부산대학교 도서관

Yang-Mills theories in Coulomb gauge are often attributed withproviding a rather direct access to bound states and other interestingquantities. However, even leading-order perturbative calculations inthe conventional Lagrangian formulation are a formidable challenge. Theauthors of this paper develop an alternative approach, which is basedon a perturbative expansion of the Schrödinger equation in aHamiltonian formulation. Their aim is, in particular, to calculatecorrelation functions.\parTo this end, the Schrödinger equation is expanded in powers of thecoupling constant. This expansion permits a diagrammaticalrepresentation of the perturbative series. The authors use this seriesto determine the transverse gluon propagator, the ghost propagator, theCoulomb potential, and the ghost-gluon vertex. Under the assumption ofmultiplicative renormalizability, the divergent integrals which appear aredimensionally regulated and renormalized. This reproduces the knownresults of other approaches. In particular, the same value of the firstcoefficient of the beta function is obtained, irrespective of whetherthe running coupling is obtained from either the Coulomb potential orthe ghost-gluon vertex. This result is used to determinerenormalization-group improved correlation functions, and to determinethe respective anomalous exponents. These are compared with resultsfrom lattice computations, which indicate that there are somediscrepancies between the two, though this may depend on the particularlattice parameters.\parIn total, the presentation is very clear, and the paper is veryrecommendable to anyone interested in Coulomb gauge calculations.However, whether this representation is advantageous, as the authorsdiscuss, remains to be seen.