UC Santa Barbara

This dissertation presents results from a search for physics beyond the

Standard Model, using 19.39 pb-1 of data collected by the CMS detector

at the Large Hadron Collider, during its 2012 operation at center of mass energy of 8 TeV.

It focuses on models of supersymmetry that lead to

final states with multiple jets, especially those from

b-quark decay, and a large amount of missing transverse momentum.

The amounts of background from

top-quark, W+jets, Z to invisible, and multi-jet production

are determined from data-driven techniques.

In particular, this includes a novel estimation of the missing transverse energy spectrum from

semi-leptonic top/anti-top decay,

which takes advantage of the precise knowledge of the W boson polarization.

Predicted yields are consistent with simulated Standard Model

processes and the observed data.

Since no evidence of new physics is

observed, limits are placed on the rate of gluino pair production to a

final state with four b-quarks and two neutralinos.

This process is excluded at 95% CL for a gluino with mass 1225 GeV and

a neutralino with mass up to 350 GeV.