The yield of charged particles associated with high-$p_t$ trigger particles ($8<p_t<15\mathrm{GeV}/\mathrm{c}$) is measured with the ALICE detector in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=2.76\mathrm{TeV}$ relative to proton-proton collisions at the same energy. The conditional per-trigger yields are extracted from the narrow jetlike correlation peaks in azimuthal dihadron correlations. In the 5% most central collisions, we observe that the yield of associated charged particles with transverse momenta $p_t>3\mathrm{GeV}/\mathrm{c}$ on the away side drops to about 60% of that observed in $pp$ collisions, while on the near side a moderate enhancement of 20%–30% is found.

• Received 1 October 2011

DOI:https://doi.org/10.1103/PhysRevLett.108.092301

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© 2012 CERN, for the ALICE Collaboration