Search For Physics Beyond The Standard Model In The Trilepton Signature In Barp P Collisions At Sqrts

Search for Physics Beyond the Standard Model in the Trilepton Signature in $\bar{p}-p$ Collisions at $\sqrt{s}

The standard model (SM) of particles and fields is a theory that has proven very accurate in the currently accessible collider energies. Nonetheless, the SM is theoretically incomplete in the sense that it leaves many questions and problems unanswered, for example, the origin of electroweak symmetry breaking (EWSB). The Higgs boson is introduced to the SM to provide a mechanism for electroweak symmetry breaking and masses to quarks and leptons. However, the introduction of the Higgs mechanism has the undesirable effect of introducing the hierarchy problem which is characterized by quadratically divergent contributions to the Higgs mass squared. Supersymmetry (SUSY) has been postulated as a way to solve the problem of the fine tuning of the Higgs self-interactions, and additionally to provide a possible mechanism for EWSB. The golden search channel for mSUGRA is the $i{̂pm}_{1} i{̂0}_{2} ightarrow 3ll$ (three leptons) channel. It offers a reasonable signal $sigma x BR$ with very small contributions from Standard Model backgrounds. This thesis, presents a search for chargino-neutralino production within the mSUGRA framework.

Search for Physics Beyond the Standard Model Using Multilepton Signatures in Pp Collisions at Sqrt(s)

A search for physics beyond the standard model in events with at least three leptons and any number of jets is presented. The data sample corresponds to 35 inverse picobarns of integrated luminosity in pp collisions at sqrt(s) = 7 TeV collected by the CMS experiment at the LHC. A number of exclusive multileptonic channels are investigated and standard model backgrounds are suppressed by requiring sufficient missing transverse energy, invariant mass inconsistent with that of the Z boson, or high jet activity. Control samples in data are used to ascertain the robustness of background evaluation techniques and to minimise the reliance on simulation. The observations are consistent with background expectations. These results constrain previously unexplored regions of supersymmetric parameter space.

Search for Physics Beyond the Standard Model in Pp Collisions at the CMS Experiment with a Signature of a Z Boson Plus Missing Transverse Energy