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Lifetimes and Heavy Quark Expansion

Lenz, Alexander

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Alexander Lenz


Ikaros Bigi

Paolo Gambino

Thomas Mannel


Kolya Uraltsev was one of the inventors of the Heavy Quark Expansion (HQE), that describes inclusive weak decays of hadrons containing heavy quarks and in particular lifetimes. Besides giving a pedagogic introduction into the subject, we review the development and the current status of the HQE, which just recently passed several non-trivial experimental tests with an unprecedented precision. In view of many new experimental results for lifetimes of heavy hadrons, we also update several theory predictions: τ (B+)/τ (Bd) = 1.04+0.05 −0.01 ± 0.02 ± 0.01, τ (Bs)/τ (Bd) = 1.001 ± 0.002, τ (b)/τ (Bd) = 0.935 ± 0.054 and ¯τ (0b )/¯τ (+ b ) = 0.95 ± 0.06. The theoretical precision is currently strongly limited by the unknown size of the nonperturbative matrix elements of four-quark operators, which could be determined with lattice simulations.


Lenz, A. (2015). Lifetimes and Heavy Quark Expansion. In I. Bigi, P. Gambino, & T. Mannel (Eds.), QCD and heavy quarks : in memoriam Nikolai Uraltsev (63-109). World Scientific Publishing

Publication Date Jul 1, 2015
Deposit Date Dec 7, 2015
Publicly Available Date Jan 28, 2016
Publisher World Scientific Publishing
Pages 63-109
Book Title QCD and heavy quarks : in memoriam Nikolai Uraltsev.
Publisher URL


Accepted Book Chapter (819 Kb)

Copyright Statement
Lifetimes and heavy quark expansion, Alexander Lenz, in QCD and heavy quarks : in memoriam Nikolai Uraltsev, ed. by Ikaros I Bigi, Paolo Gambino, Thomas Mannel Copyright @ 2015 with permission from World Scientific Publishing Co. Pte. Ltd.

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