Calculating the chiral condensate diagrammatically at strong coupling

TL;DR

This paper computes the chiral condensate in lattice QCD at infinite coupling using a diagrammatic approach, showing convergence and agreement with simulations at small Nf, but no observed transition at a critical Nf.

Contribution

It introduces a diagrammatic method for calculating the chiral condensate at strong coupling, extending previous work and providing new insights into flavor dependence.

Findings

Convergent results consistent with simulations at small Nf

No evidence of a phase transition at a critical Nf

Preliminary results for different fermion representations

Abstract

We calculate the chiral condensate of QCD at infinite coupling as a function of the number of fundamental fermion flavours using a lattice diagrammatic approach inspired by recent work of Tomboulis, and other work from the 80's. We outline the approach where the diagrams are formed by combining a truncated number of sub-diagram types in all possible ways. Our results show evidence of convergence and agreement with simulation results at small Nf. However, contrary to recent simulation results, we do not observe a transition at a critical value of Nf. We further present preliminary results for the chiral condensate of QCD with symmetric or adjoint representation fermions at infinite coupling as a function of Nf for Nc = 3. In general, there are sources of error in this approach associated with miscounting of overlapping diagrams, and over-counting of diagrams due to symmetries. These are further elaborated upon in a longer paper.