Speaker
Description
If the standard model Higgs boson were much heavier, it would appear as
a broad resonance since its decay into a pair of longitudinally polarized gauge bosons is highly enhanced. We study whether the same enhancement happens at loop level in a simple extension of the standard model with a singlet scalar boson S. In order to focus on the loop effects, S is assumed to have no interaction at tree level with the standard model particles. The singlet scalar S is linked to the standard model world radiatively by vector-like quarks running in the loop. We introduce three vector-like quark multiplets, an SU(2)L doublet, an up-type singlet, and a down-type singlet. There are two kinds of loop effects in the S phenomenology, the mixing with the Higgs boson and the radiative decays into
hh, WW, ZZ, gg, and through the triangle loops. We show that the crucial condition for enhancing loop effects including the longitudinal polarization enhancement is the large mass differences among vector-like quarks. The current LHC constraints on S from the heavy scalar searches and the Higgs precision data are shown to be very significant.