Search for the production of an excited bottom quark decaying to tW in proton-proton collisions at sqrt(s) = 8 TeV

TL;DR

This paper reports a search for excited bottom quarks decaying to top and W bosons in proton-proton collisions at 8 TeV, setting new mass exclusion limits and constraining their production and decay couplings.

Contribution

First search to set mass limits on excited bottom quarks decaying to tW in all-hadronic, lepton+jets, and dilepton channels at 8 TeV with CMS data.

Findings

No significant excess observed over standard model expectations.

Excluded b* quark masses below 1390, 1430, and 1530 GeV for different coupling scenarios.

Set the most stringent limits on b* quark mass to date.

Abstract

A search is presented for a singly produced excited bottom quark (b*) decaying to a top quark and a W boson in the all-hadronic, lepton + jets, and dilepton final states in proton-proton collisions at sqrt(s) = 8 TeV recorded by the CMS experiment at the CERN LHC. Data corresponding to an integrated luminosity of 19.7 inverse femtobarns are used. No significant excess of events is observed with respect to standard model expectations. We set limits at 95% confidence on the product of the b* quark production cross section and its branching fraction to tW. The cross section limits are interpreted for scenarios including left-handed, right-handed, and vector-like couplings of the b* quark and are presented in the two-dimensional coupling plane based on the production and decay coupling constants. The masses of the left-handed, right-handed, and vector-like b* quark states are excluded at 95% confidence below 1390, 1430, and 1530 GeV, respectively, for benchmark couplings. This analysis gives the most stringent limits on the mass of the b* quark to date.