Neutrino, photon interaction in unparticle physics

We investigate the impact of unparticle physics on the annihilation of relic neutrinos with the neutrinos identified as primary source of ultra high energy (UHE) cosmic ray events, producing a cascade of photons and charged particles. We compute the contribution of the unparticle exchange to the cross-sections νν¯→γγ and νν¯→ff¯ scattering. We estimate the neutrino–photon decoupling temperature from the reaction rate of νν¯→γγ. We find that the inclusion of unparticles can in fact account for the flux of UHE cosmic rays and can also result in the lowering of neutrino–photon decoupling temperature below the QCD phase transition for unparticle physics parameters in a certain range. We calculate the mean free path of these high energy neutrinos annihilating themselves with the relic neutrinos to produce vector, axial-vector and tensor unparticles.