Infraparticle states in the massless Nelson model -- revisited

Vincent Beaud, Wojciech Dybalski, Gian Michele Graf
May 12, 2021
We provide a new construction of infraparticle states in the massless Nelson model. The approximating sequence of our infraparticle state does not involve any infrared cut-offs. Its derivative w.r.t. the time parameter $t$ is given by a simple explicit formula. The convergence of this sequence as $t\to \infty$ to a non-zero limit is then obtained by the Cook method combined with stationary phase estimates. To apply the latter technique we exploit recent results on regularity of ground states in the massless Nelson model, which hold in the low coupling regime.