  In the absence of a tree-level scalar-field mass, renormalization-group (RG)
methods permit the explicit summation of leading-logarithm contributions to all
orders of the perturbative series for the effective-potential functions
utilized in radiative symmetry breaking. For scalar-field electrodynamics, such
a summation of leading logarithm contributions leads to upper bounds on the
magnitudes of both gauge and scalar-field coupling constants, and suggests the
possibility of an additional phase of spontaneous symmetry breaking
characterized by a scalar-field mass comparable to that of the theory's gauge
boson. For radiatively-broken electroweak symmetry, the all-orders summation of
leading logarithm terms involving the dominant three couplings (quartic
scalar-field, t-quark Yukawa, and QCD) contributing to standard-model radiative
corrections leads to an RG-improved potential characterized by a 216 GeV Higgs
boson mass. Upon incorporation of electroweak gauge couplants we find that the
predicted Higgs mass increases to 218 GeV. The potential is also characterized
by a quartic scalar-field coupling over five times larger than that anticipated
for an equivalent Higgs mass obtained via conventional spontaneous symmetry
breaking, leading to a concomitant enhancement of processes (such as $W^+ W^-
\to ZZ$) sensitive to this coupling. Moreover, if the QCD coupling constant is
taken to be sufficiently strong, the tree potential's local minimum at $\phi =
0$ is shown to be restored for the summation of leading logarithm corrections.
Thus if QCD exhibits a two-phase structure similar to that of $N = 1$
supersymmetric Yang-Mills theory, the weaker asymptotically-free phase of QCD
may be selected by the large logarithm behaviour of the RG-improved effective
potential for radiatively broken electroweak symmetry.
