Constraints on Axial Two-Body Currents from Solar Neutrino Data

We briefly review recent calculations of neutrino deuteron cross sections within the effective field theory and traditional potential model approaches. We summarize recent efforts to determine the counter term describing axial two-body currents, L_{1A}, in the effective field theory approach. We determine the counter term directly from the solar neutrino data and find several, slightly different, ranges of L_{1A} under different sets of assumptions. Our most conservative fit value with the largest uncertainty is L_{1A} = 4.5 +18/-12 fm^3. We show that the contribution of the uncertainty of L_{1A} to the analysis and interpretation of the solar neutrino data measured at the Sudbury Neutrino Observatory is significantly less than the uncertainty coming from the lack of having a better knowledge of \theta_{13}.