A.D. Dolgov

REAL AND VIRTUAL PHOTONS IN WEAK LEPTONIC PROCESSES AT HIGH ENERGIES.

Abstract Weak-electromagnetic processes in colliding ee(eμ, μμ) beams at high energy are discussed (E ≈ 2 × 200 GeV). Radiative and higher order weak corrections to the amplitude of reaction e + e − → ν ν γ are considered. The interference between weak and electromagnetic amplitudes of e + e − scattering and e + e − → μ + μ − annihilation is calculated. The formulae obtained are applicable also to the muon induced reactions. The logarithmic terms in radiative corrections to cross sections of the above processes are calculated. The corrections to the weak amplitudes due to the hadron contribution are discussed.

Infrared effects in a de Sitter background.

We have estimated higher order quantum gravity corrections to de Sitter spacetime. Our results suggest that, while the classical spacetime metric may be distorted by the graviton self-interactions, the corrections are relatively weaker than previously thought, possibly growing like a power rather than exponentially in time.

Weak interactions of colliding lepton beams with energy 102–103 GeV

Weak V-A interaction of colliding lepton beams at high energies is considered. It is assumed that the weak coupling constant G is the only parameter inherent to the weak leptonic interaction so that terms of higher order become appreciable at total energy 2E = s12 of order G−12. n nIt is shown that for colliding lepton-antilepton beams 2 × 250 GeV, the contribution of weak interactions to the differential cross section of elastic scattering at angle θ ⋍ 90° prevails over that of electromagnetic interaction. The estimate of the weak cross section is based on the calculation of the imaginary part of the amplitude which is uniquely determined in the second order in G. Phenomenological description of the real part of the amplitude in the same approximation introduces a single unknown parameter. Provided the validity of dispersion relations with two subtractions is granted this parameter is related to the integral of total cross sections of ll and ll weak interactions. n nTerms of the third order in G are studied in a similar way and an estimation of the magnitude of these terms is given.

Neutrino exchange and asymptotic behaviour of weak interaction cross sections

Abstract It is argued that total cross sections cannot increase asymptotically as a power of energy even in the presence of massless particle exchange. Elastic νν scattering is considered as an example. The properties of s- and t-channel partial waves are analysed and it is shown that the above statement is true if the amplitude is bounded by a polynomial in s for s→∞ and t>0 and if its singularity at t=0 is dominated by two-particle exchange.

Shrinkage singularities of amplitudes and weak interaction cross-section asymptotics

The energy spectrum of the quasiparticles of a one-dimensional chain of half-integral spins with a simple form of interaction, situated in an inhomogeneous magnetic field, is calculated in second-order perturbation theory. It is shown that the mixing of the levels is proportional to the squares of the perturbing inhomogeneities of the field. It is shown that, for a sufficiently large mean value of the magnetic field, the shift of the levels relative to their unperturbed values is symmetric. For small mean values of the magnetic field the higher levels are shown to shift to a greater degree than those situated closer to the ground state.The energy spectrum of the quasiparticles of a one-dimensional chain of half-integral spins with a simple form of interaction, situated in an inhomogeneous magnetic field, is calculated in second-order perturbation theory. It is shown that the mixing of the levels is proportional to the squares of the perturbing inhomogeneities of the field. It is shown that, for a sufficiently large mean value of the magnetic field, the shift of the levels relative to their unperturbed values is symmetric. For small mean values of the magnetic field the higher levels are shown to shift to a greater degree than those situated closer to the ground state.

On quark molecules

Abstract The nonrelativistic quark model with three triplets and an octet of coloured gluons is examined. The interaction energy corresponding to certain quark molecules is calculated. It is shown that systems of qq qq and qqqq q are more strongly bound than q q and qqq. Thus in order for the model to be valid there must exist exotic particles.

Massive and supermassive black holes in the contemporary and early Universe and problems in cosmology and astrophysics

This is the translation into English of the introduction, conclusion, and the list of references of the review on massive primordial black holes, which is submitted in Russian to Uspekhi Fizicheskikh Nauk (Physics-Uspekhi). If accepted, this review is translated into English by the Journal and published in Russian and a little later in English. nThe review concerns the recent astronomical data which show that massive primordial black holes play much more significant role in the universe than it was previously believed. This is true both for the the contemporary and the early universe at the red-shifts about 10. The mechanism, proposed in 1993, of primordial creation of heavy and superheavy black holes in the very early universe is discussed. This mechanism predicts the log-normal mass spectrum of the primordial black holes, which became very popular during the last couple of years. The proposed mechanism presents a natural explanation of a large amount of the recent observational data, which do not fit the standard cosmology and astrophysics.