标题： 关于现实弦构造中的软项和FCNC的更多内容 显示英文标题

标题： More about soft terms and FCNC in realistic string constructions

摘要： 在现实的四维弦构造中，异常U(1)'的存在是普遍的。 此外，与Fayet-Iliopoulos项相关的D项可以打破额外的规范对称性。 因此，物理粒子可能与其他状态结合出现。 我们证明，即使一个三代标准类似模型最初具有与味无关的软标量质量，粒子混合贡献也可能在它们之间产生非统一性。 因此，原本似乎不存在的FCNC效应会重新出现。 我们还讨论了这些贡献的大小以及如何抑制它们。 显示英文摘要

摘要： In realistic four-dimensional string constructions the presence of anomalous U(1)'s is generic. In addition, the associated Fayet-Iliopoulos contribution to the D-term can break the extra gauge symmetries. As a consequence, physical particles can appear combined with other states. We show that even if a three-generation standard-like model has originally flavour-independent soft scalar masses, the particle mixing contribution may generate non-universality among them. Thus FCNC effects which were apparently absent reappear. We also discuss the size of these contributions in an explicit model, and how they can be suppressed.