CP violation

The violation of CP symmetry has long been especially intriguing. The effect is small and could be a very sensitive indicator of physics beyond the Standard Model. Recently experiment seems to be indicating results consistent with the notion that the Standard Model is the only source of CP violation, but this conclusion was far from obvious in the past.

I spent many years on this topic, starting with my early work on T violation in leptons , and I won’t try to summarize all of it. However, some highlights are given below.

Some of the fun projects involved rare K decays. One of my favorites was that on CP violation in
K to pi e+e-. This became a complex field with many contributions includingthis one with Fabrizio Gabbiani.

My work on epsilon prime in K decay was part of a large effort in the field to understand direct CP violation. It was difficult because of conflicting contributions, such as the electroweak penguin diagram. These effects gradually became under better theoretical control.

CP violation can also be seen in hyperon decays, and there continues to be experimental searches for these signals. One simplifying technique is to look in
p pbar reactions, which form an initial state of definite CP, so that signals can be more readily extracted.

One area that is particularly relevant for the LHC era is the idea of using jet physics to probe CP violating asymmetries. Gene Golowich and I hope to update this to address its use at the LHC.

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Research and teaching pages for John Donoghue