Neutrino dispersion properties in an external magnetic field
- PDF / 667,111 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 43 Downloads / 265 Views
EMENTARY PARTICLES AND FIELDS Theory
Neutrino Dispersion Properties in an External Magnetic Field А. V. Kuznetsov* and N. V. Mikheev** Yaroslavl State University, Sovetskaya ul. 14, Yaroslavl, 150000 Russia Received April 13, 2006; in final form, August 18, 2006
Abstract—The neutrino self-energy operator Σ(p) in a magnetic field is calculated for the case of highenergy neutrinos, this corresponding to the crossed field approximation. The probability of the neutrino decay ν → e− W + is found by using the imaginary part of the operator Σ(p). A simple analytic result is obtained in the parameter region that is the most interesting from the physical point of view and which was not considered earlier. The contribution of an external magnetic field to the neutrino magnetic moment is calculated. The result obtained here for this contribution corrects formulas available previously. PACS numbers: 13.15.+g, 14.60.Lm DOI: 10.1134/S1063778807070186
1. INTRODUCTION The solution to the solar-neutrino puzzle in a unique experiment at the heavy-water detector installed at the Sudbury Neutrino Observatory (Canada) [1] has undoubtedly been the most important achievement of neutrino physics within the last decades. This experiment confirmed B. Pontecorvo’s key idea concerning neutrino oscillations [2] and, along with experiments that studied atmospheric [3] and reactor [4] neutrinos, thereby proved the existence of a nonzero neutrino rest mass and the existence of mixing in the lepton sector. In this connection, the problem of studying the possible effect of an active environment, including a strong magnetic field, on the dispersion properties of the neutrinos and, in particular, on the mechanism of neutrino oscillations becomes quite pressing [5]. An analysis of the effect of an external medium on neutrino oscillations relies on calculating the neutrino self-energy operator Σ(p), from which one can extract, among other things, the dispersion relation and then the energy difference between the neutrinos of two different flavors. The magnetized-plasma contribution to the operator Σ(p) was calculated in a number of studies (see, for example, [6–8]). In doing this, the purely field contribution to the neutrino self-energy was not considered in those studies, since their authors thought it to be insignificant. This contribution was recently calculated in [9, 10], where it is, on the contrary, stated that this is precisely the contribution that is dominant. In view of this discrepancy, it is highly * **
E-mail: [email protected] E-mail: [email protected]
desirable to calculate independently the magneticfield contribution to the neutrino self-energy. It should be noted that the behavior of the neutrino self-energy operator in a magnetic field has been investigated for more than two decades [11–13]. A comparison shows that the result obtained in [9, 10] contradicts the calculations reported in [11–13] and involves the enormous enhancement factor m2W /eB. If the result reported in [9, 10] were correct, it would have implications of crucial importan
Data Loading...
