Joint analysis of Higgs decays and electroweak precision observables in the Standard Model with a sequential fourth generation

We analyse the impact of LHC and Tevatron Higgs data on the viability of the Standard Model with a sequential fourth generation (SM4), assuming Dirac neutrinos and a Higgs mass of 125 GeV. To this end we perform a combined fit to the signal cross sections of pp -> H -> gamma gamma,ZZ*,WW* at t...

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Bibliographic Details
Published in:arXiv.org 2012-08
Main Authors: Eberhardt, Otto, Herbert, Geoffrey, Lacker, Heiko, Lenz, Alexander, Menzel, Andreas, Nierste, Ulrich, Wiebusch, Martin
Format: Article
Language:English
Subjects:
Electroweak model
Fermions
Impact analysis
Leptons
Lower bounds
Neutrinos
Quarks
Viability
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Summary:We analyse the impact of LHC and Tevatron Higgs data on the viability of the Standard Model with a sequential fourth generation (SM4), assuming Dirac neutrinos and a Higgs mass of 125 GeV. To this end we perform a combined fit to the signal cross sections of pp -> H -> gamma gamma,ZZ*,WW* at the LHC, to p pbar -> VH -> V b bbar (V = W, Z) at the Tevatron and to the electroweak precision observables. Fixing the mass of the fourth generation down-type quark b' to 600 GeV we find best-fit values of m_t' = 632 GeV, m_l4 = 113.6 GeV and m_nu4 = 58.0 GeV for the other fourth-generation fermion masses. We compare the chi-square values and pulls of the different observables in the three and four-generation case and show that the data is better described by the three-generation Standard Model. We also investigate the effects of mixing between the third and fourth-generation quarks and of a future increased lower bound on the fourth-generation charged lepton mass of 250 GeV.
ISSN:2331-8422
DOI:10.48550/arxiv.1204.3872