QCD Sum Rule Analysis Research Articles

QCD sum rule analysis of the K→ vacuum weak amplitude

We extend our previous calculation of the kaon-to-vacuum weak amplitude within the QCD sum rule approach by including the perturbative contribution. The numerical estimate is found to be substantially modified.

An exactly soluble model for the QCD vacuum

We investigate the interaction of nonrelativistic particles in a gaussian stochastic background field. The exact value for the ground state energy of this system is evaluated and compared with corresponding values of a potential model and of a nonrelativistic version of QCD sum rule analysis.

Higher dimensional renormalization group invariant vacuum condensates in quantum chromodynamics

The renormalization of the five- and six-dimensional scalar gauge invariant composite operators is performed. The corresponding renormalization group invariant vacuum condensates are studied. Our main results are that the six-dimensional gluon condensate does not mix with the quartic quark condensates nor the other way round. We also show that the factorization hypothesis of the four-quark operator does not lead to renormalization group invariant quark vacuum condensates. So, one has to be careful when keeping the six-dimensional operators in the QCD sum rule analysis.