At the CCPP Brown-Bag, Josh Ruderman (NYU) spoke about dark photons with a tiny coupling to real photons. The idea (roughly) is that the dark matter produces (by decays or transitions) dark photons, and these have a small coupling to real photons, but importantly the dark photons are not massless. He then showed that there is a huge open parameter space for such models (that is, models not yet ruled out by any observations) that could nonetheless strongly distort the cosmic background radiation at long wavelengths. And, indeed, there are claims of excesses at long wavelengths. So this is an interesting angle for a complex dark sector. My loyal reader knows I am a fan of having complexity in the dark sector.
In the afternoon, I met up with Anu Raghunathan (NYU) to discuss possible starter projects. I pitched a project to look at our ability to find (statistically) exoplanet-transit-like signals in data. I want to understand in detail how much more sensitive we could be to transiting exoplanets in resonant chains than we would be to the individual planets treated independently. There must be a boost here, but I don't know what it is yet.