Extracting a short distance top mass with light grooming

Self Cite

We provide a quantum field theory based description of the nonperturbative effects from hadronization for soft drop groomed jet mass distributions using the soft-collinear effective theory and the coherent branching formalism. There are two distinct regions of jet mass m J where grooming modifies hadronization effects. In a region with intermediate m J an operator expansion can be used, and the leading power corrections are given by three universal nonperturbative parameters that are independent of all kinematic variables and grooming parameters, and only depend on whether the parton initiating the jet is a quark or gluon. The leading power corrections in this region cannot be described by a standard normalized shape function. These power corrections depend on the kinematics of the subjet that stops soft drop through short distance coefficients, which encode a perturbatively calculable dependence on the jet transverse momentum, jet rapidity, and on the soft drop grooming parameters z cut and β. Determining this dependence requires a resummation of large logarithms, which we carry out at LL order. For smaller m J there is a nonperturbative region described by a one-dimensional shape function that is unusual because it is not normalized to unity, and has a non-trivial dependence on β. A Measurement Operator for the Boundary Term 62 B Collinear-Soft Function with a Probe Nonperturbative Gluon 64 B.1 Analysis with One Perturbative Gluon 64 B.2 Analysis with Two Perturbative Emissions 67 -1 -soft drop operator expansion (SDOE) region: QΛ QCD m 2 J m 2 J QQ cut 1 2+β Figure 2. Pythia prediction for m 2 J /E 2 J distribution indicating three different regions of the spectrum. Here we take R ee 0 = π 2 and the inequality " " in the "p + cs p + Λ " constraint for the SDOE region is replaced by a factor of 5.In Fig. 2 we show a Pythia8 Monte Carlo prediction for this groomed jet mass spectrum with z cut = 0.1 and β = 2. We distinguish three relevant regions of the spectrum: the soft drop nonperturbative region (SDNP) to the far left (left of the magenta dashed line), the soft drop operator expansion region (SDOE) in the middle (between the dashed lines), and the ungroomed resummation region on the far right where soft drop turns off but the log resummation for the ungroomed case is still active (right of the green dashed line). The distinction between the SDNP and SDOE regions is determined by Eq. (1.1), while the distinction between the SDOE and ungroomed resummation region is given by soft drop operator expansion (SDOE):ungroomed resummation region:For the hemisphere case in e + e − one has R = π/2. For R = 1, in the e + e − case this boundary roughly corresponds to m 2 J /E 2 J = z cut which we use in Fig. 2. In all three of these regions the resummation of large logarithms is important, though the precise nature of this resummation is different. There is an additional transition between resummation and fixed-order regions which occurs on the very far right of Fig. 2, near where dσ/dm J goes to zero (not indicated in th...

Section: Resultsmentioning

confidence: 61%

“…Resummation of the soft drop jet mass for top jets was studied in Ref. [62] and e (α) 2 for bottom quarks in Ref. [63].…”

Section: Contentsmentioning

confidence: 99%

See 1 more Smart Citation

Nonperturbative corrections to soft drop jet mass

Hoang

Mantry

Pathak

et al. 2019

Self Cite

“…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].…”

Section: Introductionmentioning

confidence: 99%

The soft drop groomed jet radius at NLL

Kang

Lee

Liu

et al. 2020

We present results for the soft drop groomed jet radius R g at next-to-leading logarithmic accuracy. The radius of a groomed jet which corresponds to the angle between the two branches passing the soft drop criterion is one of the characteristic observables relevant for the precise understanding of groomed jet substructure. We establish a factorization formalism that allows for the resummation of all relevant large logarithms, which is based on demonstrating the all order equivalence to a jet veto in the region between the boundaries of the groomed and ungroomed jet. Non-global logarithms including clustering effects due to the Cambridge/Aachen algorithm are resummed to all orders using a suitable Monte Carlo algorithm. We perform numerical calculations and find a very good agreement with Pythia 8 simulations. We provide theoretical predictions for the LHC and RHIC.

“…Developments in jet substructure (see [36] for a recent review) have shown that the modified mass drop tagging algorithm (mMDT) or soft-drop grooming procedure robustly removes contamination from both underlying event and non-global color-correlations, see Refs. [21,22,37], and have been applied to study a wide variety of QCD phenomenology within jets [38][39][40][41][42][43][44][45][46].…”

Section: Introductionmentioning

confidence: 99%

Predictions for energy correlators probing substructure of groomed heavy quark jets

Lee

Shrivastava

Vaidya

2019

We develop an effective field theory (EFT) framework to perform an analytic calculation for energy correlator observables computed on groomed heavy-quark jets. A soft-drop grooming algorithm is applied to a jet initiated by a massive quark to minimize soft contamination effects such as pile-up and multi-parton interactions. We specifically consider the two-particle energy correlator as an initial application of this EFT framework to compute heavy quark jet substructure. We find that there are different regimes for the event shapes, depending on the size of the measured correlator observable, that require the use of different EFT formulations, in which the quark mass and grooming parameters may be relevant or not. We use the EFT to resum large logarithms in the energy correlator observable in terms of the momentum of a reconstructed heavy hadron to NLL accuracy and subsequently match it to a full QCD O(α s ) cross section, which we also compute. We compare our predictions to simulations in Pythia for e + e − collisions. We find a good agreement with partonic simulations, as well as hadronic ones with an appropriate shape function used to describe nonperturbative effects and the heavy quark hadron decay turned off. We also predict the scaling behavior for the leading nonperturbative power correction due to hadronization. Consequently, we can give a prediction for the energy correlator distribution at the level of the reconstructed heavy hadron. This work provides a general framework for the analysis of heavy quark jet substructure observables.