209868461
Improved Measurement of the Branching Fraction and Energy Spectrum of eta-prime from Upsilon(1S) Decays
209963341
Measurement of B(Upsilon(5S) ---> B(*)(s) anti-B(*)(s)) Using phi Mesons
42582723
Measurement of the Ds+ - Ds- production asymmetry in 7 TeV pp collisions
Article history: Received 4 May 2012 Received in revised form 30 May 2012 Accepted 1 June 2012 Available online 6 June 2012 Editor: W.-D. Schlatter Heavy quark production in 7 TeV centre-of-mass energy pp collisions at the LHC is not necessarily flavour symmetric. The production asymmetry, AP, between D+s and D−s mesons is studied using the φπ± decay mode in a data sample of 1.0 fb−1 collected with the LHCb detector. The difference between π+ and π− detection efficiencies is determined using the ratios of fully reconstructed to partially reconstructed D∗± decays. The overall production asymmetry in the D±s rapidity region 2.0 to 4.5 with transverse momentum larger than 2 GeV is measured to be AP = (−0.33 ± 0.22 ± 0.10)%. This result can constrain models of heavy flavour production. © 2012 CERN. Published by Elsevier B.V. All rights reserved.
119287240
Searches for Majorana neutrinos in $B^-$ decays
Searches for heavy Majorana neutrinos in B- decays in final states containing hadrons plus a \mu- \mu- pair have been performed using 0.41/fb of data collected with the LHCb detector in proton-proton collisions at a center-of-mass energy of 7 TeV. The D+ \mu- \mu- and D*+ \mu- \mu- final states can arise from the presence of virtual Majorana neutrinos of any mass. Other final states containing \pi+, Ds+, or D0\pi+ can be mediated by an on-shell Majorana neutrino. No signals are found and upper limits are set on Majorana neutrino production as a function of mass, and also on the B- decay branching fractions.
14029193
Performance of the CLEO III LiF-TEA ring imaging Cherenkov detector in a high-energy muon beam
Abstract The CLEO III Ring Imaging Cherenkov detector uses LiF radiators to generate Cherenkov photons which are then detected by proportional wire chambers using a mixture of CH 4 and TEA gases. The first two photon detector modules which were constructed, were taken to the Fermilab and tested in a beam dump that provided high-momentum muons. We report on results using both plane and “sawtooth”–shaped radiators. Specifically, we discuss the number of photoelectrons observed per ring and the angular resolution. The particle separation ability is shown to be sufficient for the physics of CLEO III.
119969840
First spatial alignment of the LHCb VELO and analysis of beam absorber collision data
A first alignment of the LHCb Vertex Locator has been obtained from beam induced tracks at the LHC. A 450 GeV/c protons were collided on a beam absorber during the LHC synchronisation tests of the anti-clockwise beam in August and September 2008. The resulting particle tracks have been reconstructed by the Vertex Locator. This was the first full reconstruction of tracks induced by the LHC beam. The quality of the data obtained is discussed. A total of 2200 tracks were reconstructed from the full data sample, and a first spatial alignment was obtained. The detector is aligned to an accuracy of Slim in the sensor plane. The results confirm that all detector modules have not been displaced from their surveyed positions by more than 10 mm. (C) 2010 Elsevier B.V. All rights reserved.
119741336
Electron cloud instability studies in the Beijing Electron Positron Collider
The electron cloud instability (ECI) in the Beijing Electron Positron Collider (BEPC) was studied systematically with experiments and simulations in recent years. Several electron cloud detectors have been installed into the BEPC storage ring to measure the electron yield. The effects of solenoid, the clearing electrode, the chromaticity, and the octupole on ECI have been investigated in BEPC experimentally. To evaluate the ECI in BEPCII, the upgrade project of BEPC, a computer code has been developed to simulate the electron density in the antechamber under different conditions, as well as the progress of the single bunch and coupled-bunch instabilities caused by the electron cloud. The experimental and simulation results, as well as the activities, are reported in this paper.
125833326
Measurement of the decay K(L) ---> pi0 gamma gamma
123147042
Dispersion and energy compensation in high-gradient linacs for lepton colliders
34473277
Search for top-quark partners with charge 5/3 in the same-sign dilepton final state.
A search for the production of heavy partners of the top quark with charge 5/3 is performed in events with a pair of same-sign leptons. The data sample corresponds to an integrated luminosity of 19.5 fb(-1) and was collected at sqrt[s] = 8 TeV by the CMS experiment. No significant excess is observed in the data above the expected background, and the existence of top-quark partners with masses below 800 GeV is excluded at a 95% confidence level, assuming they decay exclusively to tW. This is the first limit on these particles from the LHC, and it is significantly more restrictive than previous limits.
29885350
Measurement of electroweak production of two jets in association with a Z boson in proton–proton collisions at $$\sqrt{s}=8\,\text {TeV}$$s=8TeV
The purely electroweak (EW) cross section for the production of two jets in association with a Z boson, in proton–proton collisions at $$\sqrt{s}=8\,\text {TeV}$$s=8TeV, is measured using data recorded by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 19.7$$\,\text {fb}^\text {-1}$$fb-1. The electroweak cross section for the $$\ell \ell \mathrm {jj}$$ℓℓjj final state (with $$\ell = \mathrm {e}$$ℓ=e or $$\mu $$μ and j representing the quarks produced in the hard interaction) in the kinematic region defined by $$M_{\ell \ell } >50$$Mℓℓ>50$$\,\text {GeV}$$GeV, $$M_\mathrm {jj} >120$$Mjj>120$$\,\text {GeV}$$GeV, transverse momentum $$p_\mathrm {T j}> 25$$pTj>25$$\,\text {GeV}$$GeV, and pseudorapidity $$|\eta _\mathrm {j} |< 5$$|ηj|<5, is found to be $$\sigma _\mathrm {EW}(\ell \ell \mathrm {jj})=174 \pm 15\,\text {(stat)}\pm 40\,\text {(syst)}\text {\,fb}$$σEW(ℓℓjj)=174±15(stat)±40(syst)\,fb, in agreement with the standard model prediction. The associated jet activity of the selected events is studied, in particular in a signal-enriched region of phase space, and the measurements are found to be in agreement with QCD predictions.