The photon magnetic moment problem revisited

The photon magnetic moment for radiation propagating in magnetized vacuum is defined as a pseudo-tensor quantity, proportional to the external electromagnetic field tensor. After expanding the eigenvalues of the polarization operator in powers of $k^2$, we obtain approximate dispersion equations (cubic in $k^2$), and analytic solutions for the photon magnetic moment, valid for low momentum and/or large magnetic field. The paramagnetic photon experiences a red shift, with opposite sign than the gravitational one, which differs for parallel and perpendicular polarizations. It is due to the drain of photon transverse momentum and energy by the external field. By defining an effective transverse momentum, the constancy of the speed of light orthogonal to the field is guaranteed. We conclude that the propagation of the photon non-parallel to the magnetic behaves as if there is a quantum compression of vacuum or warp of space-time in an amount depending on its angle with regard to the field.Comment: 10 pages, 2 figure

Constraints on the charged Higgs boson of the two Higgs doublet model type III

The D0 experiment has reported a direct search for a charged Higgs boson produced by $q \bar q$ annihilation and decaying to $t \bar b$ final state, in the $180 \leq M_{H^+} \leq 300$ GeV mass range. The analysis has lead to upper limits on the production cross section in the framework of the two Higgs doublet model types I, II and III. We compare the predictions of two different scenarios in the framework of the two Higgs doublet type III to the cross section limits reported by D0 collaboration, and we obtain constraints on the charged Higgs mass, for the case when the charged Higgs mass is bigger than the top quark mass. Also, searches for the charged Higgs boson with a mass smaller than top quark mass are considered, we discuss the possible limits on the charged Higgs boson mass obtained from measurements of the ratio $R_\sigma=\sigma_{t \bar t}^{l+jets}/\sigma_{t \bar t}^{dileptons}$ within the two Higgs doublet model type III.Comment: 11 pages, 4 figures, version to be publishe

2D massless QED Hall half-integer conductivity and graphene

Starting from the photon self-energy tensor in a magnetized medium, the 3D complete antisymmetric form of the conductivity tensor is found in the static limit of a fermion system $C$ non-invariant under fermion-antifermion exchange. The massless relativistic 2D fermion limit in QED is derived by using the compactification along the dimension parallel to the magnetic field. In the static limit and at zero temperature the main features of quantum Hall effect (QHE) are obtained: the half-integer QHE and the minimum value proportional to $e^2/h$ for the Hall conductivity . For typical values of graphene the plateaus of the Hall conductivity are also reproduced.Comment: 14 pages, 2 figure