Measurement of the light anti-quark flavor asymmetry in the nucleon sea

A precise measurement of the ratio of Drell-Yan yields from an 800 GeV/c proton beam incident on hydrogen and deuterium targets is reported. Over 140,000 Drell-Yan muon pairs with dimuon mass M_{mu+ mu-} >= 4.5 GeV/c^2 were recorded. From these data, the ratio of anti-down (dbar) to anti-up (ubar) quark distributions in the proton sea is determined over a wide range in Bjorken-x. A strong x dependence is observed in the ratio dbar/ubar, showing substantial enhancement of dbar with respect to ubar for x<0.2. This result is in fair agreement with recent parton distribution parameterizations of the sea. For x>0.2, the observed dbar/ubar ratio is much nearer unity than given by the parameterizations.

p p: inclusive reaction
p deuteron: inclusive reaction
muon: pair production
Drell-Yan process
channel cross section: ratio
quark: sea
up
down
antiquark: ratio
flavor: asymmetry

References(22)

Figures(0)

Sum rule for high-energy electron - proton scattering

Kurt Gottfried
(
- Cornell U., LNS
)

- Phys.Rev.Lett. 18 (1967) 1174
•
DOI:
- 10.1103/PhysRevLett.18.1174

The Gottfried sum from the ratio F2(n) / F2(p)

New Muon

Collaboration

•

P. Amaudruz

et al.

- Phys.Rev.Lett. 66 (1991) 2712-2715
•
DOI:
- 10.1103/PhysRevLett.66.2712

A Reevaluation of the Gottfried sum

New Muon

Collaboration

•

M. Arneodo

et al.

- Phys.Rev.D 50 (1994) R1-R3
•
DOI:
- 10.1103/PhysRevD.50.R1

Improved parton distributions from global analysis of recent deep inelastic scattering and inclusive jet data

H.L. Lai
(
- Michigan State U.
)
,
J. Huston
(
- Michigan State U.
)
,
S. Kuhlmann
(
- Argonne
)
,
Fredrick I. Olness
(
- Southern Methodist U.
)
,
Joseph F. Owens
(
- Florida State U.
)

et al.

- Phys.Rev.D 55 (1997) 1280-1296
•
e-Print:
- hep-ph/9606399
•
DOI:
- 10.1103/PhysRevD.55.1280

Parton distributions: A Study of the new HERA data, alpha-s, the gluon and p anti-p jet production

- Phys.Lett.B 387 (1996) 419-426
•
e-Print:
- hep-ph/9606345
•
DOI:
- 10.1016/0370-2693(96)01031-3

Partons and their Applications at High-Energies

S.D. Drell
(
- SLAC
)
,
Tung-Mow Yan
(
- SLAC
)

- Annals Phys. 66 (1971) 578,
- Annals Phys. 281 (2000) 450-493
•
DOI:
- 10.1016/0003-4916(71)90071-6

Constraints on isospin breaking in the light quark sea from the Drell-Yan process

- Phys.Lett.B 256 (1991) 258-264
•
DOI:
- 10.1016/0370-2693(91)90684-I

Limit on the anti-d / anti-u asymmetry of the nucleon sea from Drell-Yan production

P.L. McGaughey
(
- Los Alamos and
- Case Western Reserve U.
)
,
J.M. Moss
(
- Los Alamos and
- Case Western Reserve U.
)
,
D.M. Alde
(
- Los Alamos and
- Case Western Reserve U.
)
,
H.W. Baer
(
- Los Alamos and
- Case Western Reserve U.
)
,
T.A. Carey
(
- Los Alamos and
- Case Western Reserve U.
)

et al.

- Phys.Rev.Lett. 69 (1992) 1726-1728
•
DOI:
- 10.1103/PhysRevLett.69.1726

Study of the isospin symmetry breaking in the light quark sea of the nucleon from the Drell-Yan process

NA51

Collaboration

•

A. Baldit
(
- Clermont-Ferrand U.
)

et al.

- Phys.Lett.B 332 (1994) 244-250
•
DOI:
- 10.1016/0370-2693(94)90884-2

Dimuon Production in Proton - Copper Collisions at $\sqrt{s}$ = 38.8-GeV

et al.

- Phys.Rev.D 43 (1991) 2815-2836
•
DOI:
- 10.1103/PhysRevD.43.2815

Nuclear Dependence of Dimuon Production at 800-GeV

et al.

- Phys.Rev.Lett. 64 (1990) 2479-2482
•
DOI:
- 10.1103/PhysRevLett.64.2479

Flavor Symmetry Breaking in anti-Quark Distributions

D.A. Ross
(
- CERN
)
,
Christopher T. Sachrajda
(
- CERN
)

- Nucl.Phys.B 149 (1979) 497-516
•
DOI:
- 10.1016/0550-3213(79)90004-X

A Limit on the Pionic Component of the Nucleon Through SU(3) Flavor Breaking in the Sea

Anthony William Thomas
(
- CERN
)

- Phys.Lett.B 126 (1983) 97-100
•
DOI:
- 10.1016/0370-2693(83)90026-6

Flavor SU(2) symmetry breaking in deep inelastic scattering

A.I. Signal
(
- Heidelberg U. and
- Massey U.
)
,
Andreas W. Schreiber
(
- Adelaide U.
)
,
Anthony William Thomas
(
- Adelaide U.
)

- Mod.Phys.Lett.A 6 (1991) 271-276
•
DOI:
- 10.1142/S0217732391000233

Excess of anti-D over anti-U in the proton sea quark distribution

- Phys.Lett.B 251 (1990) 453-454
•
DOI:
- 10.1016/0370-2693(90)90735-O

Hard form-factors for meson baryon strong couplings as derived from deep inelastic lepton scattering

W.Y.P. Hwang
(
- Taiwan, Natl. Normal U. and
- Julich, Forschungszentrum
)
,
J. Speth
(
- Taiwan, Natl. Normal U. and
- Julich, Forschungszentrum
)
,
G.E. Brown
(
- SUNY, Stony Brook
)

- Z.Phys.A 339 (1991) 383-389
•
DOI:
- 10.1007/BF01560641

Effects of pi N N form-factor on pionic contributions to anti-u (x) anti-d (x) distribution in the nucleon

S. Kumano
(
- Indiana U.
)

- Phys.Rev.D 43 (1991) 3067-3070
•
DOI:
- 10.1103/PhysRevD.43.3067

pi N N form-factor for explaining sea quark distributions in the nucleon

S. Kumano
(
- Indiana U.
)

- Phys.Rev.D 43 (1991) 59-63
•
DOI:
- 10.1103/PhysRevD.43.59

Origin of SU(2) flavor symmetry breaking in anti-quark distributions

S. Kumano
(
- Indiana U.
)
,
J.T. Londergan
(
- Indiana U.
)

- Phys.Rev.D 44 (1991) 717-724
•
DOI:
- 10.1103/PhysRevD.44.717

Flavor asymmetry in the light quark sea of the nucleon

- Phys.Rev.D 45 (1992) 2269-2275,
- Phys. Rev. D45 (1992) 2269-2275 and Fermilab Batavia - FERMILAB-Pub-91-272 (91,rec.Nov.) 17 p
•
DOI:
- 10.1103/PhysRevD.45.2269

Theory of Disintegration of Nuclei by Neutrons

H.A. Bethe
(
- Cornell U., Phys. Dept.
)

- Phys.Rev. 47 (1935) 747-759
•
DOI:
- 10.1103/PhysRev.47.747

Testing the meson cloud in the nucleon in Drell-Yan processes

A. Szczurek
(
- Cracow, INP
)
,
Magda Ericson
(
- Lyon, IPN and
- CERN
)
,
H. Holtmann
(
- Julich, Forschungszentrum
)
,
J. Speth
(
- Julich, Forschungszentrum
)

- Nucl.Phys.A 596 (1996) 397-414
•
e-Print:
- hep-ph/9602213
•
DOI:
- 10.1016/0375-9474(95)00401-7