Coherent production of J/ψ mesons is studied in lead-lead collision data at a nucleon-nucleon centre-of-mass energy of 5 TeV collected by the LHCb experiment. The data set corresponds to an ...integrated luminosity of about 10μb−1. The J/ψ mesons are reconstructed in the dimuon final state, where the muons are detected within the pseudorapidity region 2.0 <η < 4.5. The J/ψ mesons are required to have transverse momentum pT < 1 GeV and rapidity 2.0 <y < 4.5. The cross-section within this fiducial region is measured to be σ = 5.3 ± 0.2 (stat) ± 0.5 (syst) ± 0.7 (lumi) mb. The differential cross-section is also measured in five bins of J/ψ rapidity. The results are compared to predictions from phenomenological models.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper presents the techniques used to monitor radiation damage in the LHCb Tracker Turicensis during the LHC Runs 1 and 2. Bulk leakage currents in the silicon sensors were monitored ...continuously, while the full depletion voltages of the sensors were estimated at regular intervals by performing dedicated scans of the charge collection efficiency as a function of the applied bias voltage. Predictions of the expected leakage currents and full depletion voltages are extracted from the simulated radiation profile, the luminosity delivered by the LHC, and the thermal history of the silicon sensors. Good agreement between measurements and predictions is found.
The Experiment Control System (ECS) of the LHCb Silicon Tracker sub-detectors is built on the integrated LHCb ECS framework. Although all LHCb sub-detectors use the same framework and follow the same ...guidelines, the Silicon Tracker control system uses some interesting additional features for operation and monitoring. The main details are described in this document. Since its design, the Silicon Tracker control system has been continuously evolving in a quite disorganized way. Some major maintenance activities are required in order to keep improving it. A description of those activities can also be found here.
A search for the decays Bs-->mumu and Bd-->mumu is performed with about 37 pb^{-1} of pp collisions at sqrt{s} = 7 TeV collected by the LHCb experiment at the Large Hadron Collider at CERN. The ...observed numbers of events are consistent with the background expectations. The resulting upper limits on the branching ratios are BR(Bs-->mumu) < 5.6 x 10^{-8} and BR(Bd-->mumu) <1.5 x 10^{-8} at 95% confidence level.
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GEOZS, IJS, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UPCLJ, UPUK
The Large Hadron Collider beauty experiment (LHCb) is a single-arm forward spectrometer dedicated to the study of B-meson decays in p - p collisions at the Large Hadron Collider (LHC). The LHCb ...detector has excellent tracking and particle identification capabilities. The LHCb Silicon Tracker (ST) is composed of two silicon micro-strip detectors with long readout strips. The performance of these two detectors with the first high energy p - p collisions are presented here. A detailed study of the detectors intrinsic resolution and efficiency has been performed along with precise time alignment using collision data. The latest Silicon Tracker performance results and comparison to expectations are presented.
This paper presents the techniques used to monitor radiation damage in the LHCb Tracker Turicensis during the LHC Runs 1 and 2. Bulk leakage currents in the silicon sensors were monitored ...continuously, while the full depletion voltages of the sensors were estimated at regular intervals by performing dedicated scans of the charge collection efficiency as a function of the applied bias voltage. Predictions of the expected leakage currents and full depletion voltages are extracted from the simulated radiation profile, the luminosity delivered by the LHC, and the thermal history of the silicon sensors. Good agreement between measurements and predictions is found.
Journal of High Energy Physics 04 (2019) 063 The resonant structure of the doubly Cabibbo-suppressed decay $D^+ \to
K^-K^+K^+$ is studied for the first time. The measurement is based on a sample
of ...pp-collision data, collected at a centre-of-mass energy of 8 TeV with the
LHCb detector and corresponding to an integrated luminosity of 2 fb$^-1$. The
amplitude analysis of this decay is performed with the isobar model and a
phenomenological model based on an effective chiral Lagrangian. In both models
the S-wave component in the $K^-K^+$ system is dominant, with a small
contribution of the $\phi(1020)$ meson and a negligible contribution from
tensor resonances. The $K^-K^+$ scattering amplitudes for the considered
combinations of spin (0,1) and isospin (0,1) of the two-body system are
obtained from the Dalitz plot fit with the phenomenological decay amplitude.
The resonant structure of the doubly Cabibbo-suppressed decay \(D^+ \to K^-K^+K^+\) is studied for the first time. The measurement is based on a sample of pp-collision data, collected at a ...centre-of-mass energy of 8 TeV with the LHCb detector and corresponding to an integrated luminosity of 2 fb\(^-1\). The amplitude analysis of this decay is performed with the isobar model and a phenomenological model based on an effective chiral Lagrangian. In both models the S-wave component in the \(K^-K^+\) system is dominant, with a small contribution of the \(\phi(1020)\) meson and a negligible contribution from tensor resonances. The \(K^-K^+\) scattering amplitudes for the considered combinations of spin (0,1) and isospin (0,1) of the two-body system are obtained from the Dalitz plot fit with the phenomenological decay amplitude.
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