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A. Molochkov Far Eastern National University

Sea-quark flavor asymmetry in the nucleon from a relativistic analysis of the Drell-Yan scattering off nuclei. A. Molochkov Far Eastern National University. Drell-Yan scattering. pp and pn Drell-Yan lepton pair production is sensitive to the anti-quark distribution in the nucleon

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A. Molochkov Far Eastern National University

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  1. Sea-quark flavor asymmetry in the nucleon from a relativistic analysis of the Drell-Yan scattering off nuclei A. Molochkov Far Eastern National University Chiral 07, Osaka, November 12-16, 2007

  2. Drell-Yan scattering • pp and pn Drell-Yan lepton pair production is sensitive to the anti-quark distribution in the nucleon • The only source of information about the neutron is a nucleus. • The deuteron is a simplest nucleus. Neglecting nuclear effects in the deuteron we get: Chiral 07, Osaka, November 12-16, 2007

  3. Ratio of the cross-sections provide direct information on the flavor asymmetry of the light quarks in the nucleon assuming The ratio equals 1 in case of flavor symmetry of the quark sea Chiral 07, Osaka, November 12-16, 2007

  4. Results for the ratio show flavor asymmetry FNAL E866 data 2001 Can binding effects change the conclusion? Chiral 07, Osaka, November 12-16, 2007

  5. : Integration with respect the 2. Second order pole puts the struck nucleon on-shell, but produces additional corrections that originate from the dependence of the cross-section Covariant view on the binding effect in the Drell-Yan pair production The cross section for the pD scattering within the BS formalism: 1. First order pole gives IA with off-shell nucleon. Simple, but we have to account off-mass-shell nucleon structure change. Chiral 07, Osaka, November 12-16, 2007

  6. Result of the integration where the impulse approximation and the correction The variables are defined as The derivative comes form the energy dependence of the cross-section: It can produce deviations in the ratio Chiral 07, Osaka, November 12-16, 2007

  7. Result of the numerical calculations FNAL E866 data 2001 Input DY nucleon cross-sections are constructed from fGRV98 parameterization with The relativistic kinematics can reproduce the deviation without the flavor asymmetry of the nucleon sea Chiral 07, Osaka, November 12-16, 2007

  8. A-dependence of the ratio The A-dependence of the deviations is defined by the coefficient in front of the cross-section derivative • Same dependence as in case of nuclear DIS: • Three A-independent points where R=1 • The ratio scales as number of nucleons inside the nucleus NR interpretation: contribution of the surface nucleons to the second term is small A-dependence can clarify nature of the effect Chiral 07, Osaka, November 12-16, 2007

  9. Conclusions • Observed flavor asymmetry results from the relativistic kinematics of bound nucleons • The bound nucleons structure change have the same nature in the DIS and DY processes • A-dependence data is required • High x data is required Chiral 07, Osaka, November 12-16, 2007

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