8085635
Beam test results of the BTeV silicon pixel detector
We report the main results of the BTeV silicon pixel detector beam test carried out at Fermilab during the fixed target run 1999-2000. The tests were performed using a 227 GeV/c pion beam incident on a 6 plane silicon microstrip telescope. Several single-chip silicon pixel planes were placed in the middle of the apparatus. The pixel detector spatial resolution has been studied as a function of track inclination and the number of ADC bits. The effect of an applied external magnetic field was also studied.
122717574
Search for neutralinos in Z decays
Abstract We have searched for neutralinos produced via the reactions e + e − → χχ′ and e + e − → χ′χ′, where the next-to lightest neutralino, χ′, decays into the lightest neutralino, χ, and either a photon or a fermion pair. Based on 1.8 × 10 6 hadronic Z decays collected with the L3 detector at LEP, no signal has been observed. We present upper limits of a few times 10 −5 on the branching ratios Z → χχ′ and Z → χ′χ′. In the framework of the Minimial Supersymmetric Standard Model, we exclude a lightest χ with m χ less than 18 GeV, if either tan β > 2 or the gluino mass m ≈ g > 100 GeV.
18308235
Search for new particles in hadronic events with isolated photons
Abstract A search for the neutral Higgs boson in the processes e + e − → Z → H 0 γ → q q γ and e + e − → Z → Z ∗ H 0 → q q γγ has been performed using 2.8 million hadronic Z decays collected with the L3 detector at LEP from 1991 through 1994. No evidence for these processes has been observed. Upper limits at 95% confidence level for the corresponding cross sections have been set and the results have been compared with theoretical predictions beyond the Standard Model.
122052372
Angular multiplicity fluctuations in hadronic Z decays and comparison to QCD models and analytical calculations
Abstract Local multiplicity fluctuations in angular phase space intervals are studied using factorial moments measured in hadronic events at s ≃91.2 GeV , which were collected by the L3 detector at LEP. Parton shower Monte Carlo programs agree well with the data. On the other hand, first-order QCD calculations in the Double Leading Log Approximation and the Modified Leading Log Approximation are found to deviate significantly from the data.
122751074
Production of single W bosons at LEP
We report on the observation of single W boson production in a data sample collected by the L3 detector at LEP2. The signal consists of large missing energy final states with a single energetic lepton or two hadronic jets. The cross-section is measured to be 0.61(-0.33)(+0.43) +/- 0.05 pb at the centre of mass energy root s = 172 GeV, consistent with the Standard Model expectation. From this measurement the following limits on the anomalous gamma WW gauge couplings are derived at 95% CL: -3.6 < Delta kappa gamma < 1.5 and -3.6 < lambda gamma < 3.6. (C) 1997 Published by Elsevier Science B.V.
14588649
Production of e, mu and tau pairs in untagged two-photon collisions at LEP
The two-photon collision reaction e+e- --> e+e-l+l- has been studied at root(s) ~ 91 GeV using the L3 detector at LEP for l = e, muon , tau. We have analysed untagged configurations where the two photons are quasi-real. Good agreement is found between our measurements and the order alpha**4 QED expectation.
115470739
Flavor tagged time-dependent angular analysis of the $B_s \rightarrow J/\psi \phi$ decay and extraction of $\Delta\Gamma$s and the weak phase $\phi_s$ in ATLAS
A measurement of the B0s→J/ψϕ decay parameters, updated to include flavor tagging is reported using 4.9  fb−1 of integrated luminosity collected by the ATLAS detector from s√=7  TeV pp collisions recorded in 2011 at the LHC. The values measured for the physical parameters are 
ϕs0.12±0.25(stat)±0.05(syst)  radΔΓs0.053±0.021(stat)±0.010(syst)  ps−1Γs0.677±0.007(stat)±0.004(syst)  ps 1|A∥(0)|20.220±0.008(stat)±0.009(syst)|A0(0)|20.529±0.006(stat)±0.012(syst)δ⊥=3.89±0.47(stat)±0.11(syst)  rad 
where the parameter ΔΓs is constrained to be positive. The S-wave contribution was measured and found to be compatible with zero. Results for ϕs and ΔΓs are also presented as 68% and 95% likelihood contours, which show agreement with the Standard Model expectations.
119245573
Observational constraints on unified dark matter including Hubble parameter data
Abstract We constrain a unified dark matter (UDM) model from the latest observational data. This model assumes that the dark sector is degenerate. Dark energy and dark matter are the same component. It can be described by an affine equation of state P X = p 0 + α ρ X . Our data set contains the newly revised H ( z ) data, type Ia supernovae (SNe Ia) from Union2 set, baryonic acoustic oscillation (BAO) observation from the spectroscopic Sloan Digital Sky Survey (SDSS) data release 7 (DR7) galaxy sample, as well as the cosmic microwave background (CMB) observation from the 7-year Wilkinson Microwave Anisotropy Probe (WMAP7) results. By using the Markov Chain Monte Carlo (MCMC) method, we obtain the results in a flat universe: Ω Λ = 0.719 − 0.0305 + 0.0264 ( 1 σ ) − 0.0458 + 0.0380 ( 2 σ ) , α = 1.72 − 4.79 + 3.92 ( 1 σ ) − 7.30 + 5.47 ( 2 σ ) ( × 10 − 3 ) , Ω b h 2 = 0.0226 − 0.0011 + 0.0011 ( 1 σ ) − 0.0015 + 0.0016 ( 2 σ ) . Moreover, when considering a non-flat universe, Ω Λ = 0.722 − 0.0447 + 0.0362 ( 1 σ ) − 0.0634 + 0.0479 ( 2 σ ) , α = 0.242 − 0.775 + 0.787 ( 1 σ ) − 1.03 + 1.10 ( 2 σ ) ( × 10 − 2 ) , Ω b h 2 = 0.0227 − 0.0014 + 0.0015 ( 1 σ ) − 0.0018 + 0.0021 ( 2 σ ) , Ω k = − 0.194 − 1.85 + 2.02 ( 1 σ ) − 2.57 + 2.75 ( 2 σ ) ( × 10 − 2 ) . These give a more stringent results than before. We also give the results from other combinations of these data for comparison. The observational Hubble parameter data can give a more stringent constraint than SNe Ia. From the constraint results, we can see the parameters α and Ω k are very close to zero, which means a flat universe is strongly supported and the speed of sound of the dark sector seems to be zero.
964657
Beam loading compensation in the NLCTA
In the design of the Next Linear Collider (NLC), multibunch operation is employed to improve efficiency at the cost of substantial beam loading. The RF pulse that powers the accelerator structures will be shaped to compensate for the effect of the transient loading along the bunch train. This scheme has been implemented in the Next Linear Collider Test Accelerator (NLCTA), a facility built to test the key accelerator technology of the NLC. In this paper we describe the compensation method, the techniques used to measure the energy variation along the bunch train, and results from tests with NLC-like beam currents.
16816092
Broad‐line Balmer decrements in blue active galactic nuclei
We have investigated the broad-line Balmer decrements (H alpha/H beta) for a large, homogeneous sample of Seyfert 1 galaxies and quasi-stellar objects (QSOs) using spectroscopic data obtained in the Sloan Digital Sky Survey. The sample, drawn from the Fourth Data Release, comprises 446 low-redshift (z less than or similar to 0.35) active galactic nuclei (AGN) that have blue optical continua as indicated by the spectral slopes in order to minimize the effect of dust extinction. We find that (i) the distribution of the intrinsic broad-line H alpha/H beta ratio can be well described by log-Gaussian, with a peak at H alpha/H beta = 3.06 and a standard deviation of about 0.03 dex only; (ii) the Balmer decrement does not correlate with AGN properties such as luminosity, accretion rate and continuum slope, etc.; (iii) on average, the Balmer decrements are found to be only slightly larger in radio-loud sources (3.37) and sources having double-peaked emission-line profiles (3.27) compared to the rest of the sample. We therefore suggest that the broad-line H alpha/H beta ratio can be used as a good indicator for dust extinction in the AGN broad-line region; this is especially true for radio-quiet AGN with regular emission-line profiles, which constitute the vast majority of the AGN population.
122265599
First LHC beam induced tracks reconstructed in the LHCb VELO
The Vertex Locator of the LHCb experiment has been used to fully reconstruct beam induced tracks at the LHC. A beam of protons was collided with a beam absorber during the LHC synchronisation test of the anti-clockwise beam on the weekend 22nd–24th August 2008. The resulting particles have been observed by the Vertex Locator. The LHCb Vertex Locator is a silicon micro-strip detector containing 21 planes of modules. Tracks were observed passing through up to 19 modules (38 silicon sensors). A total of over 700 tracks were reconstructed, and are being used to study the calibration and alignment of the detector.