Tuesday, March 9, 2010

Ocean of leptogenesis

For the last few days I have been trying to learn various models of leptogenesis, the mechanism of producing a lepton-antilepton asymmetry in the early Universe. When I searched for keyword "leptogenesis" in SPIRES, it returned around 750 papers. Thank God I did not give up and dared to look into the list in search of some pioneering papers with maximum citations. I was more surprised by the number of various types of leptogenesis mechanism than the huge number of papers. Before I thought it can happen only by the decays of heavy neutrinos. But there are plenty of other scenarios: like Higgs triplet decay in type 2 seesaw mechanism, resonant leptogenesis which arises from two quasi-degenerate heavy neutrinos, supersymmetric leptogenesis, electromagnetic leptogenesis, gravitational leptogenesis and many others. I am just wondering is there any other type of leptogenesis exist which no one has considered yet. I never could imagine this to be such a vast field. I don't know what I am capable of doing in this field or what new thing is there for me to tell the world about it, but the subject is pretty interesting. After all, it addresses one of the very important issues in physics: why we see only matter around us and not anti-matter? Its very unlikely that the Universe was created with a matter-antimatter asymmetry. Thus if there were equal proportion of matter and antimatter in the early Universe then why don't we see anti-galaxies, anti-planets or may be anti-human around us? ........Leptogenesis will give you the answer!!

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