Search for single production of vector-like quarks decaying into a b quark and a W boson in proton–proton collisions at s=13TeV

Abstract

A search is presented for a heavy vector-like quark, decaying into a b quark and a W boson, which is produced singly in association with a light flavor quark and a b quark. The analysis is performed using a data sample of proton-proton collisions at a center-of-mass energy of √ s = 13 TeV collected at the LHC in 2015. The data set used in the analysis corresponds to an integrated luminosity of 2.3 fb −1 . The search is carried out using events containing one electron or muon, at least one b-tagged jet with large transverse momentum, at least one jet in the forward region of the detector, and missing transverse momentum. No excess over the standard model prediction is observed. Upper limits are placed on the production cross section of heavy exotic quarks: a T quark with a charge of 2/3, and a Y quark with a charge of −4/3. For Y quarks with coupling of 0.5 and B(Y → bW) = 100%, the observed (expected) lower mass limits are 1.40 (1.0) TeV. This is the most stringent limit to date on the single production of the Y vector-like quark.

Searching for dark photons with maverick top partners

“…Never-the-less, for completeness we summarize their results here. In these traditional modes, the LHC excludes VLQ masses M T 1.1 − 1.4 TeV in pair production searches [55][56][57] and M T 1 − 1.2 TeV in single production searches [58][59][60]. Single production of an SU (2) L singlet T depends on the mixing angle θ t L and decouples as θ t L → 0 [16] weakening the above limit.…”

Single production of vectorlike quarks with large width at the Large Hadron Collider

“…A set of kinematical cuts are also imposed, and we refer to [67] for all the relevant details. In table 2 we compare the efficiencies obtained by our recast implementation with the ones reported by [67] under the same signal assumptions of the experimental search. We stress that, for the purposes of this study, we are not interested in an overly precise reconstruction of the experimental results: our intent is to achieve a realistic analysis framework to demonstrate how to reinterpret experimental data in scenarios where the VLQs have a large width.…”

“…In Fig. 9 the values ofσ S,eff andσ int SB irr ,eff are provided for the signal and for the interference term in the case of dominant LH chirality, considering the signal region targeting final states with an electron in the CMS search [67]. With such information and with the knowledge of the total background B (from experimental data), it is possible to reconstruct the number of events for S + B for each point in the (MQ, ΓQ/MQ) plane through Eqs.…”

Probing light top partners with CP violation

“…This explains the significantly lower bound with respect to the CMS analysis, which instead exploits 35.9/fb integrated luminosity. 10 Experimental searches for singly-produced heavy quarks decaying into Z t/b [82,83], h t/b [84,85] and W b [86,87] are also available in the literature. The bounds from these searches on fourplet top partners are however weaker than the ones we derived with the recast of the same-sign dilepton searches.…”