37413741
A Precision Measurement of Charm Dimuon Production in Neutrino Interactions from the NOMAD Experiment
Abstract We present our new measurement of the cross-section for charm dimuon production in neutrino–iron interactions based upon the full statistics collected by the NOMAD experiment. After background subtraction we observe 15 344 charm dimuon events, providing the largest sample currently available. The analysis exploits the large inclusive charged current sample – about 9 × 10 6 events after all analysis cuts – and the high resolution NOMAD detector to constrain the total systematic uncertainty on the ratio of charm dimuon to inclusive Charged Current (CC) cross-sections to ∼2%. We also perform a fit to the NOMAD data to extract the charm production parameters and the strange quark sea content of the nucleon within the NLO QCD approximation. We obtain a value of m c ( m c ) = 1.159 ± 0.075 GeV / c 2 for the running mass of the charm quark in the MS ¯ scheme and a strange quark sea suppression factor of κ s = 0.591 ± 0.019 at Q 2 = 20 GeV 2 / c 2 .
183101397
PRECISION MEASUREMENTS FROM THE NOMAD EXPERIMENT
18311078
Design and prototype tests of the RPC system for the OPERA spectrometers
The Inner Tracker system of the spectrometers of the OPERA experiment makes use of Resistive Plate Chambers (RPC) in a large-scale application. We present here the definition of the project and the full design of the Inner Tracker. Specific performances for the OPERA-RPC in the spectrometer are also reported. Particle detection, muon identification and trigger capability are discussed, in particular. Some results from test beam (T9 and T7 lines at the CERN PS) and measurements from laboratory test (CERN, Frascati, Padova, Gran Sasso) with prototype detectors are discussed, as well as specific solutions developed for the final set-up in OPERA. Full Monte Carlo simulations of the experimental set-up have been also developed. r 2003 Published by Elsevier Science B.V.
110065803
Status of design and construction of the Transition Radiation Tracker (TRT) for the ATLAS experiment at the LHC
The ATLAS Inner Detector consists of three sub-systems, the Pixel Detector at the innermost radius, the Semi-Conductor Tracker at intermediate radii, and the Transition Radiation Tracker (TRT) at the outermost radius in front of the electromagnetic calorimeter. The TRT provides a combination of continuous tracking with many projective measurements based on individual drift-tubes (or straws) and of electron identification based on radiator fibres or foils interleaved between the straws themselves. This paper describes the current status of design and construction of the various components of the TRT: the assembly of the barrel modules has recently been completed, that of the end-cap wheels is well underway, and the on-detector front-end electronics is in production. The detector modules and front-end electronics boards will be integrated together over the next year, the barrel and end-cap TRT parts will be assembled and tested with their SCT counterparts during 2005 and installation and commissioning in the ATLAS pit will take place at the end of 2005 and the beginning of 2006. (C) 2004 Elsevier B.V. All rights reserved. (Less)
59366071
Determination of Strange Sea Quark Distributions from Fixed-target and Collider Data
We present an improved determination of the strange sea distribution in the nucleon with constraints coming from the recent charm production data in neutrino-nucleon deep-inelastic scattering by the NOMAD and CHORUS experiments and from charged current inclusive deep-inelastic scattering at HERA. We demonstrate that the results are consistent with the data from the ATLAS and the CMS experiments on the associated production of W ± -bosons with c-quarks. We also discuss issues related to the recent strange sea determination by the ATLAS experiment using LHC collider data.
122778003
Study of energy response and resolution of the ATLAS barrel calorimeter to hadrons of energies from 20 to 350 GeV
A fully instrumented slice of the ATLAS detector was exposed to test beams from the SPS (Super Proton Synchrotron) at CERN in 2004. In this paper, the results of the measurements of the response of the barrel calorimeter to hadrons with energies in the range 20 to 350 GeV and beam impact points and angles corresponding to pseudorapidity values in the range 0.2-0.65 are reported. The results are compared to the predictions of a simulation program using the Geant 4 toolkit.
117742578
Inclusive double-helicity asymmetries in neutral-pion and eta-meson production in $\vec{p}+\vec{p}$ collisions at $\sqrt{s}=200$ GeV
Results are presented from data recorded in 2009 by the PHENIX experiment at the Relativistic Heavy Ion Collider for the double-longitudinal spin asymmetry, $A_{LL}$, for $\pi^0$ and $\eta$ production in $\sqrt{s} = 200$ GeV polarized $p$$+$$p$ collisions. Comparison of the $\pi^0$ results with different theory expectations based on fits of other published data showed a preference for small positive values of gluon polarization, $\Delta G$, in the proton in the probed Bjorken $x$ range. The effect of adding the new 2009 \pz data to a recent global analysis of polarized scattering data is also shown, resulting in a best fit value $\Delta G^{[0.05,0.2]}_{\mbox{DSSV}} = 0.06^{+0.11}_{-0.15}$ in the range $0.05<x<0.2$, with the uncertainty at $\Delta \chi^2 = 9$ when considering only statistical experimental uncertainties. Shifting the PHENIX data points by their systematic uncertainty leads to a variation of the best-fit value of $\Delta G^{[0.05,0.2]}_{\mbox{DSSV}}$ between $0.02$ and $0.12$, demonstrating the need for full treatment of the experimental systematic uncertainties in future global analyses.
118590241
Low-mass vector-meson production at forward rapidity in $p$$+$$p$ collisions at $\sqrt{s}=200$ GeV
The PHENIX experiment at the Relativistic Heavy Ion Collider has measured low mass vector meson, $\omega$, $\rho$, and $\phi$, production through the dimuon decay channel at forward rapidity ($1.2<|y|<2.2$) in $p$$+$$p$ collisions at $\sqrt{s}=200$ GeV. The differential cross sections for these mesons are measured as a function of both $p_T$ and rapidity. We also report the integrated differential cross sections over $1<p_T<7$ GeV/$c$ and $1.2<|y|<2.2$: $d\sigma/dy(\omega+\rho\rightarrow\mu\mu) = 80 \pm 6 \mbox{(stat)} \pm 12 \mbox{(syst)}$ nb and $d\sigma/dy(\phi\rightarrow\mu\mu) = 27 \pm 3 \mbox{(stat)} \pm 4 \mbox{(syst)}$ nb. These results are compared with midrapidity measurements and calculations.
118582318
Concept for an Electron Ion Collider (EIC) detector built around the BaBar solenoid
The PHENIX collaboration presents here a concept for a detector at a future Electron Ion Collider (EIC). The EIC detector proposed here, referred to as ePHENIX, will have excellent performance for a broad range of exciting EIC physics measurements, providing powerful investigations not currently available that will dramatically advance our understanding of how quantum chromodynamics binds the proton and forms nuclear matter.
54959647
Cross section for $b\bar{b}$ production via dielectrons in d$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV
We report a measurement of $e^+e^-$ pairs from semileptonic heavy-flavor decays in $d$$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV. Exploring the mass and transverse-momentum dependence of the yield, the bottom decay contribution can be isolated from charm, and quantified by comparison to {\sc pythia} and {\sc mc@nlo} simulations. The resulting $b\bar{b}$-production cross section is $\sigma^{d{\rm Au}}_{b\bar{b}}=1.37{\pm}0.28({\rm stat}){\pm}0.46({\rm syst})$~mb, which is equivalent to a nucleon-nucleon cross section of $\sigma^{NN}_{bb}=3.4\pm0.8({\rm stat}){\pm}1.1({\rm syst})\ \mu$b.
118897253
Translational Spacetime Symmetries in Gravitational Theories
How to include spacetime translations in fibre bundle gauge theories has been a subject of controversy, because spacetime symmetries are not internal symmetries of the bundle structure group. The standard method for including affine symmetry in differential geometry is to define a Cartan connection on an affine bundle over spacetime. This is equivalent to (1) defining an affine connection on the affine bundle, (2) defining a zero section on the associated affine vector bundle and (3) using the affine connection and the zero section to define an 'associated solder form', whose lift to a tensorial form on the frame bundle becomes the solder form. The zero section reduces the affine bundle to a linear bundle and splits the affine connection into translational and homogeneous parts; however, it violates translational equivariance/gauge symmetry. This is the natural geometric framework for Einstein–Cartan theory as an affine theory of gravitation. The last section discusses some alternative approaches that claim to preserve translational gauge symmetry.