Pull is a jet observable that is sensitive to color flow between dipoles. It has seen wide use for discrimination of particles with similar decay topologies but carrying different color representations and has been measured on W bosons from top quark decays by the D∅ and ATLAS experiments. In this paper, we present the first theoretical predictions of pull, focusing on a color-singlet decaying in two jets. The pull angle observable is particularly sensitive to color flow, but is not infrared and collinear safe and so cannot be calculated in fixed-order perturbation theory. Nevertheless, all-orders resummation renders its distribution finite, a property referred to as Sudakov safety. In our prediction of the pull angle we also include an estimation of the effects from hadronization, and directly compare our results to simulation and experimental data.Determining the short-distance origin of jets, manifestations of high energy quantum chromodynamics (QCD), is a problem of foremost importance at the Large Hadron Collider (LHC). Some quantum numbers, such as the mass or electric charge, are relatively straightforward to measure at the LHC. Determining the color representation of a jet or collection of jets, however, is highly nontrivial because the particles that carry color quantum numbers, quarks and gluons, are not directly observable in experiment. The color representation must be inferred through its effect on kinematic distributions. The observable pull [1], and derivative quantities, is a widely used observable sensitive to the color representation. Pull is a two-dimensional vector that points in the direction of dominant energy flow about a jet of interest that is particularly useful for determining if two jets form a colorsinglet dipole, i.e. whether they originate from the decay of resonance that carries no color, such as an electroweak boson. In a color-singlet dipole, emissions lie between the ends of the dipole; therefore the pull vector would point along the line that connects the momentum vectors of the jets.In this Letter, we present the first analytic predictions from first-principles QCD for the pull vector. We focus on the calculation of the pull vector for color-singlet dipoles, as this is the case that has been studied experimentally in detail. The most useful feature of the pull vector for studying color dipoles is the pull angle, which is the azimuthal angle about one of the jets in a pair with respect to the line connecting the jets. Both D∅ and ATLAS experiments have measured the pull angle in the boosted, hadronic decays of W bosons from top quark decay [2][3][4]. It has been found that state-ofthe-art general-purpose Monte Carlo simulations provide an unsatisfactory description of the data, thus indicating the need for dedicated first-principle calculations in QCD. However, unlike most theoretically-studied observables for jet physics, the pull angle lacks the property of infrared and collinear (IRC) safety, and so its distribution cannot be calculated in the fixed-order perturbation theory...

Jet pull is an observable designed to probe colour flow between jets. Thus far, a particular projection of the pull vector, the pull angle, has been employed to distinguish colour flow between jets produced by a colour singlet or an octet decay. This is of particular importance in order to separate the decay of a Higgs boson to a pair of bottom quarks from the QCD background. However, the pull angle is not infra-red and collinear (IRC) safe. In this paper we introduce IRC safe projections of the pull vector that exhibit good sensitivity to colour flow, while maintaining calculability. We calculate these distributions to next-to-leading logarithmic accuracy, in the context of the hadronic decay of a Higgs boson, and compare these results to Monte Carlo simulations. This study allows us to define an IRC safe version of the pull angle in terms of asymmetry distributions. Furthermore, because of their sensitivity to wide-angle soft radiation, we anticipate that these asymmetries can play an important role in assessing subleading colour correlations and their modelling in general-purpose Monte Carlo parton showers.