Abstract

Recently, a class of $\mathcal{P}\mathcal{T}$ -invariant scalar quantum field theories described by the non-Hermitian Lagrangian $\mathcal{L}$ = $ \frac{1}{2} $ (∂ϕ) 2 +gϕ 2 (iϕ)ε was studied. It was found that there are two regions of ε. For ε<0 the $\mathcal{P}\mathcal{T}$ -invariance of the Lagrangian is spontaneously broken, and as a consequence, all but the lowest-lying energy levels are complex. For ε≥0 the $\mathcal{P}\mathcal{T}$ -invariance of the Lagrangian is unbroken, and the entire energy spectrum is real and positive. The subtle transition at ε=0 is not well understood. In this paper we initiate an investigation of this transition by carrying out a detailed numerical study of the effective potential V eff (ϕc) in zero-dimensional spacetime. Although this numerical work reveals some differences between the ε<0 and the ε>0 regimes, we cannot yet see convincing evidence of the transition at ε=0 in the structure of the effective potential for $\mathcal{P}\mathcal{T}$ -symmetric quantum field theories