Néel to Valence Bond Solid Transition in the SU(N) X-Q Model

We study the Néel-Valence Bond Solid (VBS) transition in square-lattice SU(N) quantum antiferromagnets using Stochastic Series Expansion quantum Monte Carlo. The Deconfined Quantum Criticality (DQC) scenario predicts a generically continuous transition between these phases, going beyond the conventional Landay-Ginzburg paradigm. Recent numerical studies of the prototypical J-Q and related models indicate that the transition is weakly first order for SU(2), but approaches continuity as N increases. Here, we introduce the X-Q model as a new candidate for exploring near-critical DQC behavior in SU(N) systems. In this model, X represents a plaquette next-nearest-neighbor permutation operator. While the transition in the X-Q model remains weakly first order for SU(2), it becomes strongly first order for N > 2, contrary to conventional expectations that increasing N should weaken discontinuities. We present these results and discuss their implications for future numerical studies of DQC.