A search for a yet-unobserved baryon number violation is performed using CMS data, following what suggested by the UCL-CP3 phenomenology group, who first proposed such a possibility in the top-quark system. Baryon number violation can manifest itself both in the production and in the decay process. In the latter case a top quark, produced in association with an anti-top, would decay with a certain branching ratio into a lepton and a W-boson. The analysis searches for such decays in a final state where both the other top quark and the W-boson decay hadronically, which is the most probable decay scenario. A first version of the analysis is close to being finalized and its results have been scheduled by CMS to be made public for the Summer 2012 conference.
The matrix element reweighting method attempts to compute the full likelihood of an observed event given a theoretical model. The method therefore measures the degree of compatibility of the event with the given model using as much information as available. MadWeight is a tool that fully automatize the computation of the event likelihood for any model implemented in MadGraph, by performing phase-space integration and providing a framework for taking into account the experimental resolution on the observed final state objects. This project aims at validating the matrix element reweighting technique implemented in MadWeight on a number of benchmark searches. In some cases, the final goal is the efficient identification of background events. The final states that are being considered are: Zbb, single top, ttbar resonances and dimuon resonances.
