Stability of the Regular Hayward Thin-Shell Wormholes
  The aim of this paper is to construct regular Hayward thin-shell wormholes and analyze their stability. We adopt Israel formalism to calculate surface stresses of the shell and check the null and weak energy conditions for the constructed wormholes. It is found that the stress-energy tensor components violate the null and weak energy conditions leading to the presence of exotic matter at the throat. We analyze the attractive and repulsive characteristics of wormholes corresponding to $a^r>0$ and $a^r<0$, respectively. We also explore stability conditions for the existence of traversable thin-shell wormholes with arbitrarily small amount of fluids describing cosmic expansion. We find that the spacetime has non-physical regions which give rise to event horizon for $0<a_{0}<2.8$ and the wormhole becomes non-traversable producing a black hole. The non-physical region in the wormhole configuration decreases gradually and vanishes for the Hayward parameter $l=0.9$. It is concluded that the Hayward and Van der Waals quintessence parameters increase the stability of thin-shell wormholes. 
M. Sharif and Saadia Mumtaz
gr-qc