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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Salamu, Y., Ji, CR., Melnitchouk, W. et al. \({{\bar{d}} - {\bar{u}}}\) Flavor Asymmetry in the Proton in Chiral Effective Field Theory. Few-Body Syst 56, 355–362 (2015). https://doi.org/10.1007/s00601-015-0949-0
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DOI: https://doi.org/10.1007/s00601-015-0949-0