Nuclear Theory·nucl-th

Wednesday·February 7, 2018

9 papers—5 primary·4 cross-listed

01
The octupole collective Hamiltonian. Does it follow the example of the quadrupole case?
S.G.Rohozinski · L. Prochniak
A general form of the octupole collective Hamiltonian is introduced and analyzed based on fundamental tensors in the seven-dimensional tensor space. Possible definitions of intrinsic frames of reference possessing cubic symmetry for the octupole tensor are considered. Cubic intrinsic octupole coordinates or deformations are introduced. Shapes of the octupoloid are investigated. The octupole collective Hamiltonian is expressed in intrinsic coordinates. An intrinsic angular momentum carried by the octupole vibrations is discovered. Small oscillations about an axially-symmetric pear shape are analyzed. Formulation of a unified quadrupole-octupole collective model is discussed.
nucl-th1 citation
02
Impact of medium modification of the nucleon weak and electromagnetic form factors on the neutrino mean free path in dense matter
Parada T. P. Hutauruk🇰🇷 · Yongseok Oh🇰🇷 · K. Tsushima🇰🇷
Impact of the in-medium modified nucleon weak and electromagnetic form factors on the neutrino mean free path in dense matter is studied by considering both the weak and electromagnetic interactions of neutrinos with the constituents of the matter. A relativistic mean field model and the quark-meson coupling model are respectively adopted for the in-medium effective nucleon mass and nucleon form factors. We find that the cross sections of neutrino scattering in cold nuclear medium decreases when the in-medium modification of the nucleon weak and electromagnetic form factors are taken into account. This reduction results in the enhancement of the neutrino mean free path, in particular at the baryon density of around a few times of the normal nuclear matter density. The enhancement of the neutrino mean free path is estimated to be about 10--40\% compared with the values obtained without the medium modification of the nucleon form factors, and the enhancement is expected to accelerate the cooling of neutron stars.
nucl-thastro-ph.HEhep-exhep-ph+1PRD(2018)·15 citations
03
Symplectic no-core configuration interaction framework for ab initio nuclear structure
Anna E. McCoy · Mark A. Caprio · Tomas Dytrych
We introduce a symplectic no-core configuration interaction (SpNCCI) framework for ab initio nuclear structure calculations, in a correlated many-body basis which encodes an approximate Sp(3,R) symmetry of the nucleus. Such a scheme potentially provides a means of restricting the many-body space to include only those highly-excited configurations which dominantly contribute to the nuclear wave function. We examine the symplectic symmetry structure arising in an illustrative ab initio SpNCCI calculation for 6Li. We observe both the dominance of symplectic symmetry in individual wave functions and the emergence of families of states related by symplectic symmetry.
nucl-thScience(2018)·9 citations
04
Directed, elliptic and triangular flow of protons in Au+Au reactions at 1.23 AGeV: A theoretical analysis of the recent HADES data
Paula Hillmann🇩🇪 · Jan Steinheimer🇩🇪 · Marcus Bleicher🇩🇪
Recently, the HADES experiment at GSI has provided preliminary data on the directed flow, $v_{1}$ elliptic flow, $v_{2}$ and triangular flow, $v_{3}$ of protons in Au+Au reactions at a beam energy of 1.23 A GeV. Here we present a theoretical discussion of these flow harmonics within the UrQMD transport approach. We show that all flow harmonics, including the triangular flow, provide a consistent picture of the expansion of the system, if potential interactions are taken into account. Investigating the dependence of the flow harmonics on the nuclear interaction potentials it is shown that especially $v_{3}$ can serve as a sensitive probe for the nuclear equation of state at such low energies. The triangular flow and its excitation function with respect to the reaction-plane were calculated for the first time and indicate a complex interplay of the time-evolution of the system and the initial conditions at low beam-energies. Our study also indicates a significant softening of the equation of state at beam energies above $E_{lab} > 7$ A GeV which can be explored by at the future FAIR facility.
nucl-thJ.Phys.G(2018)·57 citations
05
Nonlinear waves in magnetized quark matter and the reduced Ostrovsky equation
D. A. Fogaça🇧🇷 · S. M. Sanches Jr.🇧🇷 · F. S. Navarra🇧🇷
We study nonlinear waves in a nonrelativistic ideal and cold quark gluon plasma immersed in a strong uniform magnetic field. In the context of nonrelativistic hydrodynamics with an external magnetic field we derive a nonlinear wave equation for baryon density perturbations, which can be written as a reduced Ostrovsky equation. We find analytical solutions and identify the effects of the magnetic field.
nucl-thhep-phCommun.Nonlinear Sci.Numer.Simul.(2019)·4 citations
06
Semi-inclusive production of two back-to-back hadron pairs in $e^{+} e^{-}$ annihilation revisited
Hrayr H. Matevosyan🇦🇺 · Alessandro Bacchetta🇮🇹 · Daniël Boer🇳🇱 · Aurore Courtoy🇲🇽 · Aram Kotzinian🇦🇲 · Marco Radici🇮🇹 · Anthony W. Thomas🇦🇺
The cross section for back-to-back hadron pair production in $e^{+} e^{-}$ annihilation provides access to the dihadron fragmentation functions (DiFF) needed to extract nucleon parton distribution functions from the semi-inclusive deep inelastic scattering (SIDIS) experiments with two detected final state hadrons. Particular attention is given to the so-called interference DiFF (IFF), which makes it possible to extract the transversity parton distribution of the nucleon in the collinear framework. However, previously unnoticed discrepancies were recently highlighted between the definitions of the IFFs appearing in the collinear kinematics when reconstructed from DiFFs entering the unintegrated fully differential cross sections of SIDIS and $e^{+} e^{-}$ annihilation processes. In this work, to clarify this problem we rederive the fully differential cross section for $e^{+} e^{-}$ annihilation at the leading-twist approximation. We find a mistake in the definition of the kinematics in the original expression that systematically affects a subset of terms and that leads to two significant consequences. First, the discrepancy between the IFF definitions in the cross sections for SIDIS and $e^{+} e^{-}$ annihilation is resolved. Second, the previously derived azimuthal asymmetry for accessing the helicity dependent DiFF $G_{1}^{⊥}$ in $e^{+} e^{-}$ annihilation vanishes, which explains the nonobservation of this asymmetry in the recent experimental searches by the $BELLE$ Collaboration. We discuss the recently proposed alternative option to extract $G_{1}^{⊥}$ .
↳ hep-phhep-exnucl-thPRD(2018)·32 citations
07
Quantum anomaly and thermodynamics of one-dimensional fermions with three-body interactions
Joaquín E. Drut · Joshua R. McKenney · Wilder S. Daza · Chris L. Lin · Carlos R. Ordóñez
We show that a system of three species of one-dimensional fermions, with an attractive three-body contact interaction, features a scale anomaly directly related to the anomaly of two-dimensional fermions with two-body forces. We show, furthermore, that those two cases (and their multi species generalizations) are the only non-relativistic systems with contact interactions that display a scale anomaly. While the two-dimensional case is well-known and has been under study both experimentally and theoretically for years, the one-dimensional case presented here has remained unexplored. For the latter, we calculate the impact of the anomaly on the equation of state, which appears through the generalization of Tan's contact for three-body forces, and determine the pressure at finite temperature. In addition, we show that the third-order virial coefficient is proportional to the second-order coefficient of the two-dimensional two-body case.
↳ cond-mat.quant-gashep-thnucl-thquant-phPRL(2018)·40 citations
08
Transmutation of Minor Actinides and Power Flattening in PWR MOX Fuel
Shengli Chen · Cenxi Yuan
In order to transmute long-lived MAs and flatten power distribution in a PWR MOX fuel assembly, the authors have proposed to replace some high power fuel rods by MAs loaded fuel rods. The present work proves the high efficiency of long-lived MAs transmutation in a PWR MOX assembly with 92 fuel rods with 3% MAs loaded. The power and the burnup distribution have been flatted by using the MAs loading method proposed by authors. The 237Np loading method is expected for the transmutation by comparing with natural decay time to achieve the same reduction. The mixed MAs loading has better behaviors on power flattening and negative contribution of reactivity. In addition, the mixed MAs loading can largely reduce the quantity of 241Am, while the addition of other MAs has no influence on the transmutation efficiency of 237Np.
↳ physics.app-phnucl-th0 citations
09
Hadron resonance gas EoS and the fluidity of matter produced in HIC
Guruprasad Kadam🇮🇳 · Swapnali Pawar🇮🇳
We study the equation of state (EoS) of the hot and dense hadron gas by incorporating the excluded volume corrections into the ideal hadron resonance gas model (HRG). The total hadron mass spectrum of the model is the sum of discrete mass spectrum consisting all the experimentally known hadrons and the exponentially rising continuous Hagedorn states. We confront the EoS of the model with lattice quantum chromodynamics (LQCD) results at finite baryon chemical potential. We find that this modified HRG model reproduce the LQCD results up to T = 160 MeV at zero as well as finite baryon chemical potential. We further estimate the shear viscosity coefficient within ambit of this model in the context of heavy-ion collision experiments.
↳ hep-phnucl-thAdv.High Energy Phys.(2019)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE