g(NK Lambda) and g(NK Sigma) from QCD sum rules in the gamma(5)sigma(mu nu) structure

The NKY coupling constant for Y=Lambda and Sigma is evaluated in a QCD sum rule calculation. We study the Borel sum rule for the three point function of one pseudoscalar one-nucleon and one hyperon current up to order six in the operator product expansion. The Borel transform is performed with respe ct to the nucleon and hyperon momenta, which are taken to be equal. We disc uss and extend the result of a previous analysis in the qi gamma(5), struct ure and compare it with the result obtained with the use of the gamma(5)sig ma(mu v) structure. We find that the effect of pole-continuum transitions i s very important in the qi gamma(5), structure and that it changes complete ly results obtained in previous analysis. (C) 1999 Elsevier Science B.V. Al l rights reserved.