The Glashow resonance in neutrino-photon scattering

Reactions ${\nu_l}\gamma\rightarrow W^+l^-\,(l=e,\mu,\tau)$ near the threshold $\sqrt{s}=m_W+m_l$ are analyzed. Two independent calculations of the corresponding cross sections (straightforward calculations using the Standard Electroweak Lagrangian and calculations in the framework of the parton model) are compared. It is shown that the Standard Electroweak Theory strongly suggests that these reactions proceed via the Glashow resonances. Accordingly, a hypothesis that the on-shell $W$ bosons in the reactions ${\nu_l}\gamma\rightarrow$$W^+l^-$ are the Glashow resonances is put forward. A role of these reactions for testing T symmetry at the IceCube Neutrino Observatory is discussed. A model with T-violating Glashow resonances for description of the distribution of the TeV-PeV neutrino events recently observed by the IceCube Collaboration is presented.