Baryons in QCD_{AS} at Large N_c: A Roundabout Approach
| Autor: | Cohen, Thomas D., Shafer, Daniel L., Lebed, Richard F. |
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| Rok vydání: | 2009 |
| Předmět: | |
| Zdroj: | Phys.Rev.D81:036006,2010 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevD.81.036006 |
| Popis: | QCD_{AS}, a variant of large N_c QCD in which quarks transform under the color two-index antisymmetric representation, reduces to standard QCD at N_c = 3 and provides an alternative to the usual large N_c extrapolation that uses fundamental representation quarks. Previous strong plausibility arguments assert that the QCD_{AS} baryon mass scales as N_c^2; however, the complicated combinatoric problem associated with quarks carrying two color indices impeded a complete demonstration. We develop a diagrammatic technique to solve this problem. The key ingredient is the introduction of an effective multi-gluon vertex: a "traffic circle" or "roundabout" diagram. We show that arbitrarily complicated diagrams can be reduced to simple ones with the same leading N_c scaling using this device, and that the leading contribution to baryon mass does, in fact, scale as N_c^2. Comment: 9 pages, 9 pdf figures, ReVTeX with pdflatex |
| Databáze: | arXiv |
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