Black Strings in Asymptotically Safe Gravity

TL;DR

This paper investigates black strings within asymptotic safety gravity, analyzing their thermodynamics and singularity structure when gravitational couplings run with scale, revealing stability and remnant mass predictions.

Contribution

It introduces a method to incorporate running couplings into black string metrics in ASG, analyzing thermodynamics and singularities with novel insights on stability and remnants.

Findings

Singularity is resolved when only Newton's constant runs with scale for n>1.

A remnant mass is predicted in the black string evaporation process.

Logarithmic and additional corrections to entropy are identified due to running couplings.

Abstract

In this paper, we study black strings in asymptotic safety gravity (ASG) scenario. The ASG approach is introduced by implementing gravitational and cosmological running coupling constants directly in the black string metric. We calculate the Hawking temperature, entropy, and heat capacity of the improved black string metric in two cases: considering the cosmological constant fixed in some fixed point and the general case where both Newton's constant and cosmological constant are improved. For the identification of the scale moment we used an general inverse law setting $k(r)\sim 1/r^{n}$. We show that improving only the Newton's constant the problem of singularity is solved for the identifications with $n>1$. However, if the cosmological constant is also running the singularity persists in the solution. Also, we show that the ASG effects predicts the presence of a remnant mass in the final evaporation process. Besides that, a logarithmic correction is observed in the entropy. However, a running cosmological constant introduces new correction terms to the entropy beyond that. We show that the improved black string solution remains stable, as in the usual case. Phase transitions are not observed in both cases studied here.