1. Measurements of some J/ and c decays at BES
Zhou Nengfeng
Representing BES Collaboration
Institute of High Energy Physics, CAS

2. Outline Introduction Some branching ratio measurements of J/ decays
Measurements of some c decays
c Mass and Width
c decay Branching ratios
Summary
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3. J/ Introduction (2S) World J/ and (2S) Samples (×106)
BESII Detector
BESII 58M J/
J/
BESII
14M (2S)
VC: xy = 100 m TOF: T = 180 ps
MDC: xy = m BSC: E/E= 21 %
dE/dx= 8.5 %  = 7.9 mr
p/p=1.78(1+p2) z = 2.3 cm
counter: r= 3 cm B field: T
z = 5.5 cm
BES is a conventional solenoidal magnet detector. Here are the parameters of different sub detectors. 58 million J/psi samples have been collected with the BES detector, which is the largest Jpsi sample in the world.
(2S)
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4. Measurement of J/ → +-0 (I)
from direct J/ decay:
The largest J/ decays involving hadronic resonances is J/ → (770). Its branching ratio has been reported by many experiment groups assuming all +-0 come from (770). The precision of these measurements vary from 13% to 25%.
With the data collected by BES, two independent measurements for the branching ratio are done through J/ and  (2S) samples respectively.
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The first method is an absolute measurement based on J/+ - 0 samples directly.
Here is the result through Jpsi samples.
Br (J/ →+-0) = (21.840.052.01)10-3
Phys. Rev. D 70, (2004)
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5. Measurement of J/ → +-0 (II)
from (2S) decay:
Br (J/ →+-0) = (20.90.21.1)10-3
The second method is a relative measurement which is based on the comparison of the rates for J/+ - 0 and J/+ - using J/ events produced via (2S)+ - J/
Combined BES value: (21.01.2)10-3
PDG: (15.0  2.0)  inconsistent !
Barbar’s recently result (21.81.9)10-3 support BES ! hep-ex/
This formula is used to calculate branching ratio of Jpsi->pi+pi-pi0. The result is 20.9times ten to minus …. Which is inconsistent with PDG value. Our result has better precision.
Consistent with the latest result of (BELLE?)
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6. The branching ratio of J/ → KsKl (I)
The available Br (J/ Ks Kl ) come from DMII and MARK III. These measurements have relative errors of about 18%.
Ks Momentum is used to fit the J/ → KsKl. The result is:
Br (J/ Ks Kl )
= (1.82±0.04±0.13)×10-4
This result is higher than the PDG value Br (J/ Ks Kl )
= (1.08±0.14)×10-4
MC Bkg
K*0KS+c.c.
Signal
The branching ratio of jpsi->kskl is measured by fitting signal in the Ks momentum spectra.
Ks sideband
Phys. Rev. D69, (2004)
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7. The branching ratio of J/ → KsKl (II)
There is a prediction of the relation between J/ and (2s) decay branching ratios to the same hadronic final states, that is
While some channels obey the so called “12% rule”, others violate this rule very badly. Thus it is interesting to test this rule for KsKl decay, which can only be produced through SU(3) symmetry-breaking, strong decays of these charmonium states.
With the Br ((2s) KsKl) = (5.24±0.47±0.48)×10-5 measured by the BES, considering the common errors which cancel out in the calculation of ratio between the two branching ratios, we can get
which is enhanced more than 4 relative to the pQCD “12% rule”.
The branching ratio of jpsi->kskl is measured by fitting signal in the Ks momentum spectra.
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8. Measurement of Phys. Lett. B 591, 42 (2004)
Lots of measurements have been done for the J/psi->ppbar decay. The branching ratio and angular distribution parameter alpha are measured with our data sample. Here si the angular distribution. OUR results have better precision.
The obtained  is in good agreement with predictions of first-order QCD.
Phys. Lett. B 591, 42 (2004)
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9. First measurement of J/  f2(1270)f2(1270)4 (I)
Preliminary results
J/  f2(1270)f2(1270)
f2(1270)
Gf2f2.ps draft
Clear J/  f2(1270)f2(1270) signal is seen in the M  14 VS M  23 scatter plot with M4  >2.6GeV. Where the  1 (  3) and 2 (4 ) are the  + and - with higher (lower) momentum. f2(1270) can also be clearly seen in the projection of M  14 and M  23 .
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10. First measurement of J/  f2(1270)f2(1270)4 (II)
2nd polynomial backgrounds
J/f2 f2
Preliminary results 
f2 background
The invariant mass spectrum of  + - with mass cut |M +  |<0.185GeV for another  + - pair is used to fit the signal. Four components are used in the fit. The branching ratio is measured for the first time to be:
The Branching ratio of Jpsi->gamma f2f2 decay is measured for the first time. The invariant mass spectrum of pi+pi- is used to fit the signal. Four components are used in the fit. Here is jpsi->gamma f2f2 signal, here is 2nd. Here is a rho signal. Here is f2rhopi background, which has special contribution to the f2 signal. The branching ratio is …
submitted to P. R. D. hep-ex/
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11. Measurement of J/  0,  , ’ (I)
The decays of J/ VP are allowed in strong and electromagnetic reactions and the diagrams contributing to J/ VP are shown in the Fig: (a) Three gluon annihilation; (b) electromagnetic decay proceeding via annihilation to one photon.
Preliminary results
The measured branching ratio of J/+ - 0 is (21.01.2)10-3, which is higher than PDG value about 30%. Since the dominant dynamics in the J/+ - 0 is J/ (770). So the branching ratio of J/ (770) measured by BES is also greater than those former analysis. So it’s important to determine the branching ratios of other J/ VP decays. Three other J/ VP decays , J/  0,  , ’, are analyzed in different final states.
different channels are used to measure the branching ratio of Jpsi->phi eta, phi eta’. The final results are combined from different channels.
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12. Measurement of J/  0,  , ’ (II)
No 0 signal is seen in the J/   decays. So only up limit is set for the branching ratio of J/  0.
Clear  , ’ can been seen in different final states. The final branching ratio of J/  , ’ are combined from different channels. These branching ratios are higher than the PDG value.
Preliminary results
different channels are used to measure the branching ratio of Jpsi->phi eta, phi eta’. The final results are combined from different channels.
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13. First measurement of J/2( + - ), 3( + - )
Preliminary results
Clear  signal can be seen in the distribution of M from J/  2( + - ).
Clear  signal can be seen in the distribution of M from J/  3( + - ).
The branching ratios of J/2( + - ), 3( + - ) are measured for the first time:
Br (J/ 2( + - )) = (2.26±0.08±0.27)×10-3
Br (J/ 3( + - )) = (7.24±0.96±1.11)×10-4
different channels are used to measure the branching ratio of Jpsi->phi eta, phi eta’. The final results are combined from different channels.
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14. c mass, width measurement (I)
Since 1980, numerous efforts have been made to determine the mass and full width of the c . However, from a theoretical point of view, the accuracies of these experimental measurements are still not sufficient. So additional, more precise measurements of both M c and c are needed.
A combined fit of the above five channels are done to get the mass and width of c .
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15. c mass, width measurement (II)
The c mass and width measurements of BES are in good agreement with PDG value. They have been adopted by PDG 2004.
BESII result
Phys. Lett. B 555（2003）174 – 180
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16. Some c branching ratios measurement
Hadronic decays of the c have been studied by Mark III, DM2, and other experiments. However, the branching fractions of the c still have very large errors in the Particle Data Group compilation. More recently the branching fractions of c  have been measured by the Belle experiment, and it’s smaller than the PDG value. More measurements of the branching ratio of c are needed. BES measured the following branching ratios and compared them with PDG. Most of the results are consistent with PDG. The branching fractions of c  support Belle’s result.
The branching ratio of those channels used in the etac mass measurement are shown in the table.
Phys. Lett. B 578（2004）16 – 22
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17. Summary Some branching ratios of Jpsi decays are measured.
Some of the results challenged the PDG values, such as J/ → +-0 ,J/ → KsKl and J/  , ’.
Some of the results supported the PDG value, such as
Further more, some new branching ratios are measured for the first time, such as J/  f2(1270)f2(1270) and J/2( + - ), 3( + - )
Measurements of c decays
Precise c mass, width measurement are done, which improved the PDG value.
More results about branching ratios of c decays are obtained.
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