Search for Minimal Supersymmetric Standard Model Higgs bosons $H/A$ and for a $Z^{\prime}$ boson in the $\tau \tau$ final state produced in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS Detector

A search for neutral Higgs bosons of the minimal supersymmetric standard model (MSSM) and for a heavneutral $Z^{\prime }$ boson is performed using a data sample corresponding to an integrated luminosity of 3.2 fb$^{-1}$ from proton–proton collisions at $\sqrt{s} = 13$    ${\mathrm {TeV}}$ recorded by the ATLAS detector at the LHC. The heavy resonance is assumed to decay to a $\tau ^+ \tau ^-$ pair with at least one $\tau$ lepton decaying to final states with hadrons and a neutrino. The search is performed in the mass range of 0.2–1.2   ${\mathrm {TeV}}$ for the MSSM neutral Higgs bosons and 0.5–2.5   ${\mathrm {TeV}}$ for the heavy neutral $Z^{\prime }$ boson. The data are in good agreement with the background predicted by the Standard Model. The results are interpreted in MSSM and $Z^{\prime }$ benchmark scenarios. The most stringent constraints on the MSSM $m_A$ – $\tan \beta$ space exclude at 95 % confidence level (CL) $\tan \beta > 7.6$ for $m_A = 200$   $\text {GeV}$ in the $m_{h}^{\text {mod+}}$ MSSM scenario. For the Sequential Standard Model, a $Z^{\prime }_\mathrm {SSM}$ mass up to 1.90   ${\mathrm {TeV}}$ is excluded at 95 % CL and masses up to 1.82–2.17   ${\mathrm {TeV}}$ are excluded for a $Z^{\prime \mathrm {SFM}}$ of the strong flavour model.