Triviality and the Precision Bound on the Higgs Mass

TL;DR

This paper discusses how the triviality of the Higgs sector constrains the Higgs mass and how new physics effects at a cutoff scale can reconcile heavy Higgs masses with precision electroweak data.

Contribution

It estimates the impact of dimension six operators from underlying theories on electroweak parameters, allowing heavier Higgs masses to be consistent with data.

Findings

Dimension six operators can significantly affect the T parameter.

Heavy Higgs masses up to 400-500 GeV are compatible with precision data.

Natural size coefficients of operators produce sizable corrections.

Abstract

The triviality of the scalar sector of the standard one-doublet Higgs model implies that this model is only an effective low-energy theory valid below some cut-off scale Lambda. For a heavy higgs this scale must be relatively low (10 TeV or less). Additional interactions coming from the underlying theory, and suppressed by the scale Lambda, give rise to model-dependent corrections to precisely measured electroweak quantities. Dimension six operators arising from the underlying physics naturally contribute to the S and T parameters, and their effects should be included in a global fit to the precision data that determines any limit on the Higgs mass. Using dimensional analysis, we estimate the expected size of these corrections in a custodially-symmetric strongly-interacting underlying theory. Taking these operators' coefficients to be of natural size gives sufficiently large contributions to the T parameter to reconcile Higgs masses as large as 400-500 GeV with the precision data.