TY - JOUR

T1 - Measurement of the c-jet mistagging efficiency in $$t\bar{t}$$ events using pp collision data at $$\sqrt{s}=13$$ $$\text {TeV}$$ collected with the ATLAS detector

AU - ATLAS Collaboration

AU - Barton, A.E.

AU - Bertram, I.A.

AU - Borissov, G.

AU - Bouhova-Thacker, E.V.

AU - Fox, H.

AU - Henderson, R.C.W.

AU - Jones, R.W.L.

AU - Kartvelishvili, V.

AU - Love, P.A.

AU - Muenstermann, D.

AU - Sanderswood, Izaac

AU - Smizanska, M.

AU - Wharton, A.M.

AU - Yexley, Melissa

PY - 2022/1/31

Y1 - 2022/1/31

N2 - A technique is presented to measure the efficiency with which c-jets are mistagged as b-jets (mistagging efficiency) using $$t\bar{t}$$ t t ¯ events, where one of the W bosons decays into an electron or muon and a neutrino and the other decays into a quark–antiquark pair. The measurement utilises the relatively large and known $$W\rightarrow cs$$ W → c s branching ratio, which allows a measurement to be made in an inclusive c-jet sample. The data sample used was collected by the ATLAS detector at $$\sqrt{s} = 13$$ s = 13 $$\text {TeV}$$ TeV and corresponds to an integrated luminosity of 139 fb$$^{-1}$$ - 1 . Events are reconstructed using a kinematic likelihood technique which selects the mapping between jets and $$t\bar{t}$$ t t ¯ decay products that yields the highest likelihood value. The distribution of the b-tagging discriminant for jets from the hadronic W decays in data is compared with that in simulation to extract the mistagging efficiency as a function of jet transverse momentum. The total uncertainties are in the range 3–17%. The measurements generally agree with those in simulation but there are some differences in the region corresponding to the most stringent b-jet tagging requirement.

AB - A technique is presented to measure the efficiency with which c-jets are mistagged as b-jets (mistagging efficiency) using $$t\bar{t}$$ t t ¯ events, where one of the W bosons decays into an electron or muon and a neutrino and the other decays into a quark–antiquark pair. The measurement utilises the relatively large and known $$W\rightarrow cs$$ W → c s branching ratio, which allows a measurement to be made in an inclusive c-jet sample. The data sample used was collected by the ATLAS detector at $$\sqrt{s} = 13$$ s = 13 $$\text {TeV}$$ TeV and corresponds to an integrated luminosity of 139 fb$$^{-1}$$ - 1 . Events are reconstructed using a kinematic likelihood technique which selects the mapping between jets and $$t\bar{t}$$ t t ¯ decay products that yields the highest likelihood value. The distribution of the b-tagging discriminant for jets from the hadronic W decays in data is compared with that in simulation to extract the mistagging efficiency as a function of jet transverse momentum. The total uncertainties are in the range 3–17%. The measurements generally agree with those in simulation but there are some differences in the region corresponding to the most stringent b-jet tagging requirement.

KW - Physics and Astronomy (miscellaneous)

KW - Engineering (miscellaneous)

U2 - 10.1140/epjc/s10052-021-09843-w

DO - 10.1140/epjc/s10052-021-09843-w

M3 - Journal article

VL - 82

JO - European Physical Journal C

JF - European Physical Journal C

IS - 1

M1 - 95

ER -