Pseudoscalar conversion and X-rays from the sun

Abstract We investigate the detection of a pseudoscalar φ that couples electromagnetically via an interaction 1 4 gφF F . In particular, we focus on the conversion of pseudoscalars produced in the sun's interior in the presence of the sun's external magnetic dipole field and sunspot-related magnetic fields. We find that the sunspot approach is superior. Measurements by the SXT on the Yohkoh satellite can measure the coupling constant down to g = 0.5-1 × 10−10 GeV−1, provided the pseudoscalar mass m