# Presentation: 014192

## Recent (2S) and J/ results from CLEO

**Ψ****(2S) → XJ/****ψ**
**  ****J/****ψ****   →  ****l****+ ****l****- **
**Ψ****(2S) → baryon pair**
**Ψ****(2S) → multi-body hadrons**
**Ψ****(2S) → K****S****K****L**

**PANIC05, Santa Fe, NM**
**Oct 24 - 28, 2005**

**GuangShun Huang**
**Purdue University**
**(Representing the CLEO collaboration)**

- G.S.Huang, Purdue Univ.

## Charmonium

- G.S.Huang, Purdue Univ.

## CLEO-c detector

**B=1 Tesla**
**0.6% p @ 1GeV/c**
**2.2% E******** @ 1 GeV**
**5% E******** @100 MeV**
**Track 93% of 4****π**
**RICH 80% of 4****π**

**Data sets:**
**Ψ****(2S) (3686)    5.63pb****-1**
**Cont.  (3670) 20.70pb****-1**

- G.S.Huang, Purdue Univ.

## CLEO vs other experiments

**Ψ**(2S) in millions of resonance decays

| Detector | Magnetic field | p /p resolution at p=1 GeV |
| --- | --- | --- |
| CLEO-c | 1.0T | 0.5% |
| BES-II | 0.4T | 2.4% |
| C.Ball | 0 | -- |

| Detector | Calorimeter
crystals | E resolution at E=100 MeV | Number of inner segments (crystals) | Inner radius
(cm) |
| --- | --- | --- | --- | --- |
| CLEO-c | CsI(Tl) |   4.8 MeV | 7800 | 100 |
| C.Ball | NaI(Tl) |   4.8 MeV |   672 |   25 |
| BES-II | Sampling | 70    MeV |  |  |

- CLEO-c **Ψ**(2S) data sample is not the biggest in the world, but the detector is excellent (both tracking **and**  detection),
- and we also have a large continuum data sample.

- G.S.Huang, Purdue Univ.

## (2S)→X J/(1S)

- Hadronic transitions (X=,,):
-  BR((2S)→XJ/(1S)) needed in phenomenological models;
-  BR((2S)→  J/(1S)) often used as normalization;
-  BR((2S)→  J/(1S)) / BR((2S)→  J/(1S)) is sensitive to
- mu-md (isospin violation)
-  Previous ratio of BR((2S)→  J/(1S)) / BR((2S)→  J/(1S)) at odds with isospin symmetry (beyond amount of expected violation)
- Photon cascades (2S)→ cJ(1P) → J/(1S):
-  Serves as determination of BR(cJ (1P) → J/(1S))
- Inclusively measured BR((2S)→X J/(1S)):
-  *i* BR((2S)→X*i* J/(1S)) = BR((2S)→X J/(1S))inclusive
- a powerful check on validity of the measurements
-  Test if “12% rule” satisfied with inclusive decays

- G.S.Huang, Purdue Univ.

## Inclusive BR((2S)→X J/(1S))

- scaled continuum

- (2S)
- BW tail

- (2S)
- data

- (2S)
- continuum
- subtracted

- MC

- c0,2 → 
- 

- cut

- cut

- J/

- Inclusive
-  dilepton pairs:
- Electrons and muons identified with loose E/p cuts

- G.S.Huang, Purdue Univ.

## c2

**Exclusive ****BR(********(2S)→ ********cJ****(1P)→ ********J/********(1S))**

- Fully reconstructed events
-   → , →  suppressed by 250<p(J/)<500MeV, which corresponds to 227<m()<522MeV:
- Other experiments used direct cuts on m() *(they really didn’t have a choice)*
- In CLEO-c resolution of m()  calculated via p(J/→+-) is actually better than calculated via 

- c2

- c1

- c0

- G.S.Huang, Purdue Univ.

## Ψ(2S) → XJ/ψ Results

**Ψ****(2S) → XJ/****ψ**** Results**

- All PDG values are scaled by CLEO central values

- Best measurements in all modes
- Isospin symmetry restored in /
- Significantly higher BR(cJ (1P) → J/(1S))
- Phys.Rev.Lett94,232002(2005)

- G.S.Huang, Purdue Univ.

## B(J/l+l-) from Ψ(2S) → π+π-J/ψ 

- Used in determination of tot(J/) and ee(J/) from (e+e-→ J/→hadrons)
- Sensitive to the wave function at the origin: used to test potential models
** **
**In this analysis we use **
**Ψ****(2S) → ****π****+****π****-****J/****ψ**** and measure N(J/********l****+****l****-****)**** & N(J/********X) (determined from the inclusive ****π****+****π****-**** recoil mass distribution).**

-  **π****+****π****-****J/****ψ ****(J/****ψ**** → ****l****+****l****-****)**** **
**solid line: MC, points: data**

**M(****l****+****l****-****)**

**M****recoil**** **

**M****ππ**

**μ****+****μ****-**

**e****+****e****-**

- G.S.Huang, Purdue Univ.

## Results for J/ψ → e+e- and μ+μ-

***B*****(J/********e****+****e****-****) = (5.945********0.067********0.042)%, rel. 1.3%*****B*****(J/********+********-****) = (5.960********0.065********0.050)%, rel. 1.4%**
***B*****(J/********l****+****l****-****) = (5.953********0.056********0.042)%*****B*****(J/********e****+****e****-****)/*****B*****(J/********+********-****) = (99.7********1.2********0.6)%**

***             ******PDG***
***B*****(J/********e****+****e****-****) = (5.93********0.10)%,  rel. 1.7%*****B*****(J/********+********-****) = (5.88********0.10)%,  rel. 1.7%**

**PRD 71, 111103(R) (2005)**

- G.S.Huang, Purdue Univ.

## Ψ(2S) to light hadrons 

**The  branching fraction for ********(2S) decaying to light hadrons can be computed as the difference between unity and the branching fraction sum of all exclusive direct transitions measured in this work (and previous CLEO results).**
**That is:         ****1 ******** (****Σ*****B*****[********(2S)********J/********+h] **
**                         ******** ****(********(2S)******** ******** ********cJ**** and ********(2S)******** ********c****) **
**                         ******** ****dilepton branching fractions  **
**This yields **
***                 ******B*****[********(2S)********light hadrons] = (16.9********2.6)%.**** **
** ****To be compared with that of the J/********, **
***                    ******B*****(J/********light hadrons) = (86.8********0.4)%,**
**yielding a ratio of **
**                                    ****(19.4********3.0)%**
**which is ~ 2.2****σ**** above **
***                  ******B*****[********(2S)********l****+****l****-****]/*****B*****(J/********l****+****l****-****) = (12.7********0.5)%.**

- G.S.Huang, Purdue Univ.

## Hadronic decays of the ψ(2S)

- For the charmonium system (cc annihilation),
- decay rate  |(0)|2,
- Information on resonant vs. non-resonant in multi-body final states.
- Hints for S-D mixing between (2S) and (3770).
- PID with combined RICH-dE/dx information;
- Scale continuum data for non-resonant subtraction;
- Use scaled energy and/or resonant mass to isolate signal.

**Hadronic decays of the ****ψ****(2S)**

- PDG04

**_**

- G.S.Huang, Purdue Univ.

## Hadronic decays of the ψ(2S)

**Scaled energy for baryon anti-baryon**

**Scaled energy and resonant production in multi-particle hadronic decays**

- G.S.Huang, Purdue Univ.

## Results for Ψ(2S) → baryon anti-baryon

- NS = S(2S) - B(2S) - Bcf - f  Bc ,   Br=Ns/( N(2S))

- To be compared with ( 12.7  0.5 )%

- S=0
-    -1
-    -2
- J=3/2

**2 first observations**

**Phys. Rev. D 72, 051108(R) (2005)**

**First observation**

- G.S.Huang, Purdue Univ.

## Results for Ψ(2S) → multi-body

**13 first observations**

**Phys. Rev. Lett 95, 062001 (2005)**

- 12.7  0.5 ?

- G.S.Huang, Purdue Univ.

## The 12% rule: Qh= B((2S)h)/B(J/h)12%

- Reasonable agreement with the rule, in contrast to VP modes and +-0.

**Q****h****(%)**

**Q****h****(%)**

- G.S.Huang, Purdue Univ.

## Measurement of B (Ψ(2S) → KSKL)

**Measurement of ****B ****(*****Ψ******(2S) → K******S******K******L*****)**

**Reconstruct  ****K****S****→****π****+****πˉ**
**DO NOT reconstruct  ****K****L**
**Allow possible ****K****L**** signature**
**Veto ****π****0****; veto ******** outside**** ****K****L**** cone**
- Scaled energy of KS:
-      Xbeam= EKs / Ebeam
-     0.98 < Xbeam <1.02

***B******(******Ψ******’→ K******S****** K******L******)***** = (5.84 ± 0.80 ± 0.43)×10****-5****     ****!!!CLEO PRELIMINARY!!!**

***B******(******Ψ******’→ K******S****** K******L******)***** = (5.24 ± 0.47 ± 0.48)×10****-5****     **BES** **[PRL.92:052001,2004]

- G.S.Huang, Purdue Univ.

## Summary

**CLEO-c has made a variety of measurements  of  charmonium  transitions:   ****Ψ****(2S) → XJ/****ψ****, J/****ψ****→****l****+ ****l****-****, ****Ψ****(2S)→baryon pair, ****Ψ****(2S)→multi-body hadrons and ****Ψ****(2S) → K****S****K****L****.**
** **
**The results presented are part of a continuing detailed systematic analysis of charmonium decays by the CLEO collaboration. Most of the results are either first observations or of higher precision than previous measurements.**
**CLEO-c plans to continue running for the next few years in the charm region both for the bound states and for open charm meson production.**

- G.S.Huang, Purdue Univ.

## Backup slides

- G.S.Huang, Purdue Univ.

## Exclusive BR((2S)→ J/(1S))

-  → 

-  → 

**Exclusive BR(********(2S)→******** J/********(1S))**

- Fully reconstructed events:
- Energy-momentum conservation
- Dilepton mass and dipion-recoil mass consistent with J/

- G.S.Huang, Purdue Univ.

## Exclusive BR((2S)→ J/(1S))

**Exclusive BR(********(2S)→************ J/********(1S))**

- Fully reconstructed events
-   →  and 
-   → 

-  → + 

- G.S.Huang, Purdue Univ.

## N+- J/, J/X : Fitting Recoil Mass Spectrum

- +-(J/**X**):
-  pT>150 MeV/c, |cos|<0.83, m(+-)=400-600 MeV
-  Fit M(+--recoil) for NX
- M(+--recoil) uses only the pions, hence ~independent of what the J/ does.
- Efficiency is obtained by weighting a set of basis modes  to produce J/X mix.

- G.S.Huang, Purdue Univ.