Search for Anomalous Wtb Couplings and Flavour-Changing Neutral Currents in t-Channel Single Top Quark Production in Pp Collisions at √s = 7 and 8 TeV

• Main Authors: CMS Collaboration (Author), Abercrombie, Daniel Robert (Contributor), Allen, Brandon Leigh (Contributor), Apyan, Aram (Contributor), Barbieri, Richard Alexander (Contributor), Baty, Austin Alan (Contributor), Bi, Ran (Contributor), Bierwagen, Katharina (Contributor), Brandt, Stephanie Akemi (Contributor), Busza, Wit (Contributor), Cali, Ivan Amos (Contributor), Demiragli, Zeynep (Contributor), Di Matteo, Leonardo (Contributor), Gomez-Ceballos, Guillelmo (Contributor), Goncharov, Maxim (Contributor), Hsu, Dylan George (Contributor), Iiyama, Yutaro (Contributor), Innocenti, Gian Michele (Contributor), Klute, Markus (Contributor), Kovalskyi, Dmytro (Contributor), Krajczar, Krisztian F. (Contributor), Lai, Yue Shi (Contributor), Lee, Yen-Jie (Contributor), Levin, Amy Elizabeth (Contributor), Luckey Jr, P David (Contributor), Marini, Andrea Carlo (Contributor), McGinn, Christopher Francis (Contributor), Mironov, Camelia Maria (Contributor), Narayanan, Siddharth Madhavan (Contributor), Niu, Xinmei (Contributor), Paus, Christoph M. E. (Contributor), Roland, Christof E (Contributor), Roland, Gunther M (Contributor), Salfeld-Nebgen, Jakob Maxillian Henry (Contributor), Stephans, George S. F. (Contributor), Sumorok, Konstanty C (Contributor), Tatar, Kaya (Contributor), Varma, Mukund Madhav (Contributor), Velicanu, Dragos Alexandru (Contributor), Veverka, Jan (Contributor), Wang, Jing (Contributor), Wang, Ta-Wei (Contributor), Wyslouch, Boleslaw (Contributor), Yang, Ming (Contributor), Wyslouch, Victoria (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Nuclear Science and Engineering (Contributor), Massachusetts Institute of Technology. Department of Physics (Contributor), Massachusetts Institute of Technology. Laboratory for Nuclear Science (Contributor)
• Format: Article
• Language: English
• Published: Springer Nature, 2018-10-16T14:25:50Z.
• Subjects: Article
• Online Access: Get fulltext

Single top quark events produced in the t channel are used to set limits on anomalous Wtb couplings and to search for top quark flavour-changing neutral current (FCNC) interactions. The data taken with the CMS detector at the LHC in proton-proton collisions at √s = 7 and 8 TeV correspond to integrated luminosities of 5.0 and 19.7 fb⁻¹, respectively. The analysis is performed using events with one muon and two or three jets. A Bayesian neural network technique is used to discriminate between the signal and backgrounds, which are observed to be consistent with the standard model prediction. The 95% confidence level (CL) exclusion limits on anomalous right-handed vector, and left- and right-handed tensor Wtb couplings are measured to be |fVR| < 0.16, |fTL| < 0.057, and − 0.049 < fTR< 0.048, respectively. For the FCNC couplings κtugand κtcg, the 95% CL upper limits on coupling strengths are |κtug|/Λ < 4.1 × 10⁻³TeV⁻¹and |κtcg|/Λ < 1.8 × 10⁻²TeV⁻¹, where Λ is the scale for new physics, and correspond to upper limits on the branching fractions of 2.0 × 10⁻⁵ and 4.1 × 10⁻⁴ for the decays t → ug and t → cg, respectively. Keywords: Flavour Changing Neutral Currents; Hadron-Hadron scattering (experiments); Top physics