Abstract
Eur. Phys. J. C (2011) 71: 1618 In the NMSSM, because of introducing a complex singlet superfield, the
lightest CP-odd Higgs boson, $a_1$, can be a singlet-like state with a tiny
doublet component in large regions of parameter space. In this paper, we
examine the discovery potential of $a_1$ produced in association with a
bottom-antibottom pair at the LHC through $\tau^+\tau^-$ and $\gamma\gamma$
decay modes. It is shown that an $a_1$ with mass $\leq M_Z$ can be extracted
from the SM backgrounds by using the $\tau^+\tau^-$ decay channel, a
possibility precluded to the MSSM. In contrast, the $\gamma\gamma$ decay mode
is overwhelmed by backgrounds despite the fact that the branching ratio of this
mode can reach unity when $a_1$ is a pure singlet.