Phenomenological Analysis of D Meson Lifetimes

TL;DR

This paper applies QCD operator-product-expansion and sum rule techniques to analyze charmed meson lifetimes, emphasizing the importance of spectator quark momentum and providing lifetime ratio estimates consistent with some experimental data.

Contribution

It introduces a systematic QCD-based approach incorporating spectator quark momentum effects and estimates hadronic matrix elements for charmed mesons.

Findings

Estimated D_s^+ to D^0 lifetime ratio of approximately 1.08.

Highlighting the significance of spectator quark momentum in decay width calculations.

Results align with some experimental measurements but differ from others.

Abstract

The QCD-based operator-product-expansion technique is systematically applied to the study of charmed meson lifetimes. We stress that it is crucial to take into account the momentum of the spectator light quark of charmed mesons, otherwise the destructive Pauli-interference effect in $D^+$ decays will lead to a negative decay width for the $D^+$. We have applied the QCD sum rule approach to estimate the hadronic matrix elements of color-singlet and color-octet 4-quark operators relevant to nonleptonic inclusive $D$ decays. The lifetime of $D_s^+$ is found to be longer than that of $D^0$ because the latter receives a constructive $W$-exchange contribution, whereas the hadronic annihilation and leptonic contributions to the former are compensated by the Pauli interference. We obtain the lifetime ratio $\tau(D_s^+)/\tau(D^0)$ $\approx 1.08\pm 0.04$, which is larger than some earlier theoretical estimates, but still smaller than the recent measurements by CLEO and E791.