Self-duality and shock dynamics in the $n$-component priority ASEP

We study the $n$-component priority asymmetric simple exclusion process ($n$-ASEP) with reflecting boundaries. We obtain all invariant measures in explicit form and prove reversibility. Using the symmetry of the generator of the process under the quantum algebra $U_q[\mathfrak{gl}(n+1)]$ we construct duality functions with respect to which the $n$-ASEP is self-dual, both for the finite and the infinite integer lattice. For the $n$-ASEP on the infinite lattice we use self-duality to derive in explicit form the time evolution of a family of measures with $K$ shocks in terms of the transition probability of $K$ coloured particles in a shock exclusion process with particle-dependent hopping rates and nearest-neighbour colour exchange. This process is a gas of particles that forms a bound state, corresponding to shock coalescence on macroscopic scale.