# Thin-Shells and Thin-Shell Wormholes in New Massive Gravity

## TL;DR

This paper explores the construction and properties of thin-shells and thin-shell wormholes within 2+1-dimensional new massive gravity, revealing their non-existence in certain solutions and unique energy characteristics of the wormholes.

## Contribution

It introduces junction conditions for fourth order terms in new massive gravity and analyzes the existence and properties of thin-shells and wormholes in this framework.

## Key findings

- No thin-shells exist for the studied solutions.
- Constructed wormholes can be non-symmetric.
- Wormholes have null energy density and null angular pressure.

## Abstract

Within 2+1-dimensional cosmological new massive gravity, we consider thin-shell and thin-shell wormhole construction. For this, we introduce first, the junction conditions apt for the fourth order terms in the action of the theory. Then, by employing some specific static solutions in new massive gravity, we study the characteristics of associated thin-shells and thin-shell wormholes. Our finding suggests that, firstly, there cannot exist any thin-shells regarding our chosen solutions of cosmological new massive gravity, and secondly, the constructed thin-shell wormhole does not need to be symmetric. More importantly, the thin-shell wormhole, if ever forms, possesses null energy density and null angular pressure on its throat which preferable to their negative-valued counterparts.