QFT
In the literature: open
Microscopic origin of $N^3$ degrees of freedom on M5-branes
In plain words
A stack of $N$ M5-branes behaves as if it carried about $N^3$ independent quantities, while a stack of $N$ ordinary D-branes carries about $N^2$. Which objects supply the $N^3$ is unknown.
Precise statement
The thermal free energy and anomaly coefficients of the $A_{N-1}$ $(2,0)$ theory scale as $N^{3}$ at large $N$ (Klebanov and Tseytlin 1996 from supergravity). Identify the microscopic degrees of freedom responsible (for example membrane states stretched between triples of M5-branes) and derive the coefficient of $N^{3}$ from them.
What would settle it
A microscopic count, in a definition of the theory, that reproduces the coefficient of $N^{3}$ in the anomaly or free energy.
Related problems
- Special case of Intrinsic definition of the six-dimensional (2,0) theory