RD50-MPW3: A fully monolithic digital CMOS sensor for future tracking detectors

The CERN-RD50 CMOS working group develops the RD50-MPWseries of monolithic high-voltage CMOS pixel sensors for potential use in future high luminosity experiments such as the HL-LHC and FCC-hh. In this contribution, the design of the latest prototype in this series, RD50-MPW3, is presented. An overview of its pixel matrix and digital readout periphery is given, with discussion of the new structures implemented in the chip and the problems they aim to solve. The main analog and digital features of the sensor are already tested and initial laboratory characterisation of the chip is presented

Dalitz plot analysis of B0→D¯0π+π- decays

The resonant substructures of B0 → D0π +π − decays are studied with the Dalitz plot technique. In this study a data sample corresponding to an integrated luminosity of 3.0 fb−1 of pp collisions collected by the LHCb detector is used. The branching fraction of the B0 → D0π +π − decay in the region m(D0π ±) > 2.1 GeV/c2 is measured to be (8.46 ± 0.14 ± 0.29 ± 0.40) × 10−4 , where the first uncertainty is statistical, the second is systematic and the last arises from the normalisation channel B0 → D∗ (2010)−π +. The π +π − S-wave components are modelled with the Isobar and K-matrix formalisms. Results of the Dalitz plot analyses using both models are presented. A resonant structure at m(D0π −) ≈ 2.8 GeV/c2 is confirmed and its spin-parity is determined for the first time as J P = 3−. The branching fraction, mass and width of this structure are determined together with those of the D∗ 0 (2400)− and D∗ 2 (2460)− resonances. The branching fractions of other B0 → D0h 0 decay components with h 0 → π +π − are also reported. Many of these branching fraction measurements are the most precise to date. The first observation of the decays B0 → D0f0(500), B0 → D0f0(980), B0 → D0ρ(1450), B0 → D∗ 3 (2760)−π + and the first evidence of B0 → D0f0(2020) are presented

Measurement of the time-dependent CP asymmetries in B {s/0} → J/ ψK {S/0}

The first measurement of decay-time-dependent CP asymmetries in the decay B0 s → J/ψ K0 S and an updated measurement of the ratio of branching fractions B(B0 s → J/ψ K0 S )/B(B0→ J/ψ K0 S ) are presented. The results are obtained using data corresponding to an integrated luminosity of 3.0 fb−1 of proton-proton collisions recorded with the LHCb detector at centre-of-mass energies of 7 and 8 TeV. The results on the CP asymmetries are A∆Γ B 0 s → J/ψ K0 S = 0.49 ± 0.77 0.65 (stat) ± 0.06 (syst) , Cdir B 0 s → J/ψ K0 S = −0.28 ± 0.41 (stat) ± 0.08 (syst) , Smix B 0 s → J/ψ K0 S = −0.08 ± 0.40 (stat) ± 0.08 (syst) . The ratio B(B0 s → J/ψ K0 S )/B(B0→ J/ψ K0 S ) is measured to be 0.0431 ± 0.0017 (stat) ± 0.0012 (syst) ± 0.0025 (fs/fd) , where the last uncertainty is due to the knowledge of the B0 s and B0 production fracti

Determination of the branching fractions of B S 0 → D S ∓ K ∓ and B 0 → D S − K +

B0 → D− s K+ relative to the decays B0 s → D− s π + and B0 → D−π +, respectively. The data used correspond to an integrated luminosity of 3.0 fb−1 of proton-proton collisions. The ratios of branching fractions are B(B0 s → D∓ s K∓) B(B0 s → D − s π+) = 0.0752 ± 0.0015 ± 0.0019 and B(B0 → D− s K+) B(B0 → D−π+) = 0.0129 ± 0.0005 ± 0.0008, where the uncertainties are statistical and systematic, respectively. Keywords: Hadron-Hadron Scattering, Branching fraction, B physics, Flavor physic

Search for lepton-flavor violating decays B+ →k+μ±eâ'

A search for the lepton-flavor violating decays B+→K+μ±eâ' is performed using a sample of proton-proton collision data, collected with the LHCb experiment at center-of-mass energies of 7 and 8 TeV and corresponding to an integrated luminosity of 3 fb-1. No significant signal is observed, and upper limits on the branching fractions are set as B(B+→K+μ-e+)<7.0(9.5)×10-9 and B(B+→K+μ+e-)<6.4(8.8)×10-9 at 90% (95)% confidence level. The results improve the current best limits on these decays by more than one order of magnitud

Measurement of the exclusive Υ production cross-section in pp collisions at √{s}=7 TeV and 8 TeV

A study is presented of central exclusive production of Υ(nS) states, where the Υ(nS) resonances decay to the µ +µ − final state, using pp collision data recorded by the LHCb experiment. The cross-section is measured in the rapidity range 2 < y(Υ) < 4.5 where the muons are reconstructed in the pseudorapidity range 2 < η(µ ±) < 4.5. The data sample corresponds to an integrated luminosity of 2.9 fb−1 and was collected at centre-of-mass energies of 7 TeV and 8 TeV. The measured Υ(1S) and Υ(2S) production cross-sections are σ(pp → pΥ(1S)p) = 9.0 ± 2.1 ± 1.7 pb and σ(pp → pΥ(2S)p) = 1.3 ± 0.8 ± 0.3 pb, where the first uncertainties are statistical and the second are systematic. The Υ(1S) cross-section is also measured as a function of rapidity and is found to be in good agreement with Standard Model predictions. An upper limit is set at 3.4 pb at the 95% confidence level for the exclusive Υ(3S) production cross-section, including possible contamination from χb(3P) → Υ(3S)γ decays

Measurement of the forward Z boson production cross-section in pp collisions at TeV

A measurement of the production cross-section for Z bosons that decay to muons is presented. The data were recorded by the LHCb detector during pp collisions at a centre-of-mass energy of 7 TeV, and correspond to an integrated luminosity of 1.0 fb−1 . The cross-section is measured for muons in the pseudorapidity range 2.0 20 GeV/c. The dimuon mass is restricted to 60 < Mµ+µ− < 120 GeV/c2 . The measured cross-section is σZ→µ+µ− = (76.0 ± 0.3 ± 0.5 ± 1.0 ± 1.3) pb where the uncertainties are due to the sample size, systematic effects, the beam energy and the luminosity. This result is in good agreement with theoretical predictions at next-to-next-to-leading order in perturbative quantum chromodynamics. The cross-section is also measured differentially as a function of kinematic variables of the Z boson. Ratios of the production cross-sections of electroweak bosons are presented using updated LHCb measurements of W boson production. A precise test of the Standard Model is provided by the measurement of the rati

Identification of beauty and charm quark jets at LHCb

Identification of jets originating from beauty and charm quarks is important for measuring Standard Model processes and for searching for new physics. The performance of algorithms developed to select b- and c-quark jets is measured using data recorded by LHCb from proton-proton collisions at √s = 7 TeV in 2011 and at √s = 8 TeV in 2012. The efficiency for identifying a b(c) jet is about 65%(25%) with a probability for misidentifying a light-parton jet of 0.3% for jets with transverse momentum pT > 20GeV and pseudorapidity 2.2 < η < 4.2. The dependence of the performance on the pT and η of the jet is also measured

Measurement of CP Violation in B0→J/ψK0S Decays

Measurements are presented of the C P violation observables S and C in the decays of B 0 and ¯ B 0 mesons to the J / ψ K 0 S final state. The data sample corresponds to an integrated luminosity of 3.0     fb − 1 collected with the LHCb experiment in proton-proton collisions at center-of-mass energies of 7 and 8 TeV, and contains a total of 41 560 selected B 0 and ¯ B 0 decays. The analysis of the time evolution of these decays yields S = 0.731 ± 0.035 ( stat ) ± 0.020 ( syst ) and C = − 0.038 ± 0.032 ( stat ) ± 0.005 ( syst ) . In the standard model, S equals sin ( 2 β ) to a good level of precision. The values are consistent with the current world averages and with the standard model expectations

Observation of two new Ξb- Baryon resonances

Two structures are observed close to the kinematic threshold in the Ξ 0 b π − mass spectrum in a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0     fb − 1 , recorded by the LHCb experiment. In the quark model, two baryonic resonances with quark content b d s are expected in this mass region: the spin-parity J P = ( 1 / 2 ) + and J P = ( 3 / 2 ) + states, denoted Ξ ' − b and Ξ * − b . Interpreting the structures as these resonances, we measure the mass differences and the width of the heavier state to be m ( Ξ ' − b ) − m ( Ξ 0 b ) − m ( π − ) = 3.653 ± 0.018 ± 0.006     MeV / c 2 , m ( Ξ * − b ) − m ( Ξ 0 b ) − m ( π − ) = 23.96 ± 0.12 ± 0.06     MeV / c 2 , Γ ( Ξ * − b ) = 1.65 ± 0.31 ± 0.10     MeV , where the first and second uncertainties are statistical and systematic, respectively. The width of the lighter state is consistent with zero, and we place an upper limit of Γ ( Ξ ' − b ) < 0.08     MeV at 95% confidence level. Relative production rates of these states are also reported