2014/05/14 by Lenz, Alexander
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.1405.3601
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 to 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(Λb)/ τ(Bd) = 0.935 ± 0.054 and τ (Ξb0) / τ (Ξb+) = 0.95 ± 0.06. The theoretical precision is currently strongly limited by the unknown size of the non-perturbative matrix elements of four-quark operators, which could be determined with lattice simulations.