Topics In High-Energy Physics: The Proton Magnetic Radius And Phenomenology Of Z0 Mediation Of Supersymmetry Breaking

TOPICS IN HIGH-ENERGY PHYSICS: THE PROTON MAGNETICRADIUS AND PHENOMENOLOGY OF Z ′ MEDIATION OFSUPERSYMMETRY BREAKINGbyJOYDEEP ROYDecember 2017Advisor: Dr. Gil PazMajor: PhysicsDegree: Doctor of Philosophy This dissertation describes two topics in high-energy physics. In the first we describethe extraction of the magnetic radius of the proton. In the second we impose LHCconstraints on the combined anomaly and Z’ mediation mechanisms of supersymmetrybreaking.We combine constraints from analyticity with experimental electron-proton scatteringdata to determine the proton magnetic radius without model-dependent assumptions onthe shape of the form factor. We also study the impact of including electron-neutronscattering data, and ππ → NN̄ data. Using representative data sets we find for acut of Q ≤ 0.5 GeV, rM = 0.91+0.03−0.06 ± 0.02 fm using just proton scattering data;rM = 0.87+0.04−0.05 ± 0.01 fm adding neutron data; and r pM = 0.87+0.02−0.02 fm adding ππ data.We also extract the neutron magnetic radius from these data sets obtaining rM = 0.89+0.03−0.03fm from the combined proton, neutron, and ππ data. Particle Data Group (PDG) hasreported both of these values, rM = 0.87± 0.02 fm and rM = 0.89± 0.03 fm in their 2016listing of the magnetic radius of the proton and neutron, respectively.Combining anomaly with Z ′ mediation allows us to solve the tachyonic problem ofthe former and avoid fine tuning in the latter. This model includes an extra U(1)′ gaugesymmetry and extra singlet scalar S which provides a solution to the ‘μ problem’ ofthe MSSM. The low-energy particle spectrum is calculated from the UV inputs using