High-precision calculation of the parity-nonconserving amplitude in francium

A high-precision calculation of the 7s-8s parity-nonconserving (PNC) transition amplitude in francium, based on a relativistic all-order method, is presented. Our values for the PNC amplitudes in Fr-223 and Fr-210 are E-PNC = 15.41(17) and 14.02(15), respectively, in units 10(-11)i \ e \ a(0)(-Q(W)/N), where Q(W) is the weak charge and N is the neutron number. Spin-dependent contributions to the PNC amplitude are calculated for Fr isotopes with nucleon numbers A = 207, 209, 211, and 213. To assess the accuracy of our calculations, we apply the present all-order method to the 6s-7s PNC amplitude in cesium and obtain a result in close agreement with previous high-precision calculations.