We present a scaling theory for the low-temperature phase transition o
f the Ising spin glass in a transverse magnetic held (Gamma). The theo
ry provides relations and bounds on some critical exponents, which are
supported by results from actual calculations. A renormalization-grou
p analysis of the zero-temperature transition in the presence of a lon
gitudinal symmetry-breaking held enables us to estimate the critical e
xponents beta and gamma, associated with the Edwards-Anderson order pa
rameter and the nonlinear susceptibility, respectively. We have found
no indications of the transition being of first order.