Combined search for the quarks of a sequential fourth generation

Combined search for the quarks of a sequential fourth generation

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 5fb-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 dow...

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Príomhchruthaitheoirí: Chatrchyan, S, Khachatryan, V, Sirunyan, A, Tumasyan, A, Adam, W, Aguilo, E, Bergauer, T, Dragicevic, M, Eroe, J, Fabjan, C, Friedl, M, Fruehwirth, R, Ghete, V, Hammer, J, Hoermann, N, Hrubec, J, Jeitler, M, Kiesenhofer, W, Knuenz, V, Krammer, M, Kraetschmer, I, Liko, D, Mikulec, I, Pernicka, M, Rahbaran, B
Formáid: Journal article
Foilsithe / Cruthaithe: 2012
Cur síos
Achoimre: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 5fb-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 685GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about ±20GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions. © 2012 CERN.

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