Long Lived Fourth Generation and the Higgs

Understand

A chiral fourth generation is a simple and well motivated extension of the standard model, and has important consequences for Higgs phenomenology.

• Here we consider a scenario where the fourth generation neutrinos are long lived and have both a Dirac and Majorana mass term.
• Such neutrinos can be as light as 40 GeV and can be the dominant decay mode of the Higgs boson for Higgs masses below the W-boson threshold.
• We study the effect of the Majorana mass term on the Higgs branching fractions and reevaluate the Tevatron constraints on the Higgs mass.