Nuclear Theory·nucl-th

Tuesday·February 9, 2016

9 papers—5 primary·4 cross-listed

01
Electromagnetic fields with electric and chiral magnetic conductivities in heavy ion collisions
Hui Li🇨🇳 · Xin-li Sheng🇨🇳 · Qun Wang🇨🇳
We derive analytic formula for electric and magnetic fields produced by a moving charged particle in a conducting medium with the electric conductivity $σ$ and the chiral magnetic conductivity $σ_{χ}$ . We use the Green function method and assume that $σ_{χ}$ is much smaller than $σ$ . The compact algebraic expressions for electric and magnetic fields without any integrals are obtained. They recover the Lienard-Wiechert formula at vanishing conductivities. Exact numerical solutions are also found for any values of $σ$ and $σ_{χ}$ and are compared to analytic results. Both numerical and analytic results agree very well for the scale of high energy heavy ion collisions. The space-time profiles of electromagnetic fields in non-central Au+Au collisions have been calculated based on these analytic formula as well as exact numerical solutions.
nucl-thPRC(2016)·110 citations
02
Light-quark baryon spectroscopy within ANL-Osaka dynamical coupled-channels approach
Hiroyuki Kamano🇯🇵
Recent results on the study of light-quark baryons with the ANL-Osaka dynamical coupled-channels (DCC) approach are presented, which contain the N* and Delta* spectroscopy via the analysis of pi N and gamma N reactions and the Lambda* and Sigma* spectroscopy via the analysis of K- p reactions. A recent application of our DCC approach to neutrino-nucleon reactions in the resonance region is also presented.
nucl-thhep-phnucl-exFew Body Syst.(2016)·4 citations
03
Polarization observables in the $e^{+} e^{-} \to Λ ˉ Λ$ reaction
Göran Fäldt
Cross-section, vector-polarization, and tensor-polarization distributions are calculated for the reactions $e^{+} e^{-} \to p ˉ p$ and $e^{+} e^{-} \to Λ ˉ Λ$ . Each reaction requires six characteristic functions that are bilinear in the, possibly complex, electromagnetic form factors, denoted $G_{E} (P^{2})$ and $G_{M} (P^{2})$ , of $p$ and $Λ$ . For the hyperon reaction also the joint-decay distributions of $Λ$ and $Λ ˉ$ are calculated. Their knowledge allow a complete determination of the hyperon electromagnetic form factors, without measuring hyperon spins. We explain how this is done in practice. For some tensor-polarization components our results are in conflict with previously repeatedly published distributions.
nucl-thEPJA(2016)·54 citations
04
Elastic pion-nucleon scattering in chiral perturbation theory: A fresh look
D. Siemens🇩🇪 · V. Bernard🇫🇷 · E. Epelbaum🇩🇪 · A. Gasparyan🇩🇪 · H. Krebs🇩🇪 · Ulf-G. Meißner🇩🇪
Elastic pion-nucleon scattering is analyzed in the framework of chiral perturbation theory up to fourth order within the heavy-baryon expansion and a covariant approach based on an extended on-mass-shell renormalization scheme. We discuss in detail the renormalization of the various low-energy constants and provide explicit expressions for the relevant $β$ -functions and the finite subtractions of the power-counting breaking terms within the covariant formulation. To estimate the theoretical uncertainty from the truncation of the chiral expansion, we employ an approach which has been successfully applied in the most recent analysis of the nuclear forces. This allows us to reliably extract the relevant low-energy constants from the available scattering data at low energy. The obtained results provide a clear evidence that the breakdown scale of the chiral expansion for this reaction is related to the $Δ$ -resonance. The explicit inclusion of the leading contributions of the $Δ$ -isobar is demonstrated to substantially increase the range of applicability of the effective field theory. The resulting predictions for the phase shifts are in an excellent agreement with the ones from the recent Roy-Steiner-equation analysis of pion-nucleon scattering.
nucl-thPRC(2016)·60 citations
05
A finite-temperature Hartree-Fock code for shell-model Hamiltonians
G.F. Bertsch · J.M Mehlhaff
The codes HFgradZ.py and HFgradT.py find axially symmetric minima of a Hartree-Fock energy functional for a Hamiltonian supplied in a shell-model basis. The functional to be minimized is the Hartree-Fock energy for zero-temperature properties or the Hartree-Fock grand potential for finite-temperature properties. Various constraints may be imposed on the minima.
nucl-thComput.Phys.Commun.(2016)·3 citations

Affiliations

first authorsco-authorsvia INSPIRE

Electromagnetic fields with electric and chiral magnetic conductivities in heavy ion collisions

Light-quark baryon spectroscopy within ANL-Osaka dynamical coupled-channels approach

Polarization observables in the e+e−→ΛˉΛ reaction

Elastic pion-nucleon scattering in chiral perturbation theory: A fresh look

A finite-temperature Hartree-Fock code for shell-model Hamiltonians

Affiliations

Polarization observables in the $e^{+} e^{-} \to Λ ˉ Λ$ reaction