Transcript Some Issues in Meson Spectroscopy Crystal Barrel and B-Factory Experiences Stefan Spanier University of Tennessee, Knoxville Stefan Spanier, PHP 2008 Workshop, JLAB.

Some Issues in Meson Spectroscopy
Crystal Barrel and B-Factory Experiences
Stefan Spanier
University of Tennessee, Knoxville
Stefan Spanier, PHP 2008 Workshop, JLAB
1
• Introduction
• Scalars in D and B Decays
• Initial State Radiation
• Study of Charmonia
• The DSJ States
Stefan Spanier, PHP 2008 Workshop, JLAB
2
• Spectroscopy
s1
qq Mesons
2.5
Glueballs
2.0
1.5
2 +–
2 –+
1 ––
1– +
1 +–
1 ++
0 +–
0 –+
0 ++
Hybrids
2 –+
0 –+
2 ++
L
s2
S=1, L=0
+ gluon
exotic
nonets
1- + 1.9 GeV
_
4.4 GeV in cc
1.0
L=0
1
2
3
4
0++ 1.6 GeV
Stefan Spanier, PHP 2008 Workshop, JLAB
Lattice QCD
3
• Access to gluon rich states in pp Annihilation
For Hybrids, the angular momentum in the flux tube transfers to one
of the daughter mesons (L=1) and (L=0) meson.
L=0: ,,,,…
L=1: a,b,h,f,…
 1b1,f1,,a1
1(1400)
  p   p
 p  n

0
pn    
0 0
pp    
pp  4

0
 not preferred.
E852: a2(1320) dominates + P-wave resonance
VES : resonances; also just phenomenolog. Bkg
t-channel exchange (‘s’-pole) [PRL 91(2003)092002]
E852: m~1260MeV  lower (m=1370MeV in diff.)
VES : a2(1320) dominates; no 10
CBAR: I(1(1400)) ~ I(a2(1320)); S=1 initial state
CBAR: 2% content; 1S0 initial only; or S=1, FSI
CBAR+OBELIX:  resonance from S=0 initial state
 Exotic waves? Resonances?
Stefan Spanier, PHP 2008 Workshop, JLAB
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• Kaon Identification with the BaBar DIRC
Stefan Spanier, PHP 2008 Workshop, JLAB
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• Scalars are special
 non-perturbative QCD (meson spectrum)
 quantum numbers 3P0 (vacuum)
Compare to
1+
2+
too many / heavily shifted !
As states are mixtures:
_
_
_ _
ann + bss + cqqqq + dglue +
Experiment:
- broad states
- often covered by tensors
- featureless decay angle distributions
Decay obscures quark content
need to study production
and decay
Stefan Spanier, PHP 2008 Workshop, JLAB
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• Formalism for X  3 body
(Dalitz plot analysis)
 assuming dominance by 2-body interaction (isobar model)
 scalar resonances strongly overlap / decay channels open
Dynamic amplitude not just a simple Breit Wigner
- Analytic
- Unitary (2-body subsystem)
- Lorentz-invariant
K-matrix formalism widely used:
production / decay
2-body scattering
a
c
c
R
R
l
b
d
 = 2-body PS
L
d
T=RK
R = (1-iK)-1
l
l
in vicinity
Spectator ?
F=RP
=QT
P-vector
Q-vector
• Watson theorem: same phase motion in T and F in elastic range
• Adler zero: at m 0 for p=0: T = 0 near threshold; also/where for F ?
• Resonance: = pole in unphysical sheet of complex energy plane
Stefan Spanier, PHP 2008 Workshop, JLAB
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• Scalars in D, DS, and B Decays
• Initial state is single, isolated particle with well defined JB,D=0, JDs=1
• Decay-operators have simple lorentz and flavor structure
• Short range QCD properties are known (better)
• Weak decay defines initial quark structure; and rules (e.g. DI=1/2)
• Large variety of transitions to different flavor and spin states with
large mass differences of the constituent quarks
- combined/coupled channel analyses
- isospin relations (simple BF measurements)
- semileptonic decays (true spectator, form factors)
• Access to higher mass scalar states in B (?)
• Input for B CP – physics
- add penguin modes for New Physics Search, e.g. B0  f0 K0
- CP composition of 3-body modes, e.g. B0K0K+K- hadronic phase for CP angle g in BDK from D-Dalitz plot
Stefan Spanier, PHP 2008 Workshop, JLAB
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• Experiments
• E791
• Focus
• BaBar
• Belle
• CLEO-c
-(500 GeV) [Pt, C]  charm
gBrems [Be]  charm
e+e-
_
 qq @ Y(4S)
_
e+e  y(3S) DD


2008
> 2008
281pb-1
B-factories are also D-factories:
In each expect
>> 2 Million of
+
D0 K-+
c.c.
BaBar
– E791 - 35,400 1
– FOCUS - 120,000
– CLEO-c - D0K-+ : 51,200 3
2
91fb-1
_
> 500 Million BB pairs
_
took more than 10BB / sec
1. E791 Collaboration, Phys.Rev.Lett. 83 (1999) 32.
2. Focus Collaboration, Phys.Lett. B485 (2000) 62.
3. CLEO-c: hep-ex/0512063.
Stefan Spanier, PHP 2008 Workshop, JLAB
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• I=1 Scalar
97.3% purity
Data:
a0(980)
K*(892)
in D decays
D0K0S+ -
f(1020)
#92935
BaBar ~100fb-1
D0K0SK+K#13536
BaBar
BaBar
f0(980)
(770)
a0(980)
a0(980)
f0(980)
Efficiency:
Stefan Spanier, PHP 2008 Workshop, JLAB
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• I=1 Scalar
a0(980) / a0(1450)
Flatte formula:
5 parameters
e.g. F1 : X   ( )
F2 : X   (KK)
b0  fixed by total BF
 couplings gi (also tune lineshape)
Production amplitude2
Scattering amplitude
  
Stefan Spanier, PHP 2008 Workshop, JLAB
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a0(980)
• Moment analysis
in D decays
 only S and P waves
• Extract S-wave and describe Flatte’ formula
with Crystal Barrel parameters
[Abele et al., PRD 57, 3860 (1998)]
 Fix m0 and coupling g, but float gKK
 Best description of S-wave from moments
and floated in PWA inconsistent with CBAR:
BaBar: gKK = 473 + 29 + 40 MeV1/2
CBAR: gKK = 329 + 27 MeV1/2
 need coupled channel analysis with
_
D0 K0  
BaBar
weight/ 5 MeV/c2
• I=1 Scalar
D0K0SK+K-
f(1020)
DP projection
• PWA needs ~3% contribution from higher mass
resonance tail (outside PS)
 assume f0(1400) ; uniform distribution worse
 what about a0(1450) ?
Stefan Spanier, PHP 2008 Workshop, JLAB
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• I=1 Scalar
a0(980)
in B decays
In 9 fb-1 @ Y(4S) CLEO finds:
CLEO
[PRL 93 (2004) 111801]
# (155 + 22) events
Main contribution from a0K0S;
also a2(1320)K0S, K*(892), K0*(1430)
_
B(D0 K0 0  ) = (1.05 ± 0.16 ± 0.14 ± 0.10) %
Stefan Spanier, PHP 2008 Workshop, JLAB
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• I=1/2 Scalar
K Scattering LASS
Data from:
• Most information on K-+ scattering comes from the
LASS experiment (SLAC, E135)
• Disentangle I=1/2 and I=3/2 with K++
K-p K-+n
and
K-p K0-p
[NPB133, 490 (1978)]
NPB 296, 493 (1988)
Phase (degrees)
150
Pennington
ChPT compliant
100
50
0
LASS parameterization
-50
0.7
0.9
1.1
1.3
MK (GeV)
1.5
0.7
0.9
1.1
MK (GeV)
1.3
1.5
K’ threshold
No data below 825 MeV/c2
• use directly in production if re-scattering is small
• require unitarity approach …
Stefan Spanier, PHP 2008 Workshop, JLAB
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• I=1/2 Scalar
LASS experiment used an effective range expansion to
parameterize the low energy behaviour:
q cot d =
1
___
a
K =
2+ab
q2
2
K-1 =  cot d
Turn into K-matrix:
am
___________
+
d: scattering phase
a: scattering length
b: effective range
q: breakup momentum
2
b
q
______
+
g0
__________
m0 –
2
m2
and add a_ pole term
(fits also pp annihilation data)
Both describe scattering on potential V(r) (a,b predicted by ChPT)
Take left hand cuts implicitly into account
 Instead treat with meson exchange in t- ( ) and u-channel (K* )
[JPA:Gen.Phys 4,883 (1971), PRD 67, 034025 (2003)]
 only K0*(1430) appears as s-pole
  (K*) exchange important for S-waves in general % kappa ?
Stefan Spanier, PHP 2008 Workshop, JLAB
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• I=1/2 Scalar
D+  (K-+) m+ nm
FOCUS
Reconstructed events: ~27,000
W+
c
D+
DI=1/2 ?
s
K+
• K system dominated by K*(892)
• Observe ~15% forward-backward
asymmetry in K rest frame
• Hadronic phase of 45o corresponds to
I=1/2 K wave measured by LASS
required by Watson theorem in semileptonic
decay below inelastic threshold
• S-wave is modeled as constant
(~7% of K*(892) Breit-Wigner at pole).
a phase of 90o would correspond to a
kappa resonance, but …
Study semileptonic D decays
down to threshold ! [PLB 621, 72 (2005)]
Stefan Spanier, PHP 2008 Workshop, JLAB
[PLB 535, 43 (2002)]
16
• I=1/2 Scalar
W+
D+
+
E791
Fit with Breit-Wigner (isobar model):
KK-
+

D+
+
+
W+
A
 K-++
~138 %
c2/d.o.f. = 2.7
~89 %
c2/d.o.f. = 0.73
#15090
C
K*(892)
K*(1430)
[PRL 89, 121801 (2002)]
unitarity
Mk = (797  19  42) MeV/c2
Gk = (410  43  85) MeV/c2
Stefan Spanier, PHP 2008 Workshop, JLAB
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• I=1/2 Scalar
E791
Fit with Breit-Wigner + energy-independent fit to K S-wave
(P(K*(892), K*(1680)) and D-waves (K*2(1430))act as interferometer)
Model P- and D-wave (Beit-Wigner),
S-wave A = ak eifk bin-by-bin (40)
Phase
S wave
0.75
1.5
M(K) / GeV/c2
Compares well with BW Isobar fit
Stefan Spanier, PHP 2008 Workshop, JLAB
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• I=1/2 Scalar
E791
[Edera, Pennington: hep-ph/0506117]
… but differs from LASS elastic scattering
• Quasi-two body K interaction
(isobar model ) broken ?
if not
• Watson theorem does not apply ?
-75o
K’ threshold
• Isospin composition
I=1/2 % I=3/2 in D decay
same as in K  K ?
Q-vector approach with Watson:
if not
|FI |
A(s) eif(s) = F1/2(s) + F3/2(s) , s = mK2
I
FI(s) = QI(s) T11 (s) eibI
s – s 0I
 T11 from LASS ( same poles ?)
 Constraint: Q smooth functions
 Adler zero s0I removed
Stefan Spanier, PHP 2008 Workshop, JLAB
big !
19
D+  -++
• I=0 Scalar
Focus/E791
• E791: BW fit + s(500)
ms = (478 24  17) MeV
Gs = (324  42  21) MeV
• FOCUS: use K-matrix A&S
(no s pole)
~ 1680 events
m() GeV
E791
f0(980)
Extract S-wave phase d(s)
from left-right
asymmetry in
f2(1270)
(770)
F = a sind(s) ei(d(s)+g)
f2(1270)
[PLB 633, 167 (2006)]
Stefan Spanier, PHP 2008 Workshop, JLAB
E791 fit
(s(500))
d (o)
Choose phase
from 4 solutions 
0.1
m132 (GeV2)
0.8
20
• I=0 Scalar
I=0  S-wave parameterization (several on market)
Anisovich, Sarantsev,
Au, Morgan, Pennington,
Eur. Phys. A16, 229 (2003)
Phys. Rev. D35, 1633 (1987)
5 pole, 5 resonance
4 pole, 2 resonance
f0(1500)
f0(980)
_
… from fits to data from scattering, pp annihilation, …
• f0(980) :
(988 – i 23) MeV
(1024 – i 43) MeV
describes f g (00)
• no s(500) pole, but feature included
• also with t (u) channel  (f2,..) exchange
[Li,Zou,Li:PRD 63,074003(2001)] (also I=2 phase shift)
_
Coupled channel for pp-annihilation into 3 neutral PS, 3x3 K-matrix finds pole at low mass
Stefan Spanier, PHP 2008 Workshop, JLAB
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DS + - +
• I=0 Scalar
FOCUS(#1475)
E791 (#848)
S-wave
f0+f0(1370)+NR
87%
K matrix,P vector*
f2(1270)
(1450)
10%
6%
FOCUS
(1450)
90%
phase ~0,; G(f0) = 44 MeV
(770)
20%
6%
6%
f2(1270)
f0(980)
* not sensitive to Adler zero

c

s
DS _
s
FOCUS

_
ss
flavor tag
Stefan Spanier, PHP 2008 Workshop, JLAB
22
• Charmless 3-body B Decays
Mode
Events
(1/fb-1 )
~140
D0→K+K- K0
B0→K+K-K0
~11
B+→+ K+
Belle
BABAR
B+→K+K- K+
Belle
~8
B0→0 K+
BABAR
~5
B0→+ K0
Belle
2005
~3
B0→K+K- K0
BABAR
2005
Dalitz
Plot
analysis
~2.5
B+→KSKS K+
~0.9
B0→00 K0
S
~0.5
B0→KSKS KS
~0.4
D0→K+K-K0
- B→odd # of K : penguin-dominated decays
- large phase-space, limited number of events
- Dalitz plot analyses at feasibility limit
Stefan Spanier, PHP 2008 Workshop, JLAB
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• Charmless
B Decay Reconstruction
Main background from continuum events:
Some standard discrimination variables:
Energy-substituted mass
BB
events
*2
mES = Ebeam
 pB*2
e+e  qq, q =  u,d, s, c
Energy difference
Event shape
*
ΔE = EB*  Ebeam
e + e   qq
events
 Likelihood fit
Stefan Spanier, PHP 2008 Workshop, JLAB
* = e+e- CM frame
24
• X(1500)
Is bump at 1.5GeV really f0(1500)?
- PDG: BF( f0(1500)→ )/BF( f0(1500)→KK ) ≈ 4
Belle
[PRD71]
- hard to assign a
small excess of
events in K
to f0(1500)
(770)
K+K+K-
K++
f0(980)
Belle
[hep-ex/0509001]
-events assigned
to f0(1370),
f2(1270)
K+K-KS
[hep-ex/0507094]
- f0(1500)
interferes with Swave background
constructively for
KKK,
destructively for
K ?
+KS
BABAR
[hep-ex/0507094]
[Minkowski,Ochs,EPJC
39,71(2005)]
Stefan Spanier, PHP 2008 Workshop, JLAB
25
• Initial State Radiation – ISR
e-
gISR
g*
hadrons
hadrons
e+
BaBar
e- (9 GeV)
e+ (3 GeV)
gISR
The radiative process effectively varies the CM
energy of the e+e- collider  access to
processes at energies below Y(4S)
If the ISR photon is detected in BaBar
the hadrons are found in opposite
direction
 Precision test of Standard Model
(hadronic vacuum polarization)
 Low mass particle spectroscopy
Stefan Spanier, PHP 2008 Workshop, JLAB
26
• ISR
BaBar
The hard photon must be detected and well measured:
- Eg > 3 GeV ( s < 4.68 GeV )
only directional information used in kinematic fit
- Acceptance ~ 10 – 15 %
polar angle range 30o – 150o
- BaBar runs an open trigger (lot of storage), high luminosity
e.g. visible cross section: e s(e+e-  m+ m- g ) ~ 1.2 pb





_
pp
 +  0
2+2, K+K- +,
K+K- + K+K- 00 , 2K+2K3+3 2+200 K+K-2+2
Most Recent results:
 K+K0 KSK+ K+K
   0  00
  +   0  0
 2+202+2  +0 +
PRD 73, 012005 (2006)
PRD 70, 072004 (2004)
PRD 71, 052001 (2005)
PRD 76, 012008 (2007)
PRD 73, 052003 (2006)
BaBar Preliminary
arXiv:0709.1988 (submitted to PRD)
BaBar Preliminary
arXiv:0708.2461 (submitted to PRD)
Stefan Spanier, PHP 2008 Workshop, JLAB
27

• e+e-  K+K-0 / KK / KsK
(g)
BaBar
232fb-1
KSK+ECM < m(J/y)
BABAR
4.6
Disentangle I=0 (f-like), I=1 (-like) components in Dalitz plot
Split at ECM = 2GeV into K*(892)K and K*2(1430)K dominated region
From interference find I=0 and I=1 K*K
Fit to K*(892)K, K+K- 0/ (f, no-f (symmetric DP)), f0, and f …
Stefan Spanier, PHP 2008 Workshop, JLAB
28
• e+e-  f0 / f
BaBar
Mass fits simultaneously to s(e+e-  K*K)
f’(1680)
f0
?
 ``
M= 1710 MeV
G = 325 MeV
BABAR
```
f’’
3.3s
f
BABAR
M= 2125 MeV
G = 60 MeV
2.5s
+K+K-+0
IG=0-
IG=1+
  f 0
OZI suppressed
’’’: consistent with dip in multi-pion data!
’’: m=1570 G=145 == C(1480) ? or (1700) ?
Stefan Spanier, PHP 2008 Workshop, JLAB
29
• Evidence for X(2175)
232fb-1
s (e+e  K + K  +  )
BABAR
K + K  + 
K + K  0 0
BABAR
(+10% f)
J /y
PS model
Very rich substructure
K*(892), K1(1270), K2*0(1430), K1(1400)
Select f0(980) + f(1020) from
invariant mass spectra
m = 2175 10  15 MeV
G = 58  16  20 MeV
Phys.Rev.D 76 012008 2007
Stefan Spanier, PHP 2008 Workshop, JLAB
ss ss ?
30
• Study of Charmonia at B-Factories
• Colour-suppressed (Y(4S)) bc decay
– Predominantly from B-meson decays
• e+e- annihilation/Initial State Radiation (ISR)
– e+e- collision below nominal c.m. energy
– JPC = 1--
• Double charmonium production
– Typically one J/y or y, plus second ccbar state
• Two-photon production
– Access to C = +1 states
Stefan Spanier, PHP 2008 Workshop, JLAB
31
• ISR Study of Charmonia
BaBar discovers peaks in Y(4260)J/y +- and Y(4320)y(2S)+
298fb-1
211fb-1
PRL 95, 142001 (2005)
PRL 98, 212001 (2007)
673fb-1
arXiv:0707:3699
States confirmed by Belle, in addition to
claims for two others
Too many JPC = 1—
No evidence for YD(*)D(*) from BaBar
or Belle (no f)
-
 difficult to accommodate as cc
Stefan Spanier, PHP 2008 Workshop, JLAB
32
• Study of Charmonia
< 2004
Stefan Spanier, PHP 2008 Workshop, JLAB
33
• The DSJ States - strange charmed mesons
• Ds*, Ds1(2536)+, Ds2(2573)+:
well known, but JP only
inferred (not measured!)
• Ds0*(2317)+, Apr. 2003:
unexpected observation of a
narrow resonance in BaBar
DsJ*(2860)
*
X(2690)
DsJ(2700)
• Ds1(2460)+, May 2003: CLEO,
BaBar observed a new
narrow resonance
Ds1(2460)
Ds0*(2317)
• DsJ*(2860)+, Jul. 2006: new
state discovered by BaBar
(2112)
• X(2690)+, Jul. 2006: broad
enhancement seen in BaBar
S wave
P wave
D wave
• DsJ(2700)+, Jul. 2006: new
state discovered by Belle
(== X(2690) ? )
Stefan Spanier, PHP 2008 Workshop, JLAB
34
• Summary
B-Factories are a rich source of mesons
in many production modes
Stefan Spanier, PHP 2008 Workshop, JLAB
35
• Ds0*(2317) and Ds1(2460) Update
• Discovered 4 years ago in e+e-  cc events ;
subsequently observed in B decays
• Ds0*(2317) and Ds1(2460) very well established and
known experimentally
– Masses and tight upper limits on widths
– JP: 0+ for Ds0*(2317) and 1+ for Ds1(2460)
– decay modes and branching fractions
• Interpretation of these new states still unclear!
– One possibility: identify these 2 states as the 0+ and 1+ cs states
• However strong difficulties within the potential model
– Other possibilities
• 4 quark states? DK molecule? D atom? Chiral symmetry?
Belle: Phys. Rev. Lett. 91 (2003) 262001
BaBar: Phys. Rev. D74 (2006) 032007
Belle: Belle-Conf-0461 (2006)
BaBar: Phys. Rev. D74 (2006) 031103
Stefan Spanier, PHP 2008 Workshop, JLAB
36
• DsJ*(2860): Another New State
240 fb-1
• Reconstruct from cc continuum: e+e-  D0(K-+,K-+0)K+X and
e+e-  D+(K-++)K0sX
D0(K-+)K+
D0(K-+ 0)K+
D+(K-+ +)K0s
p* > 3.5 GeV/c2
•
•
New state at 2860 MeV/c2! (fit with a Breit-Wigner)
Bump at 2690 MeV/c2? (better fit with a Gaussian than a Breit-Wigner)
Stefan Spanier, PHP 2008 Workshop, JLAB
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• DsJ*(2860) … and X(2690)
• Combining the 3 modes
Sum of 3 modes
– M = (2856.6 ± 1.5 ± 5.0) MeV/c2
– G = (47 ± 7 ± 10) MeV
– JP = 0+, 1-, 2+, …
X(2690)
bkg
subtracted
• Final state is DK, i.e. two pseudoscalars
DsJ*(2860)
• Interpretation of DsJ*(2860)?
– Radial excitation of Ds0*(2317)?
– cs with JP = 3-?
– cs with JP = 0+?
hep-ph/0606110
hep-ph/0607245
hep-ph/0608139
• Another structure at 2690 MeV/c2?
m(DK) GeV/c2
– M = (2688 ± 4 ± 3) MeV/c2
– G = (112 ± 7 ± 36) MeV
• Needs confirmation by other experiments or in other
channels…
BaBar: Phys. Rev. Lett. 97 (2006) 222001
Stefan Spanier, PHP 2008 Workshop, JLAB
38
• DsJ (2700) - a Different State ?
347 fb-1
• New resonance decaying to D0K+ discovered by Belle in
Belle: hep-ex/0707.3491
B+  D0(D0K+) : DsJ(2700)
• Same resonance as seen by BaBar in continuum, X(2690)?
– Mass and width consistent, same decay mode
• Study of B  D(*)D(*)K decays in BaBar
– Construct 8 DK + 8 D*K invariant masses
Summing all 8 DK modes
Summing all 8 D*K modes
Ds1(2536)
Phase space
Background
(generic MC)
Background
(generic MC)
• Enhancement observed around 2700 MeV/c2 in DK and D*K
• Full Dalitz plot analysis ongoing
Stefan Spanier, PHP 2008 Workshop, JLAB
39