Measurement of the Soft-Drop Jet Mass in pp Collisions at s=13  TeV with the ATLAS Detector

Abstract

Jet substructure observables have significantly extended the search program for physics beyond the standard model at the Large Hadron Collider. The state-of-the-art tools have been motivated by theoretical calculations, but there has never been a direct comparison between data and calculations of jet substructure observables that are accurate beyond leading-logarithm approximation. Such observables are significant not only for probing the collinear regime of QCD that is largely unexplored at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many studies at the Large Hadron Collider. This Letter documents a measurement of the first jet substructure quantity at a hadron collider to be calculated at next-to-next-to-leading-logarithm accuracy. The normalized, differential cross section is measured as a function of log_{10}ρ^{2}, where ρ is the ratio of the soft-drop mass to the ungroomed jet transverse momentum. This quantity is measured in dijet events from 32.9 fb^{-1} of sqrt[s]=13 TeV proton-proton collisions recorded by the ATLAS detector. The data are unfolded to correct for detector effects and compared to precise QCD calculations and leading-logarithm particle-level Monte Carlo simulations.

Implications of the LHCb discovery of CP violation in charm decays

“…• We note that mid-range masses for the charged scalar (450 GeV ∼ < m φ − ∼ < a few TeV) are constrained by LHC dijet searches [17][18][19]. These would result in a further constraint in the (|λ|, m φ 0 ) plane, depending on the mass splitting between the neutral and charged scalars.…”

Nonperturbative corrections to soft drop jet mass

“…Theoretically, the most widely studied jet groomer is the soft drop algorithm [48] (which includes as a special case the earlier modified mass drop algorithm [45,50]). Soft drop groomed observables have been recently measured by ATLAS [51] and CMS [52]. Perturbative methods have been developed to carry out calculations for groomed jets [50,[53][54][55][56], and soft-drop factorization theorems have been derived for D 2 [57], the 2-point energy correlator, e (α) 2 [55], and the jet-mass and angularities for inclusive jets [58,59].…”

The soft drop groomed jet radius at NLL

“…In this work, we focus on the soft drop grooming algorithm of [4]. Both on the experimental [5][6][7][8] and the theoretical side [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24], significant progress has been made recently in improving our understanding of soft drop groomed jet observables. In the heavy-ion community, soft drop groomed jet substructure observables have also received increasing attention from both experiment [25][26][27][28] and theory [29][30][31][32][33][34][35][36][37][38][39].…”