Few-Body Systems

, Volume 56, Issue 6–9, pp 355–362 | Cite as

\({{\bar{d}} - {\bar{u}}}\) Flavor Asymmetry in the Proton in Chiral Effective Field Theory

Article

Abstract

The \({\bar d - \bar u}\) flavor asymmetry in the proton arising from pion loops is computed using chiral effective field theory. The calculation includes both nucleon and Δ intermediate states, and uses both the fully relativistic and heavy baryon frameworks. The x dependence of \({\bar d - \bar u}\) extracted from the Fermilab E866 Drell–Yan data can be well reproduced in terms of a single transverse momentum cutoff parameter regulating the ultraviolet behavior of the loop integrals. In addition to the distribution at x > 0, corrections to the integrated asymmetry from zero momentum contributions are computed, which arise from pion rainbow and bubble diagrams at x = 0. These have not been accounted for in previous analyses, and can make important contributions to the lowest moment of \({\bar d-\bar u}\).

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Copyright information

© Springer-Verlag Wien 2015

Authors and Affiliations

  1. 1.Institute of High Energy PhysicsCASBeijingChina
  2. 2.North Carolina State UniversityRaleighUSA
  3. 3.Jefferson LabNewport NewsUSA
  4. 4.Theoretical Physics Center for Science FacilitiesCASBeijingChina

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