Vacuum stability and the scaling behaviour of the Higgs-curvature coupling

Stability of the Higgs vacuum during early universe inflation is dependent on how the Higgs couples to the spacetime curvature. Limits on the curvature coupling parameter at the electroweak scale $\xi_{EW}$ are shown to be consistent only when quantum gravity effects are included and a covariant quantisation procedure, such as Vilkovisky-DeWitt, is adopted. Stability requires $\xi_{EW}>-0.03$ for a top quark mass $M_t=173.34\,{\rm GeV}$.