L. Dufour

Improved performance of the LHCb Outer Tracker in LHC Run 2

The LHCb Outer Tracker is a gaseous detector covering an area of

First observation of forward Z -> b(b)over-bar production in pp collisions at root s=8 TeV

5\times 6 m^2

Search for excited B-c(+) states

with 12 double layers of straw tubes. The performance of the detector is presented based on data of the LHC Run 2 running period from 2015 and 2016. Occupancies and operational experience for data collected in

First observation of B+ -> D-s(+) K+ K- decays and a search for B+ -> D-s(+) phi decays

p p

Observation of the Lambda(0)(b) -> Lambda phi decay

, pPb and PbPb collisions are described. An updated study of the ageing effects is presented showing no signs of gain deterioration or other radiation damage effects. In addition several improvements with respect to LHC Run 1 data taking are introduced. A novel real-time calibration of the time-alignment of the detector and the alignment of the single monolayers composing detector modules are presented, improving the drift-time and position resolution of the detector by 20\%. Finally, a potential use of the improved resolution for the timing of charged tracks is described, showing the possibility to identify low-momentum hadrons with their time-of-flight.

Measurement of the Ω 0 c Baryon Lifetime

Abstract The decay Z → b b ¯ is reconstructed in pp collision data, corresponding to 2 fb−1 of integrated luminosity, collected by the LHCb experiment at a centre-of-mass energy of s = 8 TeV. The product of the Z production cross-section and the Z → b b ¯ branching fraction is measured for candidates in the fiducial region defined by two particle-level b-quark jets with pseudorapidities in the range 2.2 η 4.2 , with transverse momenta p T > 20 GeV and dijet invariant mass in the range 45 m j j 165 GeV. From a signal yield of 5462 ± 763 Z → b b ¯ events, where the uncertainty is statistical, a production cross-section times branching fraction of 332 ± 46 ± 59 pb is obtained, where the first uncertainty is statistical and the second systematic. The measured significance of the signal yield is 6.0 standard deviations. This measurement represents the first observation of the Z → b b ¯ production in the forward region of pp collisions.

Observation of a New Ξ − b Resonance

A bstractA search is performed in the invariant mass spectrum of the Bc+π+π− system for the excited Bc+ states Bc(21S0)+ and Bc(23S1)+ using a data sample of pp collisions collected by the LHCb experiment at the centre-of-mass energy of s=8

Erratum to: Measurement of the J/psi pair production cross-section in pp collisions at root s = 13 TeV (vol 6, 47, 2017)

\sqrt{s}=8