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Bottomonium and Charmonium Results from CLEO PowerPoint Presentation

Bottomonium and Charmonium Results from CLEO

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### Bottomonium and CharmoniumResults from CLEO

The XLI Rencontres de Moriond

QCD and High Energy Hadronic Interactions

Outline

- The CLEO Detector
- Gee of the K(1S, 2S, 3S) Resonances
- Measurement of Gee(J/y), Gtot(J/y), Gee[y(2S)]/Gee(J/y)
- Measurement ofs(y(3770) hadrons) and Gee[y(3770)]
- Charmonium Decays of y(4040), y(4160) & U(4260)
- Summary

T. Ferguson

Carnegie Mellon University

T. Ferguson

The CLEO/CESR Experiment

CESR (Cornell Electron Storage

Ring) – Symmetric e+e- collider

with capability of running at

√s = 3-11 GeV

Located at Wilson Synchrotron

Laboratory in Ithaca, NY

CLEO and CESR have been

producing results in B, K, t, and

2-photon physics for almost 30

years

T. Ferguson

The CLEO detector

Inner Drift Chamber:

- 6 stereo layers
- 100 mm hit resolution
Drift Chamber:

- 47 layers
- 93% of 4
- Dp/p = 0.6% @ p=1.0 GeV
CsI Calorimeter:

- 93% of 4
- DE/E = 4% @ E=100 MeV
B field 1.0 T

Muon Chambers:

- 85% of 4
- Identify muons for p > 1 GeV
Particle Identification:

- RICH detector
- dE/dx in drift chamber
- Combined e (p or K) > 90%

T. Ferguson

Di-electron Widths of K(1S,2S,3S) Resonances

Di-electron widths (Gee) are basic parameters of any onium system. Their measurement can also test new unquenched lattice QCD calculations.

Precision of previously measured Gee:

- 2.2% for K(1S)
- 4.2% for K(2S)
- 9.4% for K(3S)

CESR scanned center-of-mass energies in the vicinity of the K(1S), K(2S) and K(3S) resonances.

Data below resonances to

constrain backgrounds

11 scans @ K(1S): ∫L dt = 0.27 fb-1

6 scans @ K(2S): ∫L dt = 0.08 fb-1

7 scans @ K(3S): ∫L dt = 0.22 fb-1

∫L dt = 0.19 fb-1

∫L dt = 0.41 fb-1

∫L dt = 0.14 fb-1

T. Ferguson

Di-electron Widths of K(1S,2S,3S) Resonances

Gee measurement method:

- Fit the hadronic cross-section and get
GeeGhad/Gtot.

- Correct for the missing leptonic modes.
Use Bmm to get Gee (assuming Bee=Bmm=Btt).

Main backgrounds:

- Two-photon events (e+e- e+e-X). ~ln s.
- Cosmic rays and beam gas interactions.
- Background from the high-energy tails of
the K(1S) and K(2S).

The figure shows the event yields as a function of Ecm in the K(3S) region.

Top points are data with the fit superimposed.

Dashed curve – the sum of all backgrounds.

The lower points and lines show the individual backgrounds.

T. Ferguson

Di-electron Widths of K(1S,2S,3S) Resonances

- Subtract cosmic ray and beam-gas backgrounds.
- Fit each resonance to convolution of:
- Breit-Wigner resonance including interference between K qq and e+e- qq

- Initial-state radiation

- Gaussian spread in CESR beam energy of (4 MeV)

- Background terms proportional to 1/s and ln(s)

- Statistical errors: 0.3% (K(1S)), 0.7% (K(2S)), 1.0% (K(3S)).
- Main systematic errors: luminosity measurement (1.3%),
hadronic efficiency (0.5%).

T. Ferguson

Di-electron Widths of K(1S,2S,3S) Resonances

PDG

% Error

% Error

Assuming Bee = Bmm gives:

Gtot[K(1S)] = 54.4 0.2 (stat.) 0.8 (syst.) 1.6 (sBmm) keV

Gtot[K(2S)] = 30.5 0.2 (stat.) 0.5 (syst.) 1.3 (sBmm)keV

Gtot[K(3S)] = 18.6 0.2 (stat.) 0.3 (syst.) 0.9 (sBmm)keV

T. Ferguson

Di-electron Widths of K(1S,2S,3S) Resonances

- Comparison with newest unquenched lattice QCD results,
- Most precise parameter =
- = 0.48 0.05 - Lattice QCD, A.Gray et al., Phys. Rev. D72, 094507 (2005).
- =0.514 0.007 – CLEO, J.L.Rosner et al., Phys. Rev. Lett. 96, 092003 (2006).

The final lattice QCD results are expected to have a few percent precision in Gee(nS)/Gee(mS) and

~10% in Gee(nS).

T. Ferguson

Measurement of Gee(J/y), Gtot(J/y), Gee[y(2S)]/Gee(J/y)

- Use data at y(3770), look for radiative
return events to J/y.

- Select m+m-(g) events with a
M(m+m-) = M(J/y).

- Resulting cross-section proportional to
Bmmx Gee(J/y).

- Divide by new CLEO Bmm (1.2% precision)
to get Gee(J/y).

- Assume Bee = Bmm,divide by again to get
Gtot(J/y).

R e s u l t s:

B(J/ym+m-) x Gee(J/y) = 0.3384 0.0058 (stat.) 0.0071 (syst.) keV

Gee(J/y) = 5.68 0.11 (stat.) 0.13 (syst.)keV

Gtot(J/y) = 95.5 2.4 (stat.) 2.4 (syst.)keV

T. Ferguson

Measurement of Gee(J/y), Gtot(J/y), Gee[y(2S)]/Gee(J/y)

- Using a recent CLEO measurement of Gee[y(2S)],
Gee[y(2S)] = 2.54 0.03 0.11 keV,we determine the ratio:

Gee[y(2S)]/Gee(J/y) = 0.45 0.01 (stat.) 0.02 (syst.)

G.S. Adams et al., Phys. Rev. D73, 051103 (R), (2006).

T. Ferguson

Measurement of s(y(3770)hadrons) and Gee(y(3770)

- Lead-Glass Wall (1977), Mark II (1981) measured
s(y(3770) hadrons) ~10 nb.

- Mark III (1988) using a double-tag technique measured
s(y(3770) DD) ~5 nb.

- Complete surprise since s(y(3770) non-DD)<<s(y(3770) DD).
- CLEO repeats Mark III measurement:
s(y(3770) DD) = (6.39 0.10 +0.17-0.08) nb.

Q. He et al., Phys. Rev. Lett. 95, 121801 (2005).

- So remeasure s(y(3770) hadrons) using:

Ny(3770) = number of observed hadron events from y(3770) decays.

ey(3770)= hadron event efficiency, = 80%.

Ly(3770) = integrated luminosity, = (281.3 2.8) pb-1.

T. Ferguson

Measurement of s(y(3770)hadrons) and Gee(y(3770)

Non-y(3770)is the observed number of hadronic events in the y(3770) data.

Nqq– number of the hadronic events from e+e- g* qq.

Ny(2S) / NJ/y &Nl+l-- number of hadronic events from y(2S) / J/y & from e+e-l+l-.

sy(3770) = (6.38 0.08 +0.41-0.30) nb

D. Besson et al., hep-ex/0512038

Significantly smaller than Lead-Glass Wall and Mark II measurements.

sy(3770) – sy(3770)DD= (-0.01 0.08 +0.41-0.30) nb

Consistent with only small s(y(3770) non-DD). Mystery solved.

- Using our s(y(3770) hadron) number and M and Gtot from PDG, get:

Gee (y(3770)) = (0.204 0.003 +0.041-0.027) keV

- Consistent with PDG value of 0.26 0.04.

T. Ferguson

Charmonium decays of y(4040), y(4160) & U(4260)

The region at center-of-mass energies above charmonium open-flavor production

threshold is of great theoretical interest due to its richness of cc states, the

properties of which are not well understood.

C. Quigg, J. Rosner, Phys. Lett. B71, 153 (1977)

U(4260)

V(r) = C ln(r/r0)

Main characteristics of states above open-charm threshold:

- Large total widths;
- Weaker couplings to leptons than the J/y and y(2S);
- Decays to closed-charm states are not favored.

Prominent structures in the hadronic

cross-section are the y(3770), the

y(4040) and the y(4160).

T. Ferguson

Charmonium decays of y(4040), y(4160) & U(4260)

B.Aubert et al., Phys. Rev. Lett. 95, 142001 (2005)

Mass: M = 4259 8 +2-6 MeV

Width: Gtot = 88 23 +6-4 MeV

Coupling: Gee x B(U(4260) p+p-J/y) =

5.5 1.0 +0.8-0.7 eV

JPC of U(4260) is 1-- since it is observed in ISR

U(4260) located at a local minimum of the

total hadronic cross-section.

BaBar finds enhancement in e+e- g(p+p-J/y). Not yet confirmed.

BaBar

Theory explanations of U(4260)

Hybrid charmonium (ccg): suppress D(*)D(*), Ds(*)Ds(*);

K+K- ≈ p+p-?; p0J/y? p+p-?

DD1 as another possible decay of the U(4260).

Tetraquark (cs)(cs): member of nonet along with

X(3872) & X(3940). Must decay into DsDs.

cCJ ρ0 molecule:no decay into p0p0J/y.

cCJ wmolecule:p0p0/p+p- ≈ 0.5;gcCJ, ggJ/y, gp+p-p0J/y.

Baryonium molecule:tiny KKJ/y; p0p0/p+p- ≈ 1.

y(4S) cc state: interference effects produce dip in open-

charm. y(4040) p+p-J/y.

R

Ecm

4260 MeV

T. Ferguson

Charmonium decays of y(4040), y(4160) & U(4260)

- To confirm and clarify U(4260), CLEO performed scan from √s = 3.97 – 4.26 GeV.
- Look for decays to 16 final states containing a J/y, y(2S), cCJ or f.

Scan regions:

- y(4040): ∫L dt = 20.7 pb-1 @ √s = 3.97-4.06 GeV
- y(4160): ∫L dt = 26.3 pb-1 @ √s = 4.12-4.20 GeV
- U(4260):∫L dt = 13.2 [email protected] √s = 4.26 GeV

Born-level Breit-Wigner line shapes between √s = 3.97

& 4.4 GeV indicating the grouping of scan points.

The radiative return (RR) process e+e- g y(2S) XJ/y

results in final states which are identical to some of our

signal modes.

This is one indication that our efficiencies, luminosities

and overall normalizations are understood.

T. Ferguson

Charmonium decays of y(4040), y(4160) & U(4260)

Data taken @ √s = 4.26 GeV.

Solid line histogram from MC simulation.

Efficiency corrected. Solid histogram

from y(2S)-like MC.

T. Ferguson

Charmonium decays of y(4040), y(4160) & U(4260)

- We confirm (@ 11s significance) the U(4260) p+p-J/y discovery.
- First observation of U(4260) p0p0J/y (5.1s).
- First evidence for U(4260) K+K-J/y (3.7s).
- We measure the following production cross-sections @ √s = 4.26 GeV:
- No compelling evidence is found for any other decays in the three resonance regions. We find:
- The observation of the p0p0J/y mode disfavors cCJρ0 molecular model.
- The fact that the p0p0J/y rate is about half that of p+p-J/y disagrees with the prediction of the baryonium model.
- Observation of the KKJ/y decay is also incompatible with these 2 models.
- No enhancement for y(4040) p+p-J/y. Identification U(4260) = y(4S) less attractive.
- The results are compatible with hybrid-charmonium interpretation.

s(p+p-J/y) = 58 +12-10 4 pb,

s(p0p0J/y) = 23 +12-8 1 pb,

s(K+K-J/y) = 9 +9-5 1 pb.

T.E. Coan et al., hep-ex/0602034

B(y(4040) p+p-J/y) < 0.4% and B(y(4160) p+p-J/y) < 0.4%

T. Ferguson

- Precise measurement of Gee for K(1S, 2S, 3S). Good agreement with unquenched lattice QCD result.
- Improved determinations of Gee and Gtot for J/y.
- New measurement of s(y(3770) hadrons) – mystery of a large
y(3770) non-DD cross-section solved.

- New measurements of closed-charm decays for the y(4040), y(4160) and U(4260):
- Confirm the BaBar discovery of U(4260) p+p-J/y.

- First observation of U(4260) p0p0J/y.

- First evidence of U(4260) K+K-J/y.

- Many CLEO heavy-quarkonium results not covered in this talk – see next slide.

T. Ferguson

Other Recent CLEO Heavy-Quarkonium Results

“Branching Fractions for y(2S) to J/y Transitions“, PRL 94, 232002 (2005);

“Measurement of the Branching Fractions for J/y l+l-“, PRD 71, 111103 (2005);

“Observation of Thirteen New Exclusive Multi-Body Hadronic Decays of the y(2S)“, PRL 95, 062001 (2005);

“Branching Fraction Measurements of y(2S) Decay to Baryon-Antibaryon Final States“, PRD 72, 051108 (2005);

“Observation of the hc(1P1) State of Charmonium“, PRL 95, 102003 (2005), PRD 72, 092004 (2005);

“Search for Exclusive Multi-Body Non-DD Decays at the y(3770)“, PRL 96, 032003 (2006);

“Measurement of the Direct Photon Momentum Spectrum in K(1S), K(2S), and K(3S) Decays“, hep-ex/0512061;

“Radiative Decays of the K(1S) to a Pair of Charged Hadrons“, PRD 73, 032001 (2006);

“First Observation of y(3770) gcc1ggJ/y“, hep-ex/0509030;

“Decay of the y(3770) to Light Hadrons“, PRD 73, 012002 (2006);

“Two-Photon Width of the cc2“, S. Dobbs et al., hep-ex/0510033;

“Experimental Study of cb(2P) ppcb(1P)“, PRD 73, 012003 (2006);

“Radiative Decays of the K(1S) to gp0p0, ghh and gp0h“, hep-ex/0512003;

“Observation of y(3770) ppJ/y and Measurement of Gee[y(2S)]”, hep-ex/0508023;

“Measurement of y(2S) Decays to two Pseudoscalar Mesons”, hep-ex/0603020;

“Search for the non-DD decay y(3770) KSKL”, hep-ex/0603026.

T. Ferguson

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