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Author ORCID Identifier



Open Access Dissertation

Document Type


Degree Name

Doctor of Philosophy (PhD)

Degree Program


Year Degree Awarded


Month Degree Awarded


First Advisor

Carlo Dallapiccola

Second Advisor

Ben Brau

Third Advisor

Michael Ramsey-Musolf

Fourth Advisor

Grant Wilson

Subject Categories

Elementary Particles and Fields and String Theory


A search for long-lived, massive particles decaying into dimuon pairs, in 32.9 fb-1 of data analyzed from the ATLAS detector is presented. Two signal models are considered: GGM SUSY, where the long lived particle mass is between 300-1000 GeV, and the dark photon model, where the ZD mass is between 20-60 GeV. An excess over the predicted background is observed in the GGM channel, however the angular/kinematic distributions of the excess vertices are consistent with a detec- tor/conditions related issue. A modified selection is used for the GGM channel which increases the signal sensitivity. 95% confidence level (CL) upper limits on the signal cross sections times branching fraction are set as a function of cτ for both benchmark models. The cτ limits for the GGM channel extend from 2.57-1050 cm, and the cτ limit for the ZD channel extends from 0.32-1572 cm. 95% CL upper limits on the ZD cross section are also set in the coupling-cτ plane, for a range of BF(H→ ZDZD).