Theory and Satellite Experiment for Critical Exponent alpha of lambda-Transition in Superfluid Helium

On the basis recent seven-loop perturbation expansion for nu^{-1} = 3/(2 - alpha) we perform a careful reinvestigation of the critical exponent alpha governing the power behavior |T_c-T|^{- alpha} of the specific heat of superfluid helium near the phase transition. With the help of variational strong-coupling theory. we find alpha = - 0.01126 +- 0.0010, in very good agreement with the space shuttle experimental value alpha = - 0.01056 +- 0.00038.