Observation of the suppressed ADS modes B± →[π±K∓π+π-] D K± and B± →[π±K∓π+π-] Dπ±

An analysis of B± → DK± and B± → Dπ± decays is presented where the D meson is reconstructed in the four-body nal state K±π∓π+π-. Using LHCb data corresponding to an integrated luminosity of 1.0 fb-1, rst observations are made of the suppressed ADS modes B± →[π±K∓π+π-] D K± and B± → [π±K∓π+π-]Dπ± with a signicance of 5.1σ and greater than 10σ, respectively. Measurements of CP asymmetries and CP-conserving ratios of partial widths from this family of decays are also performed. The magnitude of the ratio between the suppressed and favoured B± → DK± amplitudes is determined to be rK B = 0.097±0.011. © CERN for the benet of the LHCb Collaboration

LHCb detector performance

The LHCb detector is a forward spectrometer at the Large Hadron Collider (LHC) at CERN. The experiment is designed for precision measurements of CP violation and rare decays of beauty and charm hadrons. In this paper the performance of the various LHCb sub-detectors and the trigger system are described, using data taken from 2010 to 2012. It is shown that the design criteria of the experiment have been met. The excellent performance of the detector has allowed the LHCb collaboration to publish a wide range of physics results, demonstrating LHCb's unique role, both as a heavy flavour experiment and as a general purpose detector in the forward region

Observation of the suppressed ADS modes B± →[π±K∓π+π-] D K± and B± →[π±K∓π+π-] Dπ±

An analysis of B± → DK± and B± → Dπ± decays is presented where the D meson is reconstructed in the four-body nal state K±π∓π+π-. Using LHCb data corresponding to an integrated luminosity of 1.0 fb-1, rst observations are made of the suppressed ADS modes B± →[π±K∓π+π-] D K± and B± → [π±K∓π+π-]Dπ± with a signicance of 5.1σ and greater than 10σ, respectively. Measurements of CP asymmetries and CP-conserving ratios of partial widths from this family of decays are also performed. The magnitude of the ratio between the suppressed and favoured B± → DK± amplitudes is determined to be rK B = 0.097±0.011. © CERN for the benet of the LHCb Collaboration

Measurement of the B ± production cross-section in pp collisions at √s = 7 TeV

The production of B ± mesons in proton-proton collisions at √s = 7TeVis studied using 35 pb -1 of data collected by the LHCb detector. The B ± mesons are reconstructed exclusively in the B ± → J/ΨK ± mode, with J/Ψ→μ +μ -. The differential production cross-section is measured as a function of the B ± transverse momentum in the ducial region 0 < pT < 40 GeV=c and with rapidity 2:0 < y < 4:5. The total cross-section, summing up B + and B -, is measured to be σ(pp → B ±X; 0 < pT < 40 GeV=c; 2:0 < y < 4:5) = 41:4 ± 1:5 (stat:) ± 3:1 (syst:) μb. Copyright CERN

Measurement of CP violation in the B-s(0)-> phi phi decay and search for the B-0 -> phi phi decay

A measurement of the time-dependent CP-violating asymmetry in B0s→ϕϕ decays is presented. Using a sample of proton-proton collision data corresponding to an integrated luminosity of 5.0 fb−1 collected by the LHCb experiment at centre-of-mass energies s√ = 7 TeV in 2011, 8 TeV in 2012 and 13 TeV in 2015 and 2016, a signal yield of around 9000 B0s→ϕϕ decays is obtained. The CP-violating phase ϕss¯¯¯ss is measured to be −0.073 ± 0.115(stat) ± 0.027(syst) rad, under the assumption it is independent of the helicity of the ϕϕ decay. In addition, the CP-violating phases of the transverse polarisations under the assumption of CP conservation of the longitudinal phase are measured. The helicity-independent direct CP-violation parameter is also measured, and is found to be |λ| = 0.99 ± 0.05(stat) ± 0.01(syst). In addition, T-odd triple-product asymmetries are measured. The results obtained are consistent with the hypothesis of CP conservation in b¯¯→s¯¯¯ss¯¯¯s transitions. Finally, a limit on the branching fraction of the B0 → ϕϕ decay is determined to be B(B0→ϕϕ)<2.7×10−8 at 90 % confidence level