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I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 1
The Y(4260) at CLEO
Y(4260) Discovery at BABAR
Y(4260) in ISR from s=10 GeV
PreliminaryDirect e+e-X J/ in charmonium region: Y(4260)
Coan et al., PRL 96 (2006) 162003.
Status of Y(4260)Open Charm
ConclusionsIan ShipseyPurdue UniversityFor the CLEO Collaboration
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 2
Y(4260) Discovery BABARPRL 95, 142001 (2005) e+e-→ISRY(4260),
Y(4260)+-J/ JPC=1- -
At a minimum in (e+e-→hadrons)
Why hasn’t this been seen before? (e+e- J/)
50 pb-1 at 4.26 GeV (based on ISR rate at BaBar)
R~0.05<<Error on e+e hadrons
June 06, Belle also see the
state at a 2.5sigma (35 MeV)
higher mass than BaBar,&larger width (Olsen, QWG2006)
233 fb-1
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 3
In 2005:BaBar observation of Y(4260) added another perplexing state to the charm region Proposed explanations mostly unconventional Y(4260) needed confirmation, Arguably most intriguing of XYZ’s, hybrid candidate?
1-- state: can be directly produced in e+e-
Two-pronged approach:Confirm/refute BaBar with RR’s from s=10 GeV Y(1S,2S,3S,4S) (CLEO III)Direct production at s=4.26 GeV (CLEO-c)
If confirmed, goal: limit theory explanations by measuring the pattern of decay modes
CLEO & Y(4260)
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 4
Like BaBar, search for/study
Y(4260) production in ISR
13.3 fb-1 of CLEO III Y(nS) data
Reconstruct ee and µµ decays of the J/ψ
Select ISR events by plotting the missing mass squared of the J/ψππ system
CLEO Y(4260) in ISR @s=10 GeV
(2S)
(2S)
Missing Mass2 (GeV2)
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 5
CLEO Y(4260) in ISR @s=10 GeV
CLEOPreliminary
M() consistent w/S-wave,no structure, This & ISR production verifies
vector nature of state
Note very low bgd:
hermeticity in the c.m.
M() (GeV)
Y(4260)
NEWbinned likelihood fit to single Breit-Wigner convoluted with MC determined resolution & linear background
5.24.2
+17-16
+40-25
( (4260)) 14.1 4 MeV
(Y(4260)) = 4283 4MeV
(Y(4260)) = 70 5MeV
N Y
M
M Γ dominant syst: cut variations
4.9σ significance CLEOPreliminary
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 6
Comparison to other experiments
CLEOPreliminary
Y(4260)+5.2-4.2
17 +2 +1116 -6 -5
+40 +6 +13-25 -4 -6
CLEO BABAR Belle
N 14 (4.9 ) 125 23( 8 ) 165 24( 7 )
M 4283 4 4259 8 4295 10 MeV
= 70 5 88 23 133 26 MeV
Single resonance describes data wellCLEO consistent with both BaBar & Belle
BABAR
BellePreliminary
BABAR-Bellediffer by 2.6sigma for massbut bracketCLEO
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 7
Observed & Predicted Spectra of Charmonium States
Y(4260) ? ?
No 1– cc slot for the Y(4260)
1S
2S
3S
4S
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 8
DD** threshold & the “Y(4260)”
4.28-mD
D** spectrum
M(J/) GeV
Single resonancedescribes data well
CLEOPreliminary
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 9
Direct Production @ s=4260
Modes:+- J/00 J/ J/K+K- J/0 J/’ J/+-0 J/+- (2S) (2S)+-
Using the following intermediate decays:
• J/+-, e+e-
, +-0
’ +-, +- (2S) +-, e+e-, +-J/ K+K-
• Suite of channels motivated by the proposed theoretical scenarios.
• Open charm modes crucial & in progress
…may prove crtical to reveal the nature of the 4260 Very wide range of decay mode (16) examined @CLEOc
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 10
The CLEO-c Scan Dataset
ArbitraryNormalization
Luminosity 4170
4260
93K decays
1.8M decays
317K decays
3770
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 11
Build on previous analysis
Recall (3770)XJ/:
• Plot k=missing momentum (radiative photon energy)
• Small signal at k=0 [direct (3770) decay]
• Huge peak corresponding to (2S), (2S) XJ/ (radiative return, “RR”)
• Direct & RR’s very well separated
• RR leaks into the k=0 region
• #RR’s ee[(2S)] : predictable
RR’s to (2S) peak
(2S) Tail
k, Missing Momentum (MeV)
Direct decay
RR’s to (2S) peak
(2S) Tail
k, Missing Momentum (MeV)
Direct decay Adam et al., PRL 96 (2006) 082004
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 12
Y(4260) direct: Large k: e+e- (2S)
3770 anchorpoint: ee[(2S)]
Agreement within 3% stat error: We understand our selection, efficiencies, & normalizations
TheoreticalRR-to-(2S) cross section
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 13
Now focus on k0
•Almost pure signal •Confirms Y(4260) ISR analyses•CLEO adds 00J/, & K+K- J/
~35 net evt11
~7.7 net evt5.1
3 net evt3.7
Backgrounds from J/ sidebands& RR’s to (2S) tail near k=0 are small!
CLEO s=4260 data
All other final statesexamined produce ULs
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 14
Results@s=4260 MeVChannel (%) Nsig Nbgd (pb) B/B(+- J/)+- J/ 38 37 2.4 58+12
-104 1
00 J/ 22 8 0.3 23+12-81
0.39+0.20-
0.150.02
K+K- J/ 21 3 0.07 9+9-5 1
0.15+0.10-
0.080.02 J/ 16 5 2.7 <32 <0.60 J/ 22 1 <12 <0.2’ J/ 11 0 1.5 <19 <0.3+-0 J/ 22 0 <7 <0.1 J/ 6 1 <44 <0.8+- (2S) 19 0 <20 <0.3 (2S) 15 0 <25 <0.4c0 9 11 11.5 <234 <4.0c1 26 1 3.3 <30 <0.5c2 27 4 3.3 <90 <1.6+-0 c1 9 0 <46 <0.8+-0 c2 9 0 <96 <1.7+- 18 7 5.5 <5 <0.1
+- : <0.102 BaBar(prelim: hep-ex/0605086)
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 15
J/ cross sections
Entire signal @4160consistent with tail of Y(4260)
(4040) signal?(3770) signal Y(4260) signals
Expected from BaBar resultPRD73 (2006) 012005
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 16
Mass Spectrum
• Plot shown is efficiency-corrected• No f0(980) or f0(600) []• Slightly softer than (2S)-like MC spectrum
• Data: disfavors Y(4260) as oddball (3g glueball) [ big rate]. (4S) 3S = (4040) should have a large +-J/ partial widthcJ 0 molecule (no decay into 00J/) or baryonium(tiny KK J/)
• Hyrbid and tetraquark remain possibilties open charm
s=4260 MeV DataMC
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 17
Open Charm@4260Hybrid charmonium YD1D, D1’ D(D*) D2-body open charm decomposition crucial to finding a D1D enhancement from Y(4260) hybidDsDs tetraquarkTotal charm cross section at 4260 4 nbBut +-J/ is 50pbNeed to understand open charm decomposition at ~1% levalDifficult to distinguish from multibody production, e.g. D*D, D*D* ! Tools: P(D0), angles, lower s?
s (GeV)
D0 Momentum (GeV/c)
D0D0
D*D
D*D* D*DD*D*
D1D ?
Total Hadronic Cross Section
Sum of 2-Body Exclusive D(*)D(*)
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 18
Conclusions4.9 evidence for Y(4260)+-J/ in ISR from s=10 GeV data: M, consistent w/BaBar & Belle
Direct e+e-Y(4260) studies @ s=4260 MeV Signals: +- J/ (11), 00 J/ (5.1), & K+K- J/ (3.7) (+-J/) BaBar expectation M() shows no structure [ no f0(980) or f0(600) ] B[(4040) +- J/]<0.4% & B[ (4160) +- J/ ]<0.4% Limits placed on 12 other charmonium decay modes &
+- Data provides no support for Y(4260) as glueball, (4S),
cJ 0 molecule, or baryonium Hybrid interpretation has not been excluded
Y(4260)open charm under study: a challenging analysisThere is a new spectroscopy in the 4 GeV energy region- together
with precision D CKM physics (decay constants and form factors) andsearches for new physics in DCPV, Dmix and Drare the new charmspectroscopy is one more reason why charm is important again
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 20
Observed & Predicted Spectra of Charmonium States
V(r)~log r Rosner & Quigg,Phys.Lett.B71:153,1977
Y(4260) ? ? !
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 21
No 1-- cc slot for the Y(4260)
42804280
X.H. Mo et al, hep-ex/0603024
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 22
Datasets
ECM(MeV) L (pb-1) ECM(MeV) L (pb-1)
3773 281 4120 2.83970 3.9 4140 4.93990 3.4 4160 10.24010 5.6 4170 554015 1.5 4180 5.74030 3.0 4200 2.84060 3.3 4260 13.2
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 23
Selection & Backgrounds
J/l+l-: e & ID, bremm recovery, ~3 dilepton mass cutRequire event missing momentum consistent with zero within ~2.5 No missing particles!
Background: e+e- J/ with conversion Require M()>400 MeV
e+e- (2S) J/ Calibrate rate with radiative returns to peak of (2S) Breit-Wigner Will occur at a fixed missing momentum at each Ecm Tail of (2S) Breit-Wigner: (2S) J/ (no missing mom)
Looks just like signal, dead-reckon with theoretical calculation
e+e- , KK, eeee, ee, ee Will satisfy kinematics! (Corollary: Will do so for any “M(J/)”.) Subtract statistically with WIDER “Fake M(J/) Sidebands” around
2.9 & 3.3 GeV instead of 3.097 GeV 20x size of +- window ~5x size of 00 window 30x size of K+K- window 12x size of window
Naïve scaling by window size cross-checked by counting yields in signal and sideband windows in background MC
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 24
KK J/
Kinematically allowed for Ecm>4085Babar sees no signal
K/
Sep
ara
tion
(#) Our selection requires at
least one of kaon candidatesto have p=0.2-0.5 GeV/c & Kaon ID consistency @<3.
All 3 of our events have BOTH kaons id’d.
2 events in the 30x sidebands:3 evt, 0.07 bgd:3.7 significance
MC predictionfor K/ separationusing dE/dx
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 25
Systematics
Sources: tracking, lepton ID, particle ID,
mass window cuts, k window cuts: conservative estimates lead to 5-10% in all modes
Background subtraction: (2S) ~5%Fake J/ subtraction (sidebands): smaller than (2S
Statistical errors:16% (J/ at 4260) or larger
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 27
What’s knownBaBar observed 8 effect in radiative returns
e+e- Y(4260) +- J/ AND 3.1 in B-K- Y(4260) K- +- J/
50-90 MeV wide, 1 or several peaks Predict 50 pb cross section for
direct e+e- Y(4260) No signal in two-photon
production
No official comment from Belle
BKY(4260)
8
3.1
Aubert et al., PRL 95 (2005) 142001.4.26Ecm
R
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 28
Theory (see Eichten talk & others to come)
How to create enhancement & simultaneously suppress of open charm ? Lengthy papers, which include review
Eichten, Lane, & Quigg, PRD 73 (2006) 014014; Swanson, hep-ph/0601110
Hybrid Charmonium (ccg): Enhanced rate for D1D; suppress D(*)D(*), Ds
(*)Ds(*); K+K-+-; 0 J/, +- should exist
Zhu, PLB 625 (2005) 142001Close & Page, PLB 628 (2005) 215Kou & Pene, PLB 631 (2005) 164
Tetraquark (cs)(cs): member of nonet along with X(3872) & X(3940). Must decay into DsDs.
Maiani, Riquer, Piccinini, & Polosa, PRD 72 (2005) 031502
Zhu points out could be a scalar tetraquark (uu+dd)cc but if so then should also observe isovector partner Y’(4260)+-0 J/
cJ 0 molecule : no decay into 00J/Liu, Zeng, & Li, PRD 72 (2005) 054023
I. Shipsey Hadron Spectrscopy and Exotics ICHEP06 7/28/06 29
Theory (cont’d)
cJ molecule : 00/+- 0.5; Y(4260)cJ J/, Y(4260)+-0 J/Yuan, Wang, & Mo, PLB 634 (2006) 399
Baryonium (tiny KK J/; visible (2S) & D*D*; suppressed DD)
Qiao, hep-ph/0510228v1, v2
Conventional 4S cc (s-d interference suppresses open charm)
Llanes-Estrada, PRD 72 (2005) 031503
Oddball (3g glueball) [ big rate] 3S = (4040) should have a large
+-J/ partial width
Coupled channel signal: non-exotic Ds
*Ds, D*D*, Ds*Ds
* P-wave channels together create
Y(4260)Beveren & Rupp, hep-ph/0605317v1