646 research outputs found
Neutrino self-energy in a magnetized medium in arbitrary -gauge
We calculate the one-loop neutrino self-energy in a magnetized plasma to all
orders in the magnetic field. The calculation is done in a general gauge. We
obtain the dispersion relation and effective potential for neutrinos in a
CP-symmetric plasma under various conditions, and show that, while the
self-energy depends on the gauge parameter , the dispersion relation and
effective potential to leading order are independent of it.Comment: 13 pages, RevTeX, epsfig, axodra
Thermal effects on the absorption of ultra-high energy neutrinos by the cosmic neutrino background
We use the formalism of finite-temperature field theory to study the
interactions of ultra-high energy (UHE) cosmic neutrinos with the background of
relic neutrinos and to derive general expressions for the UHE neutrino
transmission probability. This approach allows us to take into account the
thermal effects introduced by the momentum distribution of the relic neutrinos.
We compare our results with the approximate expressions existing in the
literature and discuss the influence of thermal effects on the absorption dips
in the context of favoured neutrino mass schemes, as well as in the case of
clustered relic neutrinos.Comment: 3 pages, 2 figures. Prepared for the Proceedings of the 9th
International Conference on Topics in Astroparticle and Underground Physics
(TAUP 2005), Zaragoza (Spain), September 10-14, 200
UHE neutrino damping in a thermal gas of relic neutrinos
We present a calculation of the damping of an ultra-energetic (UHE) cosmic
neutrino travelling through the thermal gas of relic neutrinos, using the
formalism of finite-temperature field theory. From the self-energy diagram due
to Z exchange, we obtain the annihilation cross section for an UHE neutrino
interacting with an antineutrino from the background. This method allows us to
derive the full expressions for the UHE neutrino transmission probability,
taking into account the momentum of relic neutrinos. We compare our results
with the approximations in use in the literature. We discuss the effect of
thermal motion on the shape of the absorption dips for different UHE neutrino
fluxes as well as in the context of relic neutrino clustering. We find that for
ratios of the neutrino mass to the relic background temperature or
smaller, the thermal broadening of the absorption lines could significantly
affect the determination of the neutrino mass and of the characteristics of the
population of UHE sources.Comment: 18 pages, 6 figures. Typos corrected. More accurate treatment of the
interaction with relic neutrino clusters. Accepted for publication in
Astroparticle Physic
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