Jet angularity measurements for single inclusive jet production

Abstract

We study jet angularity measurements for single-inclusive jet production at the LHC. Jet angularities depend on a continuous parameter a allowing for a smooth interpolation between different traditional jet shape observables. We establish a factorization theorem within Soft Collinear Effective Theory (SCET) where we consistently take into account in-and out-of-jet radiation by making use of semi-inclusive jet functions. For comparison, we elaborate on the differences to jet angularities measured on an exclusive jet sample. All the necessary ingredients for the resummation at next-to-leading logarithmic (NLL) accuracy are presented within the effective field theory framework. We expect semiinclusive jet angularity measurements to be feasible at the LHC and we present theoretical predictions for the relevant kinematic range. In addition, we investigate the potential impact of jet angularities for quark-gluon discrimination.

The groomed and ungroomed jet mass distribution for inclusive jet production at the LHC

“…In this section, we present the factorization formalism of the ungroomed jet mass distribution for single inclusive jet production. We closely follow the arguments provided recently in [52] where jet angularities were discussed for inclusive jets. The jet mass distribution is a special case of the jet angularity observables τ a with a = 0.…”

“…The jet mass distribution is a special case of the jet angularity observables τ a with a = 0. See [52] for more detailed discussions. In the small jet mass limit, the factorization procedure involves two steps.…”

“…The functions G c (z, p T , R, τ, µ) are the semi-inclusive jet mass functions (siJMFs), which describe how a parton c initiates the signal jet that carries a momentum fraction z of that parton, and at the same time the jet mass τ is observed. Following earlier work [52,[56][57][58][59], the siJMFs are defined at the operator level as follows…”

“…At the same time, any hard-collinear emission of the order p T R has to be outside the jet as they would otherwise violate the hierarchy τ R 2 , and thus do not contribute to the jet mass. In summary we obtain the following factorization for the siJMFs [52]…”

Heavy quark jet fragmentation

“…(1.1) and the jet fragmentation function (JFF) [4], where the JFF describes the fragmentation within a jet to a particular hadron or a subjet, and has been widely studied [2,4,[9][10][11][12][13][14][15] on the basis of the theoretical results for the fragmenting jet functions [16][17][18]. Also, through the FFJs, we can consider the mass distribution [19][20][21] and the transverse momentum distribution (to a jet axis) [22,23] for a jet with a given p T .…”