Anomalous Gravitational TTT Vertex, Temperature Inhomogeneity, and Pressure Anisotropy
arXiv:1910.13727 · doi:10.1016/j.physletb.2020.135236
Abstract
The conformal anomaly in curved spacetime generates a nontrivial anomalous vertex, given by the three-point correlation function of the energy-momentum tensor . We show that a temperature inhomogeneity in a gas of charged massless particles generates, via the vertex, a pressure anisotropy with respect to the axis of the temperature variation. This very particular signature may provide an experimental access to the elusive gravitational coefficient which determines the anomaly contribution of the Weyl tensor to the trace of the energy-momentum tensor in curved spacetime. We present an estimate of the pressure anisotropy both for fermionic quasiparticles in the solid-state environment of Dirac semimetals as well as for a quark-gluon plasma in relativistic heavy-ion collisions. In both cases, the pressure anisotropy is small compared to the mean thermal pressure.
9 pages, 2 figures. Revised final version accepted for publication on Physics Letters B
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