Prospects of mass measurements for neutral MSSM Higgs bosons in the intense-coupling regime at a linear collider [rapid communication]

We analyze the prospects for detecting the three neutral Higgs bosons of the Minimal Supersymmetric extension of the Standard Model in the intense-coupling regime at e⁺e^- colliders. Due to the small mass differences between the Higgs states in this regime and their relative large total decay widths, the discrimination between the particles is challenging at the LHC and in some cases even impossible. We propose to use the missing mass technique in the Higgs-strahlung process in e⁺e^- collisions to distinguish between the two CP-even Higgs eigenstates h and H, relying on their bbbar decay in the bbbarℓ⁺ℓ^- event sample. Ah and AH associated production is then studied in the 4b-jet event sample to probe the CP-odd A boson. At collider energies √{ s} ≃ 300 GeV and an integrated luminosity of 500 fb^-1, accuracies in the mass measurement of the CP-even Higgs bosons are expected to range from 100 to 300 MeV, while for the CP-odd A boson, accuracies of less than 500 MeV can be obtained.