Anomalous conductivities in the holographic Stuckelberg model

TL;DR

This paper investigates how a massive gauge field in a holographic model affects anomalous conductivities, revealing new dependencies on gauge mass and Chern-Simons couplings, with implications for chiral transport phenomena.

Contribution

It introduces a comprehensive analysis of a massive gauge field in holography, showing novel effects on anomalous conductivities and their dependence on multiple Chern-Simons couplings.

Findings

Correlators depend on the gauge field mass.

Finite gauge mass induces non-zero correlators at zero chemical potential.

Anomalous conductivities depend linearly on both  and  Chern-Simons couplings.

Abstract

We have studied a massive U(1) gauge holographic model with pure gauge and mixed gauge-gravitational Chern-Simons terms. The full backreaction of the gauge field on the metric tensor has been considered in order to explore the vortical and energy transport sector. The background solution has been computed numerically. On this background, we have considered the fluctuation of the fields and evaluated the different correlators. We have found that all the correlators depend on the mass of the gauge field. Correlators such as the current-current one, $\langle J_xJ_x\rangle$, which were completely absent in the massless case, in the presence of a finite gauge boson mass start picking up some finite value even at zero chemical potential. Similarly, the energy-current correlator, $\langle T_{0x}J_x\rangle$, which was also absent in the massless theory, has now a non-vanishing value but for finite values of the chemical potential. Our findings for the chiral vortical conductivity, $\sigma_V$, and the chiral magnetic/vortical conductivity of energy current, $\sigma^\varepsilon_B = \sigma^\varepsilon_V$, are completely new results. In addition to this, we have found that these anomalous transport coefficients depend linearly both on the pure Chern-Simon coupling, $\kappa$, and on the mixed gauge-gravity Chern-Simon coupling, $\lambda$. One of the results that we would like to highlight is that its not just $\kappa$ that contributes to the $\sigma_B$ but there is an additional contribution from $\lambda$ as well unlike the previous studies.