Neutrinos and electrons in background matter

We present a rather powerful method in investigations of different phenomena that can appear when neutrinos and electrons propagate in background matter. This method is based on the use of the modified Dirac equations for particles wave functions, in which the correspondent effective potentials accounting for the matter influence on particles are included.Comment: submitted to J.Phys.: Conference Series (Proceedings of Neutrino 2006 Conference, June 2006, Santa Fe, New Mexico

New bounds on neutrino electric millicharge from limits on neutrino magnetic moment

Using the new limit on the neutrino anomalous magnetic moment recently obtained by the GEMMA experiment on measurements of the cross section for the reactor antineutrino scattering on free electrons, we get a new direct upper bound on the neutrino millicharge $\mid q_{\nu} \mid < 1.5 \times 10^{-12} e_0$. This is a factor of 2 more stringent constraint than the previous bound obtained from the TEXONO reactor experiment data that is included to the Review of Particle Properties 2012. We predict that with data from the ongoing new phase of the GEMMA experiment the upper bound on the neutrino millicharge will be reduced to $\mid q_{\nu} \mid < 3.7 \times 10^{-13}e_0$ within two years. We also predict that with the next phase of the considered experiment the upper bound on the millicharge will be reduced by an order of magnitude over the present bound and reach the level $\mid q_{\nu} \mid < 1.8 \times 10^{-13}e_0$ within approximately four years.Comment: 8 pages in LaTex, the approach for accounting the neutrino millicharge contribution to the cross section has been corrected. v3: new references including a reference to Review on Particle Physics by Particle Data Group are added, new more stringent limit on millicharge is predicted for the future release of the GEMMA collaboration result

Neutrino energy quantization in rotating medium

Exact solution of the modified Dirac equation in rotating medium is found in polar coordinates in the limit of vanishing neutrino mass. The solution for the active left-handed particle exhibit properties similar to those peculiar for the charged particle moving in the presence of a constant magnetic field. Accordingly, the particle in the rotating matter has circle orbits with energy levels, analogous to the Landau levels in magnetic field. The relevant physical realization of the problem is motion of neutrino inside the rotating neutron star. The feature of such motion to form binding states leads to the prediction of the new mechanism for neutrino trapping. The solution found can be used for detailed description of relativistic and nearly massless neutrino dynamics in neutron stars. Results obtained further develop the "method of exact solutions" in application to particle interactions in presence of dense matter.Comment: 5 pages, in: "Particle Physics on the Eve of LHC" (Proc. of the 13th Lomonosov Conference on Elementary Particle Physics, Moscow, August 2007), ed. by A.Studenikin, p.176, World Scientific, Singapore, 200