2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/194213A general formalism for calculating the bulk viscosity of strange quark matter is developed. Contrary to the common belief that the non-leptonic processes alone give the dominant contribution to the bulk viscosity, the inclusion of the Urca processes is shown to play an important role at intermediate densities when the characteristic r-mode oscillation frequencies are not too high. The interplay of non-leptonic and Urca processes is analyzed in detail9 pages, 4 figures, v2: revised figures, no change in resultsAstrophysicsHigh Energy Physics - PhenomenologyNuclear Theorytext