Abstract
A search for the decay to a pair of new particles of either the 125 GeV Higgs boson (h ) or a second CP-even Higgs boson (H ) is presented. The dataset correspods to an integrated luminosity of 20.3 fb__ of pp collisions at ís = 8 TeV recorded by the ATLAS experiment at the LHC in 2012. The search was done in the context of the next-to-minimal supersymmetric standard model, in which the new particles are the lightest neutral pseudoscalar Higgs bosons (a ). One of the two a bosons is required to decay to two muons while the other is required to decay to two _ -leptons. No significant excess is observed above the expected backgrounds in the dimuon invariant mass range from 3.7 GeV to 50 GeV. Upper limits are placed on the production of h_aa relative to the Standard Model gg_h production, assuming no coupling of the a boson to quarks. The most stringent limit is placed at 3.5\\% for m a = 3.75 GeV. Upper limits are also placed on the production cross section of H_aa from 2.33 pb to 0.72 pb, for fixed ma = 5 GeV with m H ranging from 100 GeV to 500 GeV.