The spontaneous generation of magnetic fields at high temperature in a supersymmetric theory

The spontaneous generation of magnetic and chromomagnetic fields at high temperature in the minimal supersymmetric standard model (MSSM) is investigated. The consistent effective potential including the one-loop and the daisy diagrams of all bosons and fermions is calculated and the magnetization of the vacuum is observed. The mixing of the generated fields due to the quark and s-quark loop diagrams and the role of superpartners are studied in detail. It is found that the contribution of these diagrams increases the magnetic and chromomagnetic field strengths as compared with the case of a separate generation of fields. The magnetized vacuum state is found to be stable due to the magnetic masses of gauge fields included in the daisy diagrams. Applications of the results obtained are discussed. A comparison with the standard model case is done.Comment: 14 pages, 2 figures, 3 table

Model-independent search for the Abelian Z' boson in the Bhabha process

Model-independent observables to pick out the Abelian Z' signal in the Bhabha process are introduced at energies >= 200 GeV. They measure separately the Z'-induced vector and axial-vector four-fermion contact couplings. The analysis of the LEP2 data constrains the value of the Z'-induced vector four-fermion coupling at the 2-sigma confidence level that corresponds to the Abelian Z' boson with the mass of order 1 TeV.Comment: 7 pages, 5 figures, uses RevTeX4. The text of the paper is completely rewritte

The spontaneous generation of magnetic and chromomagnetic fields at high temperature in the Standard Model

The spontaneous generation of the magnetic and chromomagnetic fields at high temperature is investigated in the Standard Model. The consistent effective potential including the one-loop and the daisy diagrams of all boson and fermion fields is calculated. The mixing of the generated fields due to the quark loop diagram is studied in detail. It is found that the quark contribution increases the magnetic and chromomagnetic field strengths as compared with the separate generation of fields. The magnetized vacuum state is stable due to the magnetic gauge field masses included in the daisy diagrams. Some applications of the results obtained are discussed.Comment: 9 pages, 2 tables, 2 figures, LaTeX with svjour clas

Long range chromomagnetic fields at high temperature

The magnetic mass of neutral gluons in Abelian chromomagnetic field at high temperature is calculated in SU(2)$ gluodynamics. It is noted that such type fields are spontaneously generated at high temperature. The mass is computed either from the Schwinger-Dyson equation accounting for the one-loop polarization tensor or in Monte-Carlo simulations on a lattice. In latter case, an average magnetic flux penetrating a plaquette is measured for a number of lattices. Both calculations are in agreement with each other and result in zero magnetic mass. Some applications of the results obtained are discussed.Comment: 14 pages, 1 figur

Z' signal from the LEP2 data

The many-parametric fit of the LEP2 data on e^+e^-\to e^+e^-, \mu^+\mu^-, \tau^+\tau^- processes is performed to estimate signals of the Abelian Z'-boson beyond the standard model. The model-independent relations between the Z' couplings to the standard model particles allow to describe the Z' effects in lepton processes by 4 independent parameters. No signal is found by the complete LEP2 data set, and the 1.3\sigma signal is detected by the fit of the backward bins. The Z' couplings to the vector and axial-vector lepton currents are constrained. The comparisons with the one-parameter fits and with the LEP1 experiments are performed.Comment: 6 pages, 2 figures, RevTeX. The paper was completely rewritten. The errors in the first version were eliminated. The comparison with the LEP1 data is adde

Signals of Z' boson in the Bhabha process within the LEP2 data set

The LEP2 data set on the Bhabha process is analyzed with the aim to detect the signals of the heavy virtual Z' gauge bosons. The state interacting with the left-handed standard-model doublets and called the Chiral Z' is investigated. This particle was introduced already as the low-energy state allowed by the renormalizability of the model. The contribution of the Chiral Z' state to the Bhabha process is described by two parameters: the coupling to electrons and the Z-Z' mixing angle. The sign-definite one-parameter observable is proposed to measure the Z' coupling to the electron current. The one-parameter fit of the data shows no signals of the particle. The alternative two-parameter fit of the differential cross-sections is also performed. It also shows no Chiral Z' signals. The comparisons with other fits are discussed.Comment: 15 pages, 4 figures. The paper was completely rewritten on the base of new dat

Polarization tensor of charged gluons in color magnetic background field at finite temperature

We calculate the polarization tensor of charged gluons in a Abelian homogeneous magnetic background field at finite temperature in one loop order Lorentz background field gauge in full generality. Thereby we first determine the ten independent tensor structures. For the calculation of the corresponding form factors we use the Schwinger representation and represent form factors as double parametric integrals and a sum resulting from the Matsubara formalism used. The integrands are given explicitly in terms of hyperbolic trigonometric functions. Like in the case of neutral gluons, the polarization tensor is not transversal. Out of the tensor structures, seven are transversal and three are not. The nontransversal part follows explicitly from our calculations.Comment: 28 pages, submitted to Phys.Rev.

QCD dynamics in a constant chromomagnetic field

We investigate the phase transition in full QCD with two flavors of staggered fermions in presence of a constant abelian chromomagnetic field. We find that the critical temperature depends on the strength of the chromomagnetic field and that the deconfined phase extends to very low temperatures for strong enough fields. As in the case of zero external field, a single transition is detected, within statistical uncertainties, where both deconfinement and chiral symmetry restoration take place. We also find that the chiral condensate increases with the strength of the chromomagnetic field.Comment: 18 pages, 8 figures, 1 tabl

Energy States of Colored Particle in a Chromomagnetic Field

The unitary transformation, which diagonalizes squared Dirac equation in a constant chromomagnetic field is found. Applying this transformation, we find the eigenfunctions of diagonalized Hamiltonian, that describe the states with definite value of energy and call them energy states. It is pointed out that, the energy states are determined by the color interaction term of the particle with the background chromofield and this term is responsible for the splitting of the energy spectrum. We construct supercharge operators for the diagonal Hamiltonian, that ensure the superpartner property of the energy states.Comment: 25 pages, some calculation details have been removed, typos correcte