On the forward-backward charge asymmetry in e+e- -annihilation into hadrons at high energies

Abstract

The forward-backward asymmetry in e+ e- annihilation into a quark-antiquark pair is considered in the double-logarithmic approximation at energies much higher than the masses of the weak bosons. It is shown that after accounting to all orders for the exchange of virtual photons and W, Z -bosons one is lead to the following effect (asymmetry): quarks with positive electric charge (e.g. u, \bar{d}) tend to move in the e+ - direction whereas quarks with negative charges (e.g. d, \bar{u}) tend to move in the e- - direction. The value of the asymmetry grows with increasing energy when the produced quarks are within a cone with opening angle, in the cmf, θ_0\sim 2M_Z/\sqrt{s} around the e+e- -beam. Outside this cone, at θ_0 << θ<< 1, the asymmetry is inversely proportional to θ.