Last week at the KITP, Keith Dienes gave a talk on A Statistical Study of the Heterotic Landscape. He gave a good idea of the state of the art of the investigation of the Landscape, focusing on one special type of models, heterotic models. The results he presented gave statistical distributions for just two very crude aspects of these compactifications, their gauge groups and cosmological constants. These models remain highly unrealistic, since the cosmological constants are of order the Planck scale and the compactifications are not stable.
The models studied have gauge groups of rank 22, and while many of them contain the standard model SU(3)xSU(2)xU(1), they also contain many more gauge group factors, with typically not one, but about seven SU(2) factors. These models, with their instabilities, far too large gauge groups and cosmological constants, are extremely far from anything like the standard model. It’s not at all clear what the point is in enumerating them and studying their statistics, but Dienes describes in detail various problems that arise with the whole concept of generating “random” models of this kind and trying to get sensible statistical distributions. He also looks for correlations between gauge groups and cosmological constants, finding that at small cosmological constant one is somewhat more likely to get many factors in the gauge group (although in his case, both the gauge group and the cosmological constant are very different than in the real world).
Despite the very crude state of these calculations, Dienes reports that a group of 17 prominent string theorists have banded together to form the “String Vacuum Project”, with the goal over the next few years of accumulating a database of 10s of billions of string models, with the hope of finding within this mountain of data about 100 models that have crude features of the standard model. I don’t at all see what the point of this is, but it certainly is a computationally intensive project that could keep many people occupied for a long time. It also appears to be just the beginning, with the longer term goal being to devote the next decades to expanding from 10s of billions farther into the 10^500 or whatever exorbitantly large number is thought to be the number of all string models.
The String Vacuum Project submitted a proposal to the NSF last year, which seems to have been turned down, and they appear to be planning to resubmit the proposal. They have a Wiki, with all sorts of details about the project. Most recent additions to the Wiki are from Bert Schellekens in August, who discusses a proposed “String Vacuum Markup Language” (SVML) format, with links to a web-page that produces data in this format for certain sorts of models. There’s also a European String Vacuum Project web-site.
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