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marcus

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## Main Question or Discussion Point

http://arxiv.org/abs/0805.1265

Song He, Yidun Wan

28 pages, 5 figures

(Submitted on 9 May 2008)

"We study the discrete transformations of four-valent braid excitations of framed spin networks embedded in a topological three-manifold. We show that four-valent braids allow seven and only seven discrete transformations. These transformations can be uniquely mapped to C, P, T, and their products. Each CPT multiplet of actively-interacting braids is found to be uniquely characterized by a non-negative integer. Finally, braid interactions turn out to be invariant under C, P, and T."

I think this is an important paper. It is the companion of another He-Wan paper that I nominated last week for this quarter's MVP (most valuable non-string QG research) prediction poll. The braid-matter program is high risk. It began as a long shot with only a slim chance of working out. It was not at all clear that braids (in this case in four-valent networks used to describe states of geometry and gravity) would turn out to reproduce some of the basic patterns of matter----key symmetries and invariants. This paper is, for me, the first sign that braid-matter might work. Others might see differently and I would be glad to have some comments.

In any case the whole thing is very new. It goes back only to Bilson-Thompson's work in 2005----which had braids but without the context of four-valent networks.

**C, P, and T of Braid Excitations in Quantum Gravity**Song He, Yidun Wan

28 pages, 5 figures

(Submitted on 9 May 2008)

"We study the discrete transformations of four-valent braid excitations of framed spin networks embedded in a topological three-manifold. We show that four-valent braids allow seven and only seven discrete transformations. These transformations can be uniquely mapped to C, P, T, and their products. Each CPT multiplet of actively-interacting braids is found to be uniquely characterized by a non-negative integer. Finally, braid interactions turn out to be invariant under C, P, and T."

I think this is an important paper. It is the companion of another He-Wan paper that I nominated last week for this quarter's MVP (most valuable non-string QG research) prediction poll. The braid-matter program is high risk. It began as a long shot with only a slim chance of working out. It was not at all clear that braids (in this case in four-valent networks used to describe states of geometry and gravity) would turn out to reproduce some of the basic patterns of matter----key symmetries and invariants. This paper is, for me, the first sign that braid-matter might work. Others might see differently and I would be glad to have some comments.

In any case the whole thing is very new. It goes back only to Bilson-Thompson's work in 2005----which had braids but without the context of four-valent networks.

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