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Behavior of the neutrino magnetic form factor in a renormalizable model

par Frère, Jean-Marie ;Nevzorov, Roman;Novikov, V.A.;Vysotsky, Mikhail
Référence Physics of atomic nuclei, 60, 10, page (1662-1665)
Publication Publié, 1997-10

Article révisé par les pairs

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Résumé :

We have recently shown that the neutrino magnetic form factor μv(q2) could be considerably enhanced at low momentum transfers (q2 ≤ m2N) by introducing an extra light neutral fermion N with mass mN and nonzero magnetic moment. It was assumed that the magnetic moment of N would originate in a renormalizable way at a heavy scale M. While the enhancement of the neutrino magnetic moment was unambiguous, we stressed that, in this effective-Lagrangian approach, there is an ambiguity in the behavior μv(q2) in the interval m2N ≪ q2 ≪ M2. This is not unexpected in the presence of an unrenormalizable effective theory (a particle with a bare magnetic moment). In a simple renormalizable model for the magnetic moment of particle N, we show how a two-loop calculation solves the ambiguity. In the domain m2N ≪ q2 ≪ M2, we confirm our previous result obtained by using a sharp cutoff. As might have been expected, correct results are deduced through dimensional regularization in the full theory but not in the effective-Lagrangian approach.