Light meson spectroscopy and threshold effects

We discuss the light meson spectrum, with special emphasis on hadronic mass shifts related to thresholds. In particular we discuss the puzzle of the scalar mesons a0(980), a0/S(1322) and f0(975) and comment on the K*(1410) and the K*(1680). We also emphasize that, as data have improved, the fine-splitting of light qanti q resonances well above the first threshold seems to be systematically smaller than previous model estimates. This suggests that hadronic self-energy mass shifts are at least as important as the one-gluon exchange in understanding the spectrum. Apart from providing a possible resolution to the puzzle of the light scalars one can then also within the pseudoscalar sector understand better the dual role of the pion as both a Nambu-Goldstone boson and a1S0 qanti q state. (orig.)