A renormalization framework is presented for calculating radiative SU(2)×U(1) gauge symmetry breaking in no-scale supergravity models. In this framework one naturally incorporates so-called threshold effects due to finite particle masses, without introducing an infrared cutoff scale. In this way it is possible to calculate the weak scale directly in terms of the fundamental parameters of the theory. The conventional way of calculating radiative symmetry breaking, using a renormalization-group (RG) approach, is reviewed, and it is explained why this approach fails to go beyond a leading-logarithmic approximation. It is pointed out that for an adequate calculation of the weak scale one has to include the two-loop leading logarithms and the one-loop calculation has to be performed in the vacuum where SU(2)×U(1) is broken. The new renormalization framework is illustrated by performing a one-loop calculation in the no-scale ${\mathrm{E}}_6$ model. Instead of using running parameters, as in the RG approach, all quantities correspond to physical observables in this framework. For the study of radiative symmetry breaking a coupled set of linear algebraic equations is obtained, whose solutions coincide with those of the RG approach to the order of accuracy of the latter method.

• Received 24 February 1987

DOI:https://doi.org/10.1103/PhysRevD.35.3923