Today was the first day of the COSMO 2013 conference at Cambridge. Walking up the path to the hallowed Department of Applied Mathematics and Theoretical Physics (DAMTP), I was gripped by my usual fear that I might meet with a frosty reception at the door; “No experimentalists, please!”
The hallowed halls of DAMTP
But it’s not that sort of conference. COSMO 2013 is a very nice mix of cosmology and particle physics, theory and experiment. You can see the conference poster and programme here.
This morning started with two contrasting plenary talks on particle physics; an experimental talk by Lars Sonneschein, and a more general talk ‘From the Higgs boson to Cosmology’ by well-known CERN theoretician John Ellis.
In his talk ‘Recent Results from the LHC’, Professor Sonnenschein gave a brief overview of recent results at the LHC, from current production rates of top anti-top quarks to the famous discovery of the Higgs boson. Much of this probably wasn’t that new to the audience given the number of Higgs talks last year, but it was good to see up-to-date information on the decay modes and coupling constants for the Higgs.The main point was that with more and more accurate measurements, there is still no evidence yet of any physics beyond the Standard Model, whether one was searching for dark matter, microscopic black holes or indeed supersymmetry (SUSY). On the other hand, there were grounds for good cheer for the experimentalists given the projections Lars gave for increased luminosity at the LHC in the next few years.
John Ellis’s talk took a very different tack. He starting by explaining why a light Higgs mass and weak couplings is a good result for supersymmetry (SUSY can stabilize a light Higgs), giving theorists yet another reason to take the theory seriously, despite the ecent narrowing of windows of possibility at the LHC (at least for minimal models). Professor Ellis then made a connection with cosmology, remarking that basic Wess-Zumino SUSY models can be shown to fit very well with many generic models of inflation;in particular, adding supersymmetry to the mix can give models that fit very comfortably within the recent PLANCK results (some fall well within the dark blue region in the famous Planck figure below). A colleague of a certain age commented to me afterwards that he isn’t quite reconciled with the way inflation has become the dominant paradigm in today’s cosmology; for my part, I can never get used to today’s discussions of supersymmetry in both cosmology and particle physics, having grown up thinking of it as an obscure theory practised only by my father and a few colleagues around the world! Science truly evolves…
Prof Ellis wearing his Standard Model t-shirt
Generic SUSY versions of inflation can give models that fall within the most probable region (dark blue)
At question time afterwards, I commented that I was struck by the contrast between the two talks, i.e. the strong motivation for SUSY from theory but the lack of results so far at the LHC, and asked Professor Ellis whether he thought the first evidence for SUSY might indeed come from the cosmic microwave background rather than particle accelerators (I made a mess of the question, nervous for once!). He responded by pointing out that it took 40 years to find the Higgs in particle accelerators, thus we should not be too impatient. This answer makes a lot of sense to me, I’m a bit dismayed at the way SUSY scepticism has quickly become almost as popular a sport as string theory scepticism. After all, theory is often decades ahead of experiment, particularly in particle physics…
There were two other plenary lectures after coffee, an overview of Dark Matter by Malcolm Fairbairn and a talk on neutrino masses by Silvia Pascoli. They were both excellent talks but there is so much going on I just can’t keep up! Also, Stephen Hawking is sitting three tables away, also working away at a computer – I’m going to tidy myself off to the afternoon sessions before someone mistakes me for a journalist and chases me out of the canteen!