Enhancing the sensitivity to new physics in the tt̄ invariant mass distribution

Abstract

We propose selection cuts on the LHC tt̄ production sample which should enhance the sensitivity to new physics signals in the study of the tt̄ invariant mass distribution. We show that selecting events in which the tt̄ object has little transverse and large longitudinal momentum enlarges the quark-fusion fraction of the sample and therefore increases its sensitivity to new physics which couples to quarks and not to gluons. We find that systematic error bars play a fundamental role and assume a simple model for them. We check how a non-visible new particle would become visible after the selection cuts enhance its resonance bump. A final realistic analysis should be done by the experimental groups with a correct evaluation of the systematic error bars. © 2012 American Physical Society.