I really wish they tied this into representation theory, because it looks like the R-tensors are similar to representations of the permutation group, but I don't see exactly how to write them in terms of representations.
It was previously known as a possibility, but it wasn't believed to have observable consequences. This paper relates it to degeneracy pressure in noninteracting systems.
It's not impossible that there could also be fundamental particles with this property. It would require some new symmetry to be found, for which there is currently no evidence, but it might be found be reconsidering existing data.
Right now they are neither a real particle or quasiparticle. They are a hole in a "theorem" that was previously thought to close off our imagination to new basic categories of particles.
I really wish they tied this into representation theory, because it looks like the R-tensors are similar to representations of the permutation group, but I don't see exactly how to write them in terms of representations.