The KPZ equation in a half space with flat initial condition and the unbinding of a directed polymer from an attractive wall

Abstract

We present an exact solution for the height distribution of the KPZ equation at any time $t$ in a half space with flat initial condition. This is equivalent to obtaining the free energy distribution of a polymer of length $t$ pinned at a wall at a single point. In the large $t$ limit a binding transition takes place upon increasing the attractiveness of the wall. Around the critical point we find the same statistics as in the Baik-Ben--Arous-Péché transition for outlier eigenvalues in random matrix theory. In the bound phase, we obtain the exact measure for the endpoint and the midpoint of the polymer at large time. We also unveil curious identities in distribution between partition functions in half-space and certain partition functions in full space for Brownian type initial condition.

27 pages. v4: typos corrected. v3: references added, appendix reorganized (some sections numbers have changed). Accepted version

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Cited by in corpus (4)

• Boundary current fluctuations for the half space ASEP and six vertex model
• Half-space stationary Kardar-Parisi-Zhang equation beyond the Brownian case
• High temperature behaviors of the directed polymer on a cylinder
• A stationary model of non-intersecting directed polymers