Pheno 2019, day 3

I spent the day at Pheno 2019, where I gave a plenary about Gaia and dark matter. It was a fun day, and I learned a lot. For example, I learned that when you have a dark photon, you naturally get tiny couplings between the dark matter and the photon, as if the dark matter has a tiny charge. And there are good experiments looking for milli-charged particles. I learned that deep learning methods applied to LHC events are starting to approach information-theoretic bounds for classifying jets. That's interesting, because in the absence of a likelihood function, how do you saturate bounds? I learned that the Swampland (tm) is the set of effective field theories that can't be represented in any string theory. That's interesting: If we could show that there are many EFTs that are incompatible with string theory, then string theory has strong phenomenological content!

In the last talk of the day, Mangano (CERN) talked about the future of accelerators. He made a very interesting point, which I have kind-of known for a long time, but haven't seen articulated explicitly before: If you are doing a huge project to accomplish a huge goal (like build the LHC to find the Higgs), you need to design it such that you know you will produce lots and lots of interesting science along the way. That's an important idea, and it is a great design principle for scientific research.