Reconstruction of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll" id="d1e281" altimg="si100.gif"><mml:mi>τ</mml:mi></mml:math> lepton pair invariant mass using an artificial neural network

The reconstruction of the invariant mass of τ lepton pairs is important for analyses containing Higgs and Z bosons decaying to τ+τ−, but highly challenging due to the neutrinos from the τ lepton decays, which cannot be measured in the detector. In this paper, we demonstrate how artificial neural networks can be used to reconstruct the mass of a di-τ system and compare this procedure to an algorithm used by the CMS Collaboration for this purpose. We find that the neural network output shows a smaller bias and better resolution of the di-τ mass reconstruction and an improved discrimination between a Higgs boson signal and the Drell–Yan background with a much shorter computation time.