Very high-\pt\ triggered dihadron correlations in PbPb and pp collisions at \rootsNN\ = 2.76\TeV

Measurements of dihadron correlations triggered by very high-\pt\ particles in 2.76 TeV PbPb collisions are presented. The analysis explores the full 2011 PbPb data set corresponding to an integrated luminosity of 150 $\mu$b$^{-1}$ collected by CMS. Long-range correlations driven by single-particle azimuthal anisotropies (characterized by the Fourier harmonics, $v_n$) are measured up to \pt\ $\sim$ 50\GeVc. After subtracting the $v_2$-$v_4$ harmonic components, the associated particle yields on the near and away side of the residual jet-like dihadron correlations are studied over a wide kinematic range in trigger and associated particle \pt, as a function of collision centrality. By comparing to pp data at the same energy, a suppression of about 50\% in the away-side associated yield is observed for $\ptass>3$\GeVc. The yield is found to be significantly enhanced up to a factor of 3--4 on the away side at \ptass $\sim$ 0.5\GeVc, while a moderate enhancement is suggested on the near side.