Isovector EMC effect explains the NuTeV anomaly

Understand

A neutron or proton excess in nuclei leads to an isovector-vector mean-field which, through its coupling to the quarks in a bound nucleon, implies a shift in the quark distributions with respect to the Bjorken scaling variable.

• We show that this result leads to an additional correction to the NuTeV measurement of sin^2(Theta_W).
• The sign of this correction is largely model independent and acts to reduce their result.
• Explicit calculation within a covariant and confining Nambu--Jona-Lasinio model predicts that this vector field correction accounts for approximately two-thirds of the NuTeV anomaly.