Effective mass and symmetry breaking in the Ishibashi-Kawai-Kitazawa-Tsuchiya matrix model from compactification

The Ishibashi-Kawai-Kitazawa-Tsuchiya (IKKT) model is a promising candidate for a nonperturbative description of type IIB superstring theory. It is known from analytic approaches and numerical simulations that the IKKT matrix model with a mass term admits interesting cosmological solutions. However, this mass term is often introduced by hand and serves as a regulator in the theory. In the present paper, we show that an effective mass matrix can arise naturally in the IKKT model by imposing a toroidal compactification where the space-time fermions acquire antiperiodic boundary conditions. When six spatial dimensions are chosen to be compact, the effective mass matrix breaks the SO(1,9) space-time symmetry of the IKKT model to SO(1,3)×SO(6). This paves the way for space-time solutions of the IKKT model where SO(1,9) symmetry is naturally broken to SO(1,3)×SO(6). Published by the American Physical Society 2024