Can one measure C-odd asymmetry in e+e- --> pi+pi-

Jacques Layssac (1) , Stéphan Narison (1)

1 LPTA - Laboratoire de Physique Théorique et Astroparticules

C-odd asymmetry can be studied from an accurate measurement of the angulardistribution due to the interference between the S- and P-waves in e+e- --> pi+pi- at order alpha^3. The asymmetry is dominated by the pion rescatteringdiagram which is enhanced by the presence of the ln(s/m^2_e), and is quitelarge (10% at theta=30^0 and sqrt{s} < M_{f_2}) compared to alpha/pi=0.3%. Thisprocess can also be used for alternatively measuring the size of therescattering term and the phase of the S-wave amplitude, but does not help tosolve the present discrepancy between the hadronic spectral functions from e+e-and tau-decay data.

Domaines: Physique des Hautes Energies - Phénoménologie [hep-ph]; Physique des Hautes Energies - Expérience [hep-ex]

Jacques Layssac, Stéphan Narison. Can one measure C-odd asymmetry in e+e- --> pi+pi-. Nuclear Physics B, 2009, 186, pp.203-206. ⟨10.1016/j.nuclphysbps.2008.12.047⟩. ⟨hal-00377714⟩