The Drell-Yan Process
The helicity distribution of antiquark in nucleon
can be obtained by the polarized Drell-Yan Processes.
The following figure shows the schematic diagram of the
Drell-Yan process.
In a parton-model, the cross section for the Drell-Yan processes is given by
the following equation.
The asymmetry for the longitudinal spin polarization is given by the
following euqation,
, where 
Therefore, the measurement of the longitudinal spin asymmetry of the
Drell-Yan process will
provide information about the helicity distributions of quarks and
antiquarks in nucleon.
References
- S. Drell and T.M.Yan, Phys. Rev. Lett. 25 316 (1970).
- F.E. Close et al., Phys. Rev. Lett. 39 1116 (1977)
- G. Moreno et al., Phys. Rev. D43 2815 (1991).
- P.L.McGaughy et al., Phys. Rev. D50 3038 (1994).
- The PHENIX/Spin Collaboration, "Spin Structure Function Physics
with an Upgraded PHENIX Muon Spectrometer, 1994 (unpublished).
c.f. Deep Inelastic Scattering
The helicity distribution of charged partons (quarks and antiquarks
as a whole) in nucleon can be obtained from
the Polarized Deep Inelastic Scattering of leptons.
Return to the PHNEX/Spin
collaboration page
11 January 1995 T.Ichihara (Ichihara@rikvax.riken.go.jp)