Dresden 2013 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 57: Suche nach neuer Physik 3

T 57.8: Vortrag

Dienstag, 5. März 2013, 18:30–18:45, WIL-C133

Model Independent Search in di-Mass-Space using Events with Missing Energy with CMS — •Sarah Beranek — RWTH Aachen Ib

A model independent method to search for particles of unknown masses in events decaying like top pairs (YY → XbXb → llbbνν, Y → Xb, X → lν) is presented. No constraints on the masses of X and Y are required, the only assumption is the topology of the decay chain. The method uses the solvability of the equation system of this decay and scans thereby the whole 2-dimensional mass space for the existence of a solution. Since the collision energy gives an upper limit to the allowed mass space, probabilities from parton density functions are taken into account. Additionally the measured particle kinematics are smeared with the detector resolution.

The method is tested in events with top pairs decaying to two leptons with the presence of two neutrinos in the final state. The events are recorded with the CMS detector with a center of mass energy of 7 TeV and 8 TeV and an integrated luminosity of 5/fb and 20/fb, respectively. Top quark and W boson are observed simultaneously without any a-priori knowledge.

Possible applications are searches for heavy resonances decaying to two top pairs as well as next generation heavy quarks. Similar topologies are predicted by supersymmetric models with R-parity conservation resulting in final states with two invisible neutralinos. This analysis can set limits on the existence of any particle decaying to the above mentioned topology and final state.