Higgs Boson Production and Decay: Effects from Light Third Generation and Vectorlike Matter

TL;DR

This paper investigates how light third-generation supersymmetric particles and vectorlike matter influence Higgs boson production and decay, explaining observed enhancements in diphoton channels within certain theoretical frameworks.

Contribution

It demonstrates that a light stau within the MSSM can account for Higgs decay enhancements, and introduces vectorlike particles as a solution for achieving the correct Higgs mass beyond MSSM constraints.

Findings

Light stau explains diphoton enhancement in MSSM.

Vectorlike particles help attain 126 GeV Higgs mass.

Light sbottom scenario struggles to explain observed excess.

Abstract

We study the implications of light third generation sparticles on the production cross section and decay widths of a light CP-even Higgs boson. For simplicity, we consider scenarios in which only one of the sfermions from the third generation is light. For each case, we attempt to explain the apparently large enhancement in the Higgs production and decay in the diphoton channel with small deviations in the ZZ channel. In the MSSM framework we find that only a light stau can explain these observations while keeping the lightest CP-even Higgs boson mass in the interval 123 GeV \lesssim m_h \lesssim 127 GeV. For the light stop scenario, the observations related to the diphoton and ZZ channel can be accommodated but, in order to satisfy the Higgs mass bound, one needs to go beyond the MSSM. In particular, we invoke vector like particles with masses around a TeV. These new particles preserve gauge coupling unification and provide additional contributions to the Higgs mass. With these new contributions a 126 GeV Higgs mass is easily achieved. We also find that with only a light sbottom quark, the above mentioned excess is hard to accommodate.