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Dark forces from extended supersymmetry Mitchell Porter presented at University of Queensland 10 November 2011
<ul><li>In supersymmetry, fermions are paired with bosons.  </li></ul>
<ul><li>For example, the spin-2 graviton is paired with the spin-3/2 gravitino, which is a candidate for the dark matter. ...
<ul><li>In extended supersymmetry, particles have  multiple  superpartners.  </li></ul>
<ul><li>Since there is about three times as much dark energy as there is dark matter, one might look for an N=4 or N=8 sup...
<ul><li>I have no such model. But there is an old proposal for particle physics in which the gravitinos are naturally divi...
<ul><li>N=8 supergravity contains 1 graviton, 8 gravitinos, 28 gauge bosons, 56 spin-1/2 fermions, and 35 complex scalars....
<ul><li>To realize Gell-Mann’s proposal, first we work in a space with negative cosmological constant (AdS4). N=8 supergra...
<ul><li>Then we break the symmetry to SU(3) x U(1).  </li></ul><ul><li>48 of the 56 spin-1/2 fermions end up in representa...
<ul><li>The proposal has some problems. For example, the weak force is not directly accounted for. Also, the masses are wr...
<ul><li>But we are in a space of the wrong curvature anyway. We need asymptotically de Sitter space, not anti-de-Sitter sp...
<ul><li>We need some extra positive energy density, to uplift to de Sitter space. What about the gravitinos?  </li></ul>
<ul><li>As it turns out, under SU(3) the N=8 gravitinos fall into two groups. Two are “singlets”, the other six are “tripl...
<ul><li>Also, the eight unused spin-1/2 fermions have the same SU(3) transformation properties as the gravitinos. They are...
<ul><li>You now know as much as I do. I still have no model, but the path ahead is clear… </li></ul>
<ul><li>Look for a solution to N=8 supergravity with the following characteristics:  </li></ul><ul><li>It is a de Sitter u...
<ul><li>Now I will describe where these ideas  actually  came from.  </li></ul>
<ul><li>In 2005, Bilson-Thompson proposed to identify the quarks and leptons with braids. He had no equation, just an idea...
<ul><li>In 2010, Marni Sheppeard noticed that there were some unused braids, the reflections of the neutrino braids. She c...
<ul><li>Sheppeard and her collaborators are trying to devise a whole new framework for physics using the extended braid se...
<ul><li>Cosmologically, they use the ideas of Louise Riofrio, who predicts 9/4 π  for the dark energy fraction and 3/4 π  ...
<ul><li>So it’s all rather unorthodox.  </li></ul>
<ul><li>Nonetheless, it was during a search for a model realizing the Riofrio-Sheppeard theory of the dark sector, that I ...
<ul><li>Sheppeard’s mirror neutrinos correspond to the SU(3)-(anti)triplet goldstone fermions in Gell-Mann’s proposal, the...
<ul><li>There are many other aspects to the possible mapping between Sheppeard et al and Gell-Mann 1983, but they are some...
<ul><li>So to sum up, we have, not just a new approach to the physics of the dark sector, but the possibility that N=8 sup...
<ul><li>I used to say that dark cosmology offered no real guidance to particle physics, because there was too little data....
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Dark forces from extended supersymmetry

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Dark forces from extended supersymmetry

  1. 1. Dark forces from extended supersymmetry Mitchell Porter presented at University of Queensland 10 November 2011
  2. 2. <ul><li>In supersymmetry, fermions are paired with bosons. </li></ul>
  3. 3. <ul><li>For example, the spin-2 graviton is paired with the spin-3/2 gravitino, which is a candidate for the dark matter. </li></ul>
  4. 4. <ul><li>In extended supersymmetry, particles have multiple superpartners. </li></ul>
  5. 5. <ul><li>Since there is about three times as much dark energy as there is dark matter, one might look for an N=4 or N=8 supergravity in which ¼ of the gravitinos are dark matter and ¾ of the gravitinos are dark energy. </li></ul>
  6. 6. <ul><li>I have no such model. But there is an old proposal for particle physics in which the gravitinos are naturally divided into a set of two and a set of six. This is Gell-Mann’s 1983 proposal for N=8 supergravity. </li></ul>
  7. 7. <ul><li>N=8 supergravity contains 1 graviton, 8 gravitinos, 28 gauge bosons, 56 spin-1/2 fermions, and 35 complex scalars. </li></ul>
  8. 8. <ul><li>To realize Gell-Mann’s proposal, first we work in a space with negative cosmological constant (AdS4). N=8 supergravity has SU(8) x SO(8) symmetry there. </li></ul>
  9. 9. <ul><li>Then we break the symmetry to SU(3) x U(1). </li></ul><ul><li>48 of the 56 spin-1/2 fermions end up in representations that can be assembled into the quarks and leptons. </li></ul>
  10. 10. <ul><li>The proposal has some problems. For example, the weak force is not directly accounted for. Also, the masses are wrong! </li></ul>
  11. 11. <ul><li>But we are in a space of the wrong curvature anyway. We need asymptotically de Sitter space, not anti-de-Sitter space, to match the real world. </li></ul>
  12. 12. <ul><li>We need some extra positive energy density, to uplift to de Sitter space. What about the gravitinos? </li></ul>
  13. 13. <ul><li>As it turns out, under SU(3) the N=8 gravitinos fall into two groups. Two are “singlets”, the other six are “triplets” or “antitriplets”. </li></ul>
  14. 14. <ul><li>Also, the eight unused spin-1/2 fermions have the same SU(3) transformation properties as the gravitinos. They are “goldstone fermions” that are absorbed by the gravitinos and give them mass. </li></ul>
  15. 15. <ul><li>You now know as much as I do. I still have no model, but the path ahead is clear… </li></ul>
  16. 16. <ul><li>Look for a solution to N=8 supergravity with the following characteristics: </li></ul><ul><li>It is a de Sitter uplift of the SU(3) x U(1) critical point. </li></ul><ul><li>Dark energy comes from a condensate of SU(3)-triplet gravitinos. </li></ul><ul><li>Dark matter comes from the remaining SU(3)-singlet gravitinos. </li></ul>
  17. 17. <ul><li>Now I will describe where these ideas actually came from. </li></ul>
  18. 18. <ul><li>In 2005, Bilson-Thompson proposed to identify the quarks and leptons with braids. He had no equation, just an idea. </li></ul>
  19. 19. <ul><li>In 2010, Marni Sheppeard noticed that there were some unused braids, the reflections of the neutrino braids. She called them “mirror neutrinos”. </li></ul>
  20. 20. <ul><li>Sheppeard and her collaborators are trying to devise a whole new framework for physics using the extended braid set. A condensate of mirror neutrinos will be responsible for gravity and for mass. </li></ul>
  21. 21. <ul><li>Cosmologically, they use the ideas of Louise Riofrio, who predicts 9/4 π for the dark energy fraction and 3/4 π for the dark matter fraction. Sheppeard wants to get the 1/4 π factor from recent “holographic” calculations of viscosity of plasmas in strongly coupled field theories. </li></ul>
  22. 22. <ul><li>So it’s all rather unorthodox. </li></ul>
  23. 23. <ul><li>Nonetheless, it was during a search for a model realizing the Riofrio-Sheppeard theory of the dark sector, that I unearthed Gell-Mann’s proposal. </li></ul>
  24. 24. <ul><li>Sheppeard’s mirror neutrinos correspond to the SU(3)-(anti)triplet goldstone fermions in Gell-Mann’s proposal, the ones that give mass to the “dark energy gravitinos”. </li></ul>
  25. 25. <ul><li>There are many other aspects to the possible mapping between Sheppeard et al and Gell-Mann 1983, but they are somewhat technical and uncertain. </li></ul>
  26. 26. <ul><li>So to sum up, we have, not just a new approach to the physics of the dark sector, but the possibility that N=8 supergravity has a radically different description in terms of quantum braids. </li></ul>
  27. 27. <ul><li>I used to say that dark cosmology offered no real guidance to particle physics, because there was too little data. I won’t say that again! </li></ul>

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