Measuring the bottom-quark forward-central asymmetry at the LHC

Abstract

Measurements of the top quark forward-backward asymmetry performed at the Tevatron suggest that new-physics may be playing a role in tt production. To better understand the source of the asymmetry, recent proposals have called for a measurement of the bottom and charm forwardbackward asymmetries at the Tevatron, using jets with embedded muons. Here we propose a corresponding measurement of the bottom quark forward-central asymmetry designed to look for similar effects in the b-sector at ATLAS and CMS. We construct a set of cuts designed to enhance sensitivity to this asymmetry, and test our analysis on a toy axigluon model representative of those used to explain the top asymmetry. We find that if the relevant new-physics couplings to the bottom quark are similar to those of the top, then the effects should be visible at the 2σ level in less than 10 fb −1 of 7 TeV LHC data. Such a measurement would be of general importance, and would provide valuable model-building input, serving to restrict the set of models put forward to explain the Tevatron tt anomaly. However, a relatively low trigger threshold on non-isolated muons inside hard jets must be maintained to allow for this measurement.

Bottom-Quark Forward-Backward Asymmetry in the Standard Model and Beyond

“…In the fourth column the first uncertainty is due to neglect of higher-order terms, and the second is the combined scale uncertainty. The uncertainty in the O(α 2 /α Based on CDF's expected sensitivities [7] and assuming the Standard Model (and the measurements follow a Gaussian distribution), CDF should be able to exclude A It has been suggested [5,6] that measuring the charm-quark forward-backward asymmetry at the Tevatron (A , the kinematic regions where the asymmetry becomes a few percent have small production cross sections, and will require the LHC to run for at least a year at 14 TeV to collect enough data for the SM asymmetry to be statistically distinguishable from zero. Furthermore, the EW contribution to the cross section in these kinematic regions is negligible, and no Zresonance effects are expected.…”

Bottom-quark forward-backward and charge asymmetries at hadron colliders

“…There is also some interest in measuring the charge asymmetry in charm-quark production [8,9], and LHCb may well have the charm-tagging capabilities to do so.…”

Diagnosing the top-quark angular asymmetry using LHC intrinsic charge asymmetries

“…1. In [60][61][62][63][64][65][66][67][68][69][70][71], comparisons between different models are carried out, and study of those models or measurements in the LHC context can be found in [72][73][74][75][76][77][78][79][80][81][82][83][84].…”