On the measurement of quarkonium state in the process and

Abstract

We show that the intermediate quarkonium state χ c 2 ( P 2 3 ) ( 3556 ) in electron–positron annihilation to proton and antiproton as well as in antiproton–proton annihilation to electron and positron can give rise to backward–forward asymmetry. We apply the dispersion relation method, which allows us to express the asymmetry in terms of partial widths of quarkonium decay. The asymmetry dependence on the center of mass energy in the resonance region is presented. Quantitative comparison with similar effects induced in these reactions by QED effects and by the mechanism with neutral Z -boson in the intermediate state is given. We show that the asymmetry arising from the resonance excitation in the intermediate state is of the same order of the asymmetry of pure QED origin ( ∼ 10 − 2 ) which arises from the interference between initial and final state real photon emission.