Measurement of Angular Distributions of Drell-Yan Dimuons in p + d Interaction at 800-GeV/c Page: 1 of 4
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to UNT Digital Library by the UNT Libraries Government Documents Department.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
FERMI LAB-PU B-07-434
Measurement of Angular Distributions of Drell-Yan Dimuons in p + d Interaction at
800 GeV/c
L.Y. Zhu,6 J.C. Peng,6,7 P.E. Reimer,2,7 T.C. Awes,10 M.L. Brooks,7 C.N. Brown,3 J.D. Bush,1 T.A. Carey,7
T.H. Chang,9 W.E. Cooper,3 C.A. Gagliardi," G.T. Garvey, D.F. Geesaman,2 E.A. Hawker,1
X.C. He,4 L.D. Isenhower,' D.M. Kaplan,' S.B. Kaufman,2 S.A. Klinksiek,8 D.D. Koetke,12 D.M. Lee,7
W.M. Lee,3,4 M.J. Leitch, N. Makins,2,6 P.L. McGaughey, J.M. Moss,7 B.A. Mueller,2 P.M. Nord,12
V. Papavassiliou,9 B.K. Park,7 G. Petitt,4 M.E. Sadler,' W.E. Sondheim,7 P.W. Stankus,10 T.N. Thompson,7
R.S. Towell,1 R.E. Tribble,"1 M.A. Vasiliev,11 J.C. Webb,9 J.L. Willis,1 D.K. Wise,1 and G.R. Young10
(FNAL E866/NuSea Collaboration)
'Abilene Christian University, Abilene, TX 79699
2Physics Division, Argonne National Laboratory, Argonne, IL 60439
3Fermi National Accelerator Laboratory, Batavia, IL 60510
4Georgia State University, Atlanta, GA 30303
5Illinois Institute of Technology, Chicago, IL 60616
6University of Illinois at Urbana-Champaign, Urbana, IL 61801
"Los Alamos National Laboratory, Los Alamos, NM 87545
s University of New Mexico, Albuquerque, NM 87131
9New Mexico State University, Las Cruces, NM 88003
"O0ak Ridge National Laboratory, Oak Ridge, TN 37831
"Texas AUM University, College Station, TX 77843
12Valparaiso University, Valparaiso, IN 46383
(Dated: September 6, 2006)
We report a measurement of the angular distributions of Drell-Yan dimuons produced using an
800 GeV/c proton beam on a deuterium target. The muon angular distributions in polar angle
0 and azimuthal angle 0 have been measured over the kinematic range 4.5 < m, < 15 GeV/c2,
0 < PT < 4 GeV/c, and 0 < xF < 0.8. No significant cos2q dependence is found in these proton-
induced Drell-Yan data, in contrast to the situation for pion-induced Drell-Yan. The data are
compared with expectations from models which attribute the cos2q distribution to a QCD vacuum
effect or to the presence of the transverse-momentum-dependent Boer-Mulders structure function
hi. Constraints on the magnitude of the sea-quark hl structure functions are obtained.
PACS numbers: 13.85.Qk, 14.20.Dh, 24.85.+p, 13.88.+eThe Drell-Yan process [1], in which a charged lepton
pair is produced in a high-energy hadron-hadron interac-
tion via the qq - l+l- process, has been a testing ground
for perturbative QCD and a unique tool for probing par-
ton distributions of hadrons. The Drell-Yan production
cross sections can be well described by next-to-leading
order QCD calculations [2]. This provides a firm theo-
retical framework for using the Drell-Yan process to de-
termine the antiquark content of nucleons and nuclei [3],
as well as the quark distributions of pions, kaons, and
antiprotons [4].
Despite the success of perturbative QCD in describing
the Drell-Yan cross sections, it remains a challenge to un-
derstand the angular distributions of the Drell-Yan pro-
cess. Assuming dominance of the single-photon process,
a general expression for the Drell-Yan angular distribu-
tion is [5]
o 1 + A cos 0+ sin 20 cos o + sin2 O cos 2o, (1)
dQ 2
where 0 and 0 denote the polar and azimuthal angle,
respectively, of the l+ in the dilepton rest frame. In
the "naive" Drell-Yan model, where the transverse mo-mentum of the quark is ignored and no gluon emission
is considered, A 1 and = v 0 are obtained.
QCD effects [6] and non-zero intrinsic transverse mo-
mentum of the quarks [7] can both lead to A $ 1 and
p, v $ 0. However, A and v should still satisfy the rela-
tion 1 - A 2v [5]. This so-called Lam-Tung relation,
obtained as a consequence of the spin-1/2 nature of the
quarks, is analogous to the Callan-Gross relation [8] in
Deep-Inelastic Scattering. While QCD effects can signif-
icantly modify the Callan-Gross relation, the Lam-Tung
relation is predicted to be largely unaffected by QCD
corrections [9].
The first measurement of the Drell-Yan angular dis-
tribution was performed by the NA10 Collaboration for
7r- + W at 140, 194, and 286 GeV/c, with the highest
statistics at 194 GeV/c [10]. The cos 2p angular depen-
dences showed a sizable v, increasing with dimuon trans-
verse momentum (PT) and reaching a value of 0.3 at
PT 2.5 GeV/c (see Fig. 1). The observed behavior of v
could not be described by perturbative QCD calculations
which predict much smaller values of v [6]. The Fermilab
E615 Collaboration subsequently performed a measure-C
C
Upcoming Pages
Here’s what’s next.
Search Inside
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Zhu, L. Y.; Peng, J. C.; Reimer, P. E.; Awes, T. C.; Brooks, M. L.; Brown, C. N. et al. Measurement of Angular Distributions of Drell-Yan Dimuons in p + d Interaction at 800-GeV/c, article, September 1, 2006; Batavia, Illinois. (https://digital.library.unt.edu/ark:/67531/metadc885955/m1/1/: accessed April 18, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.