title: (d¯)-(u¯) asymmetry in the proton in chiral effective theory.
abstract: We compute the d[over ¯]-u[over ¯] asymmetry in the proton in chiral effective theory, including both nucleon and Δ degrees of freedom, within the relativistic and heavy baryon frameworks. In addition to the distribution at x>0, we compute the corrections to the asymmetry from zero momentum contributions from pion rainbow and bubble diagrams at x=0, which have not been accounted for in previous analyses. We find that the empirical x dependence of d[over ¯]-u[over ¯] as well as the integrated asymmetry can be well reproduced in terms of a transverse momentum cutoff parameter.
authors: Institute of High Energy Physics, CAS, Beijing 100049, China.
authors: Yusupujiang
authors: Y
authors: Salamu
authors: North Carolina State University, Raleigh, North Carolina 27695, USA.
authors: Chueng-Ryong
authors: CR
authors: Ji
authors: Jefferson Lab, Newport News, Virginia 23606, USA.
authors: W
authors: W
authors: Melnitchouk
authors: Institute of High Energy Physics, CAS, Beijing 100049, China.|Theoretical Physics Center for Science Facilities, CAS, Beijing 100049, China.
authors: P
authors: P
authors: Wang