Study of $\nu_{\mu}$ - charged current interactions and search for $\nu_{\mu} \leftrightarrow \nu_{\tau}$ oscillations in the channel $\tau^{-} \to \mu^{-} \overline{\nu}_{\mu} \nu_{\tau}$ with the NOMAD detector at CERN wideband neutrino beam

title: Study of $\eta-\eta^{\prime}$ mixing from measurement of $B^0_{(s)} \rightarrow J/\psi \eta^{(\prime)}$ decay rates
abstract: A study of $B^0$~and $B^0_s$ meson decays into $J/\psi\eta$~and $J/\psi\eta^{\prime}$ final states is performed using a data set of proton-proton collisions at centre-of-mass energies of 7 and 8TeV, collected by the LHCb experiment and corresponding to 3.0fb$^{-1}$ of integrated luminosity. The decay $B^0 \rightarrow J/\psi \eta^{\prime}$ is observed for thefirst time. The following ratios of branching fractions are measured: $$ \frac{\mathcal{B}(B^0 \rightarrow J/\psi \eta^{\prime})}{\mathcal{B}(B^0_s \rightarrow J/\psi \eta^{\prime})} = (2.28\pm0.65\,(stat)\,\pm0.10\,(syst)\,\pm0.13\,(f_{s}/f_{d}))\times10^{-2},$$ $$ \frac{\mathcal{B}(B^0 \rightarrow J/\psi \eta)}{\mathcal{B}(B^0_s \rightarrow J/\psi \eta)} = (1.85\pm0.61\,(stat)\,\pm0.09\,(syst)\,\pm0.11\,(f_{s}/f_{d}))\times10^{-2},$$ where the third uncertainty is related to the present knowledge of $f_{s}/f_{d}$, the ratio between the probabilities for a $b$ quark to form a $B^0_s$ or $B^0$ meson. The branching fraction ratios are used to determine the parameters of $\eta-\eta^{\prime}$ meson mixing. In addition, the first evidence for the decay $B^0_s \rightarrow \psi(2S) \eta^{\prime}$ is reported, and the relative branching fraction is measured, 
$$\frac{\mathcal{B}(B^0_s \rightarrow \psi(2S) \eta^{\prime})}{\mathcal{B}(B^0_s \rightarrow J/\psi \eta^{\prime})} = (38.7\pm9.0\,(stat)\,\pm1.3\,(syst)\,\pm0.9(\mathcal{B}))\times10^{-2},$$ 
where the third uncertainty is due to the limited knowledge of the branching fractions of $J/\psi$ and $\psi(2S)$~mesons.

title: Study of beauty hadron decays into pairs of charm hadrons
abstract: First observations of the decays Λb 0 → Λc +D(s) - are reported using data corresponding to an integrated luminosity of 3fb-1 collected at 7 and 8 TeV center-of-mass energies in proton-proton collisions with the LHCb detector. In addition, the most precise measurement of the branching fraction B(Bs 0→D+Ds -) is made and a search is performed for the decays B(s) 0→Λc +Λc -. The results obtained are B(Λb 0→Λc +D-)/ B(Λb 0→Λc +D s -)=0.042±0.003(stat)±0.003(syst), [B(Λb 0→Λc +D s -)/B(B0→D+D s -)]/[B(Λb 0→Λ c +π-)/B(B0→D +π-)]=0.96±0.02(stat)±0.06(syst),B(B s 0→D+Ds -)/ B(B0→D+Ds -)=0. 038±0.004(stat)±0.003(syst),B(B0→Λ c +Λc -)/B(B , B(Bs 0→Λc +Λ c -)/B(Bs 0→D+D s -)<0.30[95%C.L.]. Measurement of the mass of the Λb 0 baryon relative to the B0 meson gives M(Λb 0)-M(B0)=339. 72±0.24(stat)±0.18(syst)MeV/c2. This result provides the most precise measurement of the mass of the Λb 0 baryon to date.

title: Study of D*+ production in nu/mu charged current interactions in the NOMAD experiment
abstract: A search was made among ν μ charged current events collected in the NOMAD experiment for the reaction: ν μ +N→μ − +D ★+ + hadrons ↪ D 0 +π + ↪ K − +π + . A high purity D ★+ sample composed of 35 events was extracted. The D ★+ yield in ν μ charged current interactions was measured to be T =(0.79±0.17(stat.)±0.10(syst.))%. The mean fraction of the hadronic jet energy taken by the D ★+ is 0.67±0.02(stat.)±0.02(syst.). The distributions of the fragmentation variables z, P T 2 and x F for D ★+ are also presented.

title: Searches for Majorana neutrinos in $B^-$ decays
abstract: 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.

title: Time resolution limits of the MWPCs for the LHCb muon system
abstract: Detailed simulations of the timing properties of the Multi-Wire-Proportional-Chambers of the LHCb muon system are compared with actual measurements. The simulated time resolution is in good agreement with the measurement which allows to study the resolution limiting parameters like diffusion, charge deposit fluctuations, cluster position fluctuations, electronics noise, track position and wire spacing to show how they affect the performance of the system. Methods to improve the time resolution of the muon chambers are discussed.

title: The Afterglow and Host Galaxy of the Energetic Short-Hard Gamma-Ray Burst 051221
abstract: We present detailed optical, X-ray and radio observations of the bright afterglow of the short gammaray burst 051221 obtained with Gemini, Swift/XRT, and the Very Large Array, as well as an optical spectrum from which we measure the redshift of the burst, z = 0.5459. At this redshift the isotropicequivalent prompt energy release was about 2.4×10 erg, and using the standard afterglow synchrotron model we find that the blastwave kinetic energy is similar, EKE,iso ≈ 1.4 × 10 51 erg. The lack of an observed jet break to t ≈ 13 days indicates that the opening angle is θj ∼> 13 ◦ and the total beamingcorrected energy is ∼> 1 × 10 50 erg, at least an order of magnitude larger than for previous short GRBs. We further show that the burst experienced an episode of energy injection by a factor of 3.4 between t = 1.4 and 3.4 hours, which was accompanied by reverse shock emission in the radio band. This result provides continued evidence that the central engines of short GRBs may be active significantly longer than the duration of the burst and/or produce a wide range of Lorentz factors. Finally, we show that the host galaxy of GRB051221 is actively forming stars at a rate of about 1.5 M⊙ yr , but at the same time exhibits evidence for an appreciable population of old stars (∼ 1 Gyr) and near solar metallicity. These properties are intermediate between those of long GRB hosts and those of previous short bursts suggesting that the progenitor lifetimes may have a large spread. The lack of bright supernova emission and the low circumburst density (n ∼ 10 cm), however, continue to support the idea that short bursts are not related to the death of massive stars and are instead consistent with a compact object merger. If the energy release of this burst is in fact few × 10 erg then this suggests that the neutrino annihilation mechanism may not be sufficient and magnetohydrodynamic processes may be required to power the burst.

title: Performance of the multianode cylindrical silicon drift detector in the CERES NA45 experiment: first results☆
abstract: A silicon drift detector of circular geometry giving unambiguously the radial and azimuthal coordinates of particle's interaction point for events with high multiplicity is part of the experimental set up of the NA45 experiment at CERN SPS. The paper reviews the characteristics of the detector and of its assembly among the other detectors of the experiment. The first experimental results showing the performance of the detector in term of resolution and its effectiveness in reconstructing the position of the event are reported.

title: A NEARLY POLAR ORBIT FOR THE EXTRASOLAR HOT JUPITER WASP-79b
abstract: We report the measurement of a spin-orbit misalignment for WASP-79b, a recently discovered, bloated hot Jupiter from the Wide Angle Search for Planets (WASP) survey. Data were obtained using the CYCLOPS2 optical-fiber bundle and its simultaneous calibration system feeding the UCLES spectrograph on the Anglo-Australian Telescope. We have used the Rossiter-McLaughlin effect to determine the sky-projected spin-orbit angle to be . This result indicates a significant misalignment between the spin axis of the host star and the orbital plane of the planet?the planet being in a nearly polar orbit. WASP-79 is consistent with other stars that have T eff > 6250?K and host hot Jupiters in spin-orbit misalignment.

title: Measurement of D0, D+, Ds+ and D*+ production in fixed target 920 GeV proton–nucleus collisions
abstract: The inclusive production cross sections of the charmed mesons D0,D+,Ds+ and D*+ have been measured in interactions of 920 GeV protons on C, Ti, and W targets with the HERA-B detector at the HERA storage ring. Differential cross sections as a function of transverse momentum and Feynman’s x variable are given for the central rapidity region and for transverse momenta up to pT=3.5 GeV/c. The atomic mass number dependence and the leading to non-leading particle production asymmetries are presented as well.

title: Constraints on Cosmological Models from Hubble Space Telescope Observations of High-z Supernovae
abstract: We have coordinated Hubble Space Telescope (HST) photometry with ground-based discovery for three supernovae: Type Ia supernovae near z ≈ 0.5 (SN 1997ce, SN 1997cj) and a third event at z = 0.97 (SN 1997ck). The superb spatial resolution of HST separates each supernova from its host galaxy and leads to good precision in the light curves. We use these light curves and relations between luminosity, light-curve shape, and color calibrated from low-z samples to derive relative luminosity distances that are accurate to 10% at z ≈ 0.5 and 20% at z = 1. When the HST sample is combined with the distance to SN 1995K (z = 0.48), analyzed by the same precepts, we find that matter alone is insufficient to produce a flat universe. Specifically, for Ωm+ΩΛ = 1, Ωm is less than 1 with more than 95% confidence, and our best estimate of Ωm is -0.1±0.5 if ΩΛ = 0. Although this result is based on a very small sample whose systematics remain to be explored, it demonstrates the power of HST measurements for high-redshift supernovae.