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Drell-Yan Di-Lepton Production. Why Drell-Yan? Asymmetries depend on PD only (SIDIS→convolution with QFF) Why ? Each valence quark can contribuite to the diagram. Kinematics. x 1 x 2. x F =x 1 -x 2. Drell-Yan Di-Lepton Production. Scaling: Full x 1 ,x 2 range .
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Drell-Yan Di-Lepton Production Why Drell-Yan? Asymmetries depend on PD only (SIDIS→convolution with QFF) Why ? Each valence quark can contribuite to the diagram Kinematics x1x2 xF=x1-x2
Drell-Yan Di-Lepton Production Scaling: Full x1,x2 range . needed [1] Anassontzis et al., Phys. Rew. D38 (1988) 1377
Drell-Yan Asymmetries Polarised beam and target To be corrected for: NH3 polarised target:
Drell-Yan Asymmetries Unpolarised beam and target Di-Lepton Rest Frame NLO pQCD: λ 1, 0, 0 Experimental data [1]: 30 % [1]J.S.Conway et al., Phys. Rev. D39(1989)92. involves transverse spin effects at leading twist [2]: cos2φ contribution to angular distribution provide: [2]D. Boer et al., Phys. Rev. D60(1999)014012.
Angular distribution in CM frame - + N + + - + X @ 252 GeV/c -0.6 < cos < 0.6 4 < M < 8.5 GeV/c2 • cut on PT selects asymmetry • 30% asymmetry observed Conway et al, Phys. Rew. D39 (1989) 92
Drell-Yan Asymmetries Unpolarised beam, polarised target Even unpolarised beam is a powerful tool to investigate кT dependence of QDF D. Boer et al., Phys. Rev. D60(1999)014012.
Weak decay B.R. = 0.9 % 36000 events / 100 days [1] Smith and Vogt Z. Phys. C75 (1997)271