  The NMSSM contains a Higgs singlet in addition to the two Higgs doublets
typical of the MSSM, thus resulting in a total of seven physical Higgs mass
states. Therefore, the phenomenology of the NMSSM Higgs sector can vary
considerably from that of the MSSM and there are good prospects of finding in
regions of the NMSSM parameter space Higgs signals that cannot be reproduced in
the MSSM. We examined here the two-photon decay mode of a Higgs boson and found
that up to three neutral Higgs states, heavy and/or light, could be
simultaneously observable at the LHC, a possibility precluded to the MSSM.
There are also some possibilities that only the lightest NMSSM Higgs boson be
detectable via this mode, with a mass beyond the upper limit of the
corresponding MSSM state, thus also allowing to distinguish between the two
scenarios. However, in most of the NMSSM parameter space the configurations of
the non-minimal model are not very different from those arising in the minimal
case.
