Neutrino spin relaxation in medium with stochastic characteristics

The helicity evolution of a neutrino interacting with randomly moving and polarized matter is studied. We derive the equation for the averaged neutrino helicity. The type of the neutrino interaction with background fermions is not fixed. In the particular case of a tau-neutrino interacting with ultrarelativistic electron-positron plasma we obtain the expression for the neutrino helicity relaxation rate in the explicit form. We study the neutrino spin relaxation in the relativistic primordial plasma. Supposing that the conversion of left-handed neutrinos into right-handed ones is suppressed at the early stages of the Universe evolution we get the upper limit on the tau-neutrino mass.Comment: 6 pages, RevTeX4; 2 references added; more detailed discussion of correlation functions and cosmological neutrinos is presented; version to be published in Int. J. Mod. Phys.

Neutrino spin oscillations in gravitational fields

We study neutrino spin oscillations in gravitational fields. The quasi-classical approach is used to describe the neutrino spin evolution. First we examine the case of a weak gravitational field. We obtain the effective Hamiltonian for the description of neutrino spin oscillations. We also receive the neutrino transition probability when a particle propagates in the gravitational field of a rotating massive object. Then we apply the general technique to the description of neutrino spin oscillations in the Schwarzschild metric. The neutrino spin evolution equation for the case of the neutrino motion in the vicinity of a black hole is obtained. The effective Hamiltonian and the transition probability are also derived. We examine the neutrino oscillations process on different circular orbits and analyze the frequencies of spin transitions. The validity of the quasi-classical approach is also considered.Comment: RevTeX4, 9 pages, 1 esp figure; article was revised, some misprints were corrected, 6 references added; accepted for publication in Int.J.Mod.Phys.

Covariant Treatment of Neutrino Spin (Flavour) Conversion in Matter under the Influence of Electromagnetic Fields

Within the recently proposed Lorentz invariant formalism for description of neutrino spin evolution in presence of an arbitrary electromagnetic fields effects of matter motion and polarization are considered.Comment: Extended version of contribution to "Particle Physics on Boundary of Millenniums" (Proceedings of the 9th Lomonosov Conference on Elementary Particle Physics, World Scientific, Singapure

Pairing of charged particles in a quantum plasmoid

We study a quantum spherically symmetric object which is based on radial plasma oscillations. Such a plasmoid is supposed to exist in a dense plasma containing electrons, ions, and neutral particles. The method of creation and annihilation operators is applied to quantize the motion of charged particles in a self-consistent potential. We also study the effective interaction between oscillating particles owing to the exchange of a virtual acoustic wave, which is excited in the neutral component of plasma. It is shown that this interaction can be attractive and result in the formation of ion pairs. We discuss possible applications of this phenomenon in astrophysical and terrestrial plasmas.Comment: 17 pages, no figures, two columns, LaTeX2e; paper was significantly revised; title was changed; 16 new references were included; the discussion on ion-acoustic waves was added to Sec. 2; Secs. 3 and 4 were shortened; a more detailed discussion was added to Sec. 7; accepted for publication to J.Phys.

TUMOR-ASSOCIATED LOCALIZED SCLERODERMA IN CONJUNCTION WITH ACQIRED DISSIMINATED FORM OF VITILIGO: A CLINICAL CASE

We are presenting the clinical and laboratory case of management of 62 years old patient with combined dermatological tumor-associated diseases: localized form of scleroderma, acquired disseminated form of hypopigmentation (vitiligo). The patient initial visit in a medical dermatological facility was due to the emergence of a consistent following complaints such as the sudden appearance of alterated skin sites in the left breast and some later the occurrence of rushes on the skin on the chest area and on the anterior surface of the abdomen. Upon further examination of the patient have been verified malignant tumor of the left breast, therefore appropriate (complex) treatment have been conducted in a medical institution of oncology service. After 1.5 years after the sectoral mastectomy the patient appealed to the dermatologist again with a complaints to the renewed activity of scleroderma process on the skin of the left breast. On the background of activation of dermatological symptoms the patient have been diagnosed recurrent tumor in the left breast. This clinical case is a multipurpose: first of all, it is demonstrates the importance of the principle of oncological vigilance in multidisciplinary daily medical practice which would improve early diagnosis and, consequently, treatment of the underlying disease; secondly, the present clinical case suggests an unexpected paraneoplastic contour of the diseases which are unpopular in this category previously, but generally frequent in the population

Neutrino spin oscillations in gravitational fields

We study neutrino spin oscillations in black hole backgrounds. In the case of a charged black hole, the maximum frequency of oscillations is a monotonically increasing function of the charge. For a rotating black hole, the maximum frequency decreases with increasing the angular momentum. In both cases, the frequency of spin oscillations decreases as the distance from the black hole grows. As a phenomenological application of our results, we study simple bipolar neutrino system which is an interesting example of collective neutrino oscillations. We show that the precession frequency of the flavor pendulum as a function of the neutrino number density will be higher for a charged/non-rotating black hole compared with a neutral/rotating black hole respectively.Comment: Replaced with the version accepted for publication in Gravitation and Cosmology, Springer. 10 pages. 4 figure

Quantum treatment of neutrino in background matter

Motivated by the need of elaboration of the quantum theory of the spin light of neutrino in matter ($SL\nu$), we have studied in more detail the exact solutions of the Dirac equation for neutrinos moving in the background matter. These exact neutrino wavefunctions form a basis for a rather powerful method of investigation of different neutrino processes in matter, which is similar to the Furry representation of quantum electrodynamics in external fields. Within this method we also derive the corresponding Dirac equation for an electron moving in matter and consider the electromagnetic radiation ("spin light of electron in matter", $SLe$) that can be emitted by the electron in this case.Comment: 10 pages, in: Proceedings of QFEXT'05 (The Seventh Workshop on Quantum Field Theory under the Influence of External Conditions, IEEC, CSIC and University of Barcelona, Barcelona, Catalonia, Spain, 5-9 September 2005.), ed. by Emilio Elizalde and Sergei Odintsov; published in Journal of Physics

Coriolis force corrections to g-mode spectrum in 1D MHD model

The corrections to g-mode frequencies caused by the presence of a central magnetic field and rotation of the Sun are calculated. The calculations are carried out in the simple one dimensional magnetohydrodynamical model using the approximations which allow one to find the purely analytical spectra of magneto-gravity waves beyond the scope of the JWKB approximation and avoid in a small background magnetic field the appearance of the cusp resonance which locks a wave within the radiative zone. These analytic results are compared with the satellite observations of the g-mode frequency shifts which are of the order one per cent as given in the GOLF experiment at the SoHO board. The main contribution turns out to be the magnetic frequency shift in the strong magnetic field which obeys the used approximations. In particular, the fixed magnetic field strength 700 KG results in the mentioned value of the frequency shift for the g-mode of the radial order n=-10. The rotational shift due to the Coriolis force appears to be small and does not exceed a fracton of per cent, \alpha_\Omega < 0.003.Comment: RevTeX4, 9 pages, 4 eps figures; accepted for publication in Astronomy Reports (Astronomicheskii Zhurnal