The yield of charged particles associated with high-p_{t} trigger particles (8<p_{t}<15  GeV/c) is measured with the ALICE detector in Pb-Pb collisions at sqrt[s_{NN}]=2.76  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  GeV/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.

The ALICE Collaboration has studied J/ψ production in pp collisions at sqrt[s]=7  TeV at the LHC through its muon pair decay. The polar and azimuthal angle distributions of the decay muons were measured, and results on the J/ψ polarization parameters λ_{θ} and λ_{ϕ} were obtained. The study was performed in the kinematic region 2.5<y<4, 2<p_{t}<8  GeV/c, in the helicity and Collins-Soper reference frames. In both frames, the polarization parameters are compatible with zero, within uncertainties.

Flow coefficients v_{n} for n=2, 3, 4, characterizing the anisotropic collective flow in Au+Au collisions at sqrt[s_{NN}]=200  GeV, are measured relative to event planes Ψ_{n}, determined at large rapidity. We report v_{n} as a function of transverse momentum and collision centrality, and study the correlations among the event planes of different order n. The v_{n} are well described by hydrodynamic models which employ a Glauber Monte Carlo initial state geometry with fluctuations, providing additional constraining power on the interplay between initial conditions and the effects of viscosity as the system evolves. This new constraint can serve to improve the precision of the extracted shear viscosity to entropy density ratio η/s.

Back-to-back hadron pair yields in d+Au and p+p collisions at sqrt[s_{NN}]=200  GeV were measured with the PHENIX detector at the Relativistic Heavy Ion Collider. Rapidity separated hadron pairs were detected with the trigger hadron at pseudorapidity |η|<0.35 and the associated hadron at forward rapidity (deuteron direction, 3.0<η<3.8). Pairs were also detected with both hadrons measured at forward rapidity; in this case, the yield of back-to-back hadron pairs in d+Au collisions with small impact parameters is observed to be suppressed by a factor of 10 relative to p+p collisions. The kinematics of these pairs is expected to probe partons in the Au nucleus with a low fraction x of the nucleon momenta, where the gluon densities rise sharply. The observed suppression as a function of nuclear thickness, p_{T}, and η points to cold nuclear matter effects arising at high parton densities.

We present measurements of J/ψ yields in d+Au collisions at sqrt[s_{NN}]=200  GeV recorded by the PHENIX experiment and compare them with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/ψ rapidity (-2.2<y<2.4) with high statistical precision and are compared with two theoretical models: one with nuclear shadowing combined with final state breakup and one with coherent gluon saturation effects. In order to remove model dependent systematic uncertainties we also compare the data to a simple geometric model. The forward rapidity data are inconsistent with nuclear modifications that are linear or exponential in the density weighted longitudinal thickness, such as those from the final state breakup of the bound state.

PURPOSE: The purpose of this study was to evaluate rollback of the femoral condyle in anatomical double-bundle anterior cruciate ligament reconstruction (ACL). METHODS: Twenty-two subjects who underwent anatomical double-bundle ACL reconstruction were included in this study. More than 6 months after surgery, lateral radiographic imaging of the knee was performed with active full knee flexion. The most posterior tibiofemoral contact point was measured for evaluation of femoral rollback (rollback ratio). Flexion angle was also measured using the same radiograph, and the correlation between rollback and flexion angle was analyzed. As a control, radiographs of the healthy contralateral knees were evaluated. For clinical evaluation, side-to-side difference in anterior tibial translation (ATT) and pivot shift test were analyzed approximately 1 year after surgery. RESULTS: The rollback ratios of the operated knees and the healthy contralateral knees were 28.7 ± 6.6 and 29.7 ± 6.7%, respectively, from the posterior edge of the tibia. No significant difference in rollback was observed. The flexion angles of the operated knees and the healthy contralateral knees were 136 ± 11° and 140 ± 9°, respectively. No significant difference in knee flexion angle was observed. Significant correlation between femoral rollback and knee flexion angle was observed. The side-to-side difference in ATT was 0.7 mm, and no cases of positive pivot shift were observed. CONCLUSION: Anatomical double-bundle ACL reconstruction can restore normal femoral rollback in active full knee flexion. For clinical relevance, knees with anatomical double-bundle ACL reconstruction can flex with normal kinematics at the end of knee flexion angle. LEVEL OF EVIDENCE: III.