NEW COSMOLOGICAL CONSTRAINTS ON THE HIGGS BOSON AND TOP QUARK MASSES

In the standard model, when the top quark mass is sufficiently large, the state where the Higgs field has a vacuum expectation value 〈φ〉 = 246 GeV is not the true minimum of the Higgs potential. When this is the case, and when the top quark mass exceeds some critical value, thermal fluctuations in the early universe would have rendered the state 〈gf〉=246 GeV isstable. The requirement that the state 〈φ〉=246 GeV is sufficiently long-lived constraints the masses of the Higgs boson and the top quark. We exclude top quark and Higgs boson masses which have not been excluded by previous limits. For a top quark lighter than 195 GeV, the limits of this paper are only concerned with a Higgs boson with a mass less than 42 GeV. We note that similar considerations could constrain the masses of light Higgs bosons with large couplings to fermions in other models. © 1990.