Chiral phase transitions in strong chromomagnetic fields at finite temperature and dimensional reduction

Dynamical fermion mass generation in external chromomagnetic fields is considered at non--zero temperature. The general features of dynamical chiral symmetry breaking ($D\chi SB$) are investigated for several field configurations in relation to their symmetry properties and the form of the quark spectrum. According to the fields, there arises dimensional reduction by one or two units. In all cases there exists $D\chi SB$ even at weak quark attraction, confirming the idea about the dimensional insensitivity of this mechanism in a chromomagnetic field.Comment: LATEX file, 12 pages, no figure

Neutrino magnetic moment in a magnetized plasma

The contribution of a magnetized plasma to the neutrino magnetic moment is calculated. It is shown that only part of the additional neutrino energy in magnetized plasma connecting with its spin and magnetic field strength defines the neutrino magnetic moment. It is found that the presence of magnetized plasma does not lead to the considerable increase of the neutrino magnetic moment in contrast to the results presented in literature previously.Comment: 7 page, 1 figures, based on the talk presented by E.N.Narynskaya at the XVI International Seminar Quarks'2010, Kolomna, Moscow Region, June 6-12, 2010, to appear in the Proceeding

Magnetic catalysis of parity breaking in a massive Gross-Neveu model and high-temperature superconductivity

In the framework of a (2+1)-dimensional P-even massive Gross-Neveu model, an external magnetic field is shown to induce a parity breaking first order phase transition. Possibility of applying the results obtained to description of magnetic phase transitions in high-temperature superconductors is discussed.Comment: LaTeX 2.09, 8 pages, 2 eps figure

Leptonic Decays of the W-Boson in a Strong Electromagnetic Field

The probability of W-boson decay into a lepton and a neutrino in a strong electromagnetic field is calculated. On the basis of the method for deriving exact solutions to relativistic wave equations for charged particles, an exact analytic expression is obtained for the partial W-decay width at an arbitrary value of the external field strength. It is found that, in the region of comparatively weak fields, field-induced corrections to the standard decay width of the W-boson in a vacuum are about a few percent. In these conditions at first we observe the decrease of the W-boson partial decay width with the increase of the external field strength parameter. At absolute minimum the W-width deviates from the corresponding vacuum value by a factor 0,926. Then with further augmentation of the background field intensity the W-boson decay width grows monotonously. In superstrong fields the partial W-width is greater than the corresponding one in vacuum in a dozen of times.Comment: LaTex file, 19 pages, 2 Postscript figur

Radiative Effects in the Standard Model Extension

The possibility of radiative effects induced by the Lorentz and CPT non-invariant interaction term for fermions in the Standard Model Extension is investigated. In particular, electron-positron photo-production and photon emission by electrons and positrons are studied. The rates of these processes are calculated in the Furry picture. It is demonstrated that the rates obtained in the framework of the model adopted strongly depend on the polarization states of the particles involved. As a result, ultra-relativistic particles produced should occupy states with a preferred spin orientation, i.e., photons have the sign of polarization opposite to the sign of the effective potential, while charged particle are preferably in the state with the helicity coinciding with the sign of the effective potential. This leads to evident spatial asymmetries which may have certain consequences observable at high energy accelerators, and in astrophysical and cosmological studies.Comment: 10 pages, 2 figures, Revtex4, to appear in Phys.Rev.D, misprints are correcte