A short proof of the asymptotic of the minimum of the branching random   walk after time $n$
  We write $R_n$ for the minimal position attained after time $n$ by a branching random walk in the boundary case. In this article, we prove that $R_n - \frac{1}{2} \log n$ converges in law toward a shifted Gumbel distribution. 
Bastien Mallein
math.PR