Parity violating measurements of neutron densities - art. no. 025501

Parity violating electron nucleus scattering is a clean and powerful tool f or measuring the spatial distributions of neutrons in nuclei with unprecede nted accuracy. Parity violation arises from the interference of electromagn etic and weak neutral amplitudes, and the Z(0) of the standard model couple s primarily to neutrons at low Q(2). The data can be interpreted with as mu ch confidence as electromagnetic scattering. After briefly reviewing the pr esent theoretical and experimental knowledge of neutron densities, we discu ss possible parity violation measurements, their theoretical interpretation , and applications. The experiments are feasible at existing facilities. We show that theoretical corrections are either small or well understood, whi ch makes the interpretation clean. The quantitative relationship to atomic parity nonconservation observables is examined. and we show that the electr on scattering asymmetries can be directly applied to atomic parity nonconse rvation because the observables have approximately the same dependence on n uclear shape.