Resonances and $\Omega$-results for Exponential Sums Related to Maass   Forms for $\mathrm{SL}(n,\mathbb Z)$
  We obtain resonances for short exponential sums involving Fourier coefficients of Maass forms for $\mathrm{SL}(n,\mathbb Z)$. This involves deriving asymptotics for the integrals appearing in the $\mathrm{GL}(n)$ Voronoi summation formula. As an application, we also prove an $\Omega$-result for short sums of Fourier coefficients. 
Anne-Maria Ernvall-Hyt\"onen, Jesse J\"a\"asaari, and Esa V.   Vesalainen
math.NT