Likelihood-based Technique for measuring the Energy of Hadronically Decaying Tau Leptons

We present a new technique for accurate energy measurement of hadronically decaying tau leptons at the collider experiments. The technique employs a particle flow algorithm complemented with a likelihood-based method for separating contributions of overlapping energy depositions of spatially close particles. The technique was tested at CDF experiment at the Tevatron. In addition to superior energy resolution provided by the method and better measurement of other ID variables such as invariant mass of the jet, this technique provides a direct estimate of the uncertainty in the energy measurement of each individual tau candidate. While important in itself, this latter feature can serve as a powerful identification tool in distinguishing hadronically decaying tau leptons from jet and light lepton backgrounds. This new technique is expected to provide significant improvements in sensitivity of the H→ττ search at the Tevatron and can be further extended to the case of generic (quark or gluon) jets.