Related papers: Taming the pinch singularities in the two-loop neu…
We consider the propagation of a neutrino or an antineutrino in a medium composed of fermions $f$ and scalars $\phi$ interacting via a Yukawa-type coupling of the form $\bar f\nu\phi$, for neutrino energies at which the processes like $\nu…
We consider the propagation of a neutrino in a background composed of a scalar particle and a fermion using a simple model for the coupling of the form $\lambda\bar f_R\nu_L\phi$. In the presence of these interactions there can be damping…
We consider the decoherence effects in the propagation of neutrinos in a background composed of a scalar particle and a fermion due to the non-forward neutrino scattering processes. Using a simple model for the coupling of the form $\bar…
A first principle derivation is given of the neutrino damping rate in real-time thermal field theory. Starting from the discontinuity of the neutrino self energy at the two loop level, the damping rate can be expressed as integrals over…
We analyze ill-defined pinch singularities characteristic of out of equilibrium thermal field theories. We identify two mechanisms that eliminate pinching even at the single self-energy insertion approximation to the propagator: the first…
We calculate the one-loop thermal self-energy of a neutrino in a constant and homogeneous magnetic field to all orders in the magnetic field strength using Schwinger's proper time method. We obtain the dispersion relation under various…
We consider the neutrino self-energy in a background composed of a scalar particle and a fermion using a simple model for the coupling of the form $\lambda\bar f_R\nu_L\phi$. The results are useful in the context of Dark Matter-neutrino…
We use the method of finite temperature field theory to examine the propagation of mixed neutrinos through dense media, putting the emphasis in those situations in which the neutrinos themselves are in the background. The evolution equation…
Using the exact propagators in a constant magnetic field, the neutrino self-energy has been calculated to all orders in the field strength B within the minimal extension of the Weinberg-Salam model with massive Dirac neutrinos. A simple and…
We consider the decoherence effects in the propagation of active neutrinos due to the non-forward neutrino scattering processes in a matter background composed of electrons and nucleons. We calculate the contribution to the imaginary part…
We study the propagation of a neutrino in a medium that consists of two or more thermal backgrounds of electrons and nucleons moving with some relative velocity, in the presence of a static and homogeneous electromagnetic field. We…
Using the Schwinger proper time method I calculate exactly the bubble diagram contribution to the thermal neutrino self-energy, obtaining exact results that cannot be achieved using the contact approximation. These results allow me to…
In general the zero momentum limit of thermal self-energies calculated in perturbation theory depends on the order in which the time and the space components of the momentum are taken to zero. We show that this is an artifact of the…
Long standing problem in out-of-equilibrium thermal field theories are pinching singularities. We find that the expressions suspect of pinching require loop particles to be on the mass shell. This fact, with the help of threshold effect and…
The process of neutrino propagation through an active medium consisting of magnetic field and plasma is analysed. We consider in detail the contribution of a magnetic field B into the neutrino self-energy operator Sigma (p). The results for…
We compute the dispersion curves for neutrinos propagating in an extremely dense electroweak plasma, in the presence of very strong magnetic fields of order $B \le M_W^2/e$. The neutrino self-energy is calculated in the one-loop…
We consider a system of interacting fermions in two dimensions beyond the second-order perturbation theory in the interaction. It is shown that the mass-shell singularities in the self-energy, arising already at the second order of the…
In this work we calculate the neutrino self-energy in presence of a magnetized medium. The magnetized medium consists of electrons, positrons, neutrinos and a uniform classical magnetic field. The calculation is done assuming the background…
One and two loop self-energies are worked out explicitly for a heavy scalar field interacting weakly with a light self-interacting scalar field at finite temperature. The ring/daisy diagrams and a set of necklace diagrams can be summed…
In this work we calculate the most general left-handed neutrino thermal self-energy at one-loop order in perturbation theory using the Mellin summation technique. We perform this calculation in the real-time formalism of quantum field…