Finite-dimensional algebras, gauge-string duality and thermodynamics
Sanjaye Ramgoolam
TL;DR
The work develops finite-dimensional permutation algebras to organize gauge-invariant polynomials in matrix and tensor variables, linking representation theory to finite-$N$ structure and holographic thermodynamics. It introduces representation-theoretic bases and efficient eigenvalue algorithms for multi-matrix and tensor invariants via algebras such as $ ext{A}(m,n)$ and $K(n)$, exploiting Schur-Weyl duality and central elements. Counting formulas in these algebras imply a microcanonical negative specific heat branch at low energies, with a crossover to positive specific heat at higher energies, and similar phenomena persist under $S_N$ gauge symmetry using partition algebras. Collectively, the framework connects combinatorics, representation theory, and thermodynamics to illuminate finite-$N$ effects and emergent gravitational physics in gauge/string duality, while providing practical computational tools for constructing orthogonal operator bases.
Abstract
Gauge-invariant polynomial functions of matrix and tensor variables capture combinatorial structures of gauge-string duality, which can be usefully organised using finite-dimensional associative algebras. I review recent work on eigenvalue systems using these algebras as state spaces, which provide efficient computational algorithms for the construction of orthogonal bases in the multi-matrix case. Algebraic counting formulae in matrix and tensor systems with $U(N)$ as well as $S_N$ symmetry have led to gauged quantum mechanical models which display a negative branch of specific heat capacity in the micro-canonical ensemble followed by positive specific heat capacity at larger energies measured by a polynomial degree parameter $n$. The negative branch is associated with near-exponential or factorial growth of degeneracies for $ n \gg 1$ in a region of large $N$ stability, while the positive branch occurs when the finite $N$ reduction of degrees of freedom takes over as $n$ becomes sufficiently large compared to $N$.
