Flavor Asymmetry of Antiquark Distributions in the Nucleon

Violation of the Gottfried sum rule was suggested by the New Muon Collaboration in measuring proton and deuteron F2 structure functions. The finding triggered many theoretical studies on physics mechanisms for explaining the antiquark flavor asymmetry ū − d̄ in the nucleon. Various experimental results and proposed theoretical ideas are summarized. Possibility of finding the flavor asymmetry in Drell-Yan experiments is discussed together with other processes, which are sensitive to the ū/d̄ asymmetry. * Email: [email protected]. Information on his research is available at http://www.cc.saga-u.ac.jp/saga-u/riko/physics/quantum1/structure.html. submitted to Physics Reports PREPARED FOR THE U.S. DEPARTMENT OF ENERGY UNDER GRANT DE-FG06-90ER40561 This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, mark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.