Sealing the fate of a fourth generation of fermions
By Abdelhak Djouadi, A. Lenz. 2012
133 citations recorded by the source corpus.
The search for the effects of heavy fermions in the extension of the Standard Model with a fourth generation is part of the experimental program of the Tevatron and LHC experiments. Besides being directly produced, these states affect drastically the production and decay properties of the Higgs boson. In this note, we first reemphasize the known fact that in the case of a light and long–lived fourth neutrino, the present collider searches do not permit to exclude a Higgs boson with a mass below the WW threshold. In a second step, we show that the recent results from the ATLAS and CMS collaborations which observe an excess in the γγ and 4l ± search channels corresponding to a Higgs boson with a mass MH �125 GeV, cannot rule out the fourth generation possibility if the H!γγ decay rate is evaluated when naively implementing the leading O(GFm 2 ′) electroweak corrections. Including the exact next-to-leading order electroweak corrections leads to a strong suppression of the H!γγ rate and makes this channel unobservable with present data. Finally, we point out that the observation by the Tevatron collaborations of a > 2σ excess in the mass range MH =115–135 GeV in the channel q¯ �
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/45e40fd9019d1c30df1cea9a0e2e8393937416fd
How researchers see this paper
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In Astronomy and Astrophysics
- M. Raidal
- G. Arcadi
- Abdelhak Djouadi
- Olivier Mattelaer
- Fabio Maltoni
- Alessandro Strumia
- B. Carr
- Atlas Collaboration
In Nuclear and High Energy Physics
- M. Raidal
- G. Arcadi
- Olivier Mattelaer
- Fabio Maltoni
- Abdelhak Djouadi
- R. Ruiz
- L. Mantani
- Cms Collaboration
Citations in the corpus
- Dark Matter through the Higgs portal (2019, background): “The simplest version, a fourth family that behaves exactly like the first three ones, is in fact completely and unambiguously ruled out by LHC data [101,102] but some variants have survived until recently [307,308].”
- Vector boson fusion at multi-TeV muon colliders (2020, background): “Moreover, as additional chiral generations are constrained by flavor and Higgs data [162–164], if more copies do exist, such matter particles likely belong to different EW representations or possess new quantum numbers.”