Study of compactification in superstring and low energy effective theories theory

本文从不同的角度研究了超弦低能有效理论所导出的超对称模型的特征。本课题取得的主要成果如下：1.具有额外U（1）对称性和规范单态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，通过规范单态场与普通Higgs场的相互作用有效地产生了μ项，从而使最轻中性Higgs场的质量上界大于MSSM的质量上界.我们已经估计了这个上限考虑到辐射对称性破缺和各种唯象约束。我们证明了在这些模型中tan β < 2的区域至今仍未被排除.如果R宇称破坏ε项足够小，我们可以产生中微子质量，而不会引起与其他唯象约束的矛盾。如果我们吃晚饭 ...更多信息 假设在TeV区域存在额外的U（1）和ε项，中微子质量可以由中微子-高更子混合产生。我们已经证明，这种质量产生方案可以很容易地实现在轻子部门的双大混合。我们已经扩展了这种情况下，夸克部门的质量本征值和味道混合也被解释在一个统一的方式。在这方面提出了一个具体的模式。此外，我们还提出，如果我们假设MSSM的内容与超共形场论耦合，可以实现大的反常维数，那么μ项和ε项的小值就可以得到解释.基于反常U（1）对称性的D项暴胀方案与COBE得到的密度微扰相矛盾。为了解决这个问题，我们对模型作了扩展，使μ问题和中微子质量的微小性都能得到解释，并给出了一个具体的模型。我们还研究了此类模型中的瘦源化场景。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