Nuclear Theory·nucl-th

Wednesday·February 17, 2016

6 papers—5 primary·1 cross-listed

01
[Submitted on 16 Feb 2016]
Bjorken flow in one-dimensional relativistic magnetohydrodynamics with magnetization
Shi Pu🇩🇪 · Victor Roy🇩🇪 · Luciano Rezzolla🇩🇪 · Dirk H. Rischke🇩🇪
We study the one-dimensional, longitudinally boost-invariant motion of an ideal fluid with infinite conductivity in the presence of a transverse magnetic field, i.e., in the ideal transverse magnetohydrodynamical limit. In an extension of our previous work Roy et al., [Phys. Lett. B 750, 45 (2015)], we consider the fluid to have a non-zero magnetization. First, we assume a constant magnetic susceptibility $χ_{m}$ and consider an ultrarelativistic ideal gas equation of state. For a paramagnetic fluid (i.e., with $χ_{m} > 0$ ), the decay of the energy density slows down since the fluid gains energy from the magnetic field. For a diamagnetic fluid (i.e., with $χ_{m} < 0$ ), the energy density decays faster because it feeds energy into the magnetic field. Furthermore, when the magnetic field is taken to be external and to decay in proper time $τ$ with a power law $\sim τ^{- a}$ , two distinct solutions can be found depending on the values of $a$ and $χ_{m}$ . Finally, we also solve the ideal magnetohydrodynamical equations for one-dimensional Bjorken flow with a temperature-dependent magnetic susceptibility and a realistic equation of state given by lattice-QCD data. We find that the temperature and energy density decay more slowly because of the non-vanishing magnetization. For values of the magnetic field typical for heavy-ion collisions, this effect is, however, rather small. Only for magnetic fields which are about an order of magnitude larger than expected for heavy-ion collisions, the system is substantially reheated and the lifetime of the quark phase might be extended.
Comments:
12 pages, 9 figures; minor revisions, two references added, journal version accepted by PRD
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1602.04953 [pdf]
PRD(2016)·115 citations
02
[Submitted on 16 Feb 2016]
Transverse flow induced by inhomogeneous magnetic fields in the Bjorken expansion
Shi Pu🇩🇪 · Di-Lun Yang🇯🇵
We investigate the magnetohydrodynamics in the presence of an external magnetic field following the power-law decay in proper time and having spatial inhomogeneity characterized by a Gaussian distribution in one of transverse coordinates under the Bjorken expansion. The leading-order solution is obtained in the weak-field approximation, where both energy density and fluid velocity are modified. It is found that the spatial gradient of the magnetic field results in transverse flow, where the flow direction depends on the decay exponents of the magnetic field. We suggest that such a magnetic-field-induced effect might influence anisotropic flow in heavy ion collisions.
Comments:
14 pages, 15 figures, minor revisions, two figures added, journal version accepted by PRD
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1602.04954 [pdf]
PRD(2016)·55 citations
03
[Submitted on 16 Feb 2016]
Occupation numbers of spherical orbits in self-consistent beyond-mean-field methods
Tomás R. Rodríguez🇪🇸 · Alfredo Poves🇪🇸 · Frédéric Nowacki🇫🇷
We present a method to compute the number of particles occupying spherical single-particle (SSP) levels within the energy density functional (EDF) framework. These SSP levels are defined for each nucleus by performing self-consistent mean-field calculations. The nuclear many-body states, in which the occupation numbers are evaluated, are obtained with a symmetry conserving configuration mixing (SCCM) method based on the Gogny EDF. The method allows a closer comparison between EDF and shell model with configuration mixing in large valence spaces (SM-CI) results, and can serve as a guidance to define physically sound valence spaces for SM-CI calculations. As a first application of the method, we analyze the onset of deformation in neutron-rich $N = 40$ isotones and the role of the SSP levels around this harmonic oscillator magic number, with particular emphasis in the structure of $^{64}$ Cr.
Comments:
11 pages, 5 Figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1602.05029 [pdf]
PRC(2016)·21 citations
04
[Submitted on 12 Feb 2016]
Electric Conductivity of a hot hadron gas from a kinetic approach
Moritz Greif🇩🇪 · Carsten Greiner🇩🇪 · Gabriel S. Denicol🇺🇸
We calculate the electric conductivity of a gas of relativistic particles with isotropic cross sections using the Boltzmann equation as the starting point. Our analyses is restricted to elastic collisions. We show the perfect agreement with previously published numerical results for a massless quark- gluon plasma, and give results for the electric conductivity of an interacting hadron gas, employing realistic resonance cross sections. These results for the electric conductivity of a hot hadron gas, as created in (ultra-)relativistic heavy-ion collisions, are of rich phenomenological as well as theoretical interest and can be compared to, e.g., lattice quantum field theory calculations.
Comments:
14 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:
1602.05085 [pdf]
PRD(2016)·71 citations
05
[Submitted on 16 Feb 2016]
Neutrino induced 1-pion production
R. González-Jiménez🇧🇪 · T. Van Cuyck🇧🇪 · N. Van Dessel🇧🇪 · V. Pandey🇧🇪 · N. Jachowicz🇧🇪
Neutrino-induced pion production constitutes an important contribution to neutrino-nucleus scattering cross sections at intermediate energies. A deep understanding of this process is mandatory for a correct interpretation of neutrino-oscillation experiments. We aim at contributing to the ongoing effort to understand the various experimental results obtained by different collaborations in a wide range of energies. In particular, in this work we analyze recent MiniBooNE and MINERvA charged-current neutrino 1-pion production data. We use a relativistic theoretical approach which accounts for resonant and non-resonant 1-pion production contributions.
Comments:
Proceedings of the 10th International Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt15). 16-21 November 2015, Osaka, Japan
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1602.05096 [pdf]
JPS Conf.Proc.(2016)·4 citations
06
[Submitted on 16 Feb 2016] (cross-list from hep-ph)
A Relativistic Model for the Electromagnetic Structure of Baryons from the 3rd Resonance Region
G. Ramalho🇧🇷
We present some predictions for the $γ^{*} N \to N^{*}$ transition amplitudes, where $N$ is the nucleon, and $N^{*}$ is a nucleon excitation from the third resonance region. First we estimate the transition amplitudes associated with the second radial excitation of the nucleon, interpreted as the $N (1710)$ state, using the covariant spectator quark model. After that, we combine some results from the covariant spectator quark model with the framework of the single quark transition model, to make predictions for the $γ^{*} N \to N^{*}$ transition amplitudes, where $N^{*}$ is a member of the $S U (6)$ -multiplet $[70, 1^{-}]$ . The results for the $γ^{*} N \to N (1520)$ and $γ^{*} N \to N (1535)$ transition amplitudes are used as input to the calculation of the amplitudes $A_{1/2}$ , $A_{3/2}$ , associated with the $γ^{*} N \to N (1650)$ , $γ^{*} N \to N (1700)$ , $γ^{*} N \to Δ (1620)$ , and $γ^{*} N \to Δ (1700)$ transitions. Our estimates are compared with the available data. In order to facilitate the comparison with future experimental data at high $Q^{2}$ , we derived also simple parametrizations for the amplitudes, compatible with the expected falloff at high $Q^{2}$ .
Comments:
Proceedings of the ECT* Workshop "Nucleon Resonances: From Photoproduction to High Photon Virtualities", October 12-16, 2015, Trento, Italy. Final version. 9 pages, 6 figures, 2 tables. arXiv admin note: text overlap with arXiv:1509.08436
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1602.05068 [pdf]
Few Body Syst.(2016)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Bjorken flow in one-dimensional relativistic magnetohydrodynamics with magnetization

Transverse flow induced by inhomogeneous magnetic fields in the Bjorken expansion

Occupation numbers of spherical orbits in self-consistent beyond-mean-field methods

Electric Conductivity of a hot hadron gas from a kinetic approach

Neutrino induced 1-pion production

A Relativistic Model for the Electromagnetic Structure of Baryons from the 3rd Resonance Region

Affiliations