The ALICE muon trigger system: cosmic ray commissioning and first beam-induced events.

International audienceALICE (A Large Ion Collider Experiment) is the experiment dedicated to the study of nucleus-nucleus collisions at the Large Hadron Collider (LHC). Its main physics goal is to characterize the properties of hot and dense nuclear matter created in heavy ion collisions, the so-called quark-gluon plasma (QGP). The forward part of ALICE consists of a muon spectrometer which is focused on the study of the production of heavy flavours and quarkonia via their (di)muon decay channels. This muon spectrometer is equipped of a trigger system based on four planes of large area Resistive Plate Chambers (RPCs) with 21,000 channels associated to a fast decision electronics. A commissioning phase was started in 2008 with the detection of cosmic rays and of the first beam injections into the LHC ring. In the presentation, design considerations and requirements will be discussed in view of lead-lead collisions. Next, the performances of the whole trigger system (detector and electronics) achieved in the commissioning will be presented, including the first tracks matched between the muon trigger and the muon tracking chambers

Inclusive Measurement of the Charmless Semileptonic Branching Ratio of B-hadrons

From the study of the kinematics properties of the final state produced in the semileptonic $\mathrm{B}$ decays $\mathrm{B\to \ell\nu_{\ell} X}$, the inclusive charmless semileptonic branching ratio of $\mathrm{B}$-hadrons has been measured. Using the data collected between 1992 and 1995, one gets: $\mathrm{BR(B\to \ell\nu_{\ell} X_u)} = (1.6\pm 0.4_{stat}\pm 0.4_{syst})\times 10^{-3}$, where $\mathrm{X_u}$ represents any charmless hadronic states

The muon spectrometer of the ALICE experiment at LHC

présenté par P. Rosnet, à paraître dans les proceedingsThe muon spectrometer of the ALICE experiment is a dedicated device to study heavy quark production in heavy ion collisions via their decay into muons. After more than 10 years of R&D and production, all large pieces of the muon spectrometer are installed in the ALICE experimental hall, while all detectors and their electronics are almost ready for installation

Inclusive Measurement of the Charmless Semileptonic Branching Ratio of B-hadrons

From the study of the kinematics properties of the final state produced in the semileptonic $\mathrm{B}$ decays $\mathrm{B\to \ell\nu_{\ell} X}$, the inclusive charmless semileptonic branching ratio of $\mathrm{B}$-hadrons has been measured. Using the data collected between 1992 and 1995, one gets: $\mathrm{BR(B\to \ell\nu_{\ell} X_u)} = (1.6\pm 0.4_{stat}\pm 0.4_{syst})\times 10^{-3}$, where $\mathrm{X_u}$ represents any charmless hadronic states

Front-End Electronics of the ALICE dimuon trigger

This document presents the design and performance of the Front-End Electronics (FEE) developed for the ALICE dimuon trigger operating with Resistive Plate Chambers (RPCs) in streamer mode. This electronics, yet ready for production, is based on a dedicated ASIC designed at LPC Clermont-Fd

The Rare Decays K→πννˉK\to\pi\nu\bar\nu, B→XννˉB\to X\nu\bar\nu and B→l+l−B\to l^+l^- -- An Update

We update the Standard Model predictions for the rare decays $K^+\to\pi^+\nu\bar\nu$ and $K_L\to\pi^0\nu\bar\nu$. In view of improved limits on $B_s$--$\bar B_s$ mixing we derive a stringent and theoretically clean Standard Model upper limit on $B(K^+\to\pi^+\nu\bar\nu)$, which is based on the ratio of $B_d$--$\bar B_d$ to $B_s$--$\bar B_s$ mixing, $\Delta M_d/\Delta M_s$, alone. This method avoids the large hadronic uncertainties present in the usual analysis of the CKM matrix. We find $B(K^+\to\pi^+\nu\bar\nu)< 1.67\cdot 10^{-10}$, which can be further improved in the future. In addition we consider the extraction of $|V_{td}|$ from a future measurement of $B(K^+\to\pi^+\nu\bar\nu)$, discussing the various sources of uncertainties involved. We also investigate theoretically clean constraints on $B(K_L\to\pi^0\nu\bar\nu)$. We take the opportunity to review the next-to-leading order (NLO) QCD corrections to $K\to\pi\nu\bar\nu$, $K_L\to\mu^+\mu^-$, $B\to X\nu\bar\nu$ and $B\to l^+l^-$, including a small additional term that had been missed in the original publications. The phenomenological impact of this change is negligible, the corresponding numerical shift being essentially within the small perturbative uncertainties at the NLO level.Comment: 19 pages, no figure

Interpersonal emotion regulation in team sport: mechanisms and reasons to regulate teammates' emotions examined

The interpersonal dimension of emotion regulation in the field of sport has lately received a burgeoning interest. Nevertheless, how and why athletes regulate their teammates' emotions in competitive setting remains unclear. Across two studies within a team sport context, we uncovered athletes' mechanisms for, and reasons to regulate teammates' emotions during competition. In Study 1, we investigated how rugby (N���=���22 males) players' emotions were self- and interpersonally regulated during games. Findings revealed the emergence of a continuum of self-involvement in the regulatory processes, wherein two forms of emotion regulation co-existed: self-regulation (total self-involvement) and interpersonal regulation, which included co-regulation (partial self-involvement; regulation with others) and extrinsic regulation (no self-involvement; regulation by/of others). In Study 2, we examined the motives that lead rugby (n���=���30 males) players to use interpersonal extrinsic regulation strategies during games. Interview data indicated that players regulated teammates' emotions for altruistic reasons (to help a teammate), egoistic reasons (for one's own benefits), or both. Overall, our findings further knowledge to better understand interpersonal emotion regulation within competitive team sport contexts. From an applied perspective, findings highlight the role that both individual goals and ego involvement may play in optimising efficient interpersonal regulation during competition at team level

Heavy-flavour and quarkonium production in the LHC era: from proton-proton to heavy-ion collisions

This report reviews the study of open heavy-flavour and quarkonium production in high-energy hadronic collisions, as tools to investigate fundamental aspects of Quantum Chromodynamics, from the proton and nucleus structure at high energy to deconfinement and the properties of the Quark-Gluon Plasma. Emphasis is given to the lessons learnt from LHC Run 1 results, which are reviewed in a global picture with the results from SPS and RHIC at lower energies, as well as to the questions to be addressed in the future. The report covers heavy flavour and quarkonium production in proton-proton, proton-nucleus and nucleus-nucleus collisions. This includes discussion of the effects of hot and cold strongly interacting matter, quarkonium photo-production in nucleus-nucleus collisions and perspectives on the study of heavy flavour and quarkonium with upgrades of existing experiments and new experiments. The report results from the activity of the SaporeGravis network of the I3 Hadron Physics programme of the European Union 7th Framework Programme

Deuteron and antideuteron production in Au+Au collisions at sqrt(s_NN)=200 GeV

The production of deuterons and antideuterons in the transverse momentum range 1.1 < p_T < 4.3 GeV/c at mid-rapidity in Au + Au collisions at sqrt(s_NN)=200 GeV has been studied by the PHENIX experiment at RHIC. A coalescence analysis comparing the deuteron and antideuteron spectra with those of protons and antiprotons, has been performed. The coalescence probability is equal for both deuterons and antideuterons and increases as a function of p_T, which is consistent with an expanding collision zone. Comparing (anti)proton yields p_bar/p = 0.73 +/- 0.01, with (anti)deuteron yields: d_bar/d = 0.47 +/- 0.03, we estimate that n_bar/n = 0.64 +/- 0.04.Comment: 326 authors, 6 pages text, 5 figures, 1 Table. Submitted to PRL. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm