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Silicon photonics meets the electronics requirement of increased speed and bandwidth with on-chip optical networks. All-optical data management requires nonlinear silicon photonics. In silicon only third-order optical nonlinearities are present owing to its crystalline inversion symmetry. Introducing a second-order nonlinearity into silicon photonics by proper material engineering would be highly desirable. It would enable devices for wideband wavelength conversion operating at relatively low optical powers. Here we show that a sizeable second-order nonlinearity at optical wavelengths is induced in a silicon waveguide by using a stressing silicon nitride overlayer. We carried out second-harmonic-generation experiments and first-principle calculations, which both yield large values of strain-induced bulk second-order nonlinear susceptibility, up to 40 pm V −1 at 2,300 nm. We envisage that nonlinear strained silicon could provide a competing platform for a new class of integrated light sources spanning the near- to mid-infrared spectrum from 1.2 to 10 μm. Photonic devices on silicon offer the benefit of combining advanced electronic functionality with the high bandwidth of silicon photonics. Now, efficient second-order nonlinear activity in silicon waveguides strained by a silicon nitride top layer considerably advances the potential of all-optical data management on a silicon platform.

A bstract Measurements are reported of the central exclusive production of J/ψ and ψ (2 S ) mesons in pp collisions at a centre-of-mass energy of 13 TeV. Backgrounds are significantly reduced compared to previous measurements made at lower energies through the use of new forward shower counters. The products of the cross-sections and the branching fractions for the decays to dimuons, where both muons are within the pseudorapidity range 2 . 0 < η < 4 . 5, are measured to be σ J / ψ → μ + μ − = 435 ± 18 ± 11 ± 17 p b σ ψ 2 S → μ + μ − = 11.1 ± 1.1 ± 0.3 ± 0.4 p b . The first uncertainties are statistical, the second are systematic, and the third are due to the luminosity determination. The cross-sections are also measured differentially for meson rapidities between 2.0 and 4.5. Good agreement is observed with theoretical predictions. Photoproduction cross-sections are derived and compared to previous experiments, and a deviation from a pure power-law extrapolation of lower energy data is observed.

A bstract Production cross-sections of prompt charm mesons are measured using data from pp collisions at the LHC at a centre-of-mass energy of 5 TeV. The data sample corresponds to an integrated luminosity of 8 . 60 ± 0 . 33 pb −1 collected by the LHCb experiment. The production cross-sections of D 0 , D + , D s + , and D ∗+ mesons are measured in bins of charm meson transverse momentum, p T , and rapidity, y . They cover the rapidity range 2 . 0 < y < 4 . 5 and transverse momentum ranges 0 < p T < 10 GeV /c for D 0 and D + and 1 < p T < 10 GeV /c for D s + and D ∗+ mesons. The inclusive cross-sections for the four mesons, including charge-conjugate states, within the range of 1 < p T < 8 GeV /c are determined to be σ pp → D 0 X = 1004 ± 3 ± 54 μ b , σ pp → D + X = 402 ± 2 ± 30 μ b , σ pp → D s + X = 170 ± 4 ± 16 μ b , σ pp → D ∗ + X = 421 ± 5 ± 36 μ b , where the uncertainties are statistical and systematic, respectively.

The SuperB experiment needs large samples of MonteCarlo simulated events in order to finalize the detector design and to estimate the data analysis performances. The requirements are beyond the capabilities of a single computing farm, so a distributed production model capable of exploiting the existing HEP worldwide distributed computing infrastructure is needed. In this paper we describe the set of tools that have been developed to manage the production of the required simulated events. The production of events follows three main phases: distribution of input data files to the remote site Storage Elements (SE); job submission, via SuperB GANGA interface, to all available remote sites; output files transfer to CNAF repository. The job workflow includes procedures for consistency checking, monitoring, data handling and bookkeeping. A replication mechanism allows storing the job output on the local site SE. Results from 2010 official productions are reported.

The next generation of Super Flavor Factories, like SuperB and SuperKEKB, present significant computing challenges. Extrapolating the BaBar and Belle experience to the SuperB nominal luminosity of 1036 cm−2s−1, we estimate that the data size collected after a few years of operation is 200 PB and the amount of CPU required to process them of the order of 2000 KHep-Spec06. Already in the current phase of detector design, the amount of simulated events needed for estimating the impact on very rare benchmark channels is huge and has required the development of new simulation tools and the deployment of a worldwide production distributed system. With the collider is in operation, very large data set have to be managed and new technologies with potential large impact on the computational models, like the many core CPUs, need to be effectively exploited. In addition SuperB, like the LHC experiments, will have to make use of distributed computing resources accessible via the Grid infrastructures while providing an efficient and reliable data access model to its final users. To explore the key issues, a dedicated R&D program has been launched and is now in progress. A description of the R&D goals and the status of ongoing activities is presented.

A bstract The production of B ± mesons is studied in pp collisions at centre-of-mass energies of 7 and 13 TeV, using B ± → J / ψ K ± decays and data samples corresponding to 1.0 fb −1 and 0.3 fb −1 , respectively. The production cross-sections summed over both charges and integrated over the transverse momentum range 0 < p T < 40 GeV/ c and the rapidity range 2.0 < y < 4.5 are measured to be σ pp → B ± X , s = 7 T e V = 43.0 ± 0.2 ± 2.5 ± 1.7 μ b , σ pp → B ± X , s = 13 T e V = 86.6 ± 0.5 ± 5.4 ± 3.4 μ b , where the first uncertainties are statistical, the second are systematic, and the third are due to the limited knowledge of the B ± → J / ψ K ± branching fraction. The ratio of the cross-section at 13 TeV to that at 7 TeV is determined to be 2.02 ± 0.02 (stat) ± 0.12 (syst). Differential cross-sections are also reported as functions of p T and y . All results are in agreement with theoretical calculations based on the state-of-art fixed next-to-leading order quantum chromodynamics.

A bstract This paper presents an analysis of the Λ b 0 → J/ψ Λ angular distribution and the transverse production polarisation of Λ b 0 baryons in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The measurements are performed using data corresponding to an integrated luminosity of 4.9 fb − 1 , collected with the LHCb experiment. The polarisation is determined in a fiducial region of Λ b 0 transverse momentum and pseudorapidity of 1 < p T < 20 GeV/ c and 2 < η < 5, respectively. The data are consistent with Λ b 0 baryons being produced unpolarised in this region. The parity-violating asymmetry parameter of the Λ → pπ − decay is also determined from the data and its value is found to be consistent with a recent measurement by the BES III collaboration.

A bstract The production cross-sections of ϒ (1 S ), ϒ (2 S ) and ϒ (3 S ) mesons in proton-proton collisions at s = 13 TeV are measured with a data sample corresponding to an integrated luminosity of 277 ± 11 pb −1 recorded by the LHCb experiment in 2015. The ϒ mesons are reconstructed in the decay mode ϒ → μ + μ − . The differential production cross-sections times the dimuon branching fractions are measured as a function of the ϒ transverse momentum, p T , and rapidity, y , over the range 0 < p T < 30 GeV /c and 2 . 0 < y < 4 . 5. The ratios of the cross-sections with respect to the LHCb measurement at s = 8 TeV are also determined. The measurements are compared with theoretical predictions based on NRQCD.

A bstract Forward top quark pair production is studied in pp collisions in the μeb final state using a data sample corresponding to an integrated luminosity of 1.93 fb −1 collected with the LHCb experiment at a centre-of-mass energy of 13 TeV. The cross-section is measured in a fiducial region where both leptons have a transverse momentum greater than 20 GeV and a pseudorapidity between 2.0 and 4.5. The quadrature sum of the azimuthal separation and the difference in pseudorapidities, denoted Δ R , between the two leptons must be larger than 0.1. The b -jet axis is required to be separated from both leptons by a Δ R of 0.5, and to have a transverse momentum in excess of 20 GeV and a pseudorapidity between 2.2 and 4.2. The cross-section is measured to be σ t t ¯ = 126 ± 19 stat ± 16 syst ± 5 lumi f b where the first uncertainty is statistical, the second is systematic, and the third is due to the luminosity determination. The measurement is compatible with the Standard Model prediction.

A job submission and management tool is one of the necessary components in any distributed computing system. Such a tool should provide a user-friendly interface for physics production groups and ordinary analysis users to access heterogeneous computing resources, without requiring knowledge of the underlying grid middleware. Ganga, with its common framework and customizable plug-in structure is such a tool. This paper will describe how experiment-specific job management tools for BESIII and SuperB were developed as Ganga plug-ins to meet their own unique requirements, discuss and contrast their challenges met and lessons learned.