Mainz 2004 – scientific programme

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T: Teilchenphysik

T 207: QCD II

T 207.2: Talk

Tuesday, March 30, 2004, 14:15–14:30, RW 5

QCD Short-distance Constraints and Hadronic Approximations — •E. Lipartia¹, J. Bijnens², E. Gamiz³, and J. Prades³ — ¹Institute for Theoretical Physics (T39), TU München, Germany — ²Department of Theoretical Physics, Lund Univesity, Lund, Sweden — ³Centro Andaluz de Fisica de las Particulas Elementales (CAFPE) and Departamento de Fisica Teorica y del Cosmos, Universidad de Granada, Granada, Spain

We discusses a general class of ladder resummation inspired hadronic approximations. It is found that this approach naturally reproduces many successes of single meson per channel saturation models (e.g. VMD) and NJL based models. In particular the existence of a constituent quark mass and a gap equation follows naturally. We construct an approximation that satisfies a large set of QCD short-distance and large N_c constraints and reproduces many hadronic observables. We show how there exists in general a problem between QCD short-distance constraints for Green Functions and those for form factors and cross-sections following from the quark-counting rule. This problem while expected for Green functions that do not vanish in purely perturbative QCD also persists for many Green functions that are order parameters. Work was supported in part by Swedish research Coincil and by Deutsche Forschungsgemeinschaf.

• [1] Johan Bijnens, Elvira Gamiz, Edisher Lipartia, Joaquim Prades
  [2] JHEP 0304:055,2003.