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

Outline Introduction Some branching ratio measurements of J/ decays Measurements of some c decays c Mass and Width c decay Branching ratios Summary ~ QWG ~

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 = 220 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: 0.4 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) ~ QWG ~

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. ******************* 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, 012005 (2004) ~ QWG ~

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)  10-3 inconsistent ! Barbar’s recently result (21.81.9)10-3 support BES ! hep-ex/0408078 This formula is used to calculate branching ratio of Jpsi->pi+pi-pi0. The result is 20.9times ten to minus 3. …. Which is inconsistent with PDG value. Our result has better precision. Consistent with the latest result of (BELLE?) ~ QWG ~

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, 012003 (2004) ~ QWG ~

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. ~ QWG ~

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) ~ QWG ~

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 . ~ QWG ~

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 + - - 1.27|<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/0408026 ~ QWG ~

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. ~ QWG ~

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. ~ QWG ~

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. ~ QWG ~

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 . ~ QWG ~

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 ~ QWG ~

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 ~ QWG ~

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. ~ QWG ~