The Decay Constants of Pseudoscalar Mesons in a Relativistic Quark Model

The decay constants of pseudoscalar mesons are calculated in a relativistic quark model which assumes that mesons are made of a valence quark antiquark pair and of an effective vacuum like component. The results are given in terms of quark masses and of some free parameters entering the expression of the internal wave functions of the mesons. By using the pion and kaon decay constants Fπ+ = 130.7 MeV, FK+ = 159.8 MeV to fix the parameters of the model one gets 60 MeV ≤ FD+ ≤ 185 MeV, 95 MeV ≤ FDs ≤ 230 MeV, 80 MeV ≤ FB+ ≤ 205MeV for the light quark massesmu = 5.1MeV, md = 9.3MeV, ms = 175MeV and the heavy quark masses in the range: 1. GeV ≤ mc ≤ 1.6 GeV, 4.1 GeV ≤ mb ≤ 4.5 GeV . In the case of light neutral mesons one obtains with the same set of parameters Fπ0 ≈ 138 MeV, Fη ≈ 130 MeV, Fη′ ≈ 78 MeV . The values are in agreement with the experimental data and other theoretical results. E-mail address: [email protected]