Nuclear Theory·nucl-th

Monday·January 19, 2015

13 papers—8 primary·5 cross-listed

09
Non-Extensive Quantum Statistics with Particle - Hole Symmetry
T.S. Biro · K.M. Shen · B.W. Zhang
Based on Tsallis entropy and the corresponding deformed exponential function, generalized distribution functions for bosons and fermions have been used since a while. However, aiming at a non-extensive quantum statistics further requirements arise from the symmetric handling of particles and holes (excitations above and below the Fermi level). Naive replacements of the exponential function or cut and paste solutions fail to satisfy this symmetry and to be smooth at the Fermi level at the same time. We solve this problem by a general ansatz dividing the deformed exponential to odd and even terms and demonstrate that how earlier suggestions, like the kappa- and q-exponential behave in this respect.
↳ cond-mat.stat-mechnucl-thPhysica A(2015)·16 citations
10
Charge asymmetry in the differential cross section of high-energy bremsstrahlung in the field of a heavy atom
P.A. Krachkov🇷🇺 · A.I. Milstein🇷🇺
The distinction between the charged particle and antiparticle differential cross sections of high-energy bremsstrahlung in the electric field of a heavy atom is investigated. The consideration is based on the quasiclassical approximation to the wave functions in the external field. The charge asymmetry (the ratio of the antisymmetric and symmetric parts of the differential cross section) arises due to the account for the first quasiclassical correction to the differential cross section. All evaluations are performed with the exact account of the atomic field. We consider in detail the charge asymmetry for electrons and muons. For electrons, the nuclear size effect is not important while for muons this effect should be taken into account. For the longitudinal polarization of the initial charged particle, the account for the first quasiclassical correction to the differential cross section leads to the asymmetry in the cross section with respect to the replacement $φ \to - φ$ , where $φ$ is the azimuth angle between the photon momentum and the momentum of the final charged particle.
↳ hep-phnucl-thphysics.atom-phPRA(2015)·11 citations
11
Leading chiral logarithms for the nucleon mass
Alexey A. Vladimirov🇸🇪 · Johan Bijnens🇸🇪
We give a short introduction to the calculation of the leading chiral logarithms, and present the results of the recent evaluation of the leading logarithm series for the nucleon mass within the heavy baryon theory. The presented results are the first example of leading logarithm calculation in the nucleon ChPT. We also discuss some regularities observed in the leading logarithmical series for nucleon mass. The talk has been presented at "Quark Confinement and the Hadron Spectrum XI".
↳ hep-phnucl-thAIP Conf.Proc.(2016)·1 citation
12
Supersymmetric inversion of effective-range expansions
Bikashkali Midya · Jérémie Evrard · Sylvain Abramowicz · O. L. Ramírez Suárez · Jean-Marc Sparenberg
A complete and consistent inversion technique is proposed to derive an accurate interaction potential from an effective-range function for a given partial wave in the neutral case. First, the effective-range function is Taylor or Padé expanded, which allows high precision fitting of the experimental scattering phase shifts with a minimal number of parameters on a large energy range. Second, the corresponding poles of the scattering matrix are extracted in the complex wave-number plane. Third, the interaction potential is constructed with supersymmetric transformations of the radial Schrödinger equation. As an illustration, the method is applied to the experimental phase shifts of the neutron-proton elastic scattering in the $^{1} S_{0}$ and $^{1} D_{2}$ channels on the $[0 - 350]$ MeV laboratory energy interval.
↳ quant-phnucl-thphysics.atom-phPRC(2015)·6 citations
13
Antineutrino induced Lambda(1405) production off the proton
Xiulei Ren🇨🇳 · E. Oset🇪🇸 · L. Alvarez-Ruso🇪🇸 · M. J. Vicente Vacas🇪🇸
We have studied the strangeness changing antineutrino induced reactions $ν ˉ_{l} p \to l^{+} ϕB$ , with $ϕB = K^{-} p$ , $K ˉ^{0} n$ , $π^{0} Λ$ , $π^{0} Σ^{0}$ , $η Λ$ , $η Σ^{0}$ , $π^{+} Σ^{-}$ , $π^{-} Σ^{+}$ , $K^{+} Ξ^{-}$ and $K^{0} Ξ^{0}$ , using a chiral unitary approach. These ten coupled channels are allowed to interact strongly, using a kernel derived from the chiral Lagrangians. This interaction generates two $Λ (1405)$ poles, leading to a clear single peak in the $π Σ$ invariant mass distributions. At backward scattering angles in the center of mass frame, $ν ˉ_{μ} p \to μ^{+} π^{0} Σ^{0}$ is dominated by the $Λ (1405)$ state at around 1420~MeV while the lighter state becomes relevant as the angle decreases, leading to an asymmetric line shape. In addition, there are substantial differences in the shape of $π Σ$ invariant mass distributions for the three charge channels. If observed, these differences would provide valuable information on a claimed isospin I=1, strangeness S=-1 baryonic state around 1400 MeV. Integrated cross sections have been obtained for the $π Σ$ and $K ˉ N$ channels, investigating the impact of unitarization in the results. The number of events with $Λ (1405)$ excitation in $ν ˉ_{μ} p$ collisions in the recent antineutrino run at the MINERvA experiment has also been obtained. We find that this reaction channel is relevant enough to be investigated experimentally and to be taken into account in the simulation models of future experiments with antineutrino beams.
↳ hep-phhep-exnucl-thPRC(2015)·31 citations

Affiliations

first authorsco-authorsvia INSPIRE

Non-Extensive Quantum Statistics with Particle - Hole Symmetry

Charge asymmetry in the differential cross section of high-energy bremsstrahlung in the field of a heavy atom

Leading chiral logarithms for the nucleon mass

Supersymmetric inversion of effective-range expansions

Antineutrino induced Lambda(1405) production off the proton

Affiliations