Planning an Experiment to Determine the Weinberg Running Angle for the J/ψ Meson Energy at the Charm-Tau Factory

The Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences (BINP SB RAS), plans to create the Super Charm-Tau Factory (SCTF) accelerator complex, it will operate in a wide energy range of 2E = 2–5 GeV in c.m. and have design luminosity of L = 1 × 10³⁵ cm^–2 s^–1. As part of the physical program, it is proposed to carry out the experiment by measuring the Weinberg running weak mixing angle for the J/ψ meson energy. Due to the smallness of the predicted effect, it is necessary to exclude the influence of systematic errors from unpredictable changes in the magnet lattice and the beam background. To do this, we have to organize frequent changes in sign of the longitudinal polarization of the electron beam at the interaction point. In this paper we have investigated the possibility of the spin-flip using the spin RF-rotator in a colliding electron ring with three Siberian snakes. Based on the simulation results, conclusions about the possibility of using this approach are made.