We present the results of an R&D study for a specialized processor capable of precisely reconstructing events with hundreds of charged-particle tracks in pixel and silicon strip detectors at $40,rm MHz$, thus suitable for processing LHC events at the
full crossing frequency. For this purpose we design and test a massively parallel pattern-recognition algorithm, inspired to the current understanding of the mechanisms adopted by the primary visual cortex of mammals in the early stages of visual-information processing. The detailed geometry and charged-particles activity of a large tracking detector are simulated and used to assess the performance of the artificial retina algorithm. We find that high-quality tracking in large detectors is possible with sub-microsecond latencies when the algorithm is implemented in modern, high-speed, high-bandwidth FPGA devices.
We report on the R&D for a first prototype of a silicon tracker based on an alternative approach for fast track finding. The working principle is inspired from neurobiology, in particular by the processing of visual images by the brain as it happens
in nature. It is based on extensive parallelisation of data distribution and pattern recognition. In this work we present the design of a practical device that consists of a telescope based on single-sided silicon detectors; we describe the data acquisition system and the implementation of the track finding algorithms using available digital logic of commercial FPGA devices. Tracking performance and trigger capabilities of the device are discussed along with perspectives for future applications.
We present results of an R&D study for a specialized processor capable of precisely reconstructing, in pixel detectors, hundreds of charged-particle tracks from high-energy collisions at 40 MHz rate. We apply a highly parallel pattern-recognition alg
orithm, inspired by studies of the processing of visual images by the brain as it happens in nature, and describe in detail an efficient hardware implementation in high-speed, high-bandwidth FPGA devices. This is the first detailed demonstration of reconstruction of offline-quality tracks at 40 MHz and makes the device suitable for processing Large Hadron Collider events at the full crossing frequency.
We present the results of a detailed simulation of the artificial retina pattern-recognition algorithm, designed to reconstruct events with hundreds of charged-particle tracks in pixel and silicon detectors at LHCb with LHC crossing frequency of $40,
rm MHz$. Performances of the artificial retina algorithm are assessed using the official Monte Carlo samples of the LHCb experiment. We found performances for the retina pattern-recognition algorithm comparable with the full LHCb reconstruction algorithm.
We present the results of an R&D study of a specialized processor capable of precisely reconstructing events with hundreds of charged-particle tracks in pixel detectors at 40 MHz, thus suitable for processing LHC events at the full crossing frequency
. For this purpose we design and test a massively parallel pattern-recognition algorithm, inspired by studies of the processing of visual images by the brain as it happens in nature. We find that high-quality tracking in large detectors is possible with sub-$mu$s latencies when this algorithm is implemented in modern, high-speed, high-bandwidth FPGA devices. This opens a possibility of making track reconstruction happen transparently as part of the detector readout.
First observations of the decays $Lambda_b^0 to Lambda_c^+ D_{(s)}^-$ are reported using data corresponding to an integrated luminosity of $3,{rm fb}^{-1}$ collected at 7 and 8 TeV center-of-mass energy in proton-proton collisions with the LHCb detec
tor. In addition, the most precise measurement of the branching fraction ${mathcal{B}(B_s^0 to D^+D_s^-)}$ is made and a search is performed for the decays $B^0_{(s)} to Lambda_c^+ Lambda_c^-$. The results obtained are begin{eqnarray*} mathcal{B}(Lambda_b^0 to Lambda_c^+ D^-)/mathcal{B}(Lambda_b^0 to Lambda_c^+ D_{s}^-) &=& 0.042 pm 0.003({rm stat}) pm 0.003({rm syst}), left[frac{mathcal{B}(Lambda_b^0 to Lambda_c^+ D_{s}^-)}{mathcal{B}({kern 0.2em}overline{kern -0.2em B}_d^0 to D^+D_s^-)}right]big/left[frac{mathcal{B}(Lambda_b^0 to Lambda_c^+pi^-)}{mathcal{B}({kern 0.2em}overline{kern -0.2em B}_d^0 to D^+pi^-)}right] &=& 0.96 pm 0.02({rm stat}) pm 0.06({rm syst}), mathcal{B}(B_s^0 to D^+D_s^-)/mathcal{B}({kern 0.2em}overline{kern -0.2em B}_d^0 to D^+D_s^-) &=& 0.038pm0.004({rm stat})pm0.003({rm syst}), mathcal{B}({kern 0.2em}overline{kern -0.2em B}^0 to Lambda_c^+ Lambda_c^-)/mathcal{B}({kern 0.2em}overline{kern -0.2em B}_d^0 to D^+D_s^-) & < & 0.0022; [95% ; {rm C.L.}], mathcal{B}(B^0_{s} to Lambda_c^+ Lambda_c^-)/mathcal{B}(B_s^0 to D^+D_s^-) & < & 0.30; [95% ; {rm C.L.}]. end{eqnarray*} Measurement of the mass of the $Lambda_b^0$ baryon relative to the $B^0$ meson gives ${M(Lambda_b^0) -M(B^0) = 339.72pm 0.24({rm stat}) pm 0.18({rm syst})}$ MeV$/c^2$. This result provides the most precise measurement of the mass of the $Lambda_b^0$ baryon to date.
An angular analysis of the decay $B^0 to phi K^*(892)^0$ is reported based on a $pp$ collision data sample, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected at a centre-of-mass energy of $sqrt{s} = 7$ TeV with the LHCb detector.
The P-wave amplitudes and phases are measured with a greater precision than by previous experiments, and confirm about equal amounts of longitudinal and transverse polarization. The S-wave $K^+ pi^-$ and $K^+K^-$ contributions are taken into account and found to be significant. A comparison of the $B^0 to phi K^*(892)^0$ and $bar{B}^0 to phi bar{K}^*(892)^0$ results shows no evidence for direct CP violation in the rate asymmetry, in the triple-product asymmetries or in the polarization amplitudes and phases.
