1204.3872 (Otto Eberhardt et al.)

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

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

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' = 634 GeV, m_l4 = 107.6 GeV and m_nu4 = 57.8 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.

View original: http://arxiv.org/abs/1204.3872