No abstract

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.

The preliminary LEP data on the e + e − → l + l − scattering are analysed to establish a model-independent search for the signals of virtual states of the Abelian Z ′ boson. The recently introduced observables give a possibility to pick up uniquely the Abelian Z ′ signals in these processes. The mean values of the observables are in accordance with the Z ′ existence. However, the accuracy of the experimental data is deficient to detect the signal at more than the 1σ confidence level. The results of other model-independent fits and further prospects are discussed.

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.

Basic uniform pseudo-random number generators are implemented on ATI Graphics Processing Units (GPU). The performance results of the realized generators (multiplicative linear congruential (GGL), XOR-shift (XOR128), RANECU, RANMAR, RANLUX and Mersenne Twister (MT19937)) on CPU and GPU are discussed. The obtained speed-up factor is hundreds of times in comparison with CPU. RANLUX generator is found to be the most appropriate for using on GPU in Monte Carlo simulations. The brief review of the pseudorandom number generators used in modern software packages for Monte Carlo simulations in high-energy physics is present.