# Presentation: 368656

## The New Charmonium Resonances

*Robert N. Cahn*
*Lawrence Berkeley National Lab*
- April 2006 APS Meeting

## November Revolution (1974 version)

- 10 nb GeV

*Breit-Wigner*

*Area*

*Observe*

*Conclude*

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## (2S)J/ 

- Mark I - 1974-5

- e

- e

- 

- 

| tot | 281 keV |
| --- | --- |
| ee | 2.1  keV |
| +- | 89   keV |

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## (3770)

- Above threshold for

- Measure

- Measure area under curve.  Infer

- (3770) is mixture of 3S1 and 3D1.

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## (3770)J/

- BES (PL605B,63(2005)):
- CLEO (hep-ex/0508023):

- Photon energy (MeV)

- e+e-  (3686) 

- e+e-  (3770)

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## Discovery of Y(4260) by BaBar in e+e-J/+-ISR

- Initial-state radiation:

- Area under curve:
- BF(Y(4260) +-) x (Y(4260) ee)=5.5 1.00.8 eV

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## Where is Y(4260) in e+e- Cross Section?

- Peak in R plot=

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

- “peak” < 0.5 units

- Data from BES
- PRL 88,101803

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## Comparison of JCP=1-- Charmonia

|  | (3091) | (3686) | (3770) | Y(4260) |
| --- | --- | --- | --- | --- |
| tot(keV) | 91 | 281 | 24x103 | 92x103 |
| ee(keV) | 5.4 | 2.1 | 0.26 | <0.27 |
| J/+-(keV) |  | 89 | 81 | >1.9x103 |

- Above charm threshold

- D-wave S-wave mismatch?

- Really big?

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## BaBar: B-Y(4260)K-?

- BF(B-K-Y(4260), Y(4260) J/+-)<2.9x10-5  90% CL

- PRD73,011101(2006)

- combinatorial

- combinatorial +peaking

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## CLEO Results on Y(4260)

- hep-ex/0602034

- Consistent with:
- BaBar cross section
- I=0 [also no J/0]

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## CLEO-III

- 11

- 5.1

- 3.7

- hep-ex/0602034; FPCP

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## Properties of Y(4260)

- JPC=1--
- I=0 if pure isospin
- Plausible tot(keV) = 90 MeV
- Plausible ee(keV) < 0.26 keV
- Implausible J/+-(keV) > 1.9 MeV

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## Compare ,  Systems

|  | (1S) | (2S) | (1D) | Y(4260) | (1S) | (2S) | (3S) |  (4S) |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| tot(keV) | 95.5 | 281 | 24x103 | 92x103 | 53 | 30 | 22 | 20x103 |
| ee(keV) | 5.7 | 2.1 | 0.20 | <0.27 | 1.3 | 0.62 | 0.45 | 0.25 |
| J/+-(keV) |  | 81 | 89 | >1900
 |  | 5.7 | 1.0 | <2.4 |
| M-M(1S) (MeV) |  | 589 | 673 | 1163 |  | 563 | 895 | 1120 |

- Some new CLEO values: hep-ex/0604025

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## Is it charmonium?

| Mass
(MeV) | State | (tot)
(MeV) | (e+e-)
(keV) |
| --- | --- | --- | --- |
| 3770 | 13D1 | 20 | 0.26 |
| 4040 | 33S1 | 52 | 0.75 |
| 4160 | 23D1 ? | 78 | 0.77 |
| 4260 | ? | 90 | <0.27 |
| 4415 | 43S1 | 43 | 0.47 |

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## BaBar, FPCP 2006

- Initial state radiation:

- Preliminary

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## Decays to Open Charm

|  |  |  |  |
| --- | --- | --- | --- |
| 13D1(3770) | 20 |  |  |
|  | 43 |  |  |
| 33S1(4040) | 0.1 | 33 | 33 |
|  | 0.1 | 33 | 33 |
| 23D1(4160) | 3.2 | 6.9 | 42 |
|  | 16 | 0.4 | 35 |
| 43S1(4415) | 0.4 | 2.3 | 16 |

- Predicted partial widths in MeV

- Eichten, Lane, Quigg
- PRD 73,014014 (2006)

- Barnes, Godfrey, Swanson
- PRD 72, 054026

*Important to measure DD*, D*D* !*

*No candidate with right mass.*

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## Conventional charmonium

- All likely c cbar states taken
_*Extra degrees of freedom are required*_
- Proper treatment includes mixing with continuum
*Eichten, Lane, Quigg [PRD 73014014(2006)*
- No immediate solution
- Reassign 4S to Y(4260)?
*Llanes-Estrada [PRD 72,031503(2005)]*

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## Bound States

- c+c- *[Qiao hep-ph/0510228] *
- Enhanced J/ ?
- Why Y(4260)J/KK?
- c  *[Liu,Zeng, Li PRD 72, 054023 (2005)]*
- Wrong isospin
- c  *[Yuan, Wang, Mo,hep-ph/0511107]*
- Why Y(4260)J/KK?
-                 *[Maiani et al., PRD 72, 031502 (2005)]*
- P-wave, expect

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## Hybrids: 

- Close & Page [PLB 628, 215(2005)]
- Assert Y(4260) contributes <1/8 unit R
- “The detailed production and decay signatures for hybrid states are still largely beyond the bounds of lattice QCD... In due course we anticipate that these results will be tested by the lattice.”
- Proximity to D**(2420, 1+)D(0-) threshold
- “...formation of D**D at rest may lead to significant rescattering into J/.” Deus ex machina!

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## Deus ex machinaFrom Wikipedia 

- Deus ex machina (god from the machine) is a Latin phrase that refers to an unexpected, artificial, or improbable character, device, or event introduced suddenly in a work of fiction or drama to resolve a situation or untangle a plot. The phrase has been extended to refer to any resolution to a story which does not pay due regard to the story's internal logic and is so unlikely it challenges suspension of disbelief; allowing the author to conclude the story with an unlikely, but more palatable ending. In modern terms the Deus ex machina has also come to describe a person or thing that suddenly arrives and solves a seemingly insoluble difficulty. While in storytelling this might seem unfulfilling, in real life this type of figure might be welcome and heroic.

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## Decay Pattern for Hybrid

- Close & Page:
- (Y(4260)D*D)=1-8 MeV, DD,DsDs, D*D*,Ds*Ds* smaller still.
- Prefer D*D, DD
- Similar position taken by
- Kou & Pene [PLB 631,164 (2005)]
- Early advocacy of hybrid Y(4260)
- Zhu [PLB 625, 212(2005)]

- R. Cahn - New Charmonium Resonances

- April 23, 2006

## What’s Needed Now

- Is Y(4260) single resonance?
- What are dominant decays of Y(4260)?
- DD? DsDs?
- Are there other decays to charmonium?
- What explains partial width to J/?

- Y(4260) is fundamental challenge to spectroscopy
- and dynamics.

- R. Cahn - New Charmonium Resonances

- April 23, 2006