When is field theory effective?
1992; Elsevier BV; Volume: 369; Issue: 1-2 Linguagem: Inglês
10.1016/0550-3213(92)90383-m
ISSN1873-1562
Autores Tópico(s)High-Energy Particle Collisions Research
ResumoWe analyze the relation between quark and hadron degrees of freedom in QCD in 3 + 1 and in 1 + 1 dimensions. In both cases in the weak-confinement limit low-energy properties such as charge radii of mesons are poorly described by effective field theory, yet easily calculable in terms of quark wave functions. Effective field theory fails because higher-dimension operators acquire anomalously large coefficients. In 1 + 1 dimensions, the theory is solved for strong confinement as well, working in the large-Nc limit. For strong coupling we find that effective field theory emerges as a powerful tool and there are indications that the quark model remains useful too. We characterize the relation between the quark and hadron expansions, and obtain insight into when and why effective field theories are valid.
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