Measurement of the differential jet production cross section with respect to jet mass and transverse momentum in dijet events from pp collisions at $\sqrt{s}$ = 13 TeV

A measurement of the differential jet production cross section as a function of the jet mass and transverse momentum is presented in events with a dijet topology, with and without a jet grooming algorithm applied that selectively removes low-energy portions from a jet. For ungroomed jets, all Monte Carlo event generators are found to predict the jet mass spectrum within uncertainties in the data for intermediate masses of about $10-30\%$ of the jet transverse momentum. Outside of this range, some disagreement is observed. For groomed jets, the jet mass peak is suppressed and the precision in the low and intermediate regions improves, since the grooming algorithm removes the portions of the jet arising from soft radiation that are difficult to model. Semi-analytical calculations beyond next-to-leading logarithmic accuracy of the groomed jet mass are also compared to the data for the first time at a hadron collider. These calculations are found to predict the data within their uncertainties below a jet mass of about $30\%$ of a jet's transverse momentum, where wide jets start to be split into two. Below jet masses of 20 GeV the predicted cross sections tend to be somewhat smaller than measured in data.