Abstract
Quark partners with non-chiral couplings appear in several extensions of the Standard Model. They may have non-trivial generational structure to their couplings, and may be produced either in pairs via the strong and EM interactions, or singly via the new couplings of the model. Their decays often produce heavy quarks and gauge bosons, which will contribute to a variety of already-measured ``Standard Model'' cross-sections at the LHC. We present a study of the sensitivity of such published LHC measurements to vector-like quarks, first comparing to limits already obtained from dedicated searches, and then broadening to some so-far unstudied parameter regions.
Highlights
Quark partners with vector-like couplings to the weak sector (VLQs) may exist with masses close enough to the electroweak scale that they can help solve the hierarchy problem, and yet they evade many experimental constraints since their mass is not necessarily acquired via the Brout-Englert-Higgs mechanism [1]
VLQs can be motivated by a variety of higherenergy extensions to the Standard Model (SM), and strategies for discovering them have been developed at both the Tevatron [2] and the LHC [3, 4]
In this paper we examine the sensitivity of available particle-level measurements to VLQs, using the CONTUR framework [10] 1 to inject signal into results of LHC analyses present in the RIVET library [12, 13], and derive constraints using the confidence level (CL) technique [14]
Summary
Quark partners with vector-like couplings to the weak sector (VLQs) may exist with masses close enough to the electroweak scale that they can help solve the hierarchy problem, and yet they evade many experimental constraints since their mass is not necessarily acquired via the Brout-Englert-Higgs mechanism [1]. The allowed parameter space is quite tightly constrained by theory, and searches at the LHC have set lower limits of 1 TeV to 1.3 TeV on their masses, for various scenarios within this framework [5,6,7,8,9]. Searches at the LHC have assumed the VLQs couple only to the third generation of SM quarks, since this is the scenario least constrained by previous measurements [4]. 4, we extend beyond this simplest model, and study the sensitivity for all four VLQs active, with degenerate masses, again for the case of coupling to only the third generation of SM quarks. A selection of non-standard VLQ and leptoquark signatures in different models was studied in contribution 5 of Ref. [11], showing some interesting sensitivity to these models
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