The gluon polarisation ?G/G - PowerPoint PPT Presentation

About This Presentation
Title:

The gluon polarisation ?G/G

Description:

Quarks : the spin crisis. Prediction (Ellis, Jaffe) 1988 EMC: . P. Axial anomaly. GeV2. 4. Gluons. QCD evolution of g1. . p,n ... – PowerPoint PPT presentation

Number of Views:35
Avg rating:3.0/5.0
Slides: 17
Provided by: morion
Category:

less

Transcript and Presenter's Notes

Title: The gluon polarisation ?G/G


1
  • The gluon polarisation ?G/G
  • at COMPASS

Colin Bernet (DAPNIA/SPHN), on behalf of the
collaboration
2
The nucleon longitudinal spin structure
Orbital momentum
Quarksspin
Gluonsspin
3
Quarks the spin crisis
  • Prediction (Ellis, Jaffe)
  • 1988 EMC

GeV2
µ
P
  • Axial anomaly

4
Gluons
QCD evolution of g1
Polarized SIDIS Photon-gluon fusion
(COMPASS,HERMES)
µ
p,n
Polarized p-p (PHENIX, STAR)
5
Negatively polarized µ beam, 160 GeV
LHC
COMPASS
SPS
6
Experimental setup
DeuteronTarget



µ ID
Dipoles
HCALS
  • 200 tracking planes
  • 250 physicists

µ
RICH
7
Open-charm tagging
K-
µ
D0
D
p
p
COMPASS 2002
8
High pT tagging
µ
9
Selection of high pT events
h1
µ
µ
h2
10
Selection of high pT events
  • GeV/c
  • (GeV/c)2
  • No Q2 cut

11
Preliminary results
  • Helicity asymmetry for high pT events, 2002 data
  • Careful study of false asymmetries

12
Gluon polarisation ?G/G
13
Background QCD Compton
  • Contribution to the asymmetry

14
Background Resolved photons
  • Contribution to the asymmetry

15
Conclusion
  • 2003, 2004, f.o.m. improvements
  • ? stat. lt
    0.018
  • Monte-Carlo
  • Background
  • LEPTO

16
(No Transcript)
Write a Comment
User Comments (0)
About PowerShow.com