Transcript Spectroscopy with BaBar, Belle, BES, PANDA

Hadron Spectroscopy:
an Experimental Overview
Diego Bettoni
INFN, Ferrara, Italy
30th Annual Nuclear Physics Meeting,
Uppsala, Sweden, 16-17 November 2010
Outline
• The strong interaction and QCD
• Experimental methods for the study of hadron spectroscopy
– Spectroscopy in e+e- annihilation
– Spectroscopy in pp annihilation
• Experimental Highlights
– Light mesons
– Search for exotics
– Charmonium and bottomonium
– Open charm mesons
– States above open charm threshold (XYZ states)
– Baryons
• Outlook and Conclusions
– The future
– ThePANDA experiment at FAIR
QCD
The modern theory of the strong interactions
is Quantum Chromodynamics (QCD), the
quantum field theory of quarks and gluons
based on the non abelian gauge group SU(3).
It is part of the Standard Model.
Confinement
At high energies, where the strong coupling
constant s becomes small and perturbation
theory applies, QCD is well tested.
Asymptotic
freedom
In the low-energy regime, however, QCD
becomes a strongly coupled theory, many
aspects of which are not understood.
D. Bettoni
Spectroscopy
3
Theoretical Approaches to
non-perturbative QCD
•
•
•
Potential models. Bound systems of heavy quarks can be treated in the
framework of non-relativistic potential models, with forms which reproduce the
asymptotic behaviour of QCD. Masses and widths are obtained by solving
Schrödinger’s equation.
Lattice QCD (LQCD)
– The QCD equations of motions are discretized on a 4-dimensional spacetime lattice and solved by large-scale computer simulations.
– Enormous progress in recent years (e.g. gradual transition from quenched
to unquenched calculations).
– Ever increasing precision, thanks also to sinergies with EFT.
Effective Field Theories (EFT)
They exploit the symmetries of QCD and the existence of hierarchies of scales
to provide effective lagrangians that are equivalent to QCD for the problem at
hand.
– With quark and gluon degrees of freedom (e.g. Non Relativistic QCD or
NRQCD)
– With hadronic degrees of freedom (e.g. Chiral Perturbation Theory).
D. Bettoni
PANDA at FAIR
4
Examples of Theory
Calculations
Four quark for the X(3872)
LQCD Glueball Spectrum
Maiani et al., PRD71(2005)014028
LQCD + NRQCD
Charmonium Spectrum
Morningstar und Peardon, PRD60 (1999) 034509
Experimental Measurements
• Spectroscopy of QCD bound states. Precision measurement of
particle spectra to be compared with theory calculations.
Identification of the relevant degrees of freedom.
– light quarks, cc, bb
– D meson
– baryon
• Search for new forms of hadronic matter: hybrids, glueballs,
multiquark states ...
• Hadrons in nuclear matter. Origin of mass.
• Hypernuclei.
• Study of nucleon structure.
– Form Factors
– GDAs
• Spin physics.
Experimental Techniques
e+e- collisions
direct formation
two-photon production
initial state radiation (ISR)
B meson decay
(BaBar, Belle, BES, CLEO(-c), LEP ...)
pp annihiliation
(LEAR, Fermilab E760/E835, PANDA)
+ low hadronic background
+ high discovery potential
- direct formation limited to vector states
- limited mass and width resolution for
non vector states
- high hadronic background
+ high discovery potential
+ direct formation for all (non-exotic) states
+ excellent mass and width resolution
for all states
Hadroproduction
Electroproduction
(CDF, D0, LHC)
(HERA)
Experimental Methods
e+ e pp
e+e-  hadrons
Dominated by the process e+e-  *  qq
ee+
q

 e  e   hadrons 
2
R

3
e

q
 e  e       
q
q
2


(
Q
)
R  3 eq2 1  s

 
q

u+d+s+c+b+t
5
11/3
10/3
u+d+s+c
2
u+d+s
u+d+s+c+b
Direct Formation (e.g. e+e-cc)
In e+e- annihilations direct formation is possible
only for states with the quantum numbers of the
photon JPC=1--: J/,  and (3770).
All other states can be produced in
the radiative decays of the vector
states. For example:
e   e    (2 S )    X
The precision in the measurement of masses
and widths is limited by the detector resolution.
Crystal Ball inclusive photon spectrum
Diego Bettoni
Charmonium
10
Two-photon Production e+e-e+e-+(cc)
J-even charmonium states can be
produced in e+e- annihilations at higher
energies through  collisions. The (cc)
state is usually identified by its hadronic
decays. The cross section for this process
scales linearly with the  partial width of
the (cc) state.
 e e  e e cc    d 5 L  i    cc 
   cc   8
2J 1
M
2
2


F
q
,
q
1
2
2
2
2
2
M
s  M   M 
Limititations: knowledge of hadronic branching ratios and
form factors used to extract the  partial width.
Diego Bettoni
Charmonium
q lq l+
L = Luminosity function
= e.g. 4-momenta of out
going leptons.
J,M, = spin, mass ,total
width of cc state.
s = cm energy of  system
 two-photon partial width
q1,q2 photon 4-momenta
F = Form Factor describing
evolution of cross section.
11
Initial State Radiation (ISR)
q lq l+
•Like in direct formation, only JPC=1– states can be formed in ISR.
•This process allows a large mass range to be explored.
•Useful for the measurement of R = (e+e-hadrons)/(e+e-+-).
•Can be used to search for new vector states.
Diego Bettoni
Charmonium
12
B-Meson Decay
J/,,(3770), c,c,c0,c1,D(*),D(*),X(3872)
K,KS,KL,K*(890),K(1270)...
Charmonium states can be produced at the B-factories in the decays
of the B-meson.
The large data samples available make this a promising approach.
States of any quantum numbers can be produced.
c and X(3872) discoveries illustrate the capabilities of the B-factories
for charmonium studies.
Diego Bettoni
Charmonium
13
pp Annihilation
In pp collisions the coherent
annihilation of the 3 quarks in
the p with the 3 antiquarks in
thep makes it possible to form
directly states with all non-exotic
quantum numbers.
The measurement of masses and
widths is very accurate because it
depends only on the beam parameters,
not on the experimental detector
resolution, which determines only the
sensitivity to a given final state.
Diego Bettoni
Charmonium
14
Experimental Method
The cross section for the process:
pp  R  final state
is given by the Breit-Wigner formula:
 BW
Bin Bout R2
2J  1 

4 k 2 E  M R 2  R2 / 4
The production rate  is a convolution of the
BW cross section and the beam energy distribution function f(E,E):
  L0   dEf ( E , E ) BW ( E )   b 
The resonance mass MR, total width R and product of branching ratios
into the initial and final state BinBout can be extracted by measuring the
formation rate for that resonance as a function of the cm energy E.
Diego Bettoni
Charmonium
15
Example: c1 and c2 scans in
Fermilab E835
1
2
D. Bettoni
PANDA at FAIR
16
Hybrids and Glueballs in pp Annihilation
nng
Production
all
JPC
available
Formation
only selected JPC
p
_
p
G
M
p
_
p
p
_
p
ssg/ccg
H
M
p
G
_
p
p
_
p
M
p
H
_
p
Gluon rich process creates gluonic excitation in a direct way
–
–
–
–
H
cc requires the quarks to annihilate (no rearrangement)
yield comparable to charmonium production
even at low momenta large exotic content has been proven
Exotic quantum numbers can only be achieved in production mode
H
Experimental Highlights
Light mesons
Search for exotics
Charmonium and Bottomonium
Open charm mesons
New states above open charm threshold (XYZ)
Meson Spectrum after LEAR
L=0
L=1
2 GeV/c 2
23P 2
2 P1
3
1
3 S0


K
( 1 8 0 0)
( 1 7 7 5)
( 1 8 3 0)
 1(1600)
a2
(1650)
f2
(1 8 1 0 )
f 2'
(2 0 4 0 )
K2
( 1 9 8 0)
a1
(1 7 0 0 )
– @ CERN
2 P0
3
1
2 P1
• Asterix/Obelix
b1
( 1 7 0 0)
• Crystal Barrel
f2( 1640)
f2( 1565)
1 P2
3
f0( 1515)
2 S1
(1410)
2 1S 0
3



K*
( 1 4 5 0)
(1 4 2 0 )
(1 6 8 0 )
( 1 4 1 0)


'
K
( 1 3 0 0)
(1 2 9 5 )
(1 4 9 0 )
( 1 4 6 0)
1 (1400)
1 GeV/c 2
F0 (975)
1 S1
3



K*
(770 )
(782)
(1020)
(892)
f2
f 2'
K2
( 1 3 2 0)
(1 2 7 0 )
( 1 5 2 5)
( 1 4 3 0)
a1
f1
K1
( 1 4 0 0)
( 1 2 6 0)
(1 2 8 5 )
1 P0
a0
( 1 4 5 0)
f0
f0
K0
(1 3 7 0 )
( 1 7 1 0)
(1 4 3 0 )
1 P1
b1
h1
h 1'
K1
( 1 2 3 5)
(1 1 7 0 )
( 1 3 8 0)
( 1 2 7 0)
3
1
a0(980)
a2
1 P1
3
•The LEAR Era with the experiments
• Jetset/PS185
• WA102/Gams
– @ BNL
• E818/E852
– @ FNAL
• E760/E835
not
qq ?!
– @Serpukhov
1 S0
1


'
K
(140 )
(548)
(957)
(495)
• VES/Gams
M
seen at LEAR
single decay
unambiguous
established (PDG)
produced impressive results with high
statistics and high resolution
Conventional and Exotic Hadrons
•Quarkmodels usually
account for qq states
qq
qq
+
(qq)
(q (qq)
q
)(q
q )
+
(qq))gg
q
(q
gg
+
•Other color neutral
configurations with same
quantum numbers can
(and will mix)
•Decoupling only possible for
– narrow states
– vanishing leading
qq term
Simplest Hybrids
S-Wave+Gluon (qq)8g with ()8=coloured
1S  3S 
0
1
combined with a 1+ or 1- gluon
Gluon
1– (TM)
1+(TE)
1S
0,
0–+
1++
1––
3S
1,
1––
0+-
0–+
1+-
1–+
2+-
2–+
1(1400) – E852 and Crystal Barrel

p (and

pd  p @ Rest in liq.D2
n)

m( )
BNL
E852
(770)
GeV 2 /c 4
p
3.
52.500 E.
^ (1400)
2.
1.
BNL
E852
 peak @ 1.4 GeV/c 2
phasemotion at a2 tail visible
Cr ystal
Bar r el
a2(1320)
1.
2.
m( )

Advantage: I=1
and no Scalars
GeV /c
2
4
1(1400) – Proof of Exotic Wave (CB)
Positive
 (Fit - Data)
Negative
2
GeV /c
3
m2(0) [GeV2/c4]
2
4
 (Fit - Data)
2
GeV /c
3
2
4
no 1 in Fit
2
2
a2
1
5
a2
1

0
1
2

3
2
4
GeV /c
GeV /c
3
2
0
1
3
2
4
GeV /c
2
GeV /c
3
4
2
4
1 in Fit
2
2
a2
1
Cr ystal
0
Bar r el
5
a2
1

1
2


3
2
4
GeV /c
0
1
2
3
2
4
GeV /c
m2(-) [GeV2/c4]
1(1600)
1 
BNL
E852
(X-1 )
-+
2 

0 f0
p p p (E852)
shows a clear resonance in the 1-+
wave around 1600 MeV/c2
Also observed by the VES
collaboration in the ,  and
b1(1235) channels.

1  (I=1)

1  (I=1)

2 

2f2
b1(1235) channel confirmed by CB
in pp  +-0.
1(1600)
420.000 diffractive events π−+Pb→X + (Pb)reco collected by COMPASS exp. @190 GeV/c
↳ π− π− π+
acceptance-corrected intensities of the three
most prominent waves and of the exotic one
A Partial Wave Analysis (PWA) of this data set
was performed by using the isobar model in
which a multi-particle final state is described
by a sequence of two-body decays
PRL104(2010) 241803
1(1600)
All known isovector and isoscalar ππ resonances have been included: σ(600) and f0(1370),
ρ(770), f0(980), f2(1270), and ρ3(1690)
σ(600)π− with L = 0 and JP = 0- is used to consider direct 3-body decay into π−π−π+
background wave = uniform 3-body phase space added incoherently
A total of 42 partial waves are included in the first step of the fit. The χ2 fit of the spindensity matrix elements obtained for each mass bin is performed in the mass range from 0.8
to 2.32 GeV/c2
comparison with BNL E852 results for
π−p→π+π±π-π0π0(p/n) @ 18 GeV/c
Glueballs
Detailed predictions of mass spectrum
from quenched LQCD.
– Width of ground state  100 MeV
– Several states predicted below 5
GeV/c2, some exotic (oddballs)
– Exotic heavy glueballs:
• m(0+-) = 4140(50)(200) MeV
• m(2+-) = 4740(70)(230) MeV
• predicted narrow width
Can be either formed directly or
produced in pp annihilation.
Some predicted decay modes , ,
J/, J/ ...
Morningstar und Peardon, PRD60 (1999) 034509
Morningstar und Peardon, PRD56 (1997) 4043
The detection of non-exotic glueballs is not trivial, as these states mix with
the nearby qq states with the same quantum numbers, thus modifying the
expected decay pattern.
• In 1995 through a simultaneous fit to
the channels 0, 00 and 30
produced inpp annihilations Crystal Barrel
discovered three new resonances:
– isovector a0(1450)
– isoscalar f0(1370) and f0(1500)
• Confirmed by OBELIX in analysis of +-0, K+K-0, KK0S in pp
annihilation at rest.
• Confirmed by WA102 in central pp collisions at CERN.
Pomeron-Pomeron
N
P
N
See-Quark-Formation
N
P
• Crystal Barrel and OBELIX data also confirm the broad f0(600) and
the narrow f0(980), neither of which are believed to be qq states.
f0(1500) Crystal Barrel data
Scalar Mesons
The PDG classification of the 0++ scalar mesons is tentative, because
the number of states is bigger than 9.
– a0(980) and a0(1450) isovectors
– f0(600), f0(980), f0(1370), f0(1500), f0(1710) isoscalars
– K*0(1430) and K*0(1950) isodoublets.
BUT:
The a0(980), f0(600) and f0(980) are considered non-qq states, they
are considered exotic candidates (multiquark or KK states).
It is then natural to assume that the f0(1370), a0(1450) and the strange
K*0(1430) are in the same SU(3) nonet. A higher-mass isoscalar is
required as the ninth member, but we have two: f0(1500), f0(1710).
The answer is to include a glueball.
Meson-Glueball Mixing
LQCD calculations predict for the lightest glueball a scalar with a mass
in the range 1.45 – 1.75 GeV/c2. A combined analysis of the complete set
of two-body decays of the f0(1370), f0(1500) and f0(1710) into
pseudoscalar mesons determined the mixing angles and the mass mG of
the bare glueball.
f 0 1710  0.39 gg  0.91 ss  0.14 NN
f 0 1500  0.69 gg  0.37 ss  0.62 NN
f 0 1370  0.60 gg  0.13 ss  0.79 NN
mG  1440  16 MeV / c 2
uu  dd
NN 
2
We have the following picture:
a0(1450), K*0(1430), f0(1370), f0(1710) 0++ scalar nonet
f0(600), f0(980), a0(980) multiquark or KK states
f0(1500) scalar glueball
In this scenario it is fair to say that the lightest glueball was discovered
at LEAR.
There are, however, alternative viewpoints:
a0(980), K*0(1430), f0(980), f0(1500) n=1, 0++ scalar nonet
a0(1450), K*0(1950), f0(1370), f0(1710) n=2, 0++ scalar nonet
Tensor Glueball
into KK
If there is a scalar glueball with
a mass of 1.44 GeV/c2 then
Mar kIII
LQCD predicts a tensor
glueball with a mass around
2.0 GeV/c2.
First candidate observed in
1986 in radiative J/ decays,
named (2220).
into 
DM 2
(2220) confirmed by BES
(2220) NOT confirmed by JETSET ...
J etset
pp
?
... (2220) NOT seen by
Crystal Barrel either
Tensor Glueball situation still confused
Charmonium Spectroscopy
Charmonium is a powerful tool for the
understanding of the strong interaction.
The high mass of the c quark (mc ~ 1.5
GeV/c2) makes it plausible to attempt a
description of the dynamical properties of
the (cc) system in terms of non relativistic
potential models, in which the functional
form of the potential is chosen to reproduce
the known asymptotic properties of the
strong interaction. The free parameters in
these models are determined from a
comparison with experimental data.
2  0.2 s  0.3
Non-relativistic potential models +
Relativistic corrections + PQCD + LQCD
Hyperfine splitting of charmonium states
gives access to VSS component of quark
potential model
The c(21S0)
Belle
PDG 2008
M(c) = 3637  4 MeV/c2
(c) = 14  7 MeV
Diego Bettoni
Charmonium
36
The hc(1P1)
e  e    '   0 hc  ( )( c ) The ' decay mode is isospin violating
The CLEO experiment was able to find it with a significance
of 13 σ in ψ’ decay by means of an exclusive analysis.
The width and the BF ψ’→π0hc were not measured.
A similar analysis, with higher statistic, was also done by BES
0.10  0.13 0.18MeV /c 2
Center of gravity of P-states
High-mass Charmonia Parameters
3770
4040
4160
4415
Mass (MeV)
3772.0±1.9
4039.6±4.3
4191.7±6.5
4415.1±7.9
Γtot (MeV)
30.4±8.5
84.5±12.3
71.8±12.3
71.5±19.0
Γee (KeV)
0.22±0.05
0.83±0.20
0.48±0.22
0.35±0.12
Ping Wand, QWG 2008
The b(1S0) Bottomonium State
The ϒ(13S1) state of bottomonium was discovered in 1977.
The ground state spin-singlet partner, ηb(11S0), has been found only recently by the BaBar
Collaboration by studing (3S) →  b(1S) [PRL101,071801,2008]
Then confirmed in (2S) →  b(1S) [PRL103, 161801,2009]
The observation of the ηb is an important
validation of Lattice QCD predictions
Mass of the b(1S):
• Peak in  energy spectrum at
• Corresponds to b mass 9391.1±3.1 MeV/c2
• The hyperfine ((1S)-b(1S)) mass splitting is 69.9 ± 3.1 MeV/C2
Open Charm States
For the states c(u/d) theory and experiment were in agreement.
The quark model describes the
spectrum of heavy-light systems and
it was expected to be able to predict
unobserved excited DS(cs) mesons
with good accuracy
DS1
DS*
DS
B. Aubert et al., PRD74, 032007 (2006).
DS2
Open Charm States
The discovery of the new DSJ states has brought into question potential models
Two new states DS(2317) and DS(2460)
were discovered in e+e− → cc events,
then observed in B decays by Babar,
Belle and CLEO
DS(2317)
CLEO D (2460)
S
DS2
DS1
DS(2460)
DS(2317)
DS*
The identification of these states as
the 0+ and 1+ cs states is difficult within
the potential model
DS
Open Charm States
The discovery of the new DSJ states continued …
DS(2860)
DS(2860)
DS(2710)
DS2
DS1
DS(2460)
DS(2710)
DS(2317)
DS*
DS
Belle Collab, PRL 100 (08) 092001
Open Charm States
The assignment of the q.n. to the DS(2710) was possible thanks to an analysis performed by
BaBar studying DK, D*K final states.
DSJ(3040)
In the same analysis another broad
structure in the D*K distribution DSJ(3040)
DS(2860)
DS(2710)
DS2
DS1
DS(2460)
DS(2317)
DS*
There is a problem for the potential
models in describing excited states
DS
The XYZ States
Over past few years a wealth of new states has been discovered, mostly at the B-factories,
in the region above open charm threshold. These states are usually associated to charmonium,
because they decay into charmonium, but their nature is not at all understood.
B
B-meson decay
c
b
c
W−
Initial State Radiation

Xcc
e−
s
u,d
K(*)
u,d
X(3872) Belle, Babar, Cleo, CDF, D0
Y(3940) Belle, Babar
Y(4140)? CDF
Z(4430)
Z1(4050)
Belle
Z2(4250)
Associate production
e+e−⟶J/Ψ Xcc
e−
e+
J/Ψ
c
g

c
c
c
D(*)
D(*)
cc
e+

J/Y
1−− states
X(4008)? Belle
Y(4260) BaBar, Belle, Cleo
Y(4350) BaBar, Belle
Y(4660) Belle
X(3915) Belle
Z(3930) Belle
Y(4350) Belle
X(3940) Belle
X(4160) Belle
-collisions
e+
e+
*
*
e−
Xcc
e−


The X(3872) Discovery
New state discovered by Belle in the hadronic
decays of the B-meson:
BK (J/+-), J/µ+µ- or e+e-
M = 3872.0  0.6  0.5 MeV
 2.3 MeV (90 % C.L.)
 X (3872)   c1 
 0.89 (90% C.L.)
 
X (3872)    J / 
Diego Bettoni
Charmonium
45
The X(3872) Confirmation
BaBar
CDF
D0
Diego Bettoni
Charmonium
46
X(3872) Quantum Numbers
• Non observation in ISR (BaBar, CLEO) rules out JPC=1--.
• J/ decay implies C = +1.
• From J/ decay:
– Angular correlations (Belle and CDF) rule out 0++ and 0-+.
– Mass distribution rules out 1-+ and 2-+.
• D0D00 decay mode rules out 2++.
Most likely assignment is JPC=1++.
Diego Bettoni
Charmonium
47
What is the X(3872) ?
• If X(3872) is a charmonium state, the most natural hypotheses are
the 13D2 and 13D3 (1--) states. In this case the non-observation of the
expected radiative transitions is a potential problem, but the present
experimental limits are still compatible with these hypotheses. Ruled
out by quantum number assignments.
• The charmonium hybrid (ccg) interpretation has been proposed by
Close and Godfrey. However present calculations indicate higher
mass values (around 4100 MeV/c2) for the ground state. Absence of
J/ mode a potential problem.
• A tetraquark.
• A glueball.
• Due to its closeness to the D0D*0 threshold the X(3872) could be a
D0D*0 molecule. In this case decay modes such as D0D00 might be
enhanced. Most likely interpretation ?
Further experimental evidence needed: search for charged partners,
search for further decay modes, in particular the radiative decay modes.
Diego Bettoni
Charmonium
48
Y(4260) Discovery
New state discovered by BaBar
in ISR events:
e+e- ISR+-J/
Assuming single resonance:
M  4259  8 62 MeV / c 2
  88  23 64 MeV
JPC
=
1--


 e  e   Y , Y     J /  51  12  pb


Y
ee
 B (Y     J / )  5.5  1.0 00..78 eV
Diego Bettoni
Charmonium
49
Properties of Y(4260)
Confirmed by CLEO, CLEO III, Belle
Local minimum in e+e-  hadrons cross section.
No available vector state slot in charmonium spectrum
Diego Bettoni
Charmonium
50
Z(4430)+
R. Mizuk, La Thuile
Diego Bettoni
Charmonium
51
Z(4430)-
Diego Bettoni
QWG 2008
Charmonium
52
Z(4430)+
R. Mizuk, La Thuile
Belle confirms Z(4430) signal
Belle and BaBar data are not incosistent, but due to a different understanding
of the background the significance of the Z(4430) changes dramatically.
Diego Bettoni
Charmonium
53
The XYZ of Charmonium
• The Z(3931) is tentatively being identified with the c2(2P)
– Width too small ?
• The X(3940) is tentatively being identified with the c(3S)
– Width too large ?
• A lot of other states have been discovered whose interpretation is
not at all clear (X(3872), Y(3940), Y(4260), Y(4320) ...)
– missing cc states
– molecules
– tetraquarks
– hybrids
The situation above threshold needs to be fully understood.
Diego Bettoni
Charmonium
54
Baryon Spectroscopy
An understanding of the baryon spectrum is one of the primary goals of
non-perturbative QCD. In the nucleon sector, where most of the
experimental information is available, the agreement with quark model
predictions is astonishingly small, and the situation is even worse in the
strange baryon sector.
• In pp collisions a large fraction of the inelastic cross section is
associated to channels with a baryon-antibaryon pair in the final
state.
• This opens up the opportunity for a comprehensive baryon
spectroscopy program at PANDA.
• Example: pp  cross section up to 2 b, expect sizeable
population of excited  states. In PANDA these excited states can
be studied by analyzing their various decay modes e.g. , ,
K, K,  ...
•  baryons can also be studied, but cross sections lower by
approximately two orders of magnitude.
Baryons (cont’d)
In the quark picture hyperon pair production either involves the creation
of a quark-antiquark pair or the knock out of such pairs out of the
nucleon sea. Hence, the creation mechanism of quark-antiquark pairs
and their arrangement to hadrons can be studied by measuring the
reactions of the type pp  YY, where Y denotes a hyperon. By
comparing several reactions involving different quark flavours the OZI
rule, and its possible violation, can be tested for different levels of
disconnected quark-line diagrams separately.
Furthermore the parity violating weak decay of most ground state
hyperons introduces an asymmetry of the decay particles and gives
access to spin degrees of freedom for these processes. A systematic
investigation of these reactions will bring new information on single
and multiple strangeness production and its dependence on spin
observables.
Outlook and Conclusions
The future
The PANDA Experiment at FAIR
The Future
•
•
•
•
•
BES III at BEPC
Belle, SuperB, Belle 2
LHC
JLAB 12 GeV upgrade
PANDA at FAIR
The FAIR Complex
High-Energy Storage Ring
• Production rate 2x107/sec
• Pbeam
= 1 - 15 GeV/c
• Nstored =
5x1010
_
p
• Internal Target
High resolution mode
• dp/p ~ 105 (electron cooling)
• Lumin. = 1031 cm2 s1
High luminosity mode
• Lumin. = 2 x 1032 cm2 s1
• dp/p ~ 104 (stochastic cooling)
D. Bettoni
PANDA at FAIR
60
PANDA Detector
Detector Requirements
•(Nearly) 4 solid angle coverage
(partial wave analysis)
•High-rate capability
(2×107 annihilations/s)
•Good PID (, e, µ, , K, p)
•Momentum resolution ( 1 %)
•Vertex reconstruction for D, K0s, 
•Efficient trigger
•Modular design
•Pointlike interaction region
•Lepton identification
•Excellent calorimetry
•Energy resolution
•Sensitivity to low-energy
photons
D. Bettoni
PANDA at FAIR
61
PANDA Physics Program
•
•
•
•
•
QCD BOUND STATES
– CHARMONIUM
– GLUONIC EXCITATIONS
– HEAVY-LIGHT SYSTEMS
– STRANGE AND CHARMED
BARYONS
NON PERTURBATIVE QCD
DYNAMICS
HADRONS IN THE NUCLEAR
MEDIUM
NUCLEON STRUCTURE
– GENERALIZED
DISTRIBUTION AMPLITUDES
(GDA)
– DRELL-YAN
– ELECTROMAGNETIC FORM
FACTORS
ELECTROWEAK PHYSICS
ArXiV:0903.3905
D. Bettoni
PANDA at FAIR
63
Conclusions
• Hadron spectroscopy is an invaluable tool for a deeper
understanding of the strong interaction and QCD.
• Considerable advancement in our knowledge of hadron
spectroscopy has been achieved over the past two decades thanks
to many experiments at hadron machines and e+e- colliders.
• For the near and medium term future first rate results are expected
from LHC and e+e- colliders (BES III, B-factories, Super B-factories).
• In the next decade the PANDA experiment at FAIR will take the
lead in hadron physics, exploiting p beams of unprecedented
quality to carry out high-precision, systematic measurements:
– Spectroscopy
– Nuclear Structure
A first version of the physics book has been completed, showing
that the final states of interest can be detected with good efficiency
and good background rejection.