Elie Aïdékon, Yueyun Hu, Zhan Shi
Let $(V(u),\, u\in T)$ be a (supercritical) branching random walk and $(\eta_u,\,u\in T)$ be marks on the vertices of the tree, distributed in an i.i.d. fashion. Following Aldous and Bandyopadhyay [Ann. Appl. Probab., 15, 1047-1110 (2005)], for each ray $\xi$ of the tree, we associate the discounted tree sum $D(\xi)$ which is the sum of the ${\rm e}^{-V(u)}\eta_u$ taken along the ray. The paper deals with the finiteness of $\sup_\xi D(\xi)$. To this end, we study the extreme behaviour of the local time processes of the paths $(V(u),\,u\in \xi)$. It answers a question of Nicolas Curien, and partially solves Open Problem 31 of Aldous and Bandyopadhyay [Ann. Appl. Probab., 15, 1047-1110 (2005)]. We also present several open questions.