Janus field theories from multiple M2 branes

TL;DR

The work derives (2+1)D Janus field theories from the Bagger-Lambert description of multiple M2-branes by employing a relaxed 3-algebra with extra generators, which yields a D2-brane gauge theory upon constraint reduction. By allowing the scalar zero modes $X_0^I$ to depend on spacetime, particularly along light-cone directions, the authors obtain supersymmetric Janus theories with space-time varying couplings $v(x)$, including a dynamical coupling framework with a projected field set $Y^I$. They further study a mass-deformed BL theory that introduces a Myers-like term and leads to an exponential coupling $v=f e^{\mu x^1}$ while preserving a subset of supersymmetry; this expands the Janus landscape to include nontrivial, exponentially growing/decaying couplings. The paper closes with discussions on unitarity considerations, potential matrix-model connections to M-theory, and directions for future work toward a space-time covariant description of M2/M-theory dynamics.

Abstract

Based on the recent proposal of N=8 superconformal gauge theories of the multiple M2 branes, we derive (2+1)-dimensional supersymmetric Janus field theories with a space-time dependent coupling constant. From the original Bagger-Lambert model, we get a supersymmetric field theory with a similar action to the N D2 branes, but the coupling varies with the space-time as a function of the light-cone coordinate, g(t+x). Half of the supersymmetries can be preserved. We further investigate the M2 brane action deformed by mass and Myers-like terms. In this case, the final YM action is deformed by mass and Myers terms and the coupling behaves as exp(μx) where μis a constant mass parameter. Weak coupling gauge theory is continuously changed to strong coupling in the large x region.