Isolated leptons from heavy flavor decays: Theory and data

TL;DR

This paper analyzes the contribution of heavy flavor decays to isolated leptons at colliders, validating models against Tevatron data and exploring implications for Higgs searches.

Contribution

It provides a validated simulation framework for heavy flavor contributions to isolated leptons and introduces a new rule of thumb for their production rates relative to heavy quarks.

Findings

Good agreement with Tevatron data on heavy flavor leptons.

Heavy flavor decays can dominate isolated lepton backgrounds.

Isolation acts as a momentum filter affecting Higgs background estimates.

Abstract

Events with isolated leptons play a prominent role in signatures of new physics phenomena at high energy collider physics facilities. In earlier publications, we examine the standard model contribution to isolated lepton production from bottom and charm mesons and baryons through their semileptonic decays (b, c -> l + X), showing that this source can overwhelm the effects of other standard model processes in some kinematic domains. In this paper, we show that we obtain good agreement with recent Tevatron collider data, both validating our simulations and showing that we underestimate the magnitude of the heavy-flavor contribution to the isolated lepton yields. We also show that the isolation requirement acts as a narrow bandpass filter on the momentum of the isolated lepton, and we illustrate the effect of this filter on the background to Higgs boson observation in the dilepton mode. We introduce and justify a new rule of thumb: isolated electrons and muons from heavy flavor decay are produced with roughly the same distributions as b and c quarks, but with 1/200 times the rates of b and c production, respectively.