# Exclusion of an Exotic Top Quark with -4/3 Electric Charge Using Soft Lepton Tagging

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http://hdl.handle.net/10138/24033

#### Citation

Aaltonen , T , Mehtälä , P , Orava , R , Saarikko , H , Österberg , K & CDF Collaboration 2010 , ' Exclusion of an Exotic Top Quark with -4/3 Electric Charge Using Soft Lepton Tagging ' , Physical Review Letters , vol. 105 , no. 10 , pp. 101801 . https://doi.org/10.1103/PhysRevLett.105.101801

 Title: Exclusion of an Exotic Top Quark with -4/3 Electric Charge Using Soft Lepton Tagging Alternative title: Exclusion of an Exotic Top Quark with -4/3 Electric Charge Using Soft Lepton Tagging Author: Aaltonen, Timo; Mehtälä, Petteri; Orava, Risto; Saarikko, Heimo; Österberg, Kenneth; CDF Collaboration Contributor organization: Department of PhysicsHelsinki Institute of Physics Date: 2010 Language: eng Number of pages: 7 Belongs to series: Physical Review Letters ISSN: 0031-9007 DOI: https://doi.org/10.1103/PhysRevLett.105.101801 URI: http://hdl.handle.net/10138/24033 Abstract: We present a measurement of the electric charge of the top quark using $\ppbar$ collisions corresponding to an integrated luminosity of 2.7~fb$^{-1}$ at the CDF II detector. We reconstruct $\ttbar$ events in the lepton+jets final state and use kinematic information to determine which $b$-jet is associated with the leptonically- or hadronically-decaying $t$-quark. Soft lepton taggers are used to determine the $b$-jet flavor. Along with the charge of the $W$ boson decay lepton, this information permits the reconstruction of the top quark's electric charge. Out of 45 reconstructed events with $2.4\pm0.8$ expected background events, 29 are reconstructed as $\ttbar$ with the standard model $+$2/3 charge, whereas 16 are reconstructed as $\ttbar$ with an exotic $-4/3$ charge. This is consistent with the standard model and excludes the exotic scenario at 95\% confidence level. This is the strongest exclusion of the exotic charge scenario and the first to use soft leptons for this purpose.We present a measurement of the electric charge of the top quark using pp̅ collisions corresponding to an integrated luminosity of 2.7  fb-1 at the CDF II detector. We reconstruct tt̅ events in the lepton+jets final state. We use soft lepton taggers to determine the flavor of the b jets, which we use to reconstruct the top quark’s electric charge and exclude an exotic top quark with -4/3 charge at 95% confidence level. This is the strongest exclusion of the exotic charge scenario and the first to use soft leptons for this purpose. Subject: 114 Physical sciences Peer reviewed: Yes Usage restriction: restrictedAccess
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