Phase transition of four-dimensional lattice $\phi^4$ theory with tensor renormalization group

Understand

We investigate the phase transition of the four-dimensional single-component $\phi^4$ theory on the lattice using the tensor renormalization group method.

• We have examined the hopping parameter dependence of the bond energy and the vacuum condensation of the scalar field $\langle\phi\rangle$ at a finite quartic coupling $\lambda$ on large volumes up to $V=1024^4$ in order to detect the spontaneous breaking of the $\mathbb{Z}_2$ symmetry.
• Our results show that the system undergoes the weak first-order phase transition at a certain critical value of the hopping parameter.
• We also make a comparative study of the three-dimensional $\phi^4$ theory and find that the properties of the phase transition are consistent with the universality class of the three-dimensional Ising model.