NEW MASS AND MASS-MIXING ANGLE RELATIONS FOR PSEUDOSCALAR MESONS

We study the origins of the inaccuracies of Schwinger's nonet mass, an d the Sakurai mass-mixing angle, formulae for the pseudoscalar meson n onet, and suggest new versions of them, modified by the inclusion of t he pseudoscalar decay constants. We use these new formulae to determin e the pseudoscalar decay constants and mixing angle. The results obtai ned, f(8)/f(pi) = 1.185 +/- 0.040, f(q)/f(pi) = 1.095 +/- 0.020, f(eta )/f(pi) = 1.085 +/- 0.025, f(eta)/f(pi) = 1.195 +/- 0.035, theta = (- 21.4 +/- 1.0)degrees, are in excellent agreement with experiment. (C) 1998 Published by Elsevier Science B.V. All rights reserved.