Closing in on a perturbative fourth generation
Abstract
A perturbative new family of fermions is now severely constrained, though not excluded yet. We reconsider the current bounds (i.e., direct and from Higgs searches, R_b, oblique parameters) on the fourth generation parameter space assuming the case of a small CKM mixing with the third generation. We identify viable scenarios featuring either a light or a heavy Higgs boson. A set of representative benchmark points targeted for LHC searches is proposed with a normal (inverted) quark mass hierarchy where t' -> b'W (b' -> tW) decays are sizable. In the case where the fourth generation couplings to the lighter quark families are small, we suggest that search strategies at the LHC should include both pair (strong) and single (weak) production with bb+nW (n=2,...,6) final state signatures.
Cite
@article{arxiv.1204.5403,
title = {Closing in on a perturbative fourth generation},
author = {Mathieu Buchkremer and Jean-Marc Gérard and Fabio Maltoni},
journal= {arXiv preprint arXiv:1204.5403},
year = {2015}
}
Comments
23 pages, 6 figures, v2: some issues clarified and references added. To appear in JHEP