Measurement of the gluon polarization ∆G/G at COMPASS
نویسنده
چکیده
One of the key objectives of the COMPASS experiment at CERN is the determination of the gluon contribution to the nucleon spin. The gluon polarization is measured via photon-gluon fusion in deep-inelastic scattering of 160 GeV/c polarized muons on a polarized LiD solid-state target. Photon-gluon fusion is tagged by the observation of charmed mesons or the production of hadron pairs with large transverse momenta pt. The status of the analysis of the D and D events and of the high-pt hadron pairs is shown. The gluon polarization ∆G/G has been determined from the asymmetry of high-pt hadron pairs with Q 2 > 1 (GeV/c) in an analysis of the 2002/03 data as ∆G/G = 0.06± 0.31(stat.) ± 0.06(syst.).
منابع مشابه
Measurement of the Gluon Polarisation at Compass
COMPASS measurements of the gluon polarisation in nucleon, ∆G/G, are reviewed. Two different approaches based on tagging the Photon Gluon Fusion process are described. They rely on the open charm meson or high–pT hadron pairs detection. The obtained results are: −0.57 ± 0.41 (stat.) ± 0.17 (syst.) for the open charm, 0.06 ± 0.31 (stat.) ± 0.06 (syst.) and 0.016 ± 0.058 (stat.) ± 0.055 (syst.) f...
متن کاملCompass ∗
The nucleon spin structure is studied at COMPASS via the measurement of the spin dependent properties of deep inelastic muon-deuteron scattering. Both inclusive and semi-inclusive observables are investigated, with the emphasis put on the latter. This allows to access, in particular, the gluon polarization (∆G/G) and the flavor decomposition of the quark helicity distributions. Results from mea...
متن کاملOn the new COMPASS measurement of the deuteron spin - dependent structure function
Very recently, a new measurement of the deuteron spin-dependent structure function g d 1 (x) was reported by the COMPASS group. A main change from the old SMC measurement is a considerable improvement of the statistical accuracy in the low x region 0.004 < x < 0.03. We point out that the new COMPASS data for g d 1 (x) as well as their QCD fits for ∆Σ and ∆s + ∆¯ s are all remarkably close to ou...
متن کاملRecent measurement of ∆G/G at COMPASS
The determination of the gluon polarization in the nucleon is one of the main goals of the COMPASS experiment at CERN. To do this, we collide a polarized 160 GeV muon beam on a nucleon in a polarized 6 LiD target, and compute the resulting helicity asymmetry. ∆G G is related to this asymmetry via the Photon-Gluon Fusion process, in which the virtual photon emitted by the muon interacts with a g...
متن کامل∆G from Compass
Measurements of the gluon polarization ∆G G via the open charm channel and based on the helicity asymmetry of large transverse-momentum hadrons in the final state are presented. The data have been collected in the years 2002-2004 by the COMPASS experiment at CERN using a 160 GeV/c polarized muon beam scattered off a polarized 6LiD target. The new result for ∆G G from the charm channel is −0.57 ...
متن کامل