Measurement of b-jet Shapes in Inclusive Jet Production in p pbar Collisions at sqrt{s} = 1.96 TeV

TL;DR

This paper measures the shapes of b-jets in proton-antiproton collisions at 1.96 TeV, revealing that actual b-jet shapes are broader than predictions from common Monte Carlo simulations, indicating potential modeling inaccuracies.

Contribution

First measurement of b-jet shapes over a wide transverse momentum range in p pbar collisions at 1.96 TeV, highlighting discrepancies with Monte Carlo models.

Findings

b-jets are broader than inclusive jets

b-jets with a single b-quark are narrower than those with b bbar pairs

Monte Carlo simulations underestimate the fraction of gluon splitting b-jets

Abstract

We present a measurement of the shapes of b-jets using 300 pb-1 of data obtained with the upgraded Collider Detector at Fermilab (CDF II) in p pbar collisions at center of mass energy sqrt{s}=1.96 TeV. This measurement covers a wide transverse momentum range, from 52 to 300 GeV/c. Samples of heavy-flavor enhanced jets together with inclusive jets are used to extract the average shapes of b-jets. The b-jets are expected to be broader than inclusive jets. Moreover, b-jets containing a single b-quark are expected to be narrower than those containing a b bbar pair from gluon splitting. The measured b-jet shapes are found to be significantly broader than expected from the PYTHIA and HERWIG Monte Carlo simulations. This effect may arise from an underestimation of the fraction of b-jets originating from gluon splitting in these simulations.