T-odd effects in photon-jet production at the Tevatron

Understand

The angular distribution in photon-jet production in p \bar{p} -> \gamma jet X is studied within a generalized factorization scheme taking into account the transverse momentum of the partons in the initial hadrons.

• Within this scheme an anomalously large cos(2\phi) asymmetry observed in the Drell-Yan process could be attributed to the T-odd, spin and transverse momentum dependent parton distribution function h_1^{\perp q}(x, p_{\perp}^2).
• This same function is expected to produce a cos(2\phi) asymmetry in the photon-jet production cross section.
• We give the expression for this particular azimuthal asymmetry, which is estimated to be smaller than the Drell-Yan asymmetry but still of considerable size for Tevatron kinematics.