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Recent Charmonium Results from Ψ(2S) Decays at BESII. Changzheng YUAN IHEP, Beijing for the BES Collaboration. 2nd International Workshop on Heavy Quarkonium Sept. 20 – 22, 2003, Fermilab. BESII obtained 14 M (2S) events. Study of V T channels

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Recent Charmonium Results from Ψ(2S) Decays at BESII

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Recent Charmonium Results from Ψ(2S) Decays at BESII

Changzheng YUAN

IHEP, Beijing

for the BES Collaboration

2nd International Workshop on Heavy Quarkonium

Sept. 20 – 22, 2003, Fermilab


BESII obtained14 M

(2S) events

  • Study of V T channels

    inΨ(2S) decay

  • First observation of

    K0S K0LinΨ(2S) decay (and improved analysis of J/  K0S K0L )

  • First evidence of

      in cJ decay

14

1.5

01.11-02.3


pQCD rule and “ puzzle”

  • pQCD rule

    [the relation between J/ and (2S) ]

  • Violation was revealed by MARK-II ,

    confirmed by BES at higher sensitivity


VT Channel

  • BES-I results [PRL81(1998)5080]

    [PRD67(2003)052002]

† This value from DM2 only

12 % rule ( pQCD rule )

Suppressed!!


BES Preliminary

Ψ(2S)  V T

 f2

 

+–0 +–

+–+–0

 

 a2

  

 

 

+–+–0

 

Ψ(2S)

K* K*2

 

K K

K+K– + –

 f2'

 

K+K– KK

K+K–K +K –


Event Selection

Ψ(2S)  V T

  • Four charged tracks with net charge zero;

  • |cosθ|<0.80 for all tracks;

  • PartID using TOF+dE/dx

  • At least 2 photon candidates for π0 channels;

  • Remove ψ(2S) π﹢π﹣J/ψ background;

  • Kinematic fit (4C/5C), Prob>0.01.

χ2KF of ψ(2S) 5 π

Data/MC


BES Preliminary

Ψ(2S)  V T

M.C.

Data

B.G.(  )

f2 (1270)

B.G.(M.C.)


BES Preliminary

Ψ(2S)  V T

Data

M.C.

a2 (1320)

B.G.


BES Preliminary

Ψ(2S)  V T

Data

M.C.

K*(892)

K*2 (1430)

B.G.


BES Preliminary

Ψ(2S)  V T

M.C.

Data

f2'(1525)

f0(980)

B.G.


BES Preliminary

Ψ(2S)  V T


BES Preliminary

Ψ(2S)  V T

Systematic Errors (%)

*NO evidence of continuum production according to

study with a 6 pb-1 data sample at Ecm=3.65GeV.


BES Preliminary

Ψ(2S)  V T

† This value from DM2 only

12 % rule ( pQCD rule )

Suppressed!!


Ψ(2S)  KS KL

Theoretical Background

  • pQCD rule & Phase Study

B(2S) Ks K L

Phase


Ψ(2S)  KS KL

The Relative Phase

J/ψ Decays:

1. AP: 90 ° M. Suzuki, PRD63, 054021 (2001)

2. VP: (106 ±10) ° J. Jousset et al., PRD41, 1389 (1990)

D. Coffman et al., PRD38, 2695 (1988)

N. N. Achasov, talk at Hadron2001

3. PP: (90 ±10) ° M. Suzuki, PRD60, 051501 (1999)

4. VV: (138 ±37) ° L. Köpke and N. Wermes,

Phys. Rep. 74, 67 (1989)

5. NN: (89 ±15) ° R. Baldini et al., PLB444, 111 (1998)

ψ(2S)VP

1. φ=180 °(90 ° ruled out!)

M. Suzuki, PRD63, 054021 (2001)

2. φ=﹣90 ° or φ=180 °(with continuum amplitude)

P. Wang, C. Z. Yuan and X. H. Mo, hep-ph/0303144.


Ψ(2S)  KS KL

The Relative Phase

Ψ(2S)  Pseudoscalar Pseudoscalar

A’ (π﹢π﹣) and

A’+B’ (K﹢K﹣) known,

KS KLis needed to extract

the phase

between A’ and B’.

φ


BES Preliminary

Ψ(2S)  KS KL

–

+

–

+

–

+

KL


BES Preliminary

Ψ(2S)  KS KL

  • Two Good charged tracks with net charge zero ;

  • Decay length in transverse plane greater than 1.0 cm for KS ID;

  • Total Energy of photon candidates less than 1 GeV.


BES Preliminary

Ψ(2S)  KS KL

14M ψ(2S)

Bkg

MC

signal

Ks mass sidebands


BES Preliminary

Ψ(2S)  KS KL

Systematic Errors

Lxy

Eγtot

cosθ

VC

trigger


BES Preliminary

Ψ(2S)  KS KL


BES Preliminary

J/Ψ  KS KL

58M J/ψ

signal

MC Bkg

K*0KS+c.c.

Ks mass sidebands


BES Preliminary

J/Ψ  KS KL

~4σ diff.

PDG2002: BJ/ Ks K L = ( 1.08 ± 0.14)10 – 4


J/Ψ , Ψ(2S)  KS KL

B(2S) Ks K L= (5.25± 0.45± 0.63 )  10 – 5

BJ/ Ks K L = (1.86 ± 0.04± 0.14 )  10 – 4

Ψ(2S) enhanced!


B ((2S) KS KL )

=5.2510 – 5

Ψ(2S)  KS KL

K+K– & +

 inputs ;

Input 1:DASP;

Input 2:BESI ;

Input 3: K+K–

from BESI &

+ by form

factor.

PLB567 (2003)73

–80°

120 °


COM for cJB B-bar

  • B(cJ pp-bar) fromBES, PRL81, 3091 (1998);

  • E760, NPB373, 35 (1992); R704, PLBB172, 455 (1986)

  • Nucleon wave function at small Q2:

J.Bolz, P. Kroll, Z. Phys. A356, 327 (1996)

J.Bolz, P. Kroll, Eur. Phys. J. C2, 454 (1998)

For each s quark,

introduces

S. M. Wong, Eur. Phys. J. C14, 643 (2000)


Event Selection

Final states: γπ+π-pp-bar

γ


Λ signal in πp mass

Monte

Carlo

Data

Clear

Λ Λ-bar

Signal


cJ Signal

Data/Monte Carlo

χc2

χc1

χc0


Really ΛΛ?

Yes!

we have p/p-bar!

Yes!

we have

long decay

length!


Remaining backgrounds

Monte Carlo Simulation:

Monte Carlo prediction

and a best fit


Fit the mass spectrum

MC efficiencies

χc1

χc2

χc0

ΛΛ-bar Mass (GeV)


Number of ψ(2S) events

To achieve

high precision

&

cancel out

systematic bias

=14.9(1±8%)M


Systematic Errors

Extensive

Comparison

Between

Data and

Monte Carlo

Simulation!

(Thanks for

The Large

Data sample!)

~20%!


– 3.1

– 3.4

– 4.0

–1.2

–0.9

–1.3

PRD67, 112001 (2003)


Eur. Phys. J. C 14, 643–671

–1.2

–0.9

–1.3

* The results on c1 and c2 decays only agree

marginally with model predictions.

* No prediction for c0 .


Discussions

Checked with BESII data,

no serious discrepancy!

  • B(χcJp p-bar)?

    NO!

  • COM?

    Possible!

    Hints from other

    experiments!

  • wave functions?

    Possible!

    Need other

    experiment test!

E866

BELLE


Summary

  • Ψ(2S) VT channels f2 ,  a2 , K* K*2 and  f2'

    are first observed and branching ratios measured.

    The suppression of VT is confirmed.

  • First observation of K0S K0Lin Ψ(2S) decay.

    Improved measurement of J/ψ K0S K0L .

    Ψ(2S) is enhanced relative to 12% rule.

    The phase for ψ(2S) PP is ﹣80°or 120°.

  • First evidence of   in cJ decay .

    Results disagree with

    “COM+baryon wave function” calculation.

  • More results expected from BESIIΨ(2S) sample.


Thanks a lot !

谢谢!


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