21572416
Absolute measurement of hadronic branching fractions of the Ds+ meson.
The branching fractions of D(s)(+/-) meson decays serve to normalize many measurements of processes involving charm quarks. Using 298 pb(-1) of e(+)e(-) collisions recorded at a center of mass energy of 4.17 GeV, we determine absolute branching fractions for eight D(s)(+/-) decays with a double tag technique. In particular we determine the branching fraction B(D(s)(+)-->K(-)K(+}pi(+))=(5.50+/-0.23+/-0.16)%, where the uncertainties are statistical and systematic, respectively. We also provide partial branching fractions for kinematic subsets of the K(-)K(+)pi(+) decay mode.
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.
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.
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.
209963341
Measurement of B(Upsilon(5S) ---> B(*)(s) anti-B(*)(s)) Using phi Mesons
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.
118792115
A Test accelerator for the next linear collider
At SLAC, the authors are pursuing the design of a Next Linear Collider (NLC) which would begin with a center-of-mass energy of 0.5 TeV, and be upgradable to at least 1.0 TeV. To achieve this high energy, they have been working on the development of a high-gradient 11.4-GHz (X-band) linear accelerator for the main linac of the collider. In this paper, they present the design of a {open_quotes}Next Linear Collider Test Accelerator{close_quotes} (NLCTA). The goal of the NLCTA is to incorporate the new technologies of X-band accelerator structures, RF pulse compression systems and klystrons into a short linac which will then be a test bed for beam dynamics issues related to high-gradient acceleration.
15228891
Vacuum domain walls in D dimensions: Local and global space-time structure
We study local and global gravitational effects of (D-2)-brane configurations (domain walls) in the vacuum of D-dimensional space-time. We focus on infinitely thin vacuum domain walls with arbitrary cosmological constants on either side of the wall. In the comoving frame of the wall we derive a general metric ansatz, consistent with the homogeneity and isotropy of the space-time intrinsic to the wall, and employ Israel's matching conditions at the wall. The space-time, intrinsic to the wall, is that of a (D-1)-dimensional Freedman-Lemaitre-Robertson-Walker universe (with k=-1,0,1) which has a (local) description as either anti-de Sitter, Minkowski or de Sitter space-time. For each of these geometries, we provide a systematic classification of the local and global space-time structure transverse to the walls, for those with both positive and negative tension; they fall into different classes according to the values of their energy density relative to that of the extreme (supersymmetric) configurations. We find that in any dimension D, both local and global space-time structure for each class of domain walls is universal. We also comment on the phenomenological implications of these walls in the special case of D=5. (c) 2000 The American Physical Society.
16708904
RELATIVISTIC KLYSTRON RESEARCH AT SLAC AND LLNLt
We are developing relativistic klystrons as a power source for high gradient accelerator applications such as large linear electron-positron colliders and compact accelerators. We have attained 200 MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV/m longitudinal gradient in a short 11.4 GHz accelerator section. We report here briefly on our experiments so far. 5 refs., 1 fig., 1 tab.
125503501
Measurement of branching fractions for two-body B meson decays with charmonium at Belle
118837794
Observation of Z decays to four leptons with the CMS detector at the LHC
A bstractThe first observation of the Z boson decaying to four leptons in proton-proton collisions is presented. The analyzed data set corresponds to an integrated luminosity of 5.02 fb−1 at $ \sqrt{s}=7 $ TeV collected by the CMS detector at the Large Hadron Collider. A pronounced resonance peak, with a statistical significance of 9.7 σ, is observed in the distribution of the invariant mass of four leptons (electrons and/or muons) with mass and width consistent with expectations for Z boson decays. The branching fraction and cross section reported here are defined by phase space restrictions on the leptons, namely, 80 < m4ℓ < 100 GeV, where m4ℓ is the invariant mass of the four leptons, and mℓℓ > 4 GeV for all pairs of leptons, where mℓℓ is the two-lepton invariant mass. The measured branching fraction is $ \mathcal{B}\left( {Z\to 4\ell } \right)=\left( {4.2_{-0.8}^{+0.9}\left( {\mathrm{stat}.} \right)\pm 0.2\left( {\mathrm{syst}.} \right)} \right)\times {10^{-6 }} $ and agrees with the standard model prediction of 4.45 × 10−6. The measured cross section times branching fraction is $ \sigma \left( {\mathrm{pp}\to \mathrm{Z}} \right)\mathcal{B}\left( {\mathrm{Z}\to 4\ell } \right)=112_{-20}^{+23}\left( {\mathrm{stat}.} \right)_{-5}^{+7}\left( {\mathrm{syst}.} \right)_{-2}^{+3}\left( {\mathrm{lumi}.} \right) $ fb, also consistent with the standard model prediction of 120 fb. The four-lepton mass peak arising from Z → 4ℓ decays provides a calibration channel for the Higgs boson search in the H → ZZ → 4ℓ decay mode.