Measurement of the top quark mass in the dileptonic ttbar decay channel using the mass observables Mbl, MT2, and Mblv in pp collisions at sqrt(s) = 8 TeV

A measurement of the top quark mass (Mt) in the dileptonic tt decay channel is performed using data from proton-proton collisions at a center-of-mass energy of 8 TeV. The data was recorded by the CMS experiment at the LHC and corresponding to an integrated luminosity of 19.7± 0.5 fb−1. Events are selected with two oppositely charged leptons (` = e, μ) and two jets identified as originating from b quarks. The analysis is based on three kinematic observables whose distributions are sensitive to the value of Mt. An invariant mass observable, Mb`, and a ‘stransverse mass’ observable, MT2, are employed in a simultaneous fit to determine the value of Mt and an overall jet energy scale factor (JSF). A complementary approach is used to construct an invariant mass observable, Mb`ν, that is combined with MT2 to measure Mt. The shapes of the observables, along with their evolutions in Mt and JSF, are modeled by a nonparametric Gaussian process regression technique. The sensitivity of the observables to the value of Mt is investigated using a Fisher information density method. The top quark mass is measured to be 172.22± 0.18 (stat) +0.89 −0.93 (syst) GeV. Submitted to Physical Review D c © 2017 CERN for the benefit of the CMS Collaboration. CC-BY-3.0 license ∗See Appendix C for the list of collaboration members ar X iv :s ub m it/ 18 68 61 8 [ he pex ] 2 0 A pr 2 01 7

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