Nonperturbative formulation of string theory by fermions and the study of black holes

本研究的目的是从孤子的观点出发，建立弦理论的非微扰表述。D膜费米子首先，我们建议把c<1幺正弦理论中的边界宇宙学常数φ看作是目标空间的一维复坐标，在这个坐标上世界片的边界可以存在。从这个观点出发，我们明确地构造了满足Polchinsk边界组合表的D-瞬子的类似物。“我们进一步表明，我们在前面的文章中开发的算子形式主义在评估D-瞬子效应方面是强大的，并且还证明了对于简单的情况，这些效应与弦方程精确解中发现的弦非微扰效应完全一致。我们研究了第一量子化的带电玻色子测试弦在穿过质量为M^^的带电粒子产生的冲击波后被激发的程度。并充电Q^^。激波由带电的Aichelburg-Sexl（CAS）时空给出，其中Q^^- = 0对应于普通的Aichelburg-Sexl时空。计算了带电测试弦通过CAS时空中的激波后的质量期望值。在小Q^^-的情况下，引力和库仑力相互抵消，因此弦的激发仍然很小。然而，在大Q^^-的情况下，每一个带电弦都被由规范场和轴子场引起的额外维度中的量子涨落高度激发。

The purpose of this research is to construct a nonperturbative formulation of string theory by studying it from the viewpoints of solitons. D-branes. fermions. singularities of spacetime and black holes.First, we suggest that the boundary cosmological constant ζ in c<1 unitary string theory be regarded as the one-dimensional complex coordinate of the target space on which the boundaries of world-sheets can live. From this viewpoint we explicitly construct analogues of D-instantons which satisfy Polchinsk's "combinatories of boundaries." We further show that our operator formalism developed in the preceding articles is powerful in evaluating D-instanton effects, and also demonstrate for simple cases that these effects exactly coincide with the stringy nonperturbative effects found in the exact solutions of string equations.Next, we investigate how much a first-quantized charged bosonic test string gets excited after crossing a shock wave generated by a charged particle with mass M^^- and charge Q^^-. The shock wave is given by a charged Aichelburg-Sexl (CAS) spacetime where Q^^- = 0 corresponds to the ordinary Aichelburg-Sexl one. We compute the mass expectation value of the charged test string after passing through the shock wave in the CAS spacetime. In the case of small Q^^-, gravitational and Coulomb forces are canceled out each other and hence the excitation of the string remains very small. In the case of large Q^^-, however, every charged string gets highly excited by quantum fluctuation in the extra-dimension caused by both the gauge and the axion fields.We have been also studying the enhancon mechanism for the D6-D2 system.