Probing the top-quark width using the charge identification of $b$ jets

Abstract

We propose a new method for measuring the top-quark width based on the on-/off-shell ratio of $b$-charge asymmetry in $pp\to Wbj$ production at the LHC. The charge asymmetry removes virtually all backgrounds and related uncertainties, while remaining systematic and theoretical uncertainties can be taken under control by the ratio of cross sections. Limited only by statistical error, in an optimistic scenario, we find that our approach leads to good precision at high integrated luminosity, at a few hundred MeV assuming 300-3000 fb${}^{-1}$ at the LHC. The approach directly probes the total width, in such a way that model-dependence can be minimized. It is complementary to existing cross section measurements which always leave a degeneracy between the total rate and the branching ratio, and provides valuable information about the properties of the top quark. The proposal opens up new opportunities for precision top measurements using a $b$-charge identification algorithm.

5 pages, 3 figures; V2: Journal version

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Cited by in corpus (7)

• Single top-quark production at the Tevatron and the LHC
• Analytic three-loop QCD corrections to top-quark and semileptonic $b\to u$ decays
• Analytic result for the top-quark width at next-to-next-to-leading order in QCD
• Effective operators in $t$-channel single top production and decay
• Extracting the Top-Quark Width from Non-Resonant Production
• Model independent top quark width measurement using a combination of resonant and non resonant cross sections
• Top Quark Properties