1. 1 New Results on  (3770) and D Mesons Production and Decays From BES Gang RONG (for BES Collaboration) Presented by Yi-Fang Wang Charm07 Cornell University, August 4-8 2007

2. 2 Measurements of R Introduction Inclusive decays of D Mesons Outline Summary      B[  (3770)  non-DD] and Search for Charmless decays of  (3770) Parameters of  (3770) 

3. 3 BESII  (3770) data sample of about 33 pb -1  about 17.3 pb -1 data taken at 3.773 GeV  about 7 pb -1 data taken from 3.768 GeV to 3.778 GeV pb -1 (by summer,2005) World  (3770) Samples (pb -1 )  about 8 pb -1 data taken from 3.665 to 3.878 GeV about 1 pb -1 data taken at 3.665 GeV Introduction Data Samples about 6.5 pb -1 data taken at 3.650 GeV

4. 4 Absolute measurements Double tag analysis D - and D 0 tags

5. 5 D+XD+X With the singly tagged D sample, we can do some absolute measurements of D decays on the side recoiling against the tags. e+e+ e-e- D D K+K+ π–π– tag D+D+ D-D- π–π– Singly tagged D sample P+P+ X=any particles 0.52-0.62 GeV 0.62-0.72 GeV 0.72-0.82 GeV 0.82-0.92 GeV 0.92-1.02 GeV mKnπ(D tag ) PTPT N μ obs P + is any charged particle ( , e, π and K)

6. 6 N obs i =observed particle I; N true i = true particle i ε im = ratio of a particle “i” to be identified as “m” μ true e true K true π true D+X D+X First measurements ARGUS6.0±0.7±1.2- CHORUS6.5±1.2±0.3- BES-II6.8±1.5±0.617.6±0.7±1.3 PDG6.5±0.716.1±0.4 PDG

7. 7 D  e + X and D  KX Preliminary CLEO-c6.46±0.17±0.1316.13±0.20±0.33 MarkIII7.5±1.1±0.417.0±1.9±0.7 BES-II6.3±0.7±0.415.2±1.0±0.7 PDG20076.55±0.1716.1±0.4 Comparison of Results B(D  e + X) and B(D  KX) BES-II24.7±1.3±1.215.2±1.0±0.757.8±1.6±3.43.5±0.7±0.3 PDG200727.5±2.45.5±1.653±43.4 +0.6 -0.4

8. 8  Why are we interested in R(s) ? For evaluation of the electromagnetic coupling at the Z mass scale, For determination of of the muon. Evaluate Non-DD decays of  (3770) Vacuum polarization correction needs the R(s) values, which plays an important role in the precision test of the Standard Model. The quantity R important in open charm region for the understanding of 1 -- resonance production, for searching for new states, and for studying dynamics …

9. 9   (3770) production & decays It is believed to be a mixture of and states of system. It is thought to decay almost entirely to pure DD-bar. Before BES-II & CLEO-c, previously published data indicate that more than about 35% of  (3770) does not decay to DD-bar ? This conflicts with theoretical prediction. The quantity R

10. 10  New Measurements Recently BES and CLEO-c measured the DD and  (3770) production at 3.773 GeV based on the data taken below DD threshold and at 3.773 GeV. A better way to measure the cross sections, the widths of the resonance and the DD branching fractions of  (3770) is to analyze the line-shapes of  (3770),  (3686) and DD production simultaneously. BES made several fine cross section scans covering both the  (3686) and  (3770) to measure the resonance parameters, branching fractions and search for non-DD decays … To uncover the puzzle, a better way is to make cross section scan The quantity R

11. 11 Precision measurement of the cross sections in this region The Previously Measured quantity R Including all hadrons The quantity R

12. 12 calculate R had R uds hadrons above cc-bar threshold below cc-bar threshold R had (s)=R uds(c) (s)+ΣR res,i (s), R res,i (s) is R values due to all 1 －－ resonances decay to hadrons except Ψ(3770). Definition of different R Evaluate The quantity R [where q is the light (u,d,s) quarks]

13. 13 ISR corrections Kuraev & Fadin the electron equivalent radiator thickness Effective c.m. energy Moninal c.m. energy The quantity R

14. 14 Vacuum polarization change the photon propagator results in Vacuum polarization correction Radiative correction factor The quantity R

15. 15 R uds = 2.141±0.025±0.085 R pQCD uds = 2.15±0.03 above cc-bar threshold below cc-bar threshold Results PRL 97, 262001 (2006) Below DD-bar threshold The quantity R SourcesΔ SYS (%) Luminosity1.8 Hadron selection2.5 M.C. modeling2.0 ISR1.5 Ψ(3770) resonance parameters2.7 Total (off Ψ(3770) region) 3.9 Total (within Ψ(3770) region) 4.9

16. 16 Comparison of R measurements from different experiments PLB 641 (2006) 145 The quantity R

17. 17 Resonance Parameters of  (3770) The paper is being in press (PLB) 68 energy points Dec. 2003 data New measurements

18. 18 Resonance Parameters of  (3770) Experiment  prd [e + e -  (3770)][nb]  obs [e + e -  (3770)][nb] This work [Dec. 2003 data] 10.0  0.3  0.57.2  0.2  0.4 BES [PRL 97(2006)121801] 9.6  0.7  0.46.9  0.5  0.3 MARKII 9.3  1.4 M  (3770) (MeV)  tot  (3770) (MeV)  ee  (3770) (eV) Note 3772.4  0.4  0.328.5  1.2  0.2277  11  13 PLB in press 3772.2  0.7  0.326.9  2.4  0.3251  26  11 PRL 97(2006)121801 ExperimentPLB in pressPRL 97(2006)121801PDG B[  (3770)  e + e - ][  10 -5 ]0.97  0.03  0.050.93  0.06  0.031.05  0.14 R uds =2.121  0.023  0.084 Comparison with those measured by other experiments [Dec. 2003 data] New measurements

19. 19 Comparison of measurements of the cross section for  (3770) production What about World Average Resonance Parameters of  (3770) PRL 97 (2006) 121801 Preliminary ! PDG04 PRL 97 (2006) 121801 Leptonic branching fraction

20. 20 Determined from analysis of R values and DD-bar cross sections Obtained by fitting to the inclusive hadron and the DD-bar production cross sections simultaneously. PDG07 B[  (3770)  non-DD] PLB641 (2006) 145 PRL 97 (2006) 121801

21. 21 Mode  3.773 [pb]  3.650 [pb] B up [  10 -3 ]  0 <3.5<8.9<0.5 <12.6<18.01.9 2(  +  - ) 173.7  8.4  18.4 177.7  13.3  18.8 4.8 K+K-+-K+K-+-K+K-+-K+K-+- 131.7  10.1  14.1 161.7  17.9  17.1 4.8  +  - <11.1<22.91.6 2(K + K) 19.9  3.6  2.1 24.1  6.5  2.6 1.7 K+KK+KK+KK+K 15.8  5.1  1.8 17.4  9.2  2.0 2.4 pp bar  +  - 33.2  3.4  3.8 42.1  6.1  4.8 1.6 pp bar K + K 7.1  2.0  0.8 6.1  3.1  0.7 1.1  pp bar <5.8<9.10.9 3(  +  - ) 236.7  14.7  33.4 234.9  23.8  33.1 9.1 2(  +  - )  153.7  40.1  18.4 86.6  40.3  10.4 24.3 2(  +  - )  0 80.9  13.9  10.0 124.3  21.7  14.9 6.2 K+K-+-0K+K-+-0K+K-+-0K+K-+-0 171.6  26.0  20.9 222.8  37.7  27.2 11.1 2(K + K)  0 18.1  7.7  2.1 <23.04.6 pp bar  0 10.1  2.2  1.0 9.2  3.4  1.0 1.2 pp bar  +  -  0 53.1  9.2  6.8 29.0  11.1  3.7 7.3 3(  +  - )  0 105.8  34.4  16.9 126.6  47.1  19.2 13.7 PLB650(2007)111 Search for Charmless Decays of  (3770) Search for Charmless decays of  (3770) We have searched for more than 40 modes for the light hadron decays.

22. 22 Mode  3.773 [pb]  3.650 [pb] B up [  10 -3 ] K + K - 2(  +  - ) 168.0  18.2  23. 7 164.9  30.3  23. 2 <10.3 2(K + K - )  +  - 11.9  5.8  1.7 <49.1<3.2 pp bar 2(  +  - ) 23.5  5.0  3.5 22.8  8.4  3.4 <2.6 4(  +  - ) 131.8  19.5  23.6 76.2  24.4  13.9 <16.7 K + K - 2(  +  - )  0 231.5  63.6  37.5 <375.2<52.0 4(  +  - )  0 <206.9<119.4<30.6 0+-0+-0+-0+- 111.9  13.1  13.1 113.6  21.3  13.1 <6.9 0K+K-0K+K-0K+K-0K+K- 34.2  11.5  4.4 57.6  17.9  6.3 <5.0  0 pp bar 13.1  3.2  1.8 17.7  6.2  2.8 <1.7 K *0 K -  + 94.7  15.5  10.4 85.5  26.3  14.4 <9.7  bar <2.5<6.1<0.4  bar  +  - <26.7<42.9<4.4 Preliminary Results Search for light- hadron decays of  (3770) Search for Charmless Decays of  (3770)

23. 23 Mode  3.773 [pb]  3.650 [pb] B up [  10 -3 ]  +  - <37.1<50.85.5 K+K-K+K-K+K-K+K-<44.4<53.26.6  pp bar <20.3<30.93.0  +  -  0 <25.5<66.73.8 K *0 K -  +  0 116.3  32.7  20.0 128.1  59.5  17.9 16.3 K *+ K -  +  - 173.9  73.3  26.1 189.0  116.3  28.2 32.4 K+K-00K+K-00K+K-00K+K-00<5.6 47.6  33.4  10.7 0.8 K+K-+-K+K-+-K+K-+-K+K-+- 94.2  31.6  11.7 141.9  53.3  19.7 14.6  bar  0 <7.9<21.41.2 Upper limits are set at 90% CL Preliminary Results Search for light-hadron decays of  (3770) Search for Charmless Decays of  (3770) We searched for  (3770)  light hadrons over 40 channels, but no significant signals were found. This does not mean that  (3770) does not decay into light hadrons. To extract the branching fractions for  (3770)  light hadrons from the observed cross sections, one need to make finer cross section scan covering both  (3686) and  (3770) with larger data samples (BES-III can do this well).

24. 24 SUMMARY Inclusive decays of D mesons Measured BF(D+  mu+ X)=(17.6+-2.7+-1.3)% for the first time Measured BF(D+  K- X)=(24.7+-1.3+-1.2)% Measured BF(D+  K+ X)=(6.1+-0.9+-0.4)% Measured BF(D0  K- X)=(57.8+-1.6+-3.4)% Improved measurements R value Improved measurements of R in the range from 3.65 to 3.88 GeV Measured R uds = 2.121+-0.023+-0.085 Measured R uds(c)+  (3770) for the first time  (3770) parameters Precisely measured M  (3770) =3772.3+-0.5 MeV; Γ tot =28.5+-1.2 MeV; Γ ee =277+-16 eV Precisely measured BF(   e + e - )=(0.97+-0.08+-0.05)x10 -5 σ obs  (3770) = 7.15+-0.25+-0.25 nb [combined two measurements]

25. 25 SUMMARY BF[  (3770)  non-DDbar] Measured BF[  (3770)  non-DDbar] = (15+-5)% Light hadron decays of  (3770) No significant signals for  (3770)  light hadron were found in about 40 channels. How to solve this problem ? Combined 49 energy point cross section scan results and 3 energy point cross section results (inclusive hadron and DD-bar cross sections) Finer cross section scan over  (3686) and  (3770) to measure the cross sections for exclusive modes and fitting the cross sections to extract out the branching fractions (My comment only !) Measured BF[  (3770)  DDbar] = (85+-5)% PDG07 [BES]

26. 26 Thank You ！

27. 27 Backup slides

28. 28 Comparison with those measured by CLEO-c BES-II CLEO-c Based on analysis of inclusive hadron and DD-bar cross section scan data. (hep-ex/0512038); PRL 96 (2006) 092002 Actually, considering the errors, the two results are not in contradiction. PLB 141 (2006) 145

29. 29 BES-IICLEO-c Based on measured R values. Comparison with those measured by CLEO-c Method: BES measured near DD-bar threshold and R at 3.773 GeV with traditional method, then calculate the Born order cross section for  (3770) production. By comparing the cross sections for DD-bar and  (3770) production, BES obtained the branching fraction. BES used an ISR generator to simulate the decay e + e -  hadrons and obtain the efficiency for e + e -  hadrons. Method: CLEO-c directly count the number of hadronic events observed at 3.773 GeV, and subtract the backgrounds from J/ ,  (2S) radiative tails and continuum QED background. CLEO-c used the efficiency for the decay  (3770)  J/  π + π - to estimate the efficiency for e + e -  hadrons. Use parameter Assuming that there are interference between the two amplitudes of continuum and resonance

30. 30 BES-IICLEO-c Comparison with those measured by CLEO-c Method: Discussion if we use to calculate the ISR & vacuum polarization correction factor, and assuming that there are interference between the two amplitudes of the continuum and the resonance, we would obtain CLEO-c did not consider the difference of ISR & vacuum polarization corrections for continuum hadron production at the two energy points (3.671 GeV and 3.773 GeV) when subtracting background at 3.773 GeV. PRL 97 (2006) 121801