Search for cosmic axions and experimental limits on light scalars/pseudoscalars

We present here experimental limits on the coupling constant of axions to two photons describing two different experiments. For the first one (the search for cosmic axions) we assume that 100% of the dark matter is due to axions and we find gaγγ < 10-13 GeV-1 in the mass range of (4.5-16.3)x10-6 eV. The second experiment does not assume the existence of dark matter but it is a production of light scalars and/or pseudoscalars with a polarized laser light inside a magnetic field. The observed peaks set a limit of gaγγ < 2.5x10-6 GeV-1 for a particle mass of m < 10-3 eV. (orig.)