Photon - Neutrino interaction Suppose we have a laser source, that means a coherent laser beam formed by 'in phase' photons. Is it possible to calculate how many photons can change their wavelength in neutrino - photon interaction if any? If there is no such wavelength change, can some photon loose the phase coherence in the interaction with neutrino? Obviously I suppose there could be a difference between muonic, eletronic and tau neutrino but how take into account this? Thanks
 A: 
Is it possible to calculate how many photons can change their wavelength

Photons do not have wavelength , just energy = to h*nu, where nu is the frequency of the classical electromagnetic light, the laser light. Photons  can scatter off various particles and if the scattering is inelastic, a new photon goes off.

in neutrino - photon interaction if any?

Neutrinos can couple to electromagnetic fields only in higher orders in perturbation theory, and the coupling constants are so small that any scatter will be unmeasurable.

If there is no such wavelength change, can some photon loose the phase coherence in the interaction with neutrino?

The phase coherence can only exist with the laser light, as individual photons just scatter, it would be  the emergent beam that could display a classical phase difference, as laser light on a medium does. As explained above neutrinos are not real targets to laser light.

Obviously I suppose there could be a difference between muonic, eletronic and tau neutrino but how take into account this

See above.
