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Jurčo, Möller, Schraml, Schupp, and Wess have shown how to construct noncommutative SU(N) gauge theories from a consistency relation. Within this framework, we present the Feynman rules for noncommutative QCD and compute explicitly the most dangerous Lorentz-violating operator generated through radiative corrections. We find that interesting effects appear(More)
These lectures are designed to introduce the methods and results of large N c QCD in a presentation intended for nuclear and particle physicists alike. Beginning with definitions and motivations of the approach, we demonstrate that all quark and gluon Feynman diagrams are organized into classes based on powers of 1/N c. We then show that this result can be(More)
We compute the nonleptonic weak decay width of a heavy-light meson in 1+1 spacetime dimensions with a large number of QCD colors (the 't Hooft model) as a function of the heavy quark mass. In this limit, QCD is exactly soluble, and decay modes are dominated by two-particle final states. We compare the results to the tree-level partonic decay width of the(More)
We use rigorous QCD dispersion relations to derive model-independent bounds on the B → πlν, D → πlν and D → K lν form factors. These bounds are particularly restrictive when the value of the observable form factor at one or more kinematic points is assumed. With reasonable assumptions we find f B ≤ 195 MeV and that the shape of the form factor becomes(More)
We consider in detail the mass operator analysis for the nonstrange ℓ = 1 excited baryons in large N c QCD. We present a straightforward procedure for constructing the large N c baryon wavefunctions, and provide complete analytic expressions for the matrix elements of all the independent isosin-glet mass operators. We discuss the relationship between the(More)