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. DOI: 10.1103/PhysRevD.86.112003

Combined search for the quarks of a sequential fourth generation / S., C., V., K., A. M., S., A., T., W., A., E., A., T., B., M., D., J., E., C., F., M., F., R., F., V. M., G., J., H., N., H., J., H., M., J., W., K., V., K., M., K., et al.. - In: PHYSICAL REVIEW D, PARTICLES, FIELDS, GRAVITATION, AND COSMOLOGY. - ISSN 1550-7998. - 86:11(2012). [10.1103/physrevd.86.112003]

Combined search for the quarks of a sequential fourth generation

BARONE, Luciano Maria;DEL RE, Daniele;LONGO, Egidio;MICHELI, FRANCESCO;ORGANTINI, Giovanni;PARAMATTI, Riccardo;RAHATLOU, SHAHRAM;SOFFI, LIVIA;SANTANASTASIO, FRANCESCO;TRACZYK, PIOTR WOJCIECH;
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. DOI: 10.1103/PhysRevD.86.112003
2012
01 Pubblicazione su rivista::01a Articolo in rivista
Combined search for the quarks of a sequential fourth generation / S., C., V., K., A. M., S., A., T., W., A., E., A., T., B., M., D., J., E., C., F., M., F., R., F., V. M., G., J., H., N., H., J., H., M., J., W., K., V., K., M., K., et al.. - In: PHYSICAL REVIEW D, PARTICLES, FIELDS, GRAVITATION, AND COSMOLOGY. - ISSN 1550-7998. - 86:11(2012). [10.1103/physrevd.86.112003]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/530915
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