We investigate the helicity properties of the ejectile in quasielastic neutrino-induced nucleon-knockout reactions and consider the ${}^{12}\mathrm{C}$ target as a test case. A formalism based on a relativistic mean-field model is adopted. The influence of final-state interactions is evaluated within a relativistic multiple-scattering Glauber approximation model. Our calculations reveal that the nucleon helicity asymmetries $A_l$ in quasielastic $A(\nu ,N)$ and $A(\overline{\nu },N)$ reactions are hardly affected by medium corrections, as final-state interactions and off-shell ambiguities in the electroweak current operators. On the contrary, the values of $A_l$ in $A(\overline{\nu },N)$ processes are extremely sensitive to strange-quark contributions to the weak vector form factors.

• Received 1 March 2006

DOI:https://doi.org/10.1103/PhysRevC.73.064605