Discovery-HET Seminar: Koichi Murakami – University of Copenhagen

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Discovery-HET Seminar: Koichi Murakami

Speaker: Koichi Murakami

Title: Multiloop amplitudes of light-cone gauge bosonic string field theory in noncritical dimensions

Abstract: 

Superstring field theory has not been established yet, mainly because of a divergence problem called the ``contact term problem", which occurs even at the tree-level. This happens in the light-cone gauge formulation as well as gauge invariant one. In order to deal with this divergence for the light-cone gauge NSR superstring field theory, we have proposed the regularization scheme in which the spacetime dimensions is shifted to a large negative value. So far we have verified that our dimensional regularization works for the tree-level amplitudes. As a first step towards the examination whether the dimensional regularization works for the multiloop amplitudes, we study in this work the multiloop amplitudes of the light-cone gauge closed bosonic string field theory in noncritical dimensions. We show that the amplitudes can be recast into a BRST invariant form by adding a nonstandard worldsheet theory for the longitudinal variables and the reparametrization ghost system. I would also like to comment on the superstring extension in progress.
This talk is based on the collaboration with Nobuyuki Ishibashi (University of Tsukuba).
reference: arXiv:1307.6001