Measurement of angular distributions of Drell-Yan dimuons in p+p interactions at 800 GeV/c.
/ Authors
L. Zhu, J. C. Peng, P. Reimer, T. Awes, M. Brooks, C. Brown, J. D. Bush, T. Carey, T. Chang, W. Cooper
and 32 more authors
C. Gagliardi, G. Garvey, D. Geesaman, E. Hawker, X. He, L. Isenhower, D. Kaplan, S. Kaufman, S. Klinksiek, D. Koetke, D. Lee, W. Lee, M. Leitch, N. Makins, P. McGaughey, J. Moss, B. Mueller, P. Nord, V. Papavassiliou, B. Park, G. Petitt, M. Sadler, W. Sondheim, P. Stankus, T. Thompson, R. Towell, R. Tribble, M. Vasiliev, J. Webb, J. Willis, D. Wise, G. Young
/ Abstract
We report a measurement of the angular distributions of Drell-Yan dimuons produced using an 800 GeV/c proton beam on a hydrogen target. The polar and azimuthal angular distribution parameters have been extracted over the kinematic range 4.5<m micromicro<15 GeV/c2 (excluding the Upsilon resonance region), 0<p T <4 GeV/c, and 0<x F<0.8. The p+p angular distributions are similar to those of p+d, and both data sets are compared with models which attribute the cos2varphi distribution either to the presence of the transverse-momentum-dependent Boer-Mulders structure function h1 perpendicular to 1 or to QCD effects. The data indicate the need to include QCD effects before reliable information on the Boer-Mulders function can be extracted. The validity of the Lam-Tung relation in p+p Drell-Yan data is also tested.
Journal: Physical review letters