Study of compactification in superstring and low energy effective theories theory

作为超弦低能有效理论的超对称模型，从不同角度研究了超对称模型的色调特征。本课题取得的主要成果如下：1。具有额外的U(l)对称性和规范单重场的超对称模型可以解决最小超对称标准模型（MSSM）中的μ问题。在这类模型中，通过规范单重态场和普通希格斯场的相互作用可以有效地产生μ项，因此最轻的中性希格斯场的上质量界可以大于MSSM的上质量界。考虑到辐射对称性破缺和各种现象学约束，我们估计了这个上界。我们已经证明，在这些模型中，tan β < 2区域现在仍然没有被排除。如果违反ε项的r宇称足够小，我们可以产生中微子质量，而不会引起与其他现象学约束的任何矛盾。如果我们假设在TeV区域存在一个额外的U(1)和ε项，则可以通过中微子-高介子混合产生中微子质量。我们已经证明，这种大规模产生的场景可以很容易地实现轻子扇区的双大混合。我们已经扩展了这个场景，使得夸克扇区的质量特征值和风味混合也可以用统一的方式解释。在这个方向上提出了一个具体的模型。此外，我们还提出，如果假设MSSM内容与超共形场理论耦合，可以实现大的异常维数，则μ和ε项的小性可以得到解释。基于异常U(1)对称性的D项暴胀情景被认为与COBE得到的密度摄动相矛盾。为了解决这个问题，我们对模型进行了扩展，使μ问题和中微子质量的小性都能得到解释，并提出了一个具体的模型。我们还研究了这类模型中的纤体发生情景。少

Phehomenological features of supersymmetric models derived as the low energy effective theory of superstring have been studied from various points of view. Main results obtained in this project are followings.1. Supersymmetric models with an extra U(l) symmetry and a gauge singlet field can solve a μ-problem in the minimal supersymmetric standard model (MSSM). In this kind of models a μ term is generated effectively through an interaction between the gauge singlet field and ordinary Higgs fields and as its result the upper mass bound of the lightest neutral Higgs field can be larger than the one of the MSSM. We have estimated this upper bound taking account of the radiative symmetry breaking and various phenomenological constraints. We have shown that tan β < 2 region has not been excluded still now in these models.2. If the R-parity violating ε term is small enough, we can generate the neutrino masses without causing any contradiction with other phenomenological constraints. If we sup … More pose the existence of both an extra U(1) at an TeV region and the ε term, the neutrino masses can be generated due to the neutrino-gaugino mixings. We have shown that this mass generation scenario can easily realize the bi-large mixings in the lepton sector. We have extended this scenario so that the mass eigenvalues and flavor mixings in the quark sector are also explained in a unified way. A concrete model has been proposed in this direction. Additionally we have suggested that the smallness of both μ and ε terms can be explained if we suppose the MSSM contents couple with the superconformal field theory which can realize the large anomalous dimension.3. The D term inflation scenario based on the anomalous U(1) symmetry has been suggested to contradict with the density perturbation obtained by COBE. In order to solve this problem we have extended the model in such a way that both the μ problem and the smallness of neutrino masses can be explained and we have presented a concrete model. We have also studied the leptogenesis scenario in this type of models. Less