No Arabic abstract
We report on the first measurements of the LHCb experiment, as obtained from $pp$ collisions at $sqrt{s} = 0.9$ TeV and 7 TeV recorded using a minimum bias trigger. In particular measurements of the absolute $K^0_S$ production cross section at $sqrt{s} = 0.9$ TeV and of the $bar{Lambda}/Lambda$ ratio both at $sqrt{s} = 0.9$ TeV and 7 TeV are discussed and preliminary results are presented.
Despite not being designed for it, the LHCb experiment has given world-leading contributions in kaon and hyperon physics. In this contribution I review the prospects for kaon physics at LHCb exploiting the already acquired data and the current and future Upgrade scenarios.
The LHC is the new b-hadron factory and will be dominating flavour physics until the start of Belle II, and beyond in many decay modes. While the $B$ factories and Tevatron experiments are still analysing their data, ATLAS, CMS and LHCb are producing interesting new results in CP violation and rare decays, that set strong constraints on models beyond that SM and exhibit some discrepancies with the SM predictions. The LHCb collaboration used the LHC 50 ns ramp-up period of July 2015 to measure the double-differential $J/psi$, $J/psi$-from-$b$-hadron and charm cross-sections at $sqrt{s} = 13$ TeV. Both measurements were performed directly on triggered candidates using a reduced data format that does not require offline processing.
We report on the first searches for lepton flavour violating $tau^-$ decays at a hadron collider. These include searches for the lepton flavour violating decay $tau^-to mu^+mu^-mu^-$ and the lepton flavour and baryon number violating decays $tau^-to bar{p}mu^+mu^-$ and $tau^-to pmu^-mu^-$. Upper limits of ${cal B}(tau^-to mu^+mu^-mu^-) < 4.6 times 10^{-8}$, ${cal B}(tau^-to bar{p}mu^+mu^-) < 3.4 times 10^{-7}$ and ${cal B}(tau^-to pmu^-mu^-) < 4.6 times 10^{-7}$ are set at 90% confidence level. A measurement of the inclusive $Ztotau^+tau^-$ cross-section at 7 TeV is also reported and is found to be consistent with the Standard Model. The ratio of the $Ztotau^+tau^-$ cross-section to the $Ztomu^+mu^-$ cross-section is found to be consistent with lepton universality.
Data collected by the LHCb experiment allow proton structure functions to be probed in a kinematic region beyond the reach of other experiments, both at the LHC and further afield. In these proceedings the significant impact of LHCb Run 1 measurements on PDF fits is recalled and recent LHCb results, that are sensitive to PDFs, are described.
ALICE is the dedicated heavy-ion experiment at the Large Hadron Collider. The experiment has also a broad program of QCD measurements in proton-proton (pp) collisions, which have two-fold interest: the study of particle production at the highest energy frontier, and the definition of references for the corresponding measurements in the upcoming Pb-Pb run. We present the first results on the pseudorapidity and transverse-momentum dependence of charged particle production in pp collisions at LHC energies, on the anti-p/p ratio and on the Bose-Einstein particle correlations. As an outlook, we report on the status of the ongoing analyses for strangeness and heavy-flavour production measurements.