1998/05/31 by Dan Pirjol, Nikolai Uraltsev · 1 citation
Physics and Astronomy · #Baryon #Fermion #Hadron #High-Energy Particle Collisions Research #Meson #Nuclear physics #Operator (biology) #Particle physics #Particle physics theoretical and experimental studies #Physics #Quantum Chromodynamics and Particle Interactions #Quark #hep-ph
paper · pdf · doi:10.1103/physrevd.59.034012
published as Phys. Rev. D 59, 034012 (1999) · 51 pages. The case of flavor-singlet operators is added for the two-loop anomalous dimensions
arxiv created 1998/06/07 · openalex publication_date 1999/01/08 · openalex created_date 2016/06/24 · arxiv updated 2016/08/24 · openalex updated_date 2026/08/05
We introduce and study the properties of the ``color-straight'' four-quark operators containing heavy and light quark fields. They are of the form (b\ensuremathΓbb)(q\ensuremathΓqq) where both brackets are color singlets. Their expectation values include the bulk of the nonfactorizable contributions to the nonleptonic decay widths of heavy hadrons. The expectation values of the color-straight operators in the heavy hadrons are related to momentum integrals of the elastic light-quark form factors of the respective heavy hadron. We calculate the asymptotic behavior of the light-current form factors of heavy hadrons and show that the actual decrease is 1/(q2)3/2 rather than 1/q4. The two-loop hybrid anomalous dimensions of the four-quark operators and their mixing (absent in the first loop) are obtained. Using plausible models for the elastic form factors, we estimate the expectation values of the color-straight operators in the heavy mesons and baryons. Improved estimates will be possible in the future with new data on the radiative decays of heavy hadrons. We give the Wilson coefficients of the four-fermion operators in the 1/mb expansion of the inclusive widths and discuss the numerical predictions for the lifetime ratios. Estimates of the nonfactorizable expectation values are given.