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First events from the CNGS neutrino beam detected in the OPERA experiment
(2006)New Journal of PhysicsThe OPERA neutrino detector at the underground Gran Sasso Laboratory (LNGS) was designed to perform the first detection of neutrino oscillations in appearance mode, through the study of νμ → ντ oscillations. The apparatus consists of a lead/emulsion-film target complemented by electronic detectors. It is placed in the high-energy, long-baseline CERN to LNGS beam (CNGS) 730 km away from the neutrino source. In August 2006, a first run with ...Journal Article -
Deterministic entanglement and tomography of trapped ion-spin qubits
(2006)New Journal of PhysicsWe have implemented a universal quantum logic gate between qubits stored in the spin state of a pair of trapped 40Ca ions. An initial product state was driven to a maximally entangled state deterministically, with 83% fidelity. We present a general approach to quantum state tomography which achieves good robustness to experimental noise and drift, and use it to measure the spin state of the ions. We find the entanglement of formation is 0.54.Journal Article -
The Fermi-Hubbard model at unitarity
(2006)New Journal of PhysicsWe simulate the dilute attractive Fermi–Hubbard model in the unitarity regime using a diagrammatic determinant Monte Carlo (MC) algorithm with worm-type updates. We obtain the dependence of the critical temperature on the filling factor ν and, by extrapolating to ν → 0, determine the universal critical temperature of the continuum unitary Fermi gas in units of Fermi energy: Tc/εF = 0.152(7). We also determine the thermodynamic functions ...Journal Article -
Diffractive photoproduction of ρ mesons with large momentum transfer at HERA
(2006)Physics Letters BThe diffractive photoproduction of ρ mesons, e p → e ρ Y, with large momentum transfer squared at the proton vertex, |t|, is studied with the H1 detector at HERA using an integrated luminosity of 20.1 pb-1. The photon-proton centre of mass energy spans the range 75 < W < 95 GeV, the photon virtuality is restricted to Q2 < 0.01 GeV2 and the mass MY of the proton remnant is below 5 GeV. The t dependence of the cross section is measured ...Journal Article -
Search for doubly-charged Higgs boson production at HERA
(2006)Physics Letters BA search for the single production of doubly-charged Higgs bosons H± ± in ep collisions is presented. The signal is searched for via the Higgs decays into a high mass pair of same charge leptons, one of them being an electron. The analysis uses up to 118 pb-1 of ep data collected by the H1 experiment at HERA. No evidence for doubly-charged Higgs production is observed and mass dependent upper limits are derived on the Yukawa couplings he ...Journal Article -
Low jitter up-conversion detectors for telecom wavelength GHz QKD
(2006)New Journal of PhysicsWe have developed a hybrid single photon detection scheme for telecom wavelengths based on nonlinear sum-frequency generation and silicon single-photon avalanche diodes (SPADs). The SPAD devices employed have been designed to have very narrow temporal response, i.e. low jitter ~40 ps, which we can exploit for increasing the allowable bit rate for quantum key distribution. The wavelength conversion is obtained using periodically poled ...Journal Article -
A determination of electroweak parameters at HERA
(2006)Physics Letters BUsing the deep inelastic e+p and e-p charged and neutral current scattering cross sections previously published, a combined electroweak and QCD analysis is performed to determine electroweak parameters accounting for their correlation with parton distributions. The data used have been collected by the H1 experiment in 1994-2000 and correspond to an integrated luminosity of 117.2 pb-1. A measurement is obtained of the W propagator mass in ...Journal Article -
Dynamic monetary risk measures for bounded discrete-time processes
(2006)Electronic Journal of ProbabilityWe study dynamic monetary risk measures that depend on bounded discrete-time processes describing the evolution of financial values. The time horizon can be finite or infinite. We call a dynamic risk measure time-consistent if it assigns to a process of financial values the same risk irrespective of whether it is calculated directly or in two steps backwards in time. We show that this condition translates into a decomposition property for ...Journal Article -
Global seismic tomography and modern parallel computers
(2006)Annals of GeophysicsA fast technological progress is providing seismic tomographers with computers of rapidly increasing speed and RAM, that are not always properly taken advantage of. Large computers with both shared-memory and distributedmemory architectures have made it possible to approach the tomographic inverse problem more accurately. For example, resolution can be quantified from the resolution matrix rather than checkerboard tests; the ...Journal Article -