Search for a very light CP-odd neutral Higgs boson of the MSSM

Abstract The reactions e + e − → hZ ∗ and e + e − → hA have been used to search for the neutral Higgs bosonsh and A of the MSSM in the case where the CP -odd A is lighterthan 2 m μ , taking into account the large h → AA decay branching ratio. No signal was found in the data sample collected until the end of 1991 by the ALEPH experimentat LEP. For tan β ⩾, m A m μ is excluded at 95% CL for any m h .