Search for Higgs boson exotic decays into Lorentz-boosted light bosons in the four-τ final state at s=13TeV with the ATLAS detector

A search for exotic decays of the Higgs boson into a pair of low-mass scalars that subsequently decay into tau -leptons, H -> aa -> tau(+)tau(-)tau(+)tau(-), is presented. In models with Yukawa-like couplings, the decay to tau-leptons is favoured for ligh