The electric charge of neutrinos and plasmon decay

Abstract

By using both thermal field theory and a somewhat more intuitive method, we define the electric charge as well as the charge radius of neutrinos propagating inside a plasma. We show that electron neutrinos acquire a charge radius of order ∼ 6.5 × 10 −16 cm, regardless of the properties of the medium. Then, we compute the rate of plasmon decay which such an electric charge or a charge radius implies. Taking into account the relativistic effects of the degenerate electron gas, we compare our results to various approximations as well as to recent calculations and determine the regimes where the electric charge or the charge radius does mediate the decay of plasmons. Finally, we discuss the stellar limits on any anomalous charge radius of neutrinos.

Cherenkov radiation of longitudinal photons by neutrinos

“…This effective vertex is due to the W and Z in the loops in the Feynman diagram [3,8]. The vertex tensor is gauge invariant quantity, as k µ Γ αµ = 0 [3,8]. The effective vertex tensor is [8] …”

“…that neutrino acquires an effective charge in the medium by coupling to the electromagnetic field through electrons and positrons in the plasma [2,3].…”

“…This takes place: firstly because neutrinos acquire an effective charge in the medium, by coupling to the electromagnetic field through electrons and positrons in the plasma [2,3,7], which is shown in the Feynman diagrams in figure 1. Secondly there is a range of frequencies of plasmon for which the refractive index n > 1, and the Cerenkov process is kinematically allowed.…”

“…For Cerenkov radiation to take place in the medium, the refractive index of photon should satisfy the condition n = |k|/w > 1, where k and ω are momentum and frequency of the emitted photon respectively. Recently several authors have considered the Cerenkov radiation emitted by neutrinos as they pass through a medium [2,3,4,5,6]. Olivo, Nieves and Pal have recently shown that, neutrino can emit Cerenkov radiation even in the massless limit and having no electromagnetic dipole moments [2].…”

Neutrino propagation in a weakly magnetized medium

“…[10]. And, it has also been shown that the ν − γ interaction in presence of a thermal medium induces a small effective charge to the neutrino and that the neutrino electro-magnetic vertex is related to the photon self-energy in the medium [11,12]. Recently, this effective charge has been calculated, considering not only a thermal medium but also an external magnetic field, for neutrinos coupled to dynamical photons having q 0 = 0 and | q| → 0 [13].…”