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arXiv · 1204.3872

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

Otto Eberhardt·Geoffrey Herbert·Heiko Lacker·Alexander Lenz·Andreas Menzel·Ulrich Nierste·Martin Wiebusch
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Abstract

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.

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Otto Eberhardt, Geoffrey Herbert, Heiko Lacker, Alexander Lenz, Andreas Menzel, Ulrich Nierste, Martin Wiebusch. 2012-08-27. Joint analysis of Higgs decays and electroweak precision observables in the Standard Model with a sequential fourth generation. https://doi.org/10.1103/physrevd.86.013011

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