Study of non-perturbative dynamics in superstring theory and M theory

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Kazama conducted a research which clarifies the basic structure of the "pure spinor (PS) formalism", a promising new worldsheet formalism for superstring realizing the manifest supersymmetry and Poincare covariance at the same time, and obtained the following results. First, he pointed out a difficulty associated with the non-linear constraints characteristic of the PS formalism, and constructed an "Extended PS (EPS) formalism" based on an enlarged field space without the constraints. Further he demonstrated the equivalence of this formalism with the familiar Ramond-Neveu-Schwarz (RNS) formalism and the Green-Schearz (GS) formalism by explicitly constructing the similarity transformations connecting them. Based on these results, he proposed the idea of the "double spinor formalism", where the number of the spinor fields in the GS formalism is doubled together with a new local fermionic symmetry which kills the unwanted degrees of freedom, and thereby clarified the hitherto unidentified … More basic action and its symmetry structure for the PS formalism and succeeded for the first time in deriving the fully quantized PS formalism from the first principle. Further, he applied this idea to the problem of supercovariant quantization of the 11 dimensional supermembrane theory and obtained the algebra of constraints governing the basic dynamics of the system at the classical level and clarified its structure.Hashimoto mainly studied the dynamics of the D-brane system and accomplished the following results. He gave simple field-theoretical descriptions of D-brane creation/annihilation, in some peculiar D-brane configurations such as intersecting D-branes and/or creation of lower dimensional D-branes. String field theories, which are quite complicated, have been used for the analyses of the D-brane annihilation, and he clarified perturbative aspects of those theories. Since the lower dimensional D-branes are known to correspod to solitons in gauge theories, he gave physical interpretation of the known mathematical method for constructing solitons, in terms of the D-brane creation/annihilation. D-branes enabled him to analyse interactions between solitons, and its application revealed the mechanism of reconnection of colliding cosmic strings which are phenomenological vortex solitons. Less