Background studies in the ttX, X → ττ boosted analysis at the ATLAS experiment

Under the validity of certain BSM theories, during a collision at the LHC, a low-mass resonance X can be produced which can further decay into light particles. These resonances can be for example Axion-Like Particles. For the purpose of this work, these particles are assumed to decay into two tau leptons (τ), decaying hadronically. We will focus on the motivated novel search for low-mass resonances decaying to a pair of tau leptons and produced in association with a top and anti-top quark pair (ttX, X → ττ), studying and characterizing the SM backgrounds contamination to the signal on this analysis. A preliminary Control Region will be defined for the dominant SM background process, estimating its transfer factor.