45,901 research outputs found
Peierls substitution in the energy dispersion of a hexagonal lattice
The method of the Peierls substitution in studying the magnetic subband
structure of a hexagonal lattice is re-examined. Several errors in the
formalism of a couple of recent papers are pointed out and rectified so as to
describe the effect of the magnetic field pertinently.Comment: 3 pages (two-columns), 2 EPS figures, submitted to J. Phys.: Condens.
Matte
Higher Derivative CP(N) Model and Quantization of the Induced Chern-Simons Term
We consider higher derivative CP(N) model in 2+1 dimensions with the
Wess-Zumino-Witten term and the topological current density squared term. We
quantize the theory by using the auxiliary gauge field formulation in the path
integral method and prove that the extended model remains renormalizable in the
large N limit. We find that the Maxwell-Chern-Simons theory is dynamically
induced in the large N effective action at a nontrivial UV fixed point. The
quantization of the Chern-Simons term is also discussed.Comment: 8 pages, no figure, a minor change in abstract, added Comments on the
quantization of the Chern-Simons term whose coefficient is also corrected,
and some references are added. Some typos are corrected. Added a new
paragraph checking the equivalence between (3) and (5), and a related
referenc
Pion structure in a nuclear medium
The structure and electroweak properties of the pion in symmetric nuclear
matter are presented in the framework of the Nambu--Jona-Lasinio model. The
pion is described as a bound state of a dressed quark-antiquark pair governed
by the Bethe-Salpeter equation. For the in-medium current-light-quark
properties we use the quark-meson coupling model, which describes successfully
the properties of hadron in a nuclear medium. We found that the light-quark
condensates, the pion decay constant and pion-quark coupling constant decrease
with increasing nuclear matter density. We then predict the modifications of
the charge radius of the charged pion in nuclear matter.Comment: 4 pages, 6 figures, accepted version for the QNP2018 proceedings, 8th
International Conference on Quarks and Nuclear Physics (QNP2018), November
13-17, 2018, Tsukuba, Ibaraki, Japa
Effects of medium modifications of nucleon form factors on neutrino scattering in dense matter
Effects of the in-medium modifications of nucleon form factors on neutrino
interaction in dense matter are presented by considering both the weak and
electromagnetic interactions of neutrinos with the constituents of the matter.
A relativistic mean field and the quark-meson coupling models are respectively
adopted for the effective nucleon mass and in-medium nucleon form factors. We
calculate the cross-section of neutrino scattering as well as the neutrino mean
free path. We found the cross sections of neutrino scattering in cold nuclear
medium decreases when the in-medium modifications 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.Comment: 4 pages, 2 figures, accepted for the QNP2018 proceedings, a talk
given at QNP2018, 8th International Conference on Quarks and Nuclear Physics
(QNP2018), November 13-17, 2018, Tsukuba, Ibaraki, Japa
Evidence of unconventional low-frequency dynamics in the normal phase of Ba(Fe1-xRhx)2As2 iron-based supercondutors
This work presents 75As NMR spin echo decay rate (1/T2) measurements in
Ba(Fe1-xRhx)2As2 superconductors, for 0.041 < x < 0.094. It is shown that 1/T2
increases upon cooling, in the normal phase, suggesting the onset of an
unconventional very low-frequency activated dynamic. The correlation times of
the fluctuations and their energy barriers are derived. The motion is favored
at large Rh content, while it is hindered by the application of a magnetic
field perpendicular to the FeAs layers. The same dynamic is observed in the
spin-lattice relaxation rate, in a quantitatively consistent manner. These
results are discussed in the light of nematic fluctuations involving domain
wall motion. The analogies with the behaviour observed in the cuprates are also
outlined
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