Talk:Universal extra dimensions

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"Old large dimensions"?[edit]

Why "old large dimensions"? I've never heard that, so I changed it to "large extra dimensions". Sorry if anyone objects. HEL 02:09, 8 October 2006 (UTC)[reply]

to distinguish from Randall Sundrum model "large extra dimensions" which are not that large at all, but can be microscopic. The Randall Sundrum models have matter which warps the extra dimensions, making it sometimes seem in bad coordinate systems that the extra dimensions are no longer finite-size. —Preceding unsigned comment added by 132.236.173.27 (talk) 20:43, 5 September 2007 (UTC)[reply]

""Large :D" difference between Universal extra Dimensions and ADD model "?[edit]

ADD model is not considering universal extra dimensions as the RS model for example. In ADD the SM particles are confiened in the 4 dimensional world as we know, only Gravitons propergate in these extra dimensions (all) —Preceding unsigned comment added by 134.61.12.70 (talk) 17:23, 7 January 2009 (UTC)[reply]

"This article is falsely titled"[edit]

I have done some work in the field of Universal Extra Dimensions, and this article is on a different subject - the ADD model. I don't want to delete other people's work, but this should be re-titled 'the ADD model' or something similar, and a new article on UED's written. —Preceding unsigned comment added by 74.210.12.17 (talk) 20:31, 11 March 2009 (UTC)[reply]

Ok, I see the difference, but the criticism of ADD model regarding neutrino masses and proton decay apply to any theory with a low Planck scale. The replies in the literature to this criticism (although I haven't read them all) are (to my mind) unconvincing. Is there a good reference for how you get rid of nonrenormalizable interactions in the low Planck mass theories?Likebox (talk) 15:03, 13 March 2009 (UTC)[reply]

Even the single reference provided, that Phys Rev D article, is not satisfactory--- the momentum conservation presumes the extra dimensions are structureless toroidal compactifications. If you have a brane or an orbifold, the momentum conservation goes out the window. Even if you don't, toroidal compactifications are marginally unstable in General Relativity, if you let a torus grow a little in GR it keeps on growing, if you let it shrink it collapses in finite time. You need some string scale stabilization mechanism or some gravitational analog of the Higgs mechanism to keep these things from falling apart.

But OK, putting that aside, assume KK number is conserved. So what? The loop effects are not negligible, the loops still give neutrino masses and proton decay.Likebox (talk) 18:10, 16 March 2009 (UTC)[reply]

Violation of obvious constraints[edit]

I've removed the sentence "Like any other class of models with large extra dimensions, these models violate obvious constraints from neutrino masses, proton decay, and the total absence of other nonrenormalizable interactions," because it lacked any references. Considering that there is considerable work on UED with respect to neutrino masses and proton decay, it would seem this strong statement is incorrect. The last condition doesn't even really makes sense, considering UED is an effective field theory. —Preceding unsigned comment added by 88.65.47.104 (talk) 23:46, 22 June 2010 (UTC)[reply]

General recommendations for clean up / R^-1 Limits[edit]

Someone should add to this page what the main phenomenological impact of extra dimensions is: Kaluza Klein states. I removed the completely false statement that direct collider searches exclude compactification scales below 1 TeV. This was obviously written by someone who doesn't know how hadron colliders work, or what a parton distribution function is. The direct searches at the Tevatron or LEPII exclude below 200 GeV at best. Electroweak precision measurements give the best limits. I've added this information but not the citations --- I'm not terribly familiar with how to do that in Wikipedia. These limits are easy to find on the arXiv. Someone should add the references. — Preceding unsigned comment added by Certain (talk • contribs) 00:39, 22 June 2011 (UTC)--Certain (talk) 00:41, 22 June 2011 (UTC)[reply]