Study of a Solution with COTS for the LHCb Calorimeter Upgrade

AbstractWe present a solution made out of Components Out of Shelf (COTS) for the analog processing of the signal of the LHCb calorimeters in the framework of the foreseen upgrade of the detector. The present proposal is based on the current functional solution, yet, to meet the stringent noise requirements, a number of modifications are proposed. Preliminary results on the prototype boards show promising results

First measurement of the CP-violating phase in B0s→J/ψ( →e+e−)ϕ decays

A flavour-tagged time-dependent angular analysis of B0s→J/ψϕ decays is presented where the J/ψJ/ψ meson is reconstructed through its decay to an e+e− pair. The analysis uses a sample of pp collision data recorded with the LHCb experiment at centre-of-mass energies of 7 and 8\,Te V, corresponding to an integrated luminosity of 3\,fb−1. The CP-violating phase and lifetime parameters of the B0s system are measured to be ϕs=0.00±0.28±0.07\,rad, ΔΓs=0.115±0.045±0.011\,ps−1 and Γs=0.608±0.018±0.012\,ps−1 where the first uncertainty is statistical and the second systematic. This is the first time that CP-violating parameters are measured in the B0s→J/ψϕ decay with an e+e− pair in the final state. The results are consistent with previous measurements in other channels and with the Standard Model predictions

Angular analysis of B0→D∗−D∗+s with D∗+s→D+sγ decays

The first full angular analysis of the B0→D∗−D∗+s decay is performed using 6 fb−1 of pp collision data collected with the LHCb experiment at a centre-of-mass energy of 13 TeV. The D∗+s→D+sγ and D*− → D¯0π− vector meson decays are used with the subsequent D+s → K+K−π+ and D¯¯0 → K+π− decays. All helicity amplitudes and phases are measured, and the longitudinal polarisation fraction is determined to be fL = 0.578 ± 0.010 ± 0.011 with world-best precision, where the first uncertainty is statistical and the second is systematic. The pattern of helicity amplitude magnitudes is found to align with expectations from quark-helicity conservation in B decays. The ratio of branching fractions [ℬ(B0→D∗−D∗+s) × ℬ(D∗+s→D+sγ)]/ℬ(B0 → D*−D+s) is measured to be 2.045 ± 0.022 ± 0.071 with world-best precision. In addition, the first observation of the Cabibbo-suppressed Bs → D*−D+s decay is made with a significance of seven standard deviations. The branching fraction ratio ℬ(Bs → D*−D+s)/ℬ(B0 → D*−D+s) is measured to be 0.049 ± 0.006 ± 0.003 ± 0.002, where the third uncertainty is due to limited knowledge of the ratio of fragmentation fractions

Searches for 25 rare and forbidden decays of D+ and D+s mesons

A search is performed for rare and forbidden charm decays of the form D+(s)→h±ℓ+ℓ(′)∓, where h± is a pion or kaon and ℓ(′)± is an electron or muon. The measurements are performed using proton-proton collision data, corresponding to an integrated luminosity of 1.6 fb−1, collected by the LHCb experiment in 2016. No evidence is observed for the 25 decay modes that are investigated and 90 % confidence level limits on the branching fractions are set between 1.4 × 10−8 and 6.4 × 10−6. In most cases, these results represent an improvement on existing limits by one to two orders of magnitude

Angular Analysis of the B+→K*+μ+μ− Decay

We present an angular analysis of the B+→K*+(→K0Sπ+)μ+μ− decay using 9  fb−1 of pp collision data collected with the LHCb experiment. For the first time, the full set of CP-averaged angular observables is measured in intervals of the dimuon invariant mass squared. Local deviations from standard model predictions are observed, similar to those in previous LHCb analyses of the isospin-partner B0→K*0μ+μ− decay. The global tension is dependent on which effective couplings are considered and on the choice of theory nuisance parameters

Observation of the suppressed Λ0b→DpK− decay with D→K+π− and measurement of its CP asymmetry

A study of Λ0b baryon decays to the DpK− final state is presented based on a proton-proton collision data sample corresponding to an integrated luminosity of 9  fb−1 collected with the LHCb detector. Two Λ0b decays are considered, Λ0b→DpK− with D→K−π+ and D→K+π−, where D represents a superposition of D0 and ¯D0 states. The latter process is expected to be suppressed relative to the former, and is observed for the first time. The ratio of branching fractions of the two decays is measured, and the CP asymmetry of the suppressed mode, which is sensitive to the Cabibbo-Kobayashi-Maskawa angle γ, is also reported

Search for CP violation in D+(s)→h+π0 and D+(s)→h+η decays

Searches for CP violation in the two-body decays D+(s)→h+π0 and D+(s)→h+η (where h+ denotes a π+ or K+ meson) are performed using pp collision data collected by the LHCb experiment corresponding to either 9 fb−1 or 6 fb−1 of integrated luminosity. The π0 and η mesons are reconstructed using the e+e−γ final state, which can proceed as three-body decays π0 → e+e−γ and η → e+e−γ, or via the two-body decays π0 → γγ and η → γγ followed by a photon conversion. The measurements are made relative to the control modes D+(s)→K0Sh+ to cancel the production and detection asymmetries