tag:blogger.com,1999:blog-2793748488131782896.post1325642146320575039..comments2023-08-18T11:05:05.423+01:00Comments on Cross Sections: Preprint roundupRhyshttp://www.blogger.com/profile/15520219929014063200noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-2793748488131782896.post-57306385140588537762012-05-24T13:18:12.416+01:002012-05-24T13:18:12.416+01:00I've never really looked into the details of t...I've never really looked into the details of the $G_2$ stuff, so I can't comment on that. But either way, I think it's a pretty big deal if these uplift mechanisms don't work, if only because they have been the dominant paradigm for 'realistic' string model-building for many years now.Rhyshttps://www.blogger.com/profile/15520219929014063200noreply@blogger.comtag:blogger.com,1999:blog-2793748488131782896.post-38595663777046778602012-05-24T07:19:26.836+01:002012-05-24T07:19:26.836+01:00You can obtain dS vacua without using anti branes,...You can obtain dS vacua without using anti branes, it's not really a problem. One example is the G2 construction of Acharya et al, where dS vacua arise when SUSY gets spontaneously broken by F-terms of the hidden sector matter field. Of course, there is no explicit G2 manifold example where this scenario has been implemented but the construction seems to be general enough that it should not matter.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2793748488131782896.post-52976149237576534832012-05-14T08:40:47.283+01:002012-05-14T08:40:47.283+01:00dS vacua are indeed difficult to find. But that do...dS vacua are indeed difficult to find. But that doesn't necessarily mean that they're not out there — most attempts to construct them start with a supersymmetric compactification, and then perturb it to break supersymmetry and raise the cosmological constant to a positive value. It might be that there are plenty of intrinsically non-supersymmetric vacua, but constructing these (and verifying their consistency) is much much harder.<br /><br />I have somehow missed that the debate over the consistency of these solutions has been ongoing for some time. Joe Conlon tells me that there was a workshop a couple of weeks ago to discuss exactly these issues, and that opinion is still divided.<br /><br />It's probably clear, but just to be sure: I'm far from an expert on this stuff.Rhyshttps://www.blogger.com/profile/15520219929014063200noreply@blogger.comtag:blogger.com,1999:blog-2793748488131782896.post-59133353135789030632012-05-13T20:53:18.085+01:002012-05-13T20:53:18.085+01:00Thanks Rhys...
I was searching for RSS feeds only...Thanks Rhys...<br /><br />I was searching for RSS feeds only since I didn't know the Atom feeds. Nice to know...<br /><br />Now regarding the geometry singularity in the KKLT anti-brane model although I'm not a physicist I can imagine that these are not good news for the multivesre idea in the context of String theory. The multiverse and the anthropic principle requires an abundance of de Sitter vacua to solve the CC problem and it seems that dS vacua are hard to find in String theory. I was watching a video of Strings 2011 where Gary Shiu, while presenting his work on the scarcity of dS vacua in IIA, was asked by Linde to tell if this was the case for IIB too (having in mind the KKLT model). Shiu left the question unanswered I guess mainly because the inclusion of non-perturbative effects was not covered by his latest work. <br /><br />In any case I can imagine that if it is found that dS vacua are very rare in IIB too this would have severe consequences for the multiverse paradigm.Giotisnoreply@blogger.comtag:blogger.com,1999:blog-2793748488131782896.post-78566686712146977972012-05-13T14:59:39.402+01:002012-05-13T14:59:39.402+01:00Hi Giotis. There is a link at the bottom of the m...Hi Giotis. There is a link at the bottom of the main page to a post feed, and a link at the bottom of each comment section to a comment feed. They are in Atom format, but you can apparently just add ?alt=rss to the end to get RSS. So this should be what you want:<br /><br />http://x-sections.blogspot.com/feeds/posts/default?alt=rss<br /><br />I apologise that I'm not too savvy when it comes to this stuff. I don't use RSS/Atom feeds myself.Rhyshttps://www.blogger.com/profile/15520219929014063200noreply@blogger.comtag:blogger.com,1999:blog-2793748488131782896.post-29464716723902377972012-05-12T09:11:04.232+01:002012-05-12T09:11:04.232+01:00Sorry off topic but where are your RSS feeds? I...Sorry off topic but where are your RSS feeds? I'm trying to find a way to put your blog in my Google reader...Giotisnoreply@blogger.com