Strong magnetic fields in gauge theories

The problem of photon propagation in a medium in presence of a strong magnetic field in the frame of quantum electrodynamics is discussed in the present paper, based on previous literature in this area. The breaking of the spatial symmetry by the magnetic field determine the existence of a set of basic vectors and tensors which must satisfy the gauge and CPT invariance of quantum electrodynamics. The charge symmetric and non-symmetric cases are discussed. In the second case the Faraday effect is produced. A chiral current arises, associated to a pseudovector eigenvector ofthe polarization operator (due to the breaking of the spatial symmetry by the external magnetic field), related to the so-called axial anomaly. The path integrals and functional derivation are widely used to obtain the self-energy and vertex operators, and the Dyson equations. The inadequate introduction of a chiral chemical potential in the standard model is discussed for the Weinberg-Salam model for electroweak interactions.

Exact Green’s function of photon and medium effects in QED2+1

In (2+1)­-dimensional Maxwell­-Chern­-Simons quantum electrodynamics, we derive the structure of the exact polarization operator in the presence of medium characterized by a chemical potential μ. We show that the transverse part of the operator is the sum of four tensors. These tensors and unit one form an algebra with respect to the commutation operation. Green’s function of photons at zero temperature is derived on the basis of calculations of the one­loop form factors. The spectrum of modes is investigated. We find that the transverse and longitudinal modes exist in medium. This result differs from that of other authors. Dependence of the photon Debye mass on the form factors is investigated and a static electric potential is calculated.

Dark matter polarization operator in the generalized Yukawa model

Nowadays, no dark matter candidates have been discovered. We consider the possible reason for that which is related to the approach of on-peak resonance searching for. As is believed usually, a new particle has small width and a narrow width approximation is applicable to identify such type resonant peak in the invariant mass spectrum of collision products. In the present paper, in the framework of the generalized Yukawa model, we find out the propertiesof the searched particle when its width is larger than a maximal one expected during experiments and so this state could be missed as a noise. Usually, the new particle width is considered as an arbitrary parameter. Here, we obtain the width of the dark matter particle from an imaginary part of polarization operators. Then the width is analyzed as explicit function of the couplings and masses in the underlying model of the dark matter. The corresponding constraints on the model parameters are obtained. Role of the one-loop mixing of visible and dark matter fields is investigated and constraint on the mixing angle value is derived. These estimations are quite general and, in particular, relevant to interactions between the particles of the Standard model and dark matter.

Transport properties of fermions with moat spectra

We present here polarization operator of non-relativistic fermions with spin-orbit (SO) Rashba interaction. The spectrum of this fermions is moat type having minimum on a circle. Contrary to Dirac or non-relativistic fermions, Fermi sea here has a geometry of Corbino disk which reflects in a transport properties of excitation’s.

Two-Point One-Loop Fermionic Amplitudes in Constant Homogeneous Magnetic Field

Two-point one-loop fermionic amplitudes modifiled by a constant homogeneous magnetic fileld are studied. In addition to the amplitudes resulted after an insertion of scalar, pseudoscalar, vector and axial-vector fermionic currents, we calculate similar amplitudes with the tensor and (pseudo)scalar vertices. The crossed-field limit of these amplitudes is presented. The tensor current is a fermionic part of the Pauli Lagrangian relevant for the electromagnetic interaction of fermions through the anomalous magnetic moment and its contribution to the photon polarization operator is briefly discussed.

Induced charges and quark polarization operator at A0 background

The presence of the A0 condensate in quark-gluon plasma leads to Z(3) symmetry breaking and Furry's theorem violation. Due to this phenomenon the color charges are induced and other even-number diagrams are allowed. We calculate the first diagram of this series – tadpole diagram with one gluon line and find induced color charges in the plasma. Next, quark polarization operator in presence is calculated and partially investigated.

One-loop polarization operator of the quantum gauge superfield for 𝒩 = 1 SYM regularized by higher derivatives

We consider the general [Formula: see text] supersymmetric gauge theory with matter, regularized by higher covariant derivatives without breaking the BRST invariance, in the massless limit. In the [Formula: see text]-gauge we obtain the (unrenormalized) expression for the two-point Green function of the quantum gauge superfield in the one-loop approximation as a sum of integrals over the loop momentum. The result is presented as a sum of three parts: the first one corresponds to the pure supersymmetric Yang–Mills theory in the Feynman gauge, the second one contains all gauge-dependent terms, and the third one is the contribution of diagrams with a matter loop. For the Feynman gauge and a special choice of the higher derivative regulator in the gauge fixing term, we analytically calculate these integrals in the limit [Formula: see text]. In particular, in addition to the leading logarithmically divergent terms, which are determined by integrals of double total derivatives, we also find the finite constants.

Electromagnetic Properties in Multilayer Graphene within the Ritus Formalism: Transverse Electrical Conductivity

Within the framework of the Quantum Field Theory, we discuss how to study electromagnetic properties of a multilayer graphene sample in the presence of electric and magnetic fields, both perpendicular to the graphene planes. We deal with the multilayer system by taking into account the quantum mechanical supersymmetric property of the monolayer Hamiltonian. We solve the Dirac equation for the graphene charge carriers by using the Ritus formalism. This formalism consists in the diagonalization of the operator with and the Dirac gamma matrices which contain information about the pseudo-spin. We calculate the charge carrier propagator for the monolayer case, and we obtain the photon polarization operator, the leading quantum correction to the classical Lagrangian density that encodes the electromagnetic properties of the system through the constitutive equations. With the quantum supersymmetrical properties of both, the monolayer and the multilayer graphene Hamiltonians, it is possible to extend our results to obtain the charge carrier propagator for the multilayer case.