Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5  fb-1 recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about ±20  GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.

S. Chatrchyan, V. Khachatryan, A. M. Sirunyan, A. Tumasyan, W. Adam, E. Aguilo, et al. (2012). Combined search for the quarks of a sequential fourth generation. PHYSICAL REVIEW D, PARTICLES, FIELDS, GRAVITATION, AND COSMOLOGY, 86, 112003-1-112003-20 [10.1103/PhysRevD.86.112003].

Combined search for the quarks of a sequential fourth generation

BONACORSI, DANIELE;BRAIBANT, SYLVIE;BRIGLIADORI, LUCA;CAPILUPPI, PAOLO;CASTRO, ANDREA;CUFFIANI, MARCO;FANFANI, ALESSANDRA;FASANELLA, DANIELE;GUIDUCCI, LUIGI;MENEGHELLI, MARCO;NAVARRIA, FRANCESCO LUIGI;PRIMAVERA, FEDERICA;ROSSI, ANTONIO MARIA;ROVELLI, TIZIANO;SIROLI, GIAN PIERO;
2012

Abstract

Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5  fb-1 recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about ±20  GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.
2012
S. Chatrchyan, V. Khachatryan, A. M. Sirunyan, A. Tumasyan, W. Adam, E. Aguilo, et al. (2012). Combined search for the quarks of a sequential fourth generation. PHYSICAL REVIEW D, PARTICLES, FIELDS, GRAVITATION, AND COSMOLOGY, 86, 112003-1-112003-20 [10.1103/PhysRevD.86.112003].
S. Chatrchyan;V. Khachatryan;A. M. Sirunyan;A. Tumasyan;W. Adam;E. Aguilo;T. Bergauer;M. Dragicevic;J. Erö;C. Fabjan;M. Friedl;R. Frühwirth;V. M. Ghet...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/144958
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