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A new design of a detector plane of sub-millimetre thickness for an electromagnetic sampling calorimeter is presented. It is intended to be used in the luminometers LumiCal and BeamCal in future linear e\(^{+}\)e\(^{-}\) collider experiments. The detector planes were produced utilising novel connectivity scheme technologies. They were installed in a compact prototype of the calorimeter and tested at DESY with an electron beam of energy 1–5 GeV. The performance of a prototype of a compact LumiCal comprising eight detector planes was studied. The effective Molière radius at 5 GeV was determined to be (8.1 ± 0.1 (stat) ± 0.3 (syst))more » mm, a value well reproduced by the Monte Carlo (MC) simulation (8.4 ± 0.1) mm. The dependence of the effective Molière radius on the electron energy in the range 1–5 GeV was also studied. Good agreement was obtained between data and MC simulation.« less

The Compact Linear Collider (CLIC) is an option for a future \({\mathrm{e}^{+}}{\mathrm{e}^{-}} \) collider operating at centre-of-mass energies up to \(3\,\text {TeV} \), providing sensitivity to a wide range of new physics phenomena and precision physics measurements at the energy frontier. This paper is the first comprehensive presentation of the Higgs physics reach of CLIC operating at three energy stages: \(\sqrt{s} = 350\,\text {GeV} \), 1.4 and \(3\,\text {TeV} \). The initial stage of operation allows the study of Higgs boson production in Higgsstrahlung (\({\mathrm{e}^{+}}{\mathrm{e}^{-}} \rightarrow {\mathrm{Z}} {\mathrm{H}} \)) and \({\mathrm{W}} {\mathrm{W}} \)-fusion (\({\mathrm{e}^{+}}{\mathrm{e}^{-}} \rightarrow {\mathrm{H}} {{\nu }}_{\!\mathrm{e}} {\bar{{\nu }}}_{\!\mathrm{e}}more » \)), resulting in precise measurements of the production cross sections, the Higgs total decay width \(\varGamma _{{\mathrm{H}}}\), and model-independent determinations of the Higgs couplings. Operation at \(\sqrt{s} > 1\,\text {TeV} \) provides high-statistics samples of Higgs bosons produced through \({\mathrm{W}} {\mathrm{W}} \)-fusion, enabling tight constraints on the Higgs boson couplings. Studies of the rarer processes \({\mathrm{e}^{+}}{\mathrm{e}^{-}} \rightarrow \mathrm{t} {\bar{\mathrm{t}}} {\mathrm{H}} \) and \({\mathrm{e}^{+}}{\mathrm{e}^{-}} \rightarrow {\mathrm{H}} {\mathrm{H}} {{\nu }}_{\!\mathrm{e}} {\bar{{\nu }}}_{\!\mathrm{e}} \) allow measurements of the top Yukawa coupling and the Higgs boson self-coupling. This paper presents detailed studies of the precision achievable with Higgs measurements at CLIC and describes the interpretation of these measurements in a global fit.« less

The production of beauty hadrons was measured via semi-leptonic decays at mid-rapidity with the ALICE detector at the LHC in the transverse momentum interval 1< 8 GeV/c in minimum-bias p-Pb collisions at √^sNN = 5.02 TeV and in 1.3 < pT< 8 GeV/c in the 20% most central Pb-Pb collisions at √^sNN = 2.76 TeV. The pp reference spectra at √^sNN = 5.02 TeV and √s = 2.76 TeV, needed for the calculation of the nuclear modification factors R_pPb and R_PbPb, were obtained by a pQCD-driven scaling of the cross section of electrons from beauty-hadron decays measured at √s =more » 7 TeV. In the p_T interval 3 < p_T < 8 GeV/c, a suppression of the yield of electrons from beauty-hadron decays is observed in Pb-Pb compared to pp collisions. Towards lower p_T, the R_PbPb values increase with large systematic uncertainties. The R_pPb is consistent with unity within systematic uncertainties and is well described by theoretical calculations that include cold nuclear matter effects in p-Pb collisions. The measured R_pPb and these calculations indicate that cold nuclear matter effects are small at high transverse momentum also in Pb-Pb collisions. Therefore, the observed reduction of R_PbPb below unity at high p_T may be ascribed to an effect of the hot and dense medium formed in Pb-Pb collisions.« less

This is an addendum to the article JHEP11 (2015) 205. The figures 3 (right), 4 (right) and 5 are updated with published results on non-prompt J/ψ-meson production from the CMS collaboration.

The azimuthal correlations of D mesons with charged particles were measured with the ALICE apparatus in pp collisions at $\sqrt{s}=7\mathrm{T}\mathrm{e}\mathrm{V}$ and p–Pb collisions at $\sqrt{s_{\mathrm{N}\mathrm{N}}}=5.02\mathrm{T}\mathrm{e}\mathrm{V}$ at the Large Hadron Collider. ${\mathrm{D}}^0$, ${\mathrm{D}}^{more »}$ + , and ${\mathrm{D}}^{\ast +}$ mesons and their charge conjugates with transverse momentum $3<p_{\mathrm{T}}<16\mathrm{G}\mathrm{e}\mathrm{V}/c$ and rapidity in the nucleon-nucleon centre-of-mass system $|y_{\mathrm{c}\mathrm{m}\mathrm{s}}|<0.5$ (pp collisions) and $-0.96<y_{\mathrm{c}\mathrm{m}\mathrm{s}}<0.04$ (p–Pb collisions) were correlated to charged particles with $p_{\mathrm{T}}>0.3\mathrm{G}\mathrm{e}\mathrm{V}/c$. The yield of charged particles in the correlation peak induced by the jet containing the D meson and the peak width are compatible within uncertainties in the two collision systems. The data are described within uncertainties by Monte-Carlo simulations based on PYTHIA, POWHEG, and EPOS 3 event generators.« less

A detailed study of pseudorapidity densities and multiplicity distributions of primary charged particles produced in proton–proton collisions, at s= 0.9, 2.36, 2.76, 7 and 8 TeV, in the pseudorapidity range | η| < 2 , was carried out using the ALICE detector. Measurements were obtained for three event classes: inelastic, non-single diffractive and events with at least one charged particle in the pseudorapidity interval | η| < 1. The use of an improved track-counting algorithm combined with ALICE’s measurements of diffractive processes allows a higher precision compared to our previous publications. A KNO scaling study was performed in the pseudorapiditymore » intervals | η| < 0.5, 1.0 and 1.5. The data are compared to other experimental results and to models as implemented in Monte Carlo event generators PHOJET and recent tunes of PYTHIA6, PYTHIA8 and EPOS.« less