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Status of the fourth fermion generation before ICHEP2012 : Higgs data and electroweak precision observables.

Eberhardt, Otto and Lenz, Alexander and Menzel, Andreas and Nierste, Ulrich and Wiebusch, Martin (2012) 'Status of the fourth fermion generation before ICHEP2012 : Higgs data and electroweak precision observables.', Physical review D., 86 (7). 074014.


We perform a global fit of the parameters of the Standard Model with a sequential fourth generation (SM4) to LHC and Tevatron Higgs data and electroweak precision data. Using several likelihood ratio tests, we compare the performance of the SM4 and the Standard Model (SM3) at describing the measured data. Since the SM3 and SM4 are not nested (i.e., the SM3 cannot be considered as a special case of the SM4 with some parameters fixed), the usual analytical formulae for p-values in likelihood ratio tests do not hold. We thus apply a new method to compute these p-values. For a Higgs mass of 126.5 GeV and fourth-generation quark masses above 600 GeV, we find that the SM4 is excluded at 3.1σ.

Item Type:Article
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Publisher statement:Reprinted with permission from the American Physical Society: Physical Review, D 86(7), 074014 © 2012 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modified, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.
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Date of first online publication:October 2012
Date first made open access:No date available

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