Possible manifestations of the existence of a fourth-generation neutrino

A fourth generation of fermions predicted by the phenomenological heterotic string models can possess a new, strictly conserved charge. Among other things, this leads to the hypothesis of the existence of a fourth massive stable neutrino. A comparison of this hypothesis with the data obtained in the DAMA underground experiment to search for massive weakly-interacting cosmic particles with hidden mass and with the EGRET measurements of the >1 GeV galactic gamma-ray background gives a value m≈50 GeV for the possible mass of the fourth neutrino. It is shown that the hypothesis can be checked in accelerator experiments. The positron signal from annihilation of massive relic neutrinos in the galaxy is calculated. A search for this signal is is within the reach of planned cosmic-ray investigations. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 6, 402–406 (25 March 1999)     

Possible observational manifestations of wormholes in the Brans-Dicke theory

The energy flux emitted during the accretion of matter onto a wormhole in the Brans-Dicke theory has been calculated. This characteristic is compared with its values calculated previously for wormholes in general relativity and for a Schwarzschild black hole.     

Possible manifestations of quantum effects in the boron microindentation kinetics

The kinetics of indentation of a solid (viz., the dependence of the indenter intrusion depth on the time, force, and temperature), is analyzed theoretically taking into account quantum effects in the atomic dynamics of solids. The experimental study of the temperature dependence of the boron microhardness reveals qualitative and quantitative agreement with calculated dependences. A possible manifestation of quantum (tunnel) effects in the boron microindentation kinetics is predicted.     

Neutron interferometry in gravitational field with torsion

We consider the possibility of finding experimental evidence of the fifth force with the measurement of a phase shift of neutron beams via an interferometric apparatus and also a possible rotation of the polarization plane of polarized neutron beams when torsion is introduced in a gravitational field.     

Motion of test particles in a torsion field

The solution of the Mathisson-Papapetrou equations generalized to the case of the Einstein-Cartan theory, when they describe the motion of a test particle in an external torsion field, is considered. It is shown that a particle of nonzero rest mass moves inertially in a constant polarized torsion field, but its spin precesses around the direction of polarization of the spin of the torsion source. It is also found that the motion of a massless particle in a variable torsion field leads to a torsion frequency displacement effect of a photon under the assumption that the photon spin interacts with the torsion.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 84–87, August, 1980.     

Possible field dependence of Landau level-broadening

The broadening of the Landau levels in a pure metal (which leads to a Dingle temperature in the de Haas-van Alphen effect) is probably mainly due to small angle scattering of electrons by extended defects. Simple intuitive arguments suggest that the broadening (and therefore the effective Dingle temperature) should become smaller as the magnetic field is increased into the region of the quantum limit (i.e. low quantum numbers). Some experimental evidence supporting this suggestion can be found in published studies of giant quantum oscillations in ultrasonic attenuation, and further evidence will be presented based on recent experiments on the de Haas-van Alphen effect in bismuth.     

A generalized lovelock theorem for the gravitational field with torsion

The U₄ field equations are uniquely determined up to three parameters if they are assumed to be polynomial in metric, torsion and their derivatives, respectively, and free of new fundamental constants. The parameters can be fixed by means of the equivalence principle.     

Topological invariants and the dynamics of an axial vector torsion field

A generalized theory of gravitation is discussed which is based on a Riemann-Cartan space-time,U ₄, with an axial vector torsion field. Besides Einstein's equations determining the metric of theU ₄, a system of nonlinear field equations is established coupling an axial vector source current to the axial vector torsion field. The properties of the solutions of these equations are discussed assuming a London-type condition relating the axial current and torsion field. To characterize the solutions use is made of the Euler and Pontrjagin forms and the associated quadratic curvature invariants for theU ₄ space-time. It is found that there exists for a Riemann-Cartan space-time a relation between the zeros of the axial vector torsion field and the singularities of the Pontrjagin invariant, which is analogous to the well-known Hopf relation between the zeros of vector fields and the Euler characteristic.     

Possible laser modification of field ion microscopy

A modification of field ion microscope, based on radical reduction of intensity of electric field essential for field-ionization of imaging gas atoms, is suggested. For this purpose the imaging gas atoms are excited by a laser radiation to quantum states nearby the ionization limit. As excited atoms approach the point the field ionization must occur in rather weak fields (～10⁷ V/cm) which eliminate electric field induced effects of molecular evaporation and decomposition.     

On the cosmological equations in the presence of a spatially homogeneous torsion field

It is shown that Einstein's equations obtained from the Friedmann Ansatz for the metric and an arbitrary cosmological term can be consistently extended on include a spatiall]y homogeneous contorsion field K_abc = ϵ _abc K(t), K(t) = η/R(t); η an arbitrary constant. This mechanism which guarantees covariant conservation of the Einstein tensor, amounts to replacing the arbitrary constant. This mechanism which guarantees covariant conservation of the Einstein tensor, amounts to replacing the signature parameter ϵ = ( +1: spherical space, 0: flat space, −1: hyperbolic space) by ϵ₁ = ϵ − η².     

Free vector field in a homogeneous space with torsion

The effect of torsion of space-time, induced by the spin of a vector field, upon the physical properties of the field is studied within the framework of Einstein-Cartan gravitational theory. It is shown that the torsion leads to the appearance of nonlinearities in the vector field, as a consequence of which soliton solutions are possible under certain conditions. A cosmological model without singularities is constructed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 26–29, September, 1979.     

Relativistic spinning particle in a gravitational field with torsion

A model of a relativistic spinning particle in a gravitational field with a flat metric and a constant torsion is analyzed within the framework of classical mechanics. The Lagrange equations allow an exact integration.Tomsk State Pedagogical Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 50–54, November, 1993.     

Generalized causality condition in quantum field theory with torsion

The Schwinger-De Witt method of local expansion of the effective action is applied to a model vector field theory which satisfies a generalized causality condition. One loop divergences are computed. It is shown that the theory is non-renormalizable. The effective potential of the theory has a local minimum with a nonzero average value of the vector field, stable with respect to small slowly varying perturbations.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 74–78, May, 1989.     

Possible neutrino capture in an electromagnetic field

The stationary states of a neutrino, considered a neutron with a vanishingly small mass, in the combined fields of a longitudinal and of a linearly polarized plane wave, and in the field of a circularly polarized wave, are obtained and analyzed. The effective mass of the neutrino is calculated.Tomsk Polytechnic University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 16–20, September, 1993.     

On possible light–torsion mixing in background magnetic field

The interaction of the light with propagating axial torsion fields in the presence of an external magnetic field has been investigated. Axial torsion fields appearing in higher derivative quantum gravity possess two states, with spin one and zero, with different masses. The torsion field with spin-0 state is a ghost that can be removed if its mass is infinite. We investigate the possibility when the light mixes with the torsion fields resulting in the effect of vacuum birefringence and dichroism. The expressions for ellipticity and the rotation of light polarization axis depending on the coupling constant and the external magnetic field have been obtained.     

On unified field theories,dynamical torsion and geometrical models

A new model of a nondualistic unified theory is proposed. This model is absolutely consistent from the mathematical and geometrical points of view and is based on a manifold equipped with an underlying hypercomplex structure and zero nonmetricity. Also we showed that interesting wormhole solutions, similar to the non-Abelian Born-Infeld theory of our previous work [14] can be obtained. The solution of this model is explicitly compared with our previous one and we find that the torsion plays in this unified theory a role similar to that of Yang-Mills type strength field coming from the non-Abelian Born-Infeld energy momentum tensor. The meaning of the Hosoya-Ogura ansatz (namely, the alignment of the isospin with the frame geometry of the space-time) is completely elucidated.