New measurements of the European Muon Collaboration effect in very light nuclei

Phys Rev Lett. 2009 Nov 13;103(20):202301. doi: 10.1103/PhysRevLett.103.202301. Epub 2009 Nov 13.


New Jefferson Lab data are presented on the nuclear dependence of the inclusive cross section from (2)H, (3)He, (4)He, (9)Be and (12)C for 0.3 < x < 0.9, Q(2) approximately 3-6 GeV(2). These data represent the first measurement of the EMC effect for (3)He at large x and a significant improvement for (4)He. The data do not support previous A-dependent or density-dependent fits to the EMC effect and suggest that the nuclear dependence of the quark distributions may depend on the local nuclear environment.