Determination of the b quark mass at the Z mass scale

G Abbiendi, Georgios Anagnostou, Ian Bloodworth, David Charlton, Christopher Hawkes, Roger Homer, Predrag Jovanovic, Alun Lloyd, Thomas McMahon, Stephen O'Neale, Scott Talbot, Miriam Watson, Peter Watkins, Alan Watson, Nigel Watson, John Wilson

Research output: Contribution to journalArticle

27 Citations (Scopus)


In hadronic decays of Z bosons recorded with the OPAL detector at LEP, events containing b quarks were selected using the long lifetime of b flavoured hadrons. Comparing the 3-jet rate in b events with that in d,u,s and c quark events, a significant difference was observed. Using O(alpha (2)(S)) calculations for massive quarks, this difference was used to determine the b quark mass in the YI-S renormalisation scheme at the scale of the Z boson mass. By combining the results from seven different jet finders the running b quark mass was determined to be (m) over bar (b) (m(Z)) = (2.67 +/-0.03(stat.)(-0.37)(+0.29)(syst.)+/-0.19(theo.)) GeV. Evolving this value to the b quark mass scale itself yields (m) over bar (b)((m) over bar (b)) = (3.95(-0.62)(+0.52))GeV, consistent with results obtained at the b quark production threshold. This determination confirms the QCD expectation of a scale dependent quark mass. A constant mass is ruled out by 3.9 standard deviations.
Original languageEnglish
Pages (from-to)411-422
Number of pages12
JournalEuropean Physical Journal C
Issue number3
Publication statusPublished - 1 Jul 2001


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