A description is provided of the software algorithms developed for the CMS tracker both for reconstructing charged-particle trajectories in proton-proton interactions and for using the resulting tracks to estimate the positions of the LHC luminous region and individual primary-interaction vertices. Despite the very hostile environment at the LHC, the performance obtained with these algorithms is found to be excellent. For tt events under typical 2011 pileup conditions, the average trackreconstruction efficiency for promptly-produced charged particles with transverse momenta of p T > 0.9 GeV is 94% for pseudorapidities of |η| < 0.9 and 85% for 0.9 < |η| < 2.5. The inefficiency is caused mainly by hadrons that undergo nuclear interactions in the tracker material. For isolated muons, the corresponding efficiencies are essentially 100%. For isolated muons of p T = 100 GeV emitted at |η| < 1.4, the resolutions are approximately 2.8% in p T , and respectively, 10 µm and 30 µm in the transverse and longitudinal impact parameters. The position resolution achieved for reconstructed primary vertices that correspond to interesting pp collisions is 10-12 µm in each of the three spatial dimensions. The tracking and vertexing software is fast and flexible, and easily adaptable to other functions, such as fast tracking for the trigger, or dedicated tracking for electrons that takes into account bremsstrahlung.

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The ALICE Collaboration at the LHC has measured the J/ψ and ψ′ photoproduction at mid-rapidity in ultra-peripheral Pb–Pb collisions at .The charmonium is identified via its leptonic decay for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 23 μb−1. The cross section for coherent and incoherent J/ψ production in the rapidity interval −0.9

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We study the spectroscopy and dominant decays of the bottomonium-like tetraquarks (bound diquarksantidiquarks), focusing on the lowest lying P-wave [bq][bq] states Y [bq] (with q = u, d), having J PC = 1 −−. To search for them, we analyse the BaBar data [1] obtained during an energy scan of the e + e − → bb cross section in the range of √ s = 10.54 to 11.20 GeV. We find that these data are consistent with the presence of an additional bb state Y [bq] with a mass of 10.90 GeV and a width of about 30 MeV apart from the Υ (5S) and Υ (6S) resonances. A closeup of the energy region around the Y [bq]-mass may resolve this state in terms of the two mass eigenstates, Y [b,l] and Y [b,h] , with a mass difference, estimated as about 6 MeV. We tentatively identify the state Y [bq] (10900) from the R b-scan with the state Y b (10890) observed by Belle [2] in the process e + e − → Y b (10890) → Υ (1S, 2S) π + π − due to their proximity in masses and decay widths.