Lowenergy behaviour of realistic locallysupersymmetric grand unified theories
Abstract
The recently proposed cosmologically acceptable N=1 supergravity models based on the SU(5) unification group define unambigously the minimal particle content of the theory. This fact allows us to determine quite precisely their lowenergy behaviour. The SU(2)×U(1) breaking to U(1) _{e.m.} is a consequence of radiative corrections of the supergravity induced soft breaking terms. The proposed mechanism (which is model independent) introduces naturally a hierarchy between the M_{W} and M_{X} scales. Calculating the lowenergy effective potential we shot that a corrects SU(2)×U(1) breaking is obtained without any limit (except the experimental one) on the topquark mass. The masses of the supersymmetric partners of mater and gauge fermions can be low and consequently accessible experimentally (sleptons, s quarks, gauginos ⋍ 2050 GeV). A neutral Higgs is also predicted wirth a mass m _{H}⋍O(5) GeV. In addition, we show that if m_{t}≲45 GeV, the gravitino and gluino masses are bounded from below by 10 GeV ≲ m _{{3}/{2}}and 15 GeV ≲ m _{gluino}. The values of sin ^{2}θ_{W} (in the twoloop approximation) and the {m _{b}}/{m _{τ}} ratio predicted are in very good agreement with the experimentally measured values.
 Publication:

Nuclear Physics B
 Pub Date:
 April 1984
 DOI:
 10.1016/05503213(84)905455
 Bibcode:
 1984NuPhB.236..438K