Anomalous Magnetic Moment of W-boson at high temperature

By the Schwinger proper-time method, the one-loop contribution to the anomalous magnetic moment of the W-boson is calculated at high temperature. It is shown that the value of AMM is positive and depends linearly upon temperature

Once More on a Colour Ferromagnetic Vacuum State at Finite Temperature

The spontaneous vacuum magnetization at finite temperature is investigated in SU(2) gluodynamics within a consistent effective potential approach including the one-loop and the correlation correction contributions. To evaluate the latter ones the high temperature limits of the polarization operators of charged and neutral gluon fields in a covariantly constant magnetic field and at high temperature are calculated.The radiation mass squared of charged gluons is found to be positive. It is shown that the ferromagnetic vacuum state having a field strength of order $(gH)^{1/2} \sim g^{4/3} T$ is spontaneously generated at high temperature. The vacuum stability and some applications of the results obtained are discussed.Comment: 16 pages, 2 figures, subm. to Nucl. Phys.

Optimal Renormalization-Group Improvement of R(s) via the Method of Characteristics

We discuss the application of the method of characteristics to the renormalization-group equation for the perturbative QCD series within the electron-positron annihilation cross-section. We demonstrate how one such renormalization-group improvement of this series is equivalent to a closed-form summation of the first four towers of renormalization-group accessible logarithms to all orders of perturbation theory

The Renormalization Group and the Effective Action

The renormalization group is used to sum the leading-log (LL) contributions to the effective action for a large constant external gauge field in terms of the one-loop renormalization group (RG) function beta, the next-to-leading-log (NLL) contributions in terms of the two-loop RG function etc. The log independent pieces are not determined by the RG equation, but can be fixed by the anomaly in the trace of the energy-momentum tensor. Similar considerations can be applied to the effective potential V for a scalar field phi; here the log independent pieces are fixed by the condition V'(phi=v)=0

Vector boson in constant electromagnetic field

The propagator and complete sets of in- and out-solutions of wave equation, together with Bogoliubov coefficients, relating these solutions, are obtained for vector $W$-boson (with gyromagnetic ratio $g=2$) in a constant electromagnetic field. When only electric field is present the Bogoliubov coefficients are independent of boson polarization and are the same as for scalar boson. When both electric and magnetic fields are present and collinear, the Bogoliubov coefficients for states with boson spin perpendicular to the field are again the same as in scalar case. For $W^-$ spin along (against) the magnetic field the Bogoliubov coefficients and the contributions to the imaginary part of the Lagrange function in one loop approximation are obtained from corresponding expressions for scalar case by substitution $m^2\to m^2+2eH$ $(m^2\to m^2-2eH)$. For gyromagnetic ratio $g=2$ the vector boson interaction with constant electromagnetic field is described by the functions, which can be expected by comparing wave functions for scalar and Dirac particle in constant electromagnetic field.Comment: 20 pages, LATEX2e, no figure

Spacetime and vacuum as seen from Moscow

An extended text of the talk given at the conference ``2001: A Spacetime Odyssey'', to be published in the Proceedings of the Inaugural Conference of the Michigan Center for Theoretical Physics, University of Michigan, Ann Arbor, 21-25 May 2001, M.J. Duff and J.T. Liu eds., World Scientific, Singapore, 2002; and of Historical Lecture ``Vacuum as seen from Moscow'' at the CERN Summer School, 10 August, 2001. Contents: Introduction; Pomeranchuk on vacuum; Landau on parity, P, and combined parity, CP; Search and discovery of $K_L^0 \to \pi^+ \pi^-$; "Mirror world"; Zeldovich and cosmological term; QCD vacuum condensates; Sakharov and baryonic asymmetry of the universe, BAU; Kirzhnits and phase transitions; Vacuum domain walls; Monopoles, strings, instantons, and sphalerons; False vacuum; Inflation; Brane and Bulk; Acknowledgments; References.Comment: 17 pages, 2 figure

On vacuum-vacuum amplitude and Bogoliubov coefficients

Even if the electromagnetic field does not create pairs, virtual pairs lead to the appearance of a phase in vacuum-vacuum amplitude. This makes it necessary to distinguish the in- and out-solutions even when it is commonly assumed that there is only one complete set of solutions as, for example, in the case of a constant magnetic field. Then in- and out-solutions differ only by a phase factor which is in essence the Bogoliubov coefficient. The propagator in terms of in- and out-states takes the same form as the one for pair creating fields. The transition amplitude for an electron to go from an initial in-state to out-state is equal to unity (in diagonal representation). This is in agreement with Pauli principal: if in the field there is an electron with given (conserved) set of quantum numbers, virtual pair cannot appear in this state. So even the phase of transition amplitude remains unaffected by the field. We show how one may redefine the phases of Bogoliubov coefficients in order to express the vacuum-vacuum amplitude through them.Comment: 20pages, no figures, some typos corrected, minor improvement