## Wednesday, March 28, 2007

### Jordan Algebras and Extremal Black Holes

Back in 2003, Pierre Ramond wrote a classic paper entitled Exceptional Groups and Physics where he considered the mysterious relationship between M-theory and the exceptional Lie groups. On pages 8 and 9, he discussed the exceptional Jordan algebra (EJA) and its automorphism group F4, arguing that the SO(9) subgroup of F4 should be interpreted as the light-cone little group in eleven dimensions. He concluded with the statement:

"If the SO(9) subgroup of [the] EJA automorphism group F4 can indeed be identified with the light-cone little group in eleven space-time dimensions, it will suggest the EJA as the charge space of a very special system."

In February 2005, Murat Gunaydin showed the EJA is actually the charge space of an extremal black hole in N=2, d=5 Maxwell-Einstein supergravity. Come summer 2005, Andrew Neitzke, Boris Pioline and Andrew Waldron joined forces with Murat Gunaydin and formulated a method for counting microstates of four-dimensional BPS black holes in N >= 2 Maxwell-Einstein supergravities. Gunaydin gave a December 9th talk on the approach at the KITP and by December 22 the work culminated in a paper entitled BPS black holes, quantum attractor flows and automorphic forms.

It turns out there are more Jordan algebraic goodies that add to the story, so I put together a paper and posted it here. :)

(Note: The image above is a depiction of the Bajoran wormhole from the Star Trek: Deep Space Nine series)

## Thursday, March 22, 2007

### Ternary Logic

Earlier this week, Kyle (a fellow physics grad student) got me thinking about the set of single variable functions from a finite set A={a,b,c} to a finite set B={0,1,2}. Such functions involve triples of elements of A x B, and take for example the form f_012={(a,0), (b,1), (c,2)}. I ended up using shorthand for such functions, writing f_012 as 012 for instance, to reveal the nice single variable ternary function structure. Ultimately, I came up with the above diagram to show how multiple copies of the parity cube vertices arise in this set of functions. I guess one can also look at it as a Qutrit function diagram. Kea and Carl may see further applications in particle physics. ;)

## Monday, March 19, 2007

### AIM Team Maps E8

## Friday, March 16, 2007

### 3D Discrete Dynamical Systems

## Sunday, March 11, 2007

### Standard Model Particle Masses

For all of you that suddenly awaken at night (in a cold sweat) because you forgot your SM particle masses, make sure to check out the PDG page for a refresher.

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