Measurement of CKM matrix elements in single top quark t-channel production in proton-proton collisions at root s=13 TeV

Sirunyan A. M. , Tumasyan A., Adam W., Ambrogi F., Bergauer T., Brandstetter J., ...More

PHYSICS LETTERS B, vol.808, 2020 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 808
  • Publication Date: 2020
  • Doi Number: 10.1016/j.physletb.2020.135609
  • Title of Journal : PHYSICS LETTERS B


The first direct, model-independent measurement is presented of the modulus of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements vertical bar V-tb vertical bar, vertical bar V-td vertical bar, and vertical bar V-ts vertical bar, in final states enriched in single top quark t-channel events. The analysis uses proton-proton collision data from the LHC, collected during 2016 by the CMS experiment, at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1). Processes directly sensitive to these matrix elements are considered at both the production and decay vertices of the top quark. In the standard model hypothesis of CKM unitarity, a lower limit of vertical bar V-tb vertical bar > 0.970 is measured at the 95% confidence level. Several theories beyond the standard model are considered, and by releasing all constraints among the involved parameters, the values vertical bar V-tb vertical bar = 0.988 +/- 0.024, and vertical bar V-td vertical bar(2) + vertical bar V-ts vertical bar(2) = 0.06 +/- 0.06, where the uncertainties include both statistical and systematic components, are measured. (C) 2020 The Author. Published by Elsevier B.V.