The Case Against Multiple Higgs Bosons

Paul H. Frampton (notorious in his personal life, but respected as a physicist) and Thomas W. Kephart have a new pre-print out related to the fact that the sum of the square of the Standard Model fermion masses is equal to one half of the square of the Higgs vacuum expectation value, a subject that I discussed in my most recent post and others, which is not inconsistent with experimental data, although it isn't certain to particularly high precision either since the margin of error in the top quark mass estimate is significant.

In particular, he illustrates how this relationship of the fermion masses to the Higgs vacuum expectation value, and the predicted decays of the Standard Model Higgs boson imply that any theory more than one scalar Higgs boson that couples to Standard Model particles cannot have Standard Model Higgs boson decay properties.  Yet, multiple Higgs bosons are a generic prediction of all supersymmetry (SUSY) theories.  So, to the extent that the Higgs boson decays in the manner predicted, SUSY theories are ruled out.

Frampton explains the argument less technically in a guest blog post here.

Basically, so long as the W boson mass is a function of the Higgs vacuum expectation value, and the Higgs boson decay branching fraction of a Standard Model fermion is a function of its mass, if the Yukawa of a fermion is too low, then the Higgs vev must be higher and the W boson mass will not conform to the experimental data.

As measurements of those branching fractions grow more precise, new physics theories with multiple Higgs bosons are increasingly disfavored.