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The 19th Particles and Nuclei International Conference (PANIC11)Massachusetts Institute of Technology
July 24-29, 2011, Cambridge, USA
Thomas Würschig
on behalf of the PANDA collaboration
Charm spectroscopy at the
PANDA experiment
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 2 -
Introduction
Particle
physics
Hadron
physics
Nuclear
physics
Questions:
Hadronization:
Mechanism of quark confinement?
Inner structure of hadrons?
Macroscopic properties of hadrons:
Origin of mass and spin?
Existence of other colour neutral objects?
Running coupling
constant in transition region:
Long distance features of QCD?
1015 m
• PANDA (AntiProton Annihilations at Darmstadt)
Hadron physics experiment:
Study of strong interactions
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 3 -
Introduction
• PANDA (AntiProton Annihilations at Darmstadt)• PANDA (AntiProton Annihilations at Darmstadt
Broad physics program ...
Structural analysis of nucleons
Hypernuclei physics
In-medium effects of hadrons
Hadron spectroscopy
Focus on the charm quark sector
Baryons
q c
D mesons
c c
Charmonium
Mesons
Conventional QCD states
Multi-quark systems?Glueballs? Hybrids?
Search for exotic states
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 4 -
Nucl. Instr. Meth. A 561 (2006) 305–309
• Future facility
PANDA at FAIR
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 5 -
Stochastic cooling
Stochastic cooling
Injection
Electroncooler
IJMPE 18
No.2(2009)429• High Energy Storage Ring (HESR)
Up to 1011 stored antiprotons
Beam momentum: (1.5 ... 15) GeV/c
Fixed internal target
Frozen hydrogen or
heavier nuclear targets
Operation modes
a) High luminosity: L = 2 · 1032 cm-2 s-1 p/p 10-4
b) High resolution: L = 1031 cm-2 s-1 p/p 4 · 10-5
PANDA at FAIR
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 6 -
Stochastic cooling
Stochastic cooling
Injection
Electroncooler
IJMPE 18
No.2(2009)429• High Energy Storage Ring (HESR)
Operation modes
a) High luminosity: L = 2 · 1032 cm-2 s-1 p/p 10-4
b) High resolution: L = 1031 cm-2 s-1 p/p 4 · 10-5
PANDA at FAIR
Beam-target interaction:
20 million annihilations / s
Quasi continuous
time distribution of events
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 7 -
arXiv:0903.3905v1 [hep-ex]
Physics performance
report:
PANDA at FAIR
High charm
production
rates, e.g.:
107 D pairs
per year
1011 J /
per year
High resolution
mode off by
factor of ten only...
• Mass range
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 8 -
PANDA at FAIR
Fully exclusive
measurements with a
flexible trigger
Key features :
D+
+
+K
-
c = 312 μm
D±S
c = 150 μm
c = 120 μm
D0
Vertex resolution 100 m
Momentum resolution 1%
• Detector setup
4 coverage
Detection of charged
and neutral particles
Anti-
proton
beam Target
Spectrometer
Forward
Spectrometer
SolenoidDipole
Target
material
Extension along beam pipe: 14 m
Maximum height: 8 m
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 9 -
• Detector setup
4 coverage
Detection of charged
and neutral particles
PANDA at FAIR
Fully exclusive
measurements with a
flexible trigger
Key features :
Vertex resolution 100 m
Momentum resolution 1%
Photon detection 1 MeV ... 10 GeV
Particle identification: , e, , , p
Energy resolution (E) /E 1.5%/E
Anti-
proton
beam Target
Spectrometer
Forward
Spectrometer
SolenoidDipole
Target
material
Extension along beam pipe: 14 m
Maximum height: 8 m
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 10 -
Charm spectroscopy
Discovery
Confirmation
High-precision dataMass
WidthQuantum
numbers
Partial
widths
Decay pattern
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 11 -
• High-precision data in formation experiments
Charm spectroscopy
Fine-tuned energy scan in relevant mass region necessary
... On the market: BESIII only: e+e collider limited to JPC = 1
PANDA will allow formation experiments for any JPC
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 12 -
Charmonium sector c c
Charm spectroscopy
• Experimental status
Below threshold
All states established
No high-precision data
for spin-singlets
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 13 -
Charmonium sectorc c
Charm spectroscopy
• Experimental status
Above threshold:
Incomplete picture,
no high-precision data
Only four states
confirmed, all JPC = 1
Many predicted states
not yet observed
Discovery of new states Discrepancies with
conventional models
Established:
X(3872) and Y(4260)
... but not clearly assigned
XYZ puzzle …
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 14 -
Charm spectroscopy
q c
D mesons• Experimental status:
Ground states: High-precision data
Excited states: Few experimental data
Incomplete picture
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 15 -
Physics simulation
• Radiative decay hc c
Fully exclusive reconstruction
Resonance scan (10 data points 5 days)
Achievable resolution well below 1 MeV (current upper limit)
hc c3 hc c
Expected event rate:(High luminosity mode)
20 / day 92 / day
Signal-to-background ratio:
(Efficiency)
> 87
8%
8
25%N
events
10
20
30
40
50
3.523 3.524 3.525 3.526 3.527 3.528 3.529E [GeV]
= 0.5 MeV
hc c 5 day scan
arXiv:0903.3905v1 [hep-ex]
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 16 -
d0
• production @ (3770)
Reconstruction:
Conservative estimate
Physics simulation
6 orders of magnitude lower
Signal
Efficiency:
40%
arXiv:0903.3905v1 [hep-ex]
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 17 -
Physics simulation
Full phase space coverage, isotropic reconstruction
Good recovery of the D* resonance
A. Pitka, Diploma thesis
• Dalitz plot analysis Center-of mass energy 900 MeV above threshold
Charged decay modes for D mesons
Secondary vertex resolution i 100 m
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 18 -
• Inclusive study
Reconstruction:
identification via missing mass
Excitation function around threshold
40 events / days = 4287.6 MeV
s / MeV
# reco
‘dsi
gnal
s
Achievable resolution:
Particle width 100 keV
Mass shift 0.1 MeV/c2
4 days
per
scan point
Current
PDG values
< 3.8 MeV
M = 0.6 MeV/c2
Physics simulation
M. Mertens, PhD thesis
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 19 -
Physics simulation
• Resonance scan for the X(3872)
Exclusive reconstruction
Achievable resolution for particle width 100 keV
Current upper limit: 2.3 MeV
Study of line shape accessible
Counts
20
40
60
80
100
120
140
3.8714 3.8716 3.8718 3.872 3.8722 3.8724 3.8726
Nominal Center of Mass Energy for Scanpoint [GeV]
in = 100 keV
reco = 110 keV
M. Galuska, Master thesis
20 scan points
2 days / point
200 reconstructed events / day
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 20 -
Summary
• Charm spectroscopy Interesting domain to study QCD at hadronic length scale
Many open questions within observed spectrum
Current experimental status insufficient to solve these problems
• High-precision spectroscopy at PANDA Complementary studies to existing charm experiments
Unique tool to access states of any quantum number
High luminosityOptimized
detector setup
High beam
quality
High statistics High resolutionHighly efficient
reconstruction
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 21 -
Summary
U BaselIHEP BeijingU BochumIIT BombayU BonnIFIN-HH BucharestU & INFN BresciaU & INFN CataniaJU CracowTU CracowIFJ PAN CracowGSI DarmstadtTU DresdenJINR Dubna
(LIT,LPP,VBLHE)U EdinburghU ErlangenNWU Evanston
U & INFN FerraraU FrankfurtLNF-INFN FrascatiU & INFN GenovaU GlasgowU GießenKVI GroningenIKP Jülich I + IIU KatowiceIMP LanzhouU LundU MainzU MinskITEP MoscowMPEI MoscowTU MünchenU MünsterBINP Novosibirsk
IPN OrsayU & INFN PaviaIHEP ProtvinoPNPI GatchinaU of SilesiaU StockholmKTH StockholmU & INFN TorinoPolitechnico di TorinoU & INFN TriesteU TübingenTSL UppsalaU UppsalaU ValenciaSMI ViennaSINS WarsawTU Warsaw
More than 400 physicists from 53 institutions in 16 countries
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 22 -
Backup slides
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 23 -
Charmonium sector c cq c
D mesons
u
d
s
q =
Charm spectroscopy
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 24 -
• High-precision data in formation ... with antiprotons!
Charm spectroscopy
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 25 -
Charmonium
Thomas Würschig, Charm spectroscopy at PANDA, PANIC 2011 - 26 -
Introduction
• - Detection concept
Hermetic detector with modular sub-systems
Measurement of charged and neutral particles
Good particle identification and momentum resolution
Tracking
Central trackers
Forward trackers
Particle
identification
Čerenkov detectors
(DIRC, RICH)
TOF systems
Muon system
Electromagnetic
calorimeter (EMC)
Four-momentum
reconstruction
Tracking system:
Particle momentum
Muon system+EMC:
Particle energy
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