the y(4260) at cleo

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


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


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)


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)


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


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


Observed & Predicted Spectra of Charmonium States

Y(4260) ? ?

No 1– cc slot for the Y(4260)

1S

2S

3S

4S


DD** threshold & the “Y(4260)”

4.28-mD

D** spectrum

M(J/) GeV

Single resonancedescribes data well

CLEOPreliminary


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


The CLEO-c Scan Dataset

ArbitraryNormalization

Luminosity 4170

4260

93K decays

1.8M decays

317K decays

3770


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


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


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


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)


J/ cross sections

Entire signal @4160consistent with tail of Y(4260)

(4040) signal?(3770) signal Y(4260) signals

Expected from BaBar resultPRD73 (2006) 012005


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


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(*)


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


Backup Slides


Observed & Predicted Spectra of Charmonium States

V(r)~log r Rosner & Quigg,Phys.Lett.B71:153,1977

Y(4260) ? ? !


No 1-- cc slot for the Y(4260)

42804280

X.H. Mo et al, hep-ex/0603024


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


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


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


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


Other Features

00J/


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


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


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

the y(4260) at cleo

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