Coupling dependence of jet quenching in hot strongly-coupled gauge theories

摘要

Previous top-down studies of jet stopping in strongly-coupled QCD-like plasmas with gravity duals have been in the infinite ’t Hooft coupling limit λ → ∞. They have found that, though a wide range of jet stopping distances are possible depending on initial conditions, the maximum jet stopping distance ℓmax scales with energy as E 1/3 at large energy. But it has always been unclear whether the large-coupling and high-energy limits commute. In this paper, we use the string α ′ expansion in AdS-CFT to study the corrections to the λ = ∞ result in powers of 1/λ. For the particular type of “jets” that we study, we find that (i) the naive expansion in 1/λ breaks down for certain initial conditions but (ii) the relative corrections to the maximum stopping distance are small when 1/λ is small. More specifically, we find that the expansion in 1/λ is well behaved for jets whose stopping distance ℓstop is in the range λ −1/6ℓmax ≪ ℓstop ≲ ℓmax, but the expansion breaks down (and the fate of λ = ∞ results is uncertain) for jets created in such a way that ℓstop ≪ λ −1/6ℓmax. The analysis requires assessing the effects of all higher-derivative corrections to the supergravity action for the gravity dual.