119217152
Observation of $B^+_c \rightarrow J/\psi D_s^+$ and $B^+_c \rightarrow J/\psi D_s^{*+}$ decays
The decays $B^+_c \rightarrow J/\psi D_s^+$ and $B^+_c \rightarrow J/\psi D_s^{*+}$ are observed for the first time using a dataset, corresponding to an integrated luminosity of 3$fb^{-1}$, collected by the LHCb experiment in proton-proton collisions at centre-of-mass energies of $\sqrt{s}$=7 and 8 TeV. The statistical significance for both signals is in excess of 9 standard deviations. The following ratios of branching fractions are measured to be $BR(B^+_c \rightarrow J/\psi D_s^+)/BR(B^+_c \rightarrow J/\psi \pi+) = 2.90 \pm 0.57 \pm 0.24$, $BR(B^+_c \rightarrow J/\psi D_s^{*+}) / BR (B^+_c \rightarrow J/\psi D_s^+) = 2.37 \pm 0.56 \pm 0.10$, where the first uncertainties are statistical and the second systematic. The mass of the \Bc meson is measured to be $m_{B^+_c} = 6276.28 \pm 1.44 (stat) \pm 0.36(syst) MeV/c^2$, using the $B^+_c \rightarrow J/\psi D_s^+$ decay mode.
119113679
Search for CP violation in the decay $D^+ \to \pi^-\pi^+\pi^+$
A search for CP violation in the phase space of the decay $D^+\to\pi^-\pi^+\pi^+$ is reported using $pp$ collision data, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected by the LHCb experiment at a centre-of-mass energy of 7 TeV. The Dalitz plot distributions for $3.1\times 10^6$ $D^+$ and $D^-$ candidates are compared with binned and unbinned model-independent techniques. No evidence for CP violation is found.
209834344
Measurement of the CKM angle $\gamma$ using $B^\pm \to D K^\pm$ with $D \to K^0_{\rm S} \pi^+\pi^-, K^0_{\rm S} K^+ K^-$ decays
54960779
Measurement of the resonant and CP components in $\overline{B}^0\to J/\psi \pi^+\pi^-$ decays
The resonant structure of the reaction $\overline{B}^0\rightarrow J/\psi \pi^+\pi^-$ is studied using data from 3 fb$^{-1}$ of integrated luminosity collected by the LHCb experiment, one-third at 7 Tev center-of-mass energy and the remainder at 8 Tev. The invariant mass of the $\pi^+\pi^-$ pair and three decay angular distributions are used to determine the fractions of the resonant and non-resonant components. Six interfering $\pi^+\pi^-$ states: $\rho(770)$, $f_0(500)$, $f_2(1270)$, $\rho(1450)$, $\omega(782)$ and $\rho(1700)$ are required to give a good description of invariant mass spectra and decay angular distributions. The positive and negative CP fractions of each of the resonant final states are determined. The $f_0(980)$ meson is not seen and the upper limit on its presence, compared with the observed $f_0(500)$ rate, is inconsistent with a model of tetraquark substructure for these scalar mesons at the eight standard deviation level. In the $q\overline{q}$ model, the absolute value of the mixing angle between the $f_0(980)$ and the $f_0(500)$ scalar mesons is limited to be less than $17^{\circ}$ at 90% confidence level.
118506737
Measurement of CP violation in the phase space of $B^{\pm} \to K^{\pm} \pi^{+} \pi^{-}$ and $B^{\pm} \to K^{\pm} K^{+} K^{-}$ decays
The charmless decays $B^{\pm}\to K^{\pm}\pi^+\pi^-$ and $B^{\pm}\to K^{\pm}K^+K^-$ are reconstructed using data, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected by LHCb in 2011. The inclusive charge asymmetries of these modes are measured as $A_{C\!P}(B^{\pm}\to K^{\pm}\pi^+\pi^-) = 0.032 \pm 0.008 \stat \pm 0.004 \syst \pm 0.007 (J\psi K^{\pm})$ and $A_{C\!P}(B^{\pm}\to K^{\pm}K^+K^-) = -0.043 \pm 0.009 \stat \pm 0.003 \syst \pm 0.007 (J\psi K^{\pm})$, where the third uncertainty is due to the $C\!P$ asymmetry of the $B^{\pm}\to J\psi K^{\pm}$ reference mode. The significance of $A_{C\!P}(B^{\pm}\to K^{\pm}K^+K^-)$ exceeds three standard deviations and is the first evidence of an inclusive $C\!P$ asymmetry in charmless three-body $B$ decays. In addition to the inclusive $C\!P$ asymmetries, larger asymmetries are observed in localised regions of phase space.
11478351
Determination of the X(3872) meson quantum numbers.
The quantum numbers of the X(3872) meson are determined to be J(PC)=1(++) based on angular correlations in B(+)→X(3872)K(+) decays, where X(3872)→π(+)π(-)J/ψ and J/ψ→μ(+)μ(-). The data correspond to 1.0 fb(-1) of pp collisions collected by the LHCb detector. The only alternative assignment allowed by previous measurements J(PC)=2(-+) is rejected with a confidence level equivalent to more than 8 Gaussian standard deviations using a likelihood-ratio test in the full angular phase space. This result favors exotic explanations of the X(3872) state.
55383487
Operational Experience with Tevatron I Antiproton Source
The secondaries are transported down the AP2 line into the Debuncher ring. The Debdncher ring has a 207 x 23~ transverse acceptance and 4% momentum acceptance. The antiprotons are then rotated using 4.2 MV of 53 MHz R.F. to .4% Ap/p in 80 turns and the adIabatically debunched to .2% APIP. The antiproton are then stochastically cooled for 2 seconds in the transverse planes with 2-4 GHz cooling systems to 771 x 77. The antiproton are then extracted from the Debuncher and transported across the D/A line to the Accumulator.
17341590
A study of lithium deuteride as a material for a polarized target
Abstract Experiment E155 at the Stanford Linear Accelerator Center (SLAC) measured the spin-dependent structure of the proton and neutron, using for the first time 6 LiD as the polarized deuteron target material in a high-energy electron beam. This compound provides a significantly higher dilution factor than any other solid deuteron target material currently used in high-energy physics experiments. Results of the polarization behavior of the 6 LiD target material before and after exposure to the 50 GeV/ c electron beam used in E155 are presented.
45908480
Multi-GeV Electron Linac-Pulse Stretcher Design Options
The Linac-Pulse Stretcher Ring system is evaluated as a design for a high duty factor (> 90%), intense (240 ¿A), electron accelerator for operation in the 0.5 to multi-GeV (> 4 GeV) region. Options within this system are discussed in light of their predicted initial and operational cost, flexibility, and reliability. The ramifications of the choice of a particular cavity type, accelerating gradient, repetition rate, beam pulse length, and number of beam recirculations for the linac design are discussed both with respect to the linac itself and to the Pulse Stretcher Ring. The Pulse Stretcher Ring concept is analysed in terms of injection schemes (single or multi-turn), extraction methods (half or third integer, chromatic or achromatic), and operation parameters (machine tune and chromaticity).
122989017
Measurement of the SMC muon beam polarisation using the asymmetry in the elastic scattering off polarised electrons
A muon beam polarimeter was built for the SMC experiment at the CERN SPS, for beam energies of 100 and 190 GeV. The beam polarisation is determined from the asymmetry in the elastic scattering off the polarised electrons of a ferromagnetic target whose magnetisation is periodically reversed. At muon energies of 100 and 190 GeV the measured polarisation is P-mu = -0.80 +/- 0.03 (stat.) +/- 0.02 (syst.) and P-mu = - 0.797 +/- 0.011 (stat.) +/- 0.012 (syst.), respectively. These results agree with measurements of the beam polarisation using a shape analysis of the decay positron energy spectrum. (C) 2000 Elsevier Science B.V. All rights reserved.
121021036
G**p(E) / G**p(M) for bound protons: first results for O-16 with the recoil polarization technique
The first (e,e'p) polarization transfer measurements on a nucleus heavier than deuterium have been carried out at Jefferson Laboratory. Transverse and longitudinal components of the polarization of protons ejected in the reaction 16O(e,e'p) were measured in quasielastic perpendicular kinematics at a Q^2 of 0.8 (GeV/c)^2. The data are in good agreement with state of the art calculations, but do not exclude possible changes in the ratio of the electric to magnetic form factors of the nucleon in the nuclear medium at the level of recent theoretical predictions.