Thursday, August 20, 2009

Today's Seminar by Dr. Arunansu Sil (CEA/Saclay)

Today there was a good seminar in the department. Well, by "good" I mean a seminar related to some field which I truly appreciate. I know I am very biased in saying that, we should appreciate any scientific work no matter what field it is. Anyway coming back to the main point, the seminar was given by Dr. Arunansu Sil, a post doctoral fellow in CEA, Saclay. He talked about his recent works with his collaborators on Inflation and Supersymmetry Breaking. I will just state the main points which I can recall or may be I could understood from the seminar:

1. To explain the slow-roll inflation as well as the origin of quantum fluctuations at the reheat temperature T_R which gives rise to temperature anisotropy in the CMBR they have introduced a new approach incorporating supersymmetry.

2. The inflaton field couples to the supersymmetry breaking sector and its couplings to the MSSM sector is higly suppressed so that quantum corrections don't destroy the slow roll behaviour.

3. Then he discussed the various possible mechanisms of SUSY breaking and also introduced the famous ISS (Intrilligator-Seiberg-Shih) model of dynamical SUSY breaking.

4. Then he used inflaton field as well as the so called "waterfall" field ( I have no idea about the origin of this name) and the interaction of the inflation and SUSY breaking sector via gravity.

5. He showed that such scenario can lead to a long-lived metastable non-SUSY vacuum which could be the true vacuum of our present Universe.

6. He also talks about a distorted version of ISS model where gauge mediation is considered responsible for SUSY breaking. In that case the reheat temperature comes out to be of the order of 1 TeV whereas in the previous case (gravity mediated) it was of the order of 10^9 GeV.

I could not fully understand since I am not familiar with dynamical supersymmetry breaking as well as SQCD where he considered various accidental non-abelian global symmetries which gives rise to an SQCD duality (It basically makes possible to study the theory in both infra-red as well as Ultra-violet limit). Details of his work can be found in the references : Physics Letters B , 660, 236 and JHEP 0904, 092.

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