phys. Rev. C \textbf{90}, 044308 (2014)], we have outlined some of our results from a theoretical approach for such warm nuclei where all these effects are incorporated along within the thermal shape fluctuation model (TSFM) extended to include the fluctuations in the pairing field. In this article, we present the complete formalism based on the microscopic-macroscopic approach for determining the deformation energies and a macroscopic approach which links the deformation to GDR observables. We discuss our results for the nuclei $^{97}$ Tc, $^{120}$ Sn, $^{179}$ Au, and $^{208}$ Pb, and corroborate with the experimental data available. The TSFM could explain the data successfully at low temperature only with a proper treatment of pairing and its fluctuations. More measurements with better precision could yield rich information about several phase transitions that can happen in warm nuclei.
nucl-thPRC(2015)·25 citations
03
On the Nuclear Mechanisms Underlying the Heat Production by the E-Cat
Norman D. Cook · Andrea Rossi
We discuss the isotopic abundances found in the E-Cat reactor with regard to the nuclear mechanisms responsible for excess heat. We argue that a major source of energy is a reaction between the first excited-state of Li-7 and a proton, followed by the breakdown of Be-8 into two alphas with high kinetic energy, but without gamma radiation. The unusual property of the Li-7 isotope that allows this reaction is similar to the property that underlies the Mossbauer effect: the presence of unusually low-lying excited states in stable, odd-Z and/or odd-N nuclei. We use the lattice version of the independent-particle model (IPM) of nuclear theory to show how the geometrical structure of isotopes indicate nuclear reactions that are not predicted in the conventional version of the IPM. Finally, we speculate on similar mechanisms that may be involved in other low-energy nuclear reactions (LENR).
physics.gen-ph0 citations
04
Van der Waals Equation of State with Fermi Statistics for Nuclear Matter
V. Vovchenko · D. V. Anchishkin · M. I. Gorenstein
The van der Waals (VDW) equation of state is a simple and popular model to describe the pressure function in equilibrium systems of particles with both repulsive and attractive interactions. This equation predicts an existence of a first-order liquid-gas phase transition and contains a critical point. Two steps to extend the VDW equation and make it appropriate for new physical applications are carried out in this paper: 1) the grand canonical ensemble formulation; 2) an inclusion of the quantum statistics. The VDW equation with Fermi statistics is then applied to a description of the system of interacting nucleons. The VDW parameters $a$ and $b$ are fixed to reproduce the properties of nuclear matter at saturation density $n_{0} = 0.16$ fm $^{- 3}$ and zero temperature. The model predicts a location of the critical point for the symmetric nuclear matter at temperature $T_{c} ≅ 19.7$ MeV and nucleon number density $n_{c} ≅ 0.07$ fm $^{- 3}$ .
nucl-thPRC(2015)·108 citations
05
Comment on "New Limits on Intrinsic Charm in the Nucleon from Global Analysis of Parton Distributions"
S. J. Brodsky🇺🇸 · S. Gardner🇺🇸
A Comment on the Letter by P. Jimenez-Delgado, T.J. Hobbs, J.T. Londergan, and W. Melnitchouk, Phys. Rev. Lett. 114, 082002 (2015).
↳ hep-phnucl-thPRL(2016)·46 citations
06
Quark deconfinement and gluon condensate in a weak magnetic field
Alejandro Ayala🇲🇽 · C. A. Dominguez🇿🇦 · L. A. Hernandez🇿🇦 · M. Loewe🇿🇦 · Juan Cristobal Rojas🇨🇱 · Cristian Villavicencio🇨🇱
We study QCD finite energy sum rules (FESR) for the axial-vector current correlator in the presence of a magnetic field, in the weak field limit and at zero temperature. We find that the perturbative QCD as well as the hadronic contribution to the sum rules get explicit magnetic field-dependent corrections and that these in turn induce a magnetic field dependence on the deconfinement phenomenological parameter s_0 and on the gluon condensate. The leading corrections turn out to be quadratic in the field strength. We find from the dimension d=2 first FESR that the magnetic field dependence of s_0 is proportional to the absolute value of the light-quark condensate. Hence, it increases with increasing field strength. This implies that the parameters describing chiral symmetry restoration and deconfinement behave similarly as functions of the magnetic filed. Thus, at zero temperature the magnetic field is a catalysing agent of both chiral symmetry breaking and confinement. From the dimension d=4 second FESR we obtain the behavior of the gluon condensate in the presence of the external magnetic field. This condensate also increases with increasing field strength.
↳ hep-phhep-latnucl-thPRD(2015)·35 citations
07
Fast Traveling-Wave Reactor of the Channel Type
Vitaliy D. Rusov · Victor A. Tarasov · Volodymyr N. Vashchenko · Sergei A. Chernezhenko · Andrei A. Kakaev · Oksana I. Pantak
The main aim of this paper is to solve the technological problems of the TWR based on the technical concept described in our priority of invention reference, which makes it impossible, in particular, for the fuel claddings damaging doses of fast neutrons to excess the ~200 dpa limit. Thus the essence of the technical concept is to provide a given neutron flux at the fuel claddings by setting the appropriate speed of the fuel motion relative to the nuclear burning wave. The basic design of the fast uranium-plutonium nuclear traveling-wave reactor with a softened neutron spectrum is developed, which solves the problem of the radiation resistance of the fuel claddings material.
↳ physics.ins-detnucl-thComplex Syst.(2016)·1 citation
08
Hydrodynamics dual to Einstein-Gauss-Bonnet gravity: all-order gradient resummation
Yanyan Bu🇮🇱 · Michael Lublinsky🇮🇱 · Amir Sharon🇮🇱
Relativistic hydrodynamics dual to Einstein-Gauss-Bonnet gravity in asymptotic $AdS_{5}$ space is under study. To linear order in the amplitude of the fluid velocity and temperature, we derive the fluid's stress-energy tensor via an all-order resummation of the derivative terms. Each order is accompanied by new transport coefficients, which all together could be compactly absorbed into two functions of momenta, referred to as viscosity functions. Via inverse Fourier transform, these viscosities appear as memory functions in the constitutive relation between components of the stress-energy tensor.
↳ hep-thgr-qchep-phnucl-thJHEP(2015)·20 citations

Affiliations

first authorsco-authorsvia INSPIRE