Efficiency of electron-positron pair production by neutrino flux from accretion disk of a Kerr black hole

Dominant processes of neutrino production and neutrino-induced $e^+e^-$-pair production are examined in the model of a disk hyperaccreting onto a Kerr black hole. The efficiency of plasma production is analytically estimated for both the presence and the absence of a strong magnetic field. It is shown that the efficiency of plasma production by a neutrino flux from the disk in this model is no more than several tenths of percent and, therefore, cannot account for the origin of cosmological gamma-ray bursts.