Ph.D Thesis

Ph.D StudentGalon Iftah
SubjectPhysics beyond the Standard Model at the Large Hadron
DepartmentDepartment of Physics
Supervisor PROF. Yael Shadmi
Full Thesis textFull thesis text - English Version


This thesis is a collection of four papers exploring supersymmetric extensions of the Standard Model (SM) of Particle Physics. Both theoretical aspects of supersymmetric models and search techniques designed to detect superpartners are studied.

The first two papers are theoretical studies of a class of models called Flavored Gauge Mediation (FGM) which extend Gauge Mediated Supersymmetry Breaking (GMSB). In these models, the messengers of gauge mediation have couplings to the matter fields which lead to new contributions to scalar soft-masses, and to 1-loop A-terms. The first paper shows how these new features can result in a heavy Higgs boson, consistent with the recently measured mass, alongside viable collider accessible spectra. In the second paper, by properly choosing the flavor symmetries, these same couplings are shown to result in viable non-degenerate squark spectra.

The third and fourth papers describe techniques for the detection of superpartners. The third deals with a method for measuring charged long-lived massive particles of high velocity. These particles could be misidentified as muons and given the wrong energy value. We exploit the fact that such fast particles would typically be produced in the decay of a heavier particle along-side a visible particle, and suggest to search for a peak in the invariant mass distribution of the two decay products. This peak can be further enhanced using a scan over the true mass of the misidentified ``muon''. In the fourth paper, the kinematic edge technique is refined for flavor-dependent spectra. The example studied is of the kinematic edge of the opposite-sign di-lepton invariant mass distribution. This edge arises in the cascade decay of a heavy neutralino to a lighter one via on-shell sleptons and has a shape of an endpoint. If sleptons are mixed, the signal can appear in different-flavor channels which are usually assumed to arise from background processes only. Slepton mass-splittings also change the signal shape. We show how to take these effects into account and how to measures some flavor parameters.