Large mass splittings for fourth generation fermions allowed by LHC Higgs boson exclusion

Dighe, Amol and Ghosh, Diptimoy and Godbole, Rohini M. and Prasath, Arun (2012) Large mass splittings for fourth generation fermions allowed by LHC Higgs boson exclusion. In: PHYSICAL REVIEW D, 85 (11).

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Abstract

In the context of the standard model with a fourth generation, we explore the allowed mass spectra in the fourth-generation quark and lepton sectors as functions of the Higgs mass. Using the constraints from unitarity and oblique parameters, we show that a heavy Higgs allows large mass splittings in these sectors, opening up new decay channels involving W emission. Assuming that the hints for a light Higgs do not yet constitute an evidence, we work in a scenario where a heavy Higgs is viable. A Higgs heavier than similar to 800 GeV would in fact necessitate either a heavy quark decay channel t' -> b'W/b' -> t'W or a heavy lepton decay channel tau' -> nu'W as long as the mixing between the third and fourth generations is small. This mixing tends to suppress the mass splittings and hence the W-emission channels. The possibility of the W-emission channel could substantially change the search strategies of fourth-generation fermions at the LHC and impact the currently reported mass limits.

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW D
Publisher:	AMER PHYSICAL SOC
Additional Information:	Copyright for this article belongs to the American Physical Society
Department/Centre:	Division of Physical & Mathematical Sciences > Centre for High Energy Physics
Date Deposited:	24 Jul 2012 12:49
Last Modified:	24 Jul 2012 12:51
URI:	http://eprints.iisc.ac.in/id/eprint/44828

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