Electroweak vacuum stability in light of BICEP2

We consider the effect of a period of inflation with a high energy density upon the stability of the Higgs potential in the early Universe. The recent measurement of a large tensor-to-scalar ratio, rT∼0.16, by the BICEP2 experiment possibly implies that the energy density during inflation was very high, comparable with the GUT scale. Given that the standard model Higgs potential is known to develop an instability at Λ∼1010GeV this means that the resulting large quantum fluctuations of the Higgs field could destabilize the vacuum during inflation, even if the Higgs field starts at zero expectation value. We estimate the probability of such a catastrophic destabilization given such an inflationary scenario, and calculate that for a Higgs boson mass of mh=125.5GeV that the top mass must be less than mt∼172GeV. We present two possible cures: a direct coupling between the Higgs field and the inflaton and a nonzero temperature from dissipation during inflation.