Narrow Results

First, we give a brief review of recent development of lattice formulations for supersymmetric Yang-Mills (SYM) theories with extended supersymmetry, which preserves a part of supersymmetry on lattice. For cases of two dimensions, we can see that lattice models in such formulations lead to the target continuum theories with no fine-tuning. Namely, supersymmetries or some other symmetries not realized on the lattice are automatically restored in the continuum limit.

Next, we consider a mass deformation to and present its lattice formulation with keeping two supercharges. It provides a nonperturbative framework to investigate IIA matrix string theory. Moreover, since it has fuzzy sphere solutions around which four-dimensional theory is deconstructed, it will serve a nonperturbative formulation of four-dimensional which requires no fine-tuning. The rank of the gauge group is not restricted to large N. It opens a quite interesting possibility to test AdS/CFT correspondence in a stringy regime where string loop effects cannot be neglected. Also, for two-dimensional , a similar argument is possible to obtain four-dimensional on noncommutative space.

We find that, apart from the instanton contributions, the all genus partition function of the ABJM matrix model sums up to the Airy function. We present the result, discuss its implication and also summarize some further progress.

Non-critical string/M theory is a solvable model which has been studied to reveal various non-perturbative aspects of string theory with providing new key concepts to the next developments of string theory. Here we show some recent progress in study of Stokes phenomenon in non-critical string theory of the multi-cut two-matrix models. In particular, we argue that it is Stokes phenomenon which allows us to know concepts of non-perturbative completion with analytic study of string-theory landscape from the first principle.

We study the large-N renormalization group of scalar field theory on a fuzzy sphere. We carry out perturbative analysis and formulate the renormalization group equation. We then search for fixed points and investigate their properties.

Quantum entanglement is closely related to the structure of spacetime in quantum gravity. For quantum field theories or statistical models, we usually consider base space entanglement. However, target space instead of base space sometimes directly connects to our spacetime. In these cases, it is natural to consider a concept of target space entanglement. To define the target space entanglement, we consider a generalized definition of entanglement entropy based on an algebraic approach. This approach is reviewed and is applied to the first quantized particles, in particular, fermions. This article is based on the paper JHEP 08 (2021) 046.