Spin correlations in the $\tau$-lepton pair in polarized electron-positron annihilation

Abstract

Possible anomalous New Physics contributions to dipole and weak dipole moments of the $\tau$ lepton rise considerable interest in theoretical and experimental studies of the $\tau$-pair production in electron-positron annihilation and in proton-proton collisions at the LHC. In the present paper we discuss and calculate the spin-correlation matrix in the $e^{+}{e}^{-}\to {\tau }^{+}{\tau }^{-}$, and in general $f\bar{f}\to {\tau }^{+}{\tau }^{-}$ processes, including New Physics contributions to the $\gamma \tau \tau$ and $Z\tau \tau$ vertices and longitudinally polarized beams of initial fermions. The $\tau$ decays are included as well. This work is an upgrade of our previous studies of the spin correlations in the $\tau \tau$ system produced in the processes with unpolarized initial fermions ($e^{-}{e}^{+}$ and $q\bar{q}$). A corresponding numerical code is developed. Brief information on how to use and configure the MC programs with a new subroutine is also given.

arXiv comment11 pages