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

Recent estimates for the electromagnetic fields produced in the early stages of non-central ultra-relativistic heavy ion collisions indicate the presence of magnetic fields \(B\sim \mathcal{O}(0.1-15\,m_\pi^2)\), where \(m_\pi\) is the pion mass. It is then of special interest to study the effects o...

Ausführliche Beschreibung

Gespeichert in:
Bibliographische Detailangaben
Veröffentlicht in:arXiv.org 2014-09
Hauptverfasser: Critelli, R, Finazzo, S I, Zaniboni, M, Noronha, J
Format: Artikel
Sprache:eng
Schlagworte:
Online-Zugang:Volltext
Tags: Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
Beschreibung
Zusammenfassung:Recent estimates for the electromagnetic fields produced in the early stages of non-central ultra-relativistic heavy ion collisions indicate the presence of magnetic fields \(B\sim \mathcal{O}(0.1-15\,m_\pi^2)\), where \(m_\pi\) 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 work we study the anisotropy in the shear viscosity induced by an external magnetic field in a strongly coupled \(\mathcal{N} = 4\) SYM plasma. Due to the spatial anisotropy created by the magnetic field, the most general viscosity tensor of a magnetized plasma has 5 shear viscosity coefficients and 2 bulk viscosities. We use the holographic correspondence to evaluate two of the shear viscosities, \(\eta_{\perp} \equiv \eta_{xyxy}\) (perpendicular to the magnetic field) and \(\eta_{\parallel} \equiv \eta_{xzxz}=\eta_{yzyz}\) (parallel to the field). When \(B\neq 0\) the shear viscosity perpendicular to the field saturates the viscosity bound \(\eta_{\perp}/s = 1/(4\pi)\) while in the direction parallel to the field the bound is violated since \(\eta_{\parallel}/s < 1/(4\pi)\). 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.
ISSN:2331-8422
DOI:10.48550/arxiv.1406.6019