Nuclear Theory·nucl-th

Tuesday·January 13, 2015

9 papers—8 primary·1 cross-listed

01
Study of dynamical charge fluctuations in the hadronic medium
Bhanu Sharma🇮🇳 · Madan M. Aggarwal🇮🇳 · Nihar Ranjan Sahoo🇺🇸 · Tapan K. Nayak🇮🇳
The dynamical charge fluctuations have been studied in ultra-relativistic heavy-ion collisions by using hadronic model simulations, such as UrQMD and HIJING. The evolution of fluctuations has been calculated at different time steps during the collision as well as different observation window in pseudorapidity (\DelEta). The final state effects on the fluctuations have been investigated by varying $△ η$ ~ and the time steps with the aim of obtaining an optimum observation window for capturing maximum fluctuations. It is found that $△ η$ ~ between 2.0 and 3.5 gives the best coverage for the fluctuations studies. The results of these model calculations for Au+Au collisions at $s_{NN}$ ~=~7.7 to 200~GeV and for Pb+Pb collisions at 2.76 TeV are presented and compared with available experimental data from the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC).
nucl-thhep-phnucl-exPRC(2015)·11 citations
02
Neutrino versus antineutrino cross sections and CP violation
M. Ericson🇨🇭 · M. Martini🇧🇪
We discuss the nuclear interactions of neutrinos versus those of antineutrinos, a relevant comparison for CP violation experiments in the neutrino sector. We consider the MiniBooNE quasielastic-like double differential neutrinos and antineutrinos cross sections which are flux dependent and hence specific to the MiniBooNE set-up. We combine them introducing their sum and their difference. We show that the last combination can bring a general information, which can be exploited in other experiments, on the nuclear matrix elements of the axial vector interference term. Our theoretical model reproduces well the two cross sections combinations. This confirms the need for a sizeable multinucleon component in particular in the interference term.
nucl-thhep-exhep-phPRC(2015)·26 citations
03
Radiative Decay Width of Neutral non-Strange Baryons from PWA
Igor I. Strakovsky (GW)🇺🇸 · William J. Briscoe (GW)🇺🇸 · Alexander E. Kudryavtsev (ITEP, GW)🇺🇸 · Viacheslav V. Kulikov (ITEP)🇷🇺 · Maxim A. Martemyanov (ITEP)🇷🇺 · Vladimir E. Tarasov (ITEP)🇷🇺
An overview of the GW SAID and ITEP groups effort to analyze pion photoproduction on the neutron-target will be given. The disentanglement the isoscalar and isovector EM couplings of N* and Delta* resonances does require compatible data on both proton and neutron targets. The final-state interaction plays a critical role in the state-of-the-art analysis in extraction of the gamma n --> pi N data from the deuteron target experiments. It is important component of the current JLab, MAMI-C, SPring-8, ELSA, and ELPH programs
nucl-thhep-exhep-phnucl-exEPJ Web Conf.(2015)·0 citations
04
Wave-packet continuum discretization for quantum scattering
O.A. Rubtsova · V.I. Kukulin · V.N. Pomerantsev
A general approach to a solution of few- and many-body scattering problems based on a continuum-discretization procedure is described in detail. The complete discretization of continuous spectrum is realized using stationary wave packets which are the normalized states constructed from exact non-normalized continuum states. Projecting the wave functions and all scattering operators like $t$ -matrix, resolvent, etc. on such a wave-packet basis results in a formulation of quantum scattering problem entirely in terms of discrete elements and linear equations with regular matrices. It is demonstrated that there is a close relation between the above stationary wave packets and pseudostates which are employed often to approximate the scattering states with a finite $L_{2}$ basis. Such a fully discrete treatment of complicated few- and many-body scattering problems leads to significant simplification of their practical solution. Also we get finite-dimensional approximations for complicated operators like effective interactions between composite particles constructed via the Feshbach-type projection formalism. As illustrations to this general approach we consider several important particular problems including multichannel scattering and scattering in the three-nucleon system within the Faddeev framework.
nucl-thAnnals Phys.(2015)·22 citations
05
Study of spin polarized nuclear matter and finite nuclei with finite range simple effective interaction
B. Behera🇮🇳 · X. Viñas🇪🇸 · T. R. Routray🇮🇳 · M. Centelles🇪🇸
The properties of spin polarized pure neutron matter and symmetric nuclear matter are studied using the finite range simple effective interaction, upon its parametrization revisited. Out of the total twelve parameters involved, we now determine ten of them from nuclear matter, against the nine parameters in our earlier calculation, as required in order to have predictions in both spin polarized nuclear matter and finite nuclei in unique manner being free from uncertainty found using the earlier parametrization. The information on the effective mass splitting in polarized neutron matter of the microscopic calculations is used to constrain the one more parameter, that was earlier determined from finite nucleus, and in doing so the quality of the description of finite nuclei is not compromised. The interaction with the new set of parameters is used to study the possibilities of ferromagnetic and antiferromagnetic transitions in completely polarized symmetric nuclear matter. Emphasis is given to analyze the results analytically, as far as possible, to elucidate the role of the interaction parameters involved in the predictions.
nucl-thJ.Phys.G(2015)·21 citations
06
Beta decay of 252Cf on the way to scission from the exit point
K. Pomorski · B. Nerlo-Pomorska · P. Quentin
Upon increasing significantly the nuclear elongation, the beta-decay energy grows. This paper investigates within a simple yet partly microscopic approach, the transition rate of the beta decay of the 252Cf nucleus on the way to scission from the exit point for a spontaneous fission process. A rather crude classical approximation is made for the corresponding damped collective motion assumed to be one dimensional. Given these assumptions, we only aim in this paper at providing the order of magnitudes of such a phenomenon. At each deformation the energy available for beta decay, is determined from such a dynamical treatment. Then, for a given elongation, transition rates for the allowed (Fermi) beta decay are calculated from pair correlated wave functions obtained within a macroscopic-microscopic approach and then integrated over the time corresponding to the whole descent from exit to scission. The results are presented as a function of the damping factor (inverse of the characteristic damping time) in use in our classical dynamical approach. For instance, in the case of a descent time from the exit to the scission points of about $1 0^{- 20}$ second, one finds a total rate of beta decay corresponding roughly to 20 events per year and per milligram of 252Cf. The inclusion of pairing correlations does not affect much these results.
nucl-th0 citations
07
Finite Isospin Chiral Perturbation Theory in a Magnetic Field
Prabal Adhikari🇺🇸 · Thomas D. Cohen🇺🇸 · Julia Sakowitz🇺🇸
The phase diagram of finite isospin, zero temperature QCD with the pions coupled to photons in a uniform external magnetic field is explored in the low field, small isospin density regime for which chiral perturbation theory is a valid description. For realistic pion masses, the system behaves as a type-II superconductor: a uniform superconducting state is formed at low-enough magnetic fields, a vortex state for intermediate magnetic fields and finally a normal state for large magnetic fields. In each these phases (including the vortex phase), the $π^{0}$ remains uncondensed just as in the zero-external field problem. The critical magnetic field where the phase transition from the uniform superconducting state to a vortex state occurs was found numerically.
nucl-thhep-phPRC(2015)·28 citations
08
Microscopic Study of $α + N$ Bremsstrahlung from Effective and Realistic Multi-nucleon Interactions
Jérémy Dohet-Eraly · Sofia Quaglioni · Petr Navrátil · Guillaume Hupin
Based on an effective nucleon-nucleon interaction, a microscopic cluster model of the nucleus-nucleus bremsstrahlung, including implicitly a part of the effects of meson-exchange currents via an extension of the Siegert theorem is applied to the $α + p$ and $α + n$ systems. The contributions of the $E 1$ and $E 2$ transitions to the bremsstrahlung cross sections are evaluated and their relative importance for the mirror systems $α + p$ and $α + n$ is compared. Another approach based on realistic two- and three-nucleon interactions and the No-Core Shell Model/Resonating-Group Method is also investigated. Some preliminary results for the $α + p$ bremsstrahlung are displayed.
nucl-thJPS Conf.Proc.(2015)·0 citations

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