Low mass Higgs signals at the LHC in the Next-to-Minimal Supersymmetric Standard Model

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.