| DATE: |
2006-06-20 11:00 - 12:00 |
| PLACE: |
Kenkyu Honkan 2F Rm.220 |
| TITLE: |
Gravitino Production from Heavy Moduli Decay and Cosmological Moduli Problem Revived |
| CONTACT: |
tsuda |
| SPEAKER: |
Shuntaro Nakamura (Tohoku Univ.) |
| LANGUAGE: |
Japanese |
| ABSTRACT: |
The cosmological moduli problem for relatively heavy moduli fields is reinvestigated. For this purpose we examine the decay of a modulus field at a quantitative level. The modulus dominantly decays into gauge bosons and gauginos, provided that the couplings among them are not suppressed in the gauge kinetic function. Remarkably the modulus decay into a gravitino pair is unsuppressed generically, with a typical branching ratio of order 0.01. Such a large gravitino yield after the modulus decay causes cosmological difficulties. The constraint from the big-bang nucleosynthesis pushes up the gravitino mass above $10^5$ GeV. Furthermore to avoid the over-abundance of the stable neutralino lightest superparticles (LSPs), the gravitino must weigh more than about $10^6$ GeV for the wino-like LSP, and even more for other neutralino LSPs. This poses a stringent constraint on model building of low-energy supersymmetry. |
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