Higgs diphoton rate and mass enhancement with vectorlike leptons and the scale of supersymmetry

Analysis of contributions from vectorlike leptonic supermultiplets to the Higgs diphoton decay rate and to the Higgs boson mass is given. Corrections arising from the exchange of the new leptons and their superpartners as well as their mirrors are computed analytically and numerically. We also study the correlation between the enhanced Higgs diphoton rate and the Higgs mass corrections. Specifically, we find two branches in the numerical analysis: on the lower branch the diphoton rate enhancement is flat, while on the upper branch it has a strong correlation with the Higgs mass enhancement. It is seen that a factor of 1.4-1.8 enhancement of the Higgs diphoton rate on the upper branch can be achieved, and a 4-10 GeV positive correction to the Higgs mass can also be obtained simultaneously. The effect of this extra contribution to the Higgs mass is to release the constraint on weak-scale supersymmetry, allowing its scale to be lower than in the theory without extra contributions. The vectorlike supermultiplets also have collider implications which could be testable at the LHC and at the ILC. DOI: 10.1103/PhysRevD.87.075018