Lifetimes of heavy-flavour hadrons—whence and whither?

Abstract

A theoretical treatment for the weak decays of heavy-flavour hadrons has been developed that is genuinely based on QCD. Its methodology as it applies to total lifetimes and the underlying theoretical issues are sketched. Predictions are compared with present data. One discrepancy emerges: the beauty baryon lifetime appears to be significantly shorter than expected. The ramifications of those findings are analyzed in detail.

A measurement of the

“…Bigi et al [3] predict a difference in lifetime between the B + and B 0 meson of several percent, and between the B 0 s and B 0 mesons of about 1%. Although some assumptions in reference [3] have been questioned by Neubert and Sachrajda [4], there is agreement that the models predict a difference between the B 0 s and B 0 lifetimes of the order of ±1%.…”

“…For charm hadrons this prediction is inaccurate; the measured D + lifetime is approximately 2.5 times that of the D 0 and more than twice that of the D − s [1]. More sophisticated models predict that the differences among b-hadron lifetimes should be much smaller than those in the charm system, because of the larger mass of the b quark [2,3,4]. Bigi et al [3] predict a difference in lifetime between the B + and B 0 meson of several percent, and between the B 0 s and B 0 mesons of about 1%.…”

“…More sophisticated models predict that the differences among b-hadron lifetimes should be much smaller than those in the charm system, because of the larger mass of the b quark [2,3,4]. Bigi et al [3] predict a difference in lifetime between the B + and B 0 meson of several percent, and between the B 0 s and B 0 mesons of about 1%. Although some assumptions in reference [3] have been questioned by Neubert and Sachrajda [4], there is agreement that the models predict a difference between the B 0 s and B 0 lifetimes of the order of ±1%.…”

Measurement of theB0andB+Meson Lifetimes with Fully Reconstruct

“…Deviations from this simple picture are expected to be proportional to 1/m 2 Q [1,2]. Therefore, any lifetime differences are anticipated to be much smaller for bottom than for charm mesons.…”

“…Therefore, any lifetime differences are anticipated to be much smaller for bottom than for charm mesons. Various models [1,2] predict the ratio of the B + and B 0 meson [3] lifetimes to differ by up to 10% from unity. At present, this ratio is measured to be τ B + /τ B 0 = 1.062 ± 0.029 [4], with the most precise values obtained by experiments operating near the Z and at hadron colliders.…”