Seven-Loop Critical Exponents from Strong-Coupling phi⁴-Theory in Three Dimensions

Using strong-coupling quantum field theory we calculate highly accurate critical exponents nu, eta from new seven-loop expansions in three dimensions. Our theoretical value for the critical exponent alpha of the specific heat near the lambda-point of superfluid helium is alpha =-0.01294+-0.00060, in excellent agreement with the space shuttle experimental value alpha =-0.01285+-0.00038.