antiproton physics at gsi
DESCRIPTION
Antiproton Physics at GSI. The GSI Future project The antiproton facility The physics program Charmonium spectroscopy Charmed hybrids and glueballs Interaction of charm particles with nuclei Strange baryons in nuclear fields Further options Detector concept - PowerPoint PPT PresentationTRANSCRIPT
Antiproton Physics at GSI
• The GSI Future project• The antiproton facility• The physics program
- Charmonium spectroscopy- Charmed hybrids and glueballs- Interaction of charm particles with nuclei- Strange baryons in nuclear fields- Further options
• Detector concept• Selected simulation results• Conclusions
GSI Future Project: The Physics Case
• Research with Rare Isotope Beams Nuclei Far From Stability
• Nucleus-Nucleus Collisions Compressed Baryonic Matter
• Ion and Laser Induced PlasmasHigh Energy Density in Matter
• From Fundamentals to Applications QED, Strong Fields, Ion-Matter Interactions
• Research with AntiprotonsHadron Spectroscopy and Hadronic Matter
Conceptual Design Report: http://www.gsi.de/GSI-Future/cdr/
What does 18.3 Tm mean?
Motion of particle in B-field: P = 0.3 B Z (units=T,m,GeV/c)
cGeVZp /3.183.0
GeVmEEK
GeVmpE
55.4..
49.5
1 Z:proton afor 2222
AGeVGeV
mEEK
mpE
97.16.23
931.01278.34..
931.01263.183.0
Cfor 22222
612
The GSI p Facility
p production similar to CERN, HESR = High Energy Storage Ring
• Production rate 107/sec• Pbeam = 1.5 - 15 GeV/c• Nstored = 5x1010 p
High luminosity mode• Lumin. = 2x1032 cm-2s-1 • p/p~10-4 (stochastic cooling)
High resolution mode• p/p~10-5 (el. cooling < 8 GeV/c)• Lumin. = 1031 cm-2s-1
Fundamental Aspects of QCD
QCD is confirmed to high accuracy at small distances
At large distances, QCD is characterized by:• Confinement• Chiral symmetry breaking
Challenge: can we develop a quantitative understanding of the relevant degrees of freedom in strongly interacting systems?
Experimental approach: Charm physics opens a window in the transition regime since mc is between the chiral and heavy quark limits
Charmonium SpectroscopyThe charmonium system is the positronium of QCD. It provides a unique window to study the interplay of perturbative and non-perturbative effects.
Energy levels / widths details of QQ interaction
Exclusive decays interplay of perturb. and non-pert. effects
Comparison e+e- versus pp
e+e- interactions: Only 1-- states are formed Other states only by secondary decays (moderate mass resolution)
pp reactions: All states directly formed (very good mass resolution)
Severe limitations to existing experiments: (no B-field, beamtime, beam momentum
reproducibility,…)Many open questions: ’c, states above DD threshold,…
Charmed Hybrids
Predictions for charmed hybrids (ccg)
Mass: lowest state 3.9-4.5 GeV/c2
Quantum numbers: many allowed values, ground state JPC = 1-+ (exotic)
Width: could be narrow (~MeV) for some states since DD suppressed O+- DD,D*D*,DsDs (CP-Inv.) (QQg) (Qq)L=0+(Qq)L=0 (Dynamic Selection Rule)If DD forbidden, then the preferred decay is
(ccg) (cc) + X , e.g. 1-+ J/
Search for Charmed Hybrids
Mixing with QQ states: - Excluded for spin exotic hybrids - Possible for non-exotic states, but less probable than the light quark sector, since there are fewer states with smaller width.
Example of state with exotic q.-n. (1-+) pd X(1-+)++p, X CB@LEARStrength similar to qq states
Partial Wave Analysis as important toolExpectations at HESR: 104 non-exotic q.-n. & 102 exotic /dayA signal in production but not in formation is interesting!
Charmed Hadrons in Nuclear Matter
Investigating the properties of hadrons in matter is a main research topic at GSI. Partial restoration of chiral symmetry should take place in nuclear matter. Light quarks are sensitive to quark condensate Evidence for mass changes of pions and kaons has been deduced previously: - deeply bound pionic atoms - (anti)kaon yield and phase space distribution
D mesons are the QCD analog of the H atom. They allow chiral symmetry to be studied on a single light quark
±
The expected signal for a changing mass scenario would be a strong enhancement of the D meson cross section, and relative D+ D- yields, in the near/sub-threshold region.
This probes ground state nuclear matter density and T~0 (complementary to heavy ion collisions)
Open Charm in Nuclei
cc Production on Nuclei
A lowering of the DD mass would allow charmonium states to decay into this channel, thus resulting in a dramatic increase of width.
Thus one will study relative changes to the yield and width of the charmonium states.
J/ – Nucleon Absorbtion
The J/ suppression observed at SPS is believed to be related the generation of the QGP. Such suppression can also be generated by purely hadronic interactions, so it is very important to know the N-J/ cross section in nuclear matter.
p + A J/ + (A-1)
Proton Form Factors at large Q2
At high values of momentum transfer |Q2| the system should be describable by perturbative QCD. Due to dimensional scaling, the FF should vary as Q4.
222 lns
s
CG
p
M
q2>0
q2<0
The time like FF remains about a factor 2 above the space like. These differences should vanish in pQCD, thus the asymptotic behavior has not yet been reached at these large values of |q2|. (HESR up to s ~ 25 GeV2)
Strange Baryons in Nuclear FieldsHypernuclei open a 3rd dimension (strangeness) in the nuclear chart
-
3 GeV/c
K+KTrigger
_
secondary target
p
• New Era: high resolution -spectroscopy
• Double-hypernuclei: very little data
• Baryon-baryon interactions: -N only short ranged (no 1 exchange due to isospin) - impossible in scattering reactions
-(dss) p(uud) (uds) (uds)
Experiments with Open Charm
HESR will produce about 2.5x109 DD/year (~1% reconstr.)
• Leptonic decays: structure of D mesons(/tot D)
• D0/D0 mixing: should be small <10
• CP: direct is dominantNeed about 108 decays
Direct CP in hyperon decays (self analyzing decay)
Production of charmed baryons:excitation function, differential cross sections,
spin observables
Inverted DVCS„Deeply Virtual Compton Scattering“ (DVCS) allows the „Skewed Parton Distributions“ to be measured using the Handbag-Diagram Dynamics of quarks and gluons in hadrons
Measurements of the inverted process less stringent requirements on the detector resolution.(however the connection of DVCS to the SPDs needs to be theoretically analyzed in this kinematic region)
General Purpose DetectorDetector requests:• nearly 4 solid angle• high rate capability• good PID (,e,,,K,p)• efficient trigger (e,,K,D,)
J/+-
‘+-
pp ‘ pp (s=3.6 GeV)4K
Detector
Target• A fiber/wire target will be needed for D physics,• A pellet target is conceived:
1016 atoms/cm2 20-40 m • Open point: heating of the beam
1 mm
Central Tracking Detectors
• Micro Vertex Detector: (Si) 5 layers• Straw-Tubes: 15 skewed double-layers• Mini-Drift-Chambers
GEANT4 simulationfor HESR:
PID with DIRC
(DIRC@BaBar)
GEANT4 simulationfor HESR:
PbWO4 Calorimeter
Length = 17 X0
APD readout (in field)
pp J/
e/-Separation
Muon Detector
Performance of Full Spectrometer
Probability to measure the reaction:
GeV4.4/ sJpp J/ ee J/
Neutral Vertex Finder
K0S
+
-
-
+ -
Reaction: 2K0s
|D0|>0.4 mm or |Z0|>0.5 mm for each track
Kinematic refit (constraint=common vertex)
3-Momentum conservation
Summary
• HESR will deliver cooled antiprotons up to 15 GeV/c• The physics program
- Charmonium spectroscopy- Hybrids and glueballs- Interaction of charm particles with nuclei- Strange baryons in nuclear fields- Further options
• Detector concept• Selected simulation results
Working group: T. Barnes, D. Bettoni, R. Calabrese, M. Düren, S. Ganzhur, O. Hartmann, V. Hejny, H. Koch, U. Lynen, V. Metag, H. Orth, S. Paul, K. Peters, J. Pochodzalla, J. Ritman, L. Schmitt, C. Schwarz, K. Seth, W. Weise, U. Wiedner
Glueballs
Predictions for Glueballs:
Masses: 1.5-5.0 GeV/c2
Quantum numbers: several spin exotics, e.g. 2--
Widths: >100 MeV/c2
Mixing with qq and QQ: excluded for exotics mixing with QQ smallProduction cross section: comparable to qq systems (b)
HESR Detector
• Pellet-Target: 1016 Atoms/cm2 20-40 m• MicroVertexDetektor: (Si) 5 layers• Straw-Tubes: 15 skewed double layers• RICH: DIRC and Aerogel (Proximityfocussing)•Straw-Tubes + Mini-Drift-Chambers
• PbWO4-calorimeter 17X0
• 2T-Solenoid & 2Tm-Dipole• Muon filter• EM- & H-cal. near 0°