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Cosmological Problems in Supersymmetry Theories

超对称理论中的宇宙学问题

基本信息

批准号：
14540245
负责人：
KAWASAKI Masahiro
金额：
$ 2.56万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2005
项目状态：
已结题

项目摘要

We studied the origin of matter-anti-matter asymmetry (baryogenesis), and the cosmological effects of unstable particles in the early universe in the frame of supersymmetry. theories.We investigated the Affleck-Dine (AD) mechanism as promising baryogenesis process taking account of finite temperature effect. The AD field is trapped far away from the origin by the negative thermal correction for a long time until the temperature of the universe becomes low enough. In some case, non-linear dynamics of Q-balls produced in the AD mechanism suppresses the baryon asymmetry crucially. However, it was found that there remains some parameter space for which the dynamics of Q-ball formation does not affect the baryon asymmetry and it is possible to generate the right amount of the baryon asymmetry. We also found that there exists a soliton-like solution called "I-ball" in theories of a real scalar field if the scalar potential satisfies some conditions.We studied the big-bang nucleosynthesis (BBN) with the long-lived unstable particle such as gravitino and moduli. If the lifetime of the unstable particle is longer than about 0.1 sec, its decay may cause non-thermal nuclear reactions during or after the BBN, altering the predictions of the standard BBN scenario. We paid particular attention to its hadronic decay modes and calculate the primordial abundances of the light elements. Using the result, we derived constraints on the primordial abundance of the unstable particle. We applied our results to the gravitino problem, and obtained upper bound on the reheating temperature after inflation.We investigated the MeV-scale reheating scenario wherein the thermalization of neutrinos could be insufficient. We paid particular attention to the oscillation effects on the thermalization processes of neutrinos and obtained the stringent constraint on the reheating temperature (〜2MeV).

我们研究了物质-反物质不对称性（重子生成）的起源，以及超对称框架下早期宇宙中不稳定粒子的宇宙学效应。我们研究了Affleck-Dine（AD）机制作为考虑有限温度效应的有希望的重子生成过程。AD场在很长一段时间内被负热修正捕获在远离原点的地方，直到宇宙温度足够低。在某些情况下，AD机制中产生的Q球的非线性动力学对重子不对称性起着至关重要的抑制作用。然而，人们发现，仍然存在一些参数空间，Q球形成的动力学不影响重子不对称性，并且有可能产生适量的重子不对称性。我们还发现，当标量势满足一定条件时，在真实的标量场理论中存在一个称为“I-ball”的类孤子解。如果不稳定粒子的寿命超过0.1秒，它的衰变可能会在BBN期间或之后引起非热核反应，改变标准BBN情景的预测。我们特别注意了它的强子衰变模式，并计算了轻元素的原始丰度。利用这个结果，我们导出了不稳定粒子的原始丰度的限制。我们将所得结果应用于引力子问题，得到了暴胀后再加热温度的上界，并研究了MeV尺度下中微子热化不充分的再加热情形.我们特别注意了中微子热化过程中的振荡效应，得到了再加热温度的严格限制（~ 2 MeV）。