1. Pentaquarks and New Hadron Spectroscopy at BaBar
XIth International Conference on Elastic and Diffractive Scattering:
Towards High Energy Frontiers
Pentaquarks and New Hadron Spectroscopy at BaBar
Stefania Ricciardi
on behalf of the BaBar Collaboration
May 15-20, 2005 – XVIIth Rencontres de Blois, Chateau de Blois, France

2. BaBar Data Set BaBar: e+e- experiment running at s=10.58 GeV [Y(4S)]
General purpose detector with excellent tracking and PID capabilities
2005 Run restarted
250 fb-1
recorded at Y(4S)
Large data set: 250 fb-1 so far
500 million B mesons from Y(4S) decay
850 million e+e-qq, q=u,d,s,c
(plenty of light mesons and baryons!)
In this talk, recent results on possible new states of matter:
1. pentaquarks
2. X(3872)
Blois, May 16th, 2005
Stefania Ricciardi

3. The Pentaquark Controversy
Observations of narrow states with exotic quantum numbers
Experiment
State
Production
Decay
Significance
LEPS
gC12
K+n
4.6 s
CLAS gd
5.2s gp
7.8s
SAPHIR
4.8s
COSY pp
K0sp
3.7s
JINR
Q5+
p(C3H8)
5.5s
SVD pA
5.6s
DIANA
K+Xe
4.4s
nBC nA
6.7s
NOMAD
4.3s
HERMES ed
5.8s
ZEUS ep
4.6s
NA49
Z5-- Xp H1
Q5c
D*p
5.4s
Also ~20 recent negative searches including a new
high-statistics CLAS result (presented at APS and DIS05)
Q5(1540)+ [uudds]
X5(1860)- - [ddssu]
Q5c(3100)0 [uuddc]
Blois, May 16th, 2005
Stefania Ricciardi

4. Pentaquark Searches at BaBar
1. Inclusive search in e+e- interaction
e+e- PX
Q5(1540)+  p K0s
X5(1860) - -  X- p X5(1860) 0  X- p+
Other possible new states decaying in LK,SK,pKs
2. Inclusive search in
electro- and hadro-production
(inner detector used as target)
Q5(1540)+  p K0s 10 S I3
High statistics and
high resolution searches!
Blois, May 16th, 2005
Stefania Ricciardi

5. e+e-  Q5+ X Search for Q5(1540)+  p K0s 123 fb-1 BaBar Q5(1540)+
preliminary
Q5(1540)+
mass
resolution
~2MeV
(MC HWHM)
No evidence
near 1540 MeV
98,000 Lc+
used to check MC
mass resolution
and efficiency
Blois, May 16th, 2005
Stefania Ricciardi

6. Q5+ Yield in p* bins Look for a signal in 500 MeV p* bins
p* = momentum of Q5+ candidate in Y(4S) rest frame
Fit signal in each bin with
2 fixed values of Q5+ width
Yields consistent with 0
BaBar
preliminary
Blois, May 16th, 2005
Stefania Ricciardi

7. e+e- X5- -X and e+e- X50X 2 displaced vertices: X-,L X50 X- p+
No evidence
at 1860 MeV
2 displaced vertices: X-,L
X50 X- p+
X- L p-
L pp-
X5- - X- p-
X- p+
X- p-
BaBar
preliminary
preliminary
Clear signal for known particles:
24,000 X(1530)0  X- p+
8, Xc(2470)0  X- p+
Blois, May 16th, 2005
Stefania Ricciardi

8. Other inclusive pentaquark searches
Inclusive search in LK, S0K, pKS
LK, S0K from X5-, X50, N5+, N50
pKS from S5+
No pentaquark signal observed
BaBar
preliminary
mass(LK-) GeV/c2
Blois, May 16th, 2005
Stefania Ricciardi
mass(LK+) GeV/c2
mass(LKS) GeV/c2

9. Pentaquark and baryon production rates
Branching fraction assumptions
BF(Q5+  pKS)~25%
BF(X 5- -  X- p-)~50%
Blue and red
lines to guide
the eye only
Total x-section 95%CL
G=1 MeV
G at UL on width
Q5+ + Q5-
<171 fb
<363 fb
X X 5++
<25 fb
<36 fb
BaBar
preliminary
BaBar preliminary
upper limits (95%CL):
Q5+ <1/8 baryon rate
X5-- <1/4 baryon rate
Q5+
X5- -
Blois, May 16th, 2005
Stefania Ricciardi

10. Hadro-production and electro-production
Hadro-production: interactions of hadrons produced in e+e- annihilation with detector material
Schematic plan view of interaction region
3GeV e+
electro-production:
off-beam e- and e+
with Be beam-pipe
9 GeV e-
off beam
off beam
Results can be compared
to fixed target experiments x z
different x and z scales
Blois, May 16th, 2005
Stefania Ricciardi

11. Inner detector tomography with pKs vertices
Dch wall
Support tube
Silicon Vertex Tracker
SVT
Be beam pipe
Spatial distribution of pKs vertices reproduces inner detector features
 Interactions of primary e or secondary particles with material
Blois, May 16th, 2005
Stefania Ricciardi

12. Q5(1540)+ results in electro- and hadro- production
Well defined Ks peak
All vertices electro-+hadro- production
Ks signal region
1540 MeV
230 fb-1
BaBar
preliminary
Ks sideband regions
No evidence p
Ks sideband K p
M(Ksp)
Blois, May 16th, 2005
Stefania Ricciardi

13. Q5(1540)+ results in electro-production
High intensity region at Y=0 due mainly to e+ and e- off-beam collisions with Be beam-pipe
1540 MeV
BaBar
preliminary
Ks signal
No evidence
Separate analysis for events selected in the Be regions at Y=0
Ks sideband
Blois, May 16th, 2005
Stefania Ricciardi

14. X(3872)
X(3872) J/yp+p-, solid evidence: observed by Belle, CDF, D0 and BaBar
Hard to interpret as missing cc state  new state of matter?
DD* molecule? suppressed production in B0 decays
4-quark state? 2 mass eigenstates for X(3872) with |Dm|>5 MeV
Recent results by BaBar:
An update of the exclusive search in B decays
B-  K- J/y p+p- to suppress background
X(3872) reconstructed in J/yp+p-
Measures product of BF: BF(BX(3872)K) x BF(X(3872)  J/y p+p-)
Inclusive search on the recoil of a kaon and reconstructed B
Measures absolute BF: BF(BXK)
Search in ISR
Search also for a charged partner X(3872)
Dzierba et al.
hep-ph/
Maiani et al.
PRD71:014028,2005
Blois, May 16th, 2005
Stefania Ricciardi

15. Exclusive reconstruction: BX(3872)K, X(3872) J/y p+ p-
244 fb-1 B+ B0
BaBar
preliminary
BaBar
preliminary
N=51±14
Significance = 6.9s
mX=(3871.3±0.6)MeV/c2
BF(B+XK+,X  J/y p+ p-)=
(8.5 2.3  0.8) x 10-6
N=8.4±4.5
Significance = 2.7s
mX=(3868.6±1.2)MeV/c2
BF(B0XK0,X  J/y p+ p-)=
(5.1  2.7  0.7) x 10-6
BaBar
preliminary
DM= mX(B+)-mX(B0) = (2.7±1.3) MeV/c2
0.15 < BF(B0XKs)/BF(B- XK-) 90%CL
Not at the stage yet to discriminate among models, but method promising..
Blois, May 16th, 2005
Stefania Ricciardi

16. Inclusive Search for BXK
X = hc, J/y, cc0,cc1,hc(2S), y(2S),y(3770),X(3872),.. K- ? 4S
Fully reconstruct one B
Look for a charged K in the rest of event
Plot and fit p*(K), p* = momentum in B rest frame
Measure the absolute BF(BXK) of any state in the recoil system
Blois, May 16th, 2005
Stefania Ricciardi

17. Kaon momentum spectrum
244 fb-1
BaBar
preliminary p*
X(3872) production smaller than other charmonium states  in conjunction with the measurement of the BF product sets a PRELIMINARY lower limit
BF(X(3872) J/y pp) 90%CL
Very clear J/y and hc
N (J/y) =
N (hc) = p*
Blois, May 16th, 2005
Stefania Ricciardi

18. Branching Fractions of BXK
Recoil X
y(2S)
y(3770)
All U.L. at 90%CL
BaBar preliminary
inclusive measurements
BaBar
exclusive measurements
Blois, May 16th, 2005
Stefania Ricciardi

19. Search for X (3872)± in B decays
Is X(3872)J/yr0  J/y (p+p-)?
If so IX(3872)= 1  Expect X(3872)-  J/yr-
If X(3872) belongs to I triplet and I is conserved in the decay
 BF(B X-K) ~ 2 BF(B  X0K)
Searched for B0 X-K+ and B- X-KS with X-  J/yr-
212 fb-1 B- B0
No evidence
Isovector hypothesis
excluded
[PRD RC 71, (2005)]
X(3872)-?
X(3872)-?
m(J/yp-p0)
m(J/yp-p0)
Blois, May 16th, 2005
Stefania Ricciardi

20. Search for X(3872) in ISR events
e+e- X(3872)g, X(3872)J/y p+p-
J/y mm
89fb-1
y(2S)
X(3872)
region
X(3872) could be seen if JPC=1—
Mass difference m(2m2p)-m(2m)
for events near the J/y mass
3.05<m(2m)<3.15 GeV
No signal
Set an 90% CL:
B(X(3872) J/y p+p-)  GX ee <6.2 eV
PRD71,052001(2005)
Blois, May 16th, 2005
Stefania Ricciardi

21. Summary Pentaquarks X(3872)
No evidence from high statistics inclusive searches in e+e- . Limits below expectations for baryons
No evidence of Q5+ from hadro- and electro-production.
X(3872)
Signal firmly established in exclusive B+ J/yppK+
Gaining statistical significance in B0 decays
inclusive search of cc states sets UL on absolute B+X(3872)K+ branching fraction
No evidence of a charged partner X(3872)±
No evidence of X(3872) in ISR production
Blois, May 16th, 2005
Stefania Ricciardi

22. Any question?
Blois, May 16th, 2005
Stefania Ricciardi

23. The BABAR Experiment at PEP-II
Electromagnetic Calorimeter
6580 CsI crystals
e+ ID, p0 and g reco
Instrumented Flux Return
19 layers of RPCs
m+ and KL ID
e+ [3.1 GeV]
Cherenkov Detector (DIRC)
144 quartz bars
K,p separation
Drift Chamber
40 layers
Tracking + dE/dx
Silicon Vertex Tracker
5 layers of double sided silicon strips
e- [9 GeV]
Blois, May 16th, 2005
Stefania Ricciardi

24. Comparison of BaBar e-Be with Q5+ electro-production
Zeus: ep epKsX
Hermes: e+d  KspX
S*(1480)?
Excesses
over our
mass distribution
would have lower
significance
M=1528 3 MeV
5.8 s
M=1522 3 MeV
4.6 s
Possible acceptance loss at low mass (PID requires proton |p|> 4.1 GeV/c)
Blois, May 16th, 2005
Stefania Ricciardi

25. Search for Q*++ in B decays
Predicted uuuds state
m= GeV
G=37-80 MeV
81 fb-1
Ref.: Ellis et al. JHEP0405:002,2004
Wu and Ma, PRD69,077501,2004
Walliser et al.,J.Exp.Theor.Phys (2003)
D.Borisyuk et al. hep-ph/
Not seen in pK+ scattering  G <15 MeV
This is first search in B decays
(89M B mesons)
B+ Q5*++p , Q5*++  pK+
Main backgrounds:
baryons from the continuum
B decays to charmonium
B+ X K+, X( pp)
X=hc,J/y,cc,y(2S)
Binning dependent on resolution 4*sigma where sigma 2->10 MeV as invariant mass increases
Average efficiency 17%
NO Signal observed, set branching fraction upper limits vs m(kp)
(width independent)
Blois, May 16th, 2005
Stefania Ricciardi

26. Charmed pentaquark
Blois, May 16th, 2005
Stefania Ricciardi