Photoproduction of Excited Baryons in the 1/Nc Expansion of QCD
نویسنده
چکیده
We present results for the photoproduction helicity amplitudes of excited baryons obtained in the context of the 1/Nc expansion of QCD. The results show that, in order to get a satisfactory description of the observed photoproduction amplitudes, the sub-leading corrections in 1/Nc are important. We also find that, while onebody effective operators are dominant, there is some evidence for the need of two-body effects which, in general, are not included in quark model calculations.
منابع مشابه
Photoproduction of positive-parity excited baryons in the 1/Nc expansion of QCD.
We analyze the photoproduction helicity amplitudes for positive-parity excited baryons in the context of the 1/N(c) expansion of QCD. The results show that subleading corrections in 1/N(c) are important and that, while one-body effective operators are dominant, there is some evidence for the need for two-body effects.
متن کاملAnalysis of Negative Parity Baryon Photoproduction Amplitudes in the 1/Nc Expansion
We study the photoproduction helicity amplitudes of negative parity baryons in the context of the 1/Nc expansion of QCD. A complete analysis to next-to-leading order is carried out. The results show sub-leading effects to be within the magnitude expected from the 1/Nc power counting. They also show significant deviations from the quark model, in particular the need for 2-body effects.
متن کامل1/mQ and 1/Nc Expansions for Excited Heavy Baryons with Light Quarks in the Spin-Flavor Symmetric Representation
The mass spectrum of the L = 1 orbitally excited heavy baryons with light quarks in the spin-flavor symmetric representation is studied by the 1/Nc expansion method in the framework of the heavy quark effective theory. The mixing effect from the baryons in the mixed representation is considered. The general pattern of the spectrum is predicted which will be verified by the experiments in the ne...
متن کاملOrbitally Excited Baryon Spectroscopy in the 1/nc Expansion
The discussion of the 70-plet of negative parity baryons illustrates the large Nc QCD approach to orbitally excited baryons. In the case of the ` = 1 baryons the existing data allows to make numerous predictions to first order in the SU(3) symmetry breaking. New relations between splittings are found that follow from the spin-flavor symmetry breaking. The Λ(1405) is well described as a three-qu...
متن کاملQCD Baryons in the 1/Nc Expansion
The 1/Nc expansion provides a theoretical method for analyzing the spin-flavor symmetry properties of baryons in QCD that is quantitative, systematic and predictive. An exact spinflavor symmetry exists for large-Nc baryons, whereas for QCD baryons, the spin-flavor symmetry is approximate and is broken by corrections proportional to the symmetry-breaking parameter 1/Nc = 1/3. The 1/Nc expansion ...
متن کامل