Gregory Penn successfully defends thesis, "The Search for Evidence of Electroweak Baryogenesis with Higgs Decays to Tau Leptons at ATLAS"

On July 30, Gregory Penn successfully defended the thesis, “The Search for Evidence of Electroweak Baryogenesis with Higgs Decays to Tau Leptons at ATLAS” (advisor: Sarah Demers).

Penn explained, “Baryon asymmetry is the observed matter and anti-matter imbalance in the Universe. The origin of this imbalance is currently unknown. My work searches for sources of Charge-Parity (CP) violation in Higgs interactions with tau leptons and the W and Z vector bosons. Additional CP violation, beyond what is predicted by the Standard Model, is a generic requirement for producing the observed baryon asymmetry, while CP violation in the Higgs sector is particularly interesting for the electroweak baryogenesis hypothesis.” 

Penn will next be a postdoc at Princeton.

Thesis Abstract: The confirmation of the Standard Model particle content culminated in the discovery of the Higgs boson in 2012. Despite its many successes, the Standard Model does not explain several observed phenomena, including the baryon asymmetry of the universe. One compelling explanation for this asymmetry is Electroweak Baryogenesis, which requires additional sources of Charge-Parity (CP) violation beyond those predicted by the Standard Model. Two searches for additional sources of CP violation will be presented. One is an ongoing measurement of the CP structure of the Higgs boson coupling to tau leptons, while the other measures the CP structure of the Higgs boson coupling to electroweak vector bosons using Higgs boson decays to tau leptons.

Thesis Committee: Sarah Demers (advisor), Paul Tipton, Laura Havener, Witold Skiba, and Tae Min Hong (University of Pittsburgh)