Friday 29 June 2012

String Phenomenology: Day 3

As you will have noticed if you visit this blog, I've not done a very good job of blogging this conference. In order to keep things in order, let me post the only thing I wrote about day 3, so I can move on to the later days!

Mariana Graña discussed the consistency of putative string theory solutions which break supersymmetry via anti-D3-branes in a warped throat (I briefly discussed this in a previous post). She was fairly adamant that this setup is inconsistent, due to induced singularities in the three-form fluxes supporting the throat. The most important approximation she and her collaborators have used seems to be to 'smear' the anti-D3-branes — replace the point-like branes with a continuous charge distribution. This misses one possible resolution of the singularities, which is polarisation of the anti-D3-branes into NS5-branes, but they have arguments to suggest that this won't solve the problem. I doubt that the controversy will be resolved any time soon.

(The latest paper by Graña et al. went on the arXiv the day after this talk.)

Edit: I suppose it's reasonable to also flag my own talk, in which I spoke about my paper from May, which I already mentioned here. I wasn't particularly happy with the talk, although it went okay, and I had a fair-sized audience who seemed to pay attention, so no complaints!

Wednesday 27 June 2012

String Phenomenology: Day 2

Here are some of the highlights from day 2 of the conference, as I saw it.

Gordy Kane continued to describe his recent collaboration with Bobby Acharya and others (see the post about day 1), focussing on their prediction of the Higgs mass. Specifically, they claim to predict that the Higgs should sit between about 122 and 129 GeV, and most likely at about 125 GeV. This time, the animosity towards these claims was a lot more apparent.

Tuesday 26 June 2012

String Phenomenology: Day 1

Here is a brief overview of the more interesting points of day 1. I will link to the abstracts of each talk; hopefully, in time, the same pages will also include the slides and video from the talks.

Ben Allanach kicked things off by describing some of the lates experimental results, and what they might mean for supersymmetry (SUSY) in particular (and hence for string model building, basically all of which is supersymmetric). His most important points (I think) were the following:

  • Discovery of a standard-model-like Higgs, with a mass of around 125 GeV, could be just around the corner. In many popular realisations of SUSY breaking, a Higgs mass of 125 GeV is right at, or just beyond, the maximum possible value, assuming that superpartner masses are kept below several TeV.
  • There is an unexplained anomaly in the Tevatron data, in the 'forward-backward asymmetry' in the production of top-anti-top pairs. The Tevatron collided protons and anti-protons, and this variable measures the number of tops which are produced travelling in the same direction as the initial proton, compared to the number travelling in the direction of the anti-proton. The measured value disagrees with the standard model prediction by something like $3\sigma$.

Monday 25 June 2012

String Phenomenology 2012

This week I am in Cambridge for this year's String Phenomenology conference, and it seems like a good excuse to do some blogging. There are five days of what should be quite interesting talks, and I will try to summarise and pass comment on at least some of them every day. Watch this space!

Friday 1 June 2012

Citation tracking

I know of no good way to quantify the value of one person's contribution to science, or indeed any other field of intellectual endeavour. Nevertheless, people often try to do so, and the vast majority of these efforts focus on citation counts. There are many suggestions as to what is the most reliable indicator: total citation count, average citations per paper, or something slightly more sophisticated, like the h-index. Needless to say, all of these have major flaws, and tend to favour scientists who have simply been around for a long time, or who work on popular topics, but I get the impression that such quantities are still sometimes used as an aid in decisions on hiring, tenure etc.

Such issues have been discussed exhaustively on the blogosphere and elsewhere (although I'm too lazy to gather any links), and I don't really have anything new to add. But I did want to point out that, as far as I can tell, accurate citation data often simply aren't available.