Measurement of the jet mass in highly boosted t t-bar events from pp collisions at sqrt(s) = 8 TeV

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The first measurement of the jet mass m[jet] of top quark jets produced in t t-bar events from pp collisions at sqrt(s) = 8 TeV is reported for the jet with the largest transverse momentum pt in highly boosted hadronic top quark decays.

• The data sample, collected with the CMS detector, corresponds to an integrated luminosity of 19.7 inverse femtobarns.
• The measurement is performed in the lepton+jets channel in which the products of the semileptonic decay t to bW with W to l nu where l is an electron or muon, are used to select t t-bar events with large Lorentz boosts.
• The products of the fully hadronic decay t to bW with W to q q'-bar are reconstructed using a single Cambridge-Aachen jet with distance parameter R = 1.2, and pt > 400 GeV.