2006 Fiscal Year Final Research Report Summary
Supersymmetry breaking and its implication to cosmology
| Project/Area Number |
15540247
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Tohoku University |
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Principal Investigator |
MOROI Takeo Tohoku University, Graduate School of Science, Associate professor, 大学院・理学研究科, 助教授 (60322997)
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| Project Period (FY) |
2003 – 2006
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| Keywords | particle physics / cosmology / supersymmetry / dark matter / inflation |
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| Research Abstract |
In this work, I have studied cosmology in the framework of particle-physics models with low-energy supersymmetry. In particular, I have paid particular attention to 1) origin of the density fluctuation of the universe, and 2) big-bang nuclesynthesis.
On the first topics, I have considered the case where there exists some scalar field (other than the inflaton) which once dominates the universe in the early epoch. If such a scalar field acquires primordial amplitude fluctuation, it may become the origin of the present density fluctuation of the universe. (Such a scalar field is called the "curvaton" field.) There are various candidates of the curvaton field in supersymmetric models. I have considered the case where the right-handed scalar neutrino plays the role of the curvaton field, and possible signals in such a case. I also discussed the implication of the curvaton scenario for the so-called D-term inflation model in supersymmetric model.
On the second subject, I considered the effects of the decay of the gravitino, which is the superpartner of the graviton, on the big-bang nucleosynthesis. I have performed a detailed calculation of the decay rate of the gravitino and obtained a precise information about the decay products of the gravitino. Then, I have studied the effects of those decay products on the light-element abundances. I have obtained a very reliable upper bound on the reheating temperature after the inflation using this calculation.
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