PHYSICS PHD DISSERTATION DEFENSE: Thomas Dylan Rueter

Ph.D. Candidate:  Thomas Dylan Rueter

Research Advisor:  JoAnne Hewett

Date: Tuesday, August 24th, 2021
Time: 11:00 am PDT
 

Zoom Link: https://stanford.zoom.us/j/96885593634

Zoom Password: email mariaf67 [at] stanford.edu (mariaf67[at]stanford[dot]edu)

 

Title: A Scalar Portal to Kinetic Mixing

Abstract: Kinetic mixing between the Standard Model photon and a "dark" photon, associated with a U(1) group under which only dark matter is charged, may provide a portal for dark matter to interact with the Standard Model. We construct a model in which a dark photon mediates interactions with the SM via kinetic mixing. Unlike traditional models, in which the dark photon mixes with the hypercharge boson, our model effectively mixes the dark photon directly with the photon after electroweak symmetry is broken but remains unmixed until the symmetry breaks. Here the kinetic mixing is generated at one loop by fields whose charges satisfy a sum condition which guarantees a finite result at one loop. In the literature, this has been traditionally obtained via heavy fermions, which may lie out of the reach of current accelerators. In this model, by contrast, this process is mediated by scalar "portal matter" fields, which are charged under the electroweak group of the standard model as well as the dark U(1) group and acquire GeV-scale vevs which give mass to the dark Higgs and dark photon. The additional scalar fields are relatively light, at or below the weak scale, yet may remain undetected by current experiments since their couplings to SM fermions come only through percent level mixing with the SM Higgs. At colliders, these models are typified by relatively low MET due the BSM states decaying into MET and SM bosons, with MET which is balanced by the decay of the associated production object. Nevertheless, the higher statistics of HL-LHC may be able to probe the entirety of the model space.