Speaker
Description
New particles in the MeV-GeV range produced at colliders and escaping detection can be searched for at operating B and tau factories such as Belle II. A typical search channel involves pair-produced taus (or mesons), one of which decaying to invisible particle(s), and the other providing a tag. One crucial impediment of these searches is the limited ability to reconstruct the parents' separate boosts. This is the case in the typical topology where both decay branches include invisible particles. We observe that such topology lends itself to the use of kinematic variables such as M2, designed for pairwise decays to visible plus invisible particles. Starting from this observation, we construct several kinematic quantities able to discriminate signal from background and apply them to some benchmark searches in tau and B decays.
