1. Plans for nucleon structure studies at PANDA
The PANDA FAIR
Parton distributions
GPDs
Time-like form factors
Günther Rosner
Form factors N05, Frascati, 13/10/05

2. Form factors N05, Frascati, 13/10/05
GSI upgrade
Günther Rosner
Form factors N05, Frascati, 13/10/05

3. Facility for Antiproton and Ion Research
SIS 100
SIS 300
SIS 18
Broad range of high-intensity secondary beams
Radioactive nuclei
Antiprotons
Cooler and storage rings
Parallel operation
PANDA
HESR
Collector ring
Günther Rosner
Form factors N05, Frascati, 13/10/05

4. High Energy Storage Ring, HESR
Günther Rosner
Form factors N05, Frascati, 13/10/05

5. Form factors N05, Frascati, 13/10/05
Target
generator
Muon counters
EM and hadron
calorimeters
TOF stop
solenoid
dipole
Interaction point
Drift or wire
chambers
RICH
Tracking of charged particles
Identification of γ, e±, μ±, π±, K±, p, anti-p
High rate capability
Fast trigger scheme
Günther Rosner
Form factors N05, Frascati, 13/10/05

6. Form factors N05, Frascati, 13/10/05
pellets or
clusters
TOF stop
coil
barrel
DIRC
Straws or TPC
MVD
mini drift
chambers
beam
EMC
electro magnetic calorimeter
disk DIRC
Günther Rosner
Form factors N05, Frascati, 13/10/05

7. PANDA physics programme
Charmonium spectroscopy
Exotics: charmed hybrids & heavy glueballs
Time-like
form factors
Medium modifications of charmed mesons
Drell-Yan processes
Hard exclusive processes
CP-violation (D &  - sector)
Hypernuclei
Günther Rosner
Form factors N05, Frascati, 13/10/05

8. The nucleon spin puzzle
COMPASS RHIC
Gluon orbital angular momentum (accessible through GPDs, difficult)
Gluon polarisation positive (HERMES) negative (SMC)
HERMES COMPASS PANDA JLab (upgrade)
Quark spin   0.25
Quark orbital angular momentum (accessible through GPDs)
Transversity
HERMES, COMPASS FNAL, (PANDA), PAX
Günther Rosner
Form factors N05, Frascati, 13/10/05

9. Form factors N05, Frascati, 13/10/05
Parton distributions
Leading twist
Chirally
odd
directly accessible in
Drell-Yan
T-odd
Günther Rosner
Form factors N05, Frascati, 13/10/05

10. Form factors N05, Frascati, 13/10/05
Drell-Yan processes
Cross section depends on elementary process
Measured as a function of polar angle  and azimuthal angle 
Direct access to quark distribution functions (no fragmentation function involved)
Complementary to DIS
Günther Rosner
Form factors N05, Frascati, 13/10/05

11. Drell-Yan processes and parton distributions
Unpolarised DY  Boer-Mulders DF h1┴ HESR)
Single or double polarisation DY  transversity h1 HESR)
Günther Rosner
Form factors N05, Frascati, 13/10/05

12. Hard exclusive processes  GPDs
Crossed channel (time-like) Wide Angle Compton Scattering and DVCS:
Hard scale: large s ~ 10 GeV2 and │t│~ s, or large pT
Soft part can be separated and parameterised by generalised distribution amplitudes
Experimental problem: large hadronic background (e.g. 00)
Günther Rosner
Form factors N05, Frascati, 13/10/05

13. Count rate estimate A. Freund et al., PRL 90 (2003) 092001
Vector
Generalised form factors
Assumptions
pbeam = 5 GeV/c
s = 10 GeV2
L = 2x1032 cm-2s-1
Results
 = 2.5x10-10 fm2
Rate ~ 5x10-4 events/s > 103 events/month (probably underestimated by a factor 3-4 according to CLEO data)
Axial vector
Günther Rosner
Form factors N05, Frascati, 13/10/05

14. Form factors N05, Frascati, 13/10/05
Kinematics
Photon CMS: E = 15.5 … 0.5 GeV,  = 00 … 1800
Wide angle scattering:
Large CM angles
Large transverse momenta pT = few 100 MeV … 2.7 GeV
Photon Lab: E ~ 8 GeV,  ~ 200
4 calorimeter needed
Background suppression:
Detectors with high-rate capability
Charged particle veto in large acceptance spectrometer
Check of exclusivity (momentum balance) through high-resolution calorimetry
Günther Rosner
Form factors N05, Frascati, 13/10/05

15. Experimental requirements
Reject events with more than 2 primary final state particles
Reject neutral mesons
Tag one real photon with large pT
2nd photon’s momentum & energy must add up to initial values
Günther Rosner
Form factors N05, Frascati, 13/10/05

16. First attempt at simulations by G. Sebanut
Experiment appears feasible
Günther Rosner
Form factors N05, Frascati, 13/10/05

17. Time-like proton form factors
Crossed channel :
Goals:
To measure time-like FF from threshold up to high s = q2 in one experiment (reduced systematic error)
To compare with space-like FFs (pQCD at large s?)
PANDA:
Wide kinematical range
Large solid angle coverage
Large statistics
High-quality measurement of both GE and GM
Günther Rosner
Form factors N05, Frascati, 13/10/05

18. Form factors N05, Frascati, 13/10/05
Timelines
FAIR contract signed by participating countries by summer 2006
PANDA technical design report 2007
PANDA commissioning 2012 in Phase II of FAIR construction
Data taking 2013…
Günther Rosner
Form factors N05, Frascati, 13/10/05