To an audience of 5 astrophysicists, just last week. There was some interest, but they find it all a bit abstract. One of them did think he recognized the name Riofrio!
Ah, I see. Yes, the astrophysicists tend to be attentive, since they well know which way the wind is blowing. It has been that way for many years, for me. Years ago, I mentioned Louise's work in many seminars, with a mixture of astrophysicists and GR theorists in the audience. Needless to say, the astrophysicists would be taking notes for the first ten minutes, and then give up when I could not resist trying to explain something abstract. Most, but not all, of the theorists would sit there shaking their heads in disgust. The few theorists who listened were Cool Enough not to care what anybody thought about the fact that they weren't shaking their heads in disgust. And yes, Respectable String Theorists will avoid talks they don't like the sound of altogether ...
Interesting slides. In N=8 SUGRA, SU(8) is in E7(7) and the 28 U(1) gauge fields arise from the d=11 potential and metric. The 28 U(1) fields and their magnetic duals can be arranged in vectors, both of which are nicely packaged in a Freudenthal triple system (FTS) over the split exceptional Jordan algebra, J(3,O_s). The 28's thus break up as: 28=27+1=dim(J(3,O_s))+graviphoton. The system has an intepretation as the charge space of D=4, N=8 SUGRA extremal black holes, where E7(7) is the automorphism group of the FTS charge space.The extremal black holes are dyonic and Strominger (hep-th/9307059) and others have argued they obey anyonic statistics. I've been interested in defining and studying the generalized braiding of these dyonic black holes, which would give a topological quantum computational approach to N=8 SUGRA.
OK, so kneemo's graviphotons are the extra singlets. Morally, I think these degrees of freedom just set the physical scale for 'local' gravity (while the off diagonal braids are observable and chiral). And yes, the dark sector ...
I should also mention an interesting fact, noted by the late Joel Scherk and others as far back as 1979: extended supergravities (e.g., N=2,3,...,8) predict antigravity (gravivector and graviscalar) fields in the graviton supermultiplet (hep-ph/9710562).
kneemo, antigravity is cool, but I must strongly disagree with what that '97 paper says about the equivalence principle.
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