Okay, so I kind of missed the last day of CosPA. There were only three talks, and because I forgot to set my alarm I missed two of them; and wasn't all that interested in the third. Anyway, with everything over it's time to summarize the whole affair.
On a personal level, I found the conference okay. A lot of this was that there were a lot of talks on subjects like axions or experimental cosmology that are somewhat outside my interests. Also, there were relatively few people I knew, hardly surprising given the location. But these things do factor into my enjoyment. It also didn't help that there were a few talks I had already seen this year; Daniel Eisenstein's talk on BOSS is excellent, but I didn't need to see it twice.
If we focus on areas I am more interested in, two themes stand out. The first was an emphasis placed on "complete" models over effective theories. The second was a discussion of dark matter models away from the clasical WIMP: light hidden sectors, asymmetric dark matter, or heavy decaying dark matter. In contrast to Planck, there was very little mention of supersymmetry in the talks I went to.
The most interesting thing in the complete vs effective theory discussion is that we had a session devoted to LHC searches, where the experimentalists told us what limits they were placing on EFTs. Meanwhile, Pyongwon Ko, Myeonghun Park and Osamu Seto all told us with varying degrees of competency why that was a bad idea. I do understand why, though. EFTs are at least simple, clear and finite in number, making them easy benchmarks for experimentalists to express limits. (Also they make the LHC look better than direct detection experiments.) Complete models are theoretically under better control, but the model space is huge and it is much harder to set generic constraints. Plus, the move towards complete models is relatively recent, and experimentalists have probably not had time to make the switch.
A variety of dark matter models were discussed here. GeV-scale hidden sectors were covered by Hye-Sung Lee's plenary talk, with parallel talks from Kihyeon Cho and Tim Tait. Tim's idea was the most interesting to me; in one sense quite simple, yet also very different to the usual sorts of things people talk about. I may think about this idea, see if I can find a good project to work on.
Asymmetric dark matter (ADM) was discussed by Stephen Lonsdale and Zhaofeng Kang. Stephen's talk covered the topic of how to spontaneously break a high-scale mirror-symmetric theory to a low-scale asymmetric one, simple but informative. He also covered fitting ADM to leptogenesis. Zhaofeng was one of the few people to mention SUSY here, but in an unusual context. By having a tiny breaking of a symmetry, a non-asymmetric theory can feature asymmetric behaviour through matter oscillations. It's a very interesting idea, though I'm always a bit skeptical of ideas based on tiny mass splittings.
In all, then, the conference had some interesting and useful talks. It also had several sessions which, while intriguing, are unlikely to be directly relevant to me in the near future. Still, I probably enjoyed the sessions more than this year's Planck on the whole.
On a personal level, I found the conference okay. A lot of this was that there were a lot of talks on subjects like axions or experimental cosmology that are somewhat outside my interests. Also, there were relatively few people I knew, hardly surprising given the location. But these things do factor into my enjoyment. It also didn't help that there were a few talks I had already seen this year; Daniel Eisenstein's talk on BOSS is excellent, but I didn't need to see it twice.
If we focus on areas I am more interested in, two themes stand out. The first was an emphasis placed on "complete" models over effective theories. The second was a discussion of dark matter models away from the clasical WIMP: light hidden sectors, asymmetric dark matter, or heavy decaying dark matter. In contrast to Planck, there was very little mention of supersymmetry in the talks I went to.
The most interesting thing in the complete vs effective theory discussion is that we had a session devoted to LHC searches, where the experimentalists told us what limits they were placing on EFTs. Meanwhile, Pyongwon Ko, Myeonghun Park and Osamu Seto all told us with varying degrees of competency why that was a bad idea. I do understand why, though. EFTs are at least simple, clear and finite in number, making them easy benchmarks for experimentalists to express limits. (Also they make the LHC look better than direct detection experiments.) Complete models are theoretically under better control, but the model space is huge and it is much harder to set generic constraints. Plus, the move towards complete models is relatively recent, and experimentalists have probably not had time to make the switch.
A variety of dark matter models were discussed here. GeV-scale hidden sectors were covered by Hye-Sung Lee's plenary talk, with parallel talks from Kihyeon Cho and Tim Tait. Tim's idea was the most interesting to me; in one sense quite simple, yet also very different to the usual sorts of things people talk about. I may think about this idea, see if I can find a good project to work on.
Asymmetric dark matter (ADM) was discussed by Stephen Lonsdale and Zhaofeng Kang. Stephen's talk covered the topic of how to spontaneously break a high-scale mirror-symmetric theory to a low-scale asymmetric one, simple but informative. He also covered fitting ADM to leptogenesis. Zhaofeng was one of the few people to mention SUSY here, but in an unusual context. By having a tiny breaking of a symmetry, a non-asymmetric theory can feature asymmetric behaviour through matter oscillations. It's a very interesting idea, though I'm always a bit skeptical of ideas based on tiny mass splittings.
In all, then, the conference had some interesting and useful talks. It also had several sessions which, while intriguing, are unlikely to be directly relevant to me in the near future. Still, I probably enjoyed the sessions more than this year's Planck on the whole.
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