Impact of New Physics on the EW vacuum stability in a curved spacetime background

TL;DR

This paper investigates how new physics at high energies affects the stability of the electroweak vacuum in curved spacetime, finding that destabilizing effects persist despite gravitational stabilization.

Contribution

It extends previous flat spacetime analyses to curved spacetime, demonstrating that new physics can destabilize the EW vacuum even with gravity's stabilizing influence.

Findings

New physics destabilizes the EW vacuum in curved spacetime.

Gravity's stabilization effect is weaker than the destabilizing influence.

Results are consistent across different parametrizations of new physics.

Abstract

It has been recently shown that, contrary to an intuitive decoupling argument, the presence of new physics at very large energy scales (say around the Planck scale) can have a strong impact on the electroweak vacuum lifetime. In particular, the vacuum could be totally destabilized. This study was performed in a flat spacetime background, and it is important to extend the analysis to curved spacetime since these are Planckian-physics effects. It is generally expected that under these extreme conditions gravity should totally quench the formation of true vacuum bubbles, thus washing out the destabilizing effect of new physics. In this work we extend the analysis to curved spacetime and show that, although gravity pushes toward stabilization, the destabilizing effect of new physics is still (by far) the dominating one. In order to get model independent results, high energy new physics is parametrized in two different independent ways: as higher order operators in the Higgs field, or introducing new particles with very large masses. The destabilizing effect is observed in both cases, hinting at a general mechanism that does not depend on the parametrization details for new physics, thus maintaining the results obtained from the analysis performed in flat spacetime.