Higgs $\tau $-lepton Yukawa Coupling Measurement and the $\tau $ Embedding Method for Background Estimation

To measure the H->tautau yukawa coupling the full dataset of the LHC Run-1 period recorded by the ATLAS experiment at the LHC during 2011 and 2012 has been analysed. The data correspond to integrated luminosities of 4.5 fb−1 and 20.3 fb−1 at centre-of-mass energies of \sqrt{s} = 7 TeV and \sqrt{s} = 8 TeV, respectively. Evidence for the coupling of the Higgs boson to tau leptons at 4.5 (3.4) sigma significance was observed (expected). Recently the combination of the CMS and ATLAS datasets has been published, raising the observed significance to discovery level at 5.5 sigma. One crucial ingredient in the search for the H->tautau decay is the embedding method, which is a data-driven technique to estimate the large and irreducible background from Z→ττ decays that cannot be obtained directly from data control samples. In this paper the ATLAS search for the Higgs boson decaying to tau leptons is discussed and a detailed explanation of the embedding method is given. Other use cases of the embedding method are also mentioned.