Search for pair production of excited top quarks in the lepton + jets final state

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A search is performed for pair-produced spin-3/2 excited top quarks ((t∗\overline{t}∗)), each decaying to a top quark and a gluon. The search uses data collected with the CMS detector from pp collisions at a center-of-mass energy of (\sqrt{s})=8TeV, selecting events that have a single isolated muon or electron, an imbalance in transverse momentum, and at least six jets, of which one must be compatible with originating from the fragmentation of a b quark. The data, corresponding to an integrated luminosity of 19.5 fb⁻¹, show no significant excess over standard model predictions, and provide a lower limit of 803 GeV at 95% confidence on the mass of the spin-3/2 t * quark in an extension of the Randall-Sundrum model, assuming a 100% branching fraction of its decay into a top quark and a gluon. This is the first search for a spin-3/2 excited top quark performed at the LHC.

High Energy Physics - Experiment, Hadron-Hadron Scattering, Top physics
Chatrchyan, S., Khachatryan, V., Sirunyan, A. M., Tumasyan, A., Adam, W., Bergauer, T., Dragicevic, M., Erö, J., Fabjan, C., Friedl, M., Frühwirth, R., Ghete, V. M., Hörmann, N., Hrubec, J., Jeitler, M., Kiesenhofer, W., Knünz, V., Krammer, M., … Swanson, J. (2014). Search for pair production of excited top quarks in the lepton + jets final state. In Journal of High Energy Physics (Vol. 2014, Issue 6). Springer Science and Business Media LLC.