2021/11/16 by Scott Lawrence, Lawrence, Scott
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Theory (hep-th) #Nuclear Theory (nucl-th) #hep-th #nucl-th
paper · pdf · doi:10.48550/arxiv.2111.08158
3 pages; comments welcome
arxiv created 2021/11/16 · arxiv updated 2021/11/17
Many counterexamples to the proposed KSS bound \fracηs ≥ \frac 1 4π depend on constructing systems with large numbers of species. As a result, the entropy density grows large and \frac ηs can be made arbitrarily small. However, these constructions do not affect the dimensionless shear viscosity \frac ηTε+ P, which agrees with the traditional \frac ηs only for vanishing chemical potential. This raises the possibility that a KSS-like bound holds for all systems, not just UV-complete quantum field theories, contrary to the previous understanding.