Anisotropic shear viscosity of a strongly coupled non-Abelian plasma from magnetic branes

R. Critelli, S. I. Finazzo, M. Zaniboni, J. Noronha

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Recent estimates for the electromagnetic fields produced in the early stages of noncentral ultrarelativistic heavy ion collisions indicate the presence of magnetic fields B∼O(0.1-15mπ2), where mπ is the pion mass. It is then of special interest to study the effects of strong (Abelian) magnetic fields on the transport coefficients of strongly coupled non-Abelian plasmas, such as the quark-gluon plasma formed in heavy ion collisions. In this paper we study the anisotropy in the shear viscosity induced by an external magnetic field in a strongly coupled N=4 super Yang-Mills (SYM) plasma. Due to the spatial anisotropy created by the magnetic field, the most general viscosity tensor of a magnetized plasma has five shear viscosity coefficients and two bulk viscosities. We use the holographic correspondence to evaluate two of the shear viscosities, η≡ηxyxy (perpendicular to the magnetic field) and η≡ηxzxz=ηyzyz (parallel to the field). When B≠0 the shear viscosity perpendicular to the field saturates the viscosity bound η/s=1/(4π), while in the direction parallel to the field the bound is violated since η/s<1/(4π). However, the violation of the bound in the case of strongly coupled SYM is minimal even for the largest value of B that can be reached in heavy ion collisions.

Original languageEnglish (US)
Article number066006
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number6
StatePublished - Sep 9 2014
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)


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