Production rate of bb(bar) quark pairs from gluons and bb(bar)bb(bar) events in hadronic Z Decays

TL;DR

This paper measures the production rates of gluon splitting into bottom quark pairs and events with two bottom quark pairs in hadronic Z decays, using four-jet data from the OPAL detector to improve understanding of heavy quark production.

Contribution

It provides new measurements of g_bb and g_4b rates in Z decays, utilizing a novel event selection and likelihood analysis approach.

Findings

g_bb = (3.07 +- 0.53 (stat) +- 0.97 (syst)) x 10^-3

g_4b = (0.36 +- 0.17 (stat) +- 0.27 (syst)) x 10^-3

Results are consistent with Standard Model predictions.

Abstract

The rates are measured per hadronic Z decay for gluon splitting to bb(bar) quark pairs, g_bb, and of events containing two bb(bar) quark pairs, g_4b, using a sample of four-jet events selected from data collected with the OPAL detector. Events with an enhanced signal of gluon splitting to bb(bar) quarks are selected if two of the jets are close in phase-space and contain detached secondary vertices. For the event sample containing two bb(bar) quark pairs, three of the four jets are required to have a significantly detached secondary vertex. Information from the event topology is combined in a likelihood fit to extract the values of g_bb and g_4b, namely g_bb = (3.07 +- 0.53(stat) +- 0.97(syst))x10^-3 g_4b = (0.36 +- 0.17(stat) +- 0.27(syst))x10^-3