Soft QCD Measurements at LHCb

Abstract

The LHCb experiment at LHC was designed to test the flavour aspect of the Standard Model through precision measurements of rare b and c hadron decays [1]. The LHCb detector [2] is built as a single arm forward spectrometer fully instrumented for measurements in the forward pseudorapidity (η) region 2 < η < 5. The primary pp interaction region is located within a silicon-strip vertex detector (VELO) which allows reconstruction of tracks without momentum information also in the backward pseudorapidity interval −3.5 < η < −1.5. The high-precision tracking system [3] continues with a large area silicon tracker located upstream of a magnetic dipole with a bending power of 4 Tm and three stations of silicon-strip detectors and straw drift tubes situated downstream of the magnet. A calorimetry system is used to measure the neutral component and muons are detected by a dedicated system of alternating layers of iron and multi-wire proportional chambers [4]. The LHCb experiment is operated at a low and consistent number of visible proton-proton (pp) interactions. Monte Carlo (MC) simulated events were used to compute detection efficiencies, estimate systematic uncertainties and compare model predictions with respect to the measurements. Full simulation samples are produced using PYTHIA6.4 [6] configured according to established tunes [7] or the LHCb specific tune [8].