- Email: [email protected]
Recent ψ′ results at BES
~IU IRLEAR ~HYSIr'~S
ELSEVIER
Nuclear Physics A675 (2000) 71c-75c
A
www.elsevier.nl/locate/npe:
R e c e n t ¢ ' r e s u l t s at B E S F. Liu ~ * On behalf of the BES Collaboration Inst. of High Energy Physics, P.O. Box 918(1), Beijing 100039 Based on (3.79 4- 0.31) × 106 ¢ / d a t a sets collected with the BES detector at BEPC, the recent ¢i, XcJ and y~ results from BES are presented. 1. S T U D I E S O F ¢ ' D E C A Y S Charmonium physics is always one of the interesting and intriguing fields of particle physics. Charmonium provides us an excellent and simple system to study QCD, the production and decay mechanisms of heavy quarkonia and light hadron spectra from its decays, and can be treated nonreIativistically and perturbatively. Using (3.79 4- 0.31) × 106 ¢ ' sample collected with the BEijing Spectrometer (BES) at BEPC, the recent ¢', Xc and y~ results are presented. The BES detector is described in detail in Ref. [1]. Out of the charmonium decays, there exists a mysterious and longstanding plr puzzle of J / ¢ and ¢ ' decays [2]~ first revealed by Mark-II Collaboration. In QCD, both ¢ ' and J / ¢ decays are expected to be dominated by annihilations into three gluons. Based on the similarity between the ¢ ' and J / ¢ wave functions and the slow running of the strong interaction coupling constant as, the non-relativistic perturbative QCD predicts [3]: the ratios of the decays widths of ¢ / i n t o hadrons to those of J / ¢ into hadrons are:
Br(¢'-~ h) Qh -- B r ( J / ¢ --+ h) -
Br(¢l-~ ~+~-) B r ( ¢ ~ e+e-) = (14.7 4- 2.3)%
named as the "14%" rule. Mark II first observed the vector-pseudoscalar (V for vector, P pseudoscalar, B baryon, A axial-vector and T tensor) p~r and K*~- channels are highly suppressed w.r.t, the "14%" expectation - known as the p~r puzzle. BES has confirmed the puzzle with much lower upper limit by a suppression factor of ~ 60 and observed new highly suppressed decay modes, meanwhile BES presents many observations (Table 1). From Table 1, a large number of ¢' decay branching ratios have been measured, and most for the first time [4]. And it is found that some VP, VPP, VT, PBB and AP decay modes are suppressed w.r.t, the "14%" rule, where VT modes [5] is the first evidence for suppression other than VP. While for ¢ ' decays into AP modes [6], the normal decay blur, enhanced mode Kl(1270)R and suppressed decay KI(1400)Kare observed. The "14%" rule holds for the radiative decays into V T modes [7] within errors, but it is suppressed for the decays into VP modes[8]. Now the suppressed decays also extend to the 3-body *E-mail: [email protected], Web Site: http://hpwsl.ihep.ae.cn/~lfeng 0375-9474/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII S0375-9474(00)00216-5
72c
E L i u / N u c l e a r P h y s i c s A 6 7 5 (2000) 7 1 c - 7 5 c
decays, but the "14%" rule holds for the baryonic decays [9]. Quite a few models [10] have been put forward to explain the puzzle, but none of them is satisfactory. From the measured results, it has also been observed that the s t r o n g d o u b l e O Z I ( D O Z I ) violation in ¢ ' --+ ¢~r+~r- and the isospin violation in the decays between ¢ ' --+ w~r° and the isospin-conserving and SU(3)-allowed decay ¢1 __~ p~r, and between the charged and neutral decays ¢ ' --+ K * + K - + c.c and ¢ ' --+ K*°/~ ° + c.c. Fig. 1 shows the K + K and ~r%r- invariant masses for ¢ ' --+ ¢~r+Tr- and ¢f0(980) [11]. Also BES first measures B r ( ¢ ' --+ T+~- ) = (2.82 ± 0.45 ± 0.56) × 10 -3 (preliminary) and has precisely determined B r ( J / ~ b - + / + Z - ) = (5.87 ± 0.04 ± 0.09)% [12] with errors half of those in PDG98. Table 1 ¢ ' decay branching ratios (the unpublished results indicated by * are preliminary). Channels p~r * K + K * ( 8 9 2 ) - + c.c. * K ° ~ * ( 8 9 2 ) ° + c.c. *
BrpDa(xlO -4)
BrBES(×IO -4)
< 0.83 < 0.54
< 0.28 < 0.30 0.81 4- 0.24 4- 0.16 0.38 4- 0.17 4- 0.11 < 0.33 1.06 4- 0.11 4- 0.16 1.25 4- 0.18 4- 0.26
~ * ' (%) = Brv#, < 0.22 < 0.6 1.9 4- 0.7 9.14-5.0 <2.1 7.1 4- 1.6 2.1 4- 0.6
-
0.53 4- 0.31 4- 0.08 1.54 4-0.31 4- 0.20 < 1.7 < 2.3 < 1.2 < 0.45 5.2 4- 0.8 4- 1.0 10.0 4- 1.8 4- 2.1 < 3.1
6.2 4- 3.8 3.6 4- 0.9 < 3.9 < 2.1 < 1.8 < 3.66 17.3 4- 5.2 > 33.4 < 8.2 17.1 4- 2.9 12.8 4- 3.4 7.3 4- 3.0 22.0 4- 5.3 20.5 4- 8.1 6.3 4- 1.4 17.0 4- 9.6 4.64-2.2 18.9 4- 13.4 16.74-7.1
1.94-0.5 < 4.0
2.36 4- 0.24 4- 0.32 1.24 4- 0.20 4- 0.16 0.61 4- 0.18 4- 0.15 1.76 4- 0.22 4-0.24 0.66 4-0.17 4- 0.07 4.47 4-0.57 4- 0.54 1.26 4-0.43 4- 0.39 0.60 4-0.23 4- 0.14 0.86 4-0.50 4- 0.20 3.85 4-0.37 4- 0.56 2.58 4-0.68 -4- 0.73 0.84 =1=0.48 4- 0.48 2.62 ± 0.17 4- 0.55 1.89 4-0.21 4- 0.21
* 097f0 * ~or]
* ,Kd-.K--7~0
0.94-0.5
* KKTr
7z] 7rf(958) w f2 pa2 K*(S92)°K-~2(1430) ° 4- c.c. ¢f~(1525) b1~r Kl(1270)K KI(1400)K * -~A(1270) * -/fj(1710) * ¢K+K * (9,7£+,]r-
* ¢f0(980) * ¢ a T r + ./r -
* wK+K * (Mpp *
Cpp
* ,ff-bTf--TcOp~
* rpr+Tc-pp * ypp * AX * ~0~
0
QhBES
4.004-4.00 12.3 4- 2.8 14.0 4- 2.7
1.20 4-0.40 4- 0.30
9.2±4.1
1.00 4-0.30 4- 0.10
11.14-4.3
* A++A
1.34 4-0.11 4- 0.33
12.2 4- 4.5
. E.+~-*-
1.10 4-0.30 4- 0.30
10.7 4- 4.3
,
~-~+
< 2.0
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E L i u / N u c l e a r Physics A675 (2000) 71c-75c
2.
HADRONIC
X~J D E C A Y S
T h e (3.79 4- 0.31) × 10 ~ ¢ ' s a m p l e p e r m i t s studies of X~J w i t h u n p r e c e d e n t e d precision ( ~ 1.0 × l O S x ' s ) . T a b l e 2 shows t h e results of X~J decays [13,14]. F r o m t h e table, t h e m e a s u r e m e n t precision is i m p r o v e d m u c h , and m a n y decay m o d e s are p r e s e n t e d first t i m e , like X¢0 --+ p/5 [13]. T h e results of t h e n e u t r a l decays are preliminary. Table 2 R e s u l t s on X~J H a d r o n i c Decays (the u n p u b l i s h e d results i n d i c a t e d by * are p r e l i m i n a r y ) . decay channels Br(X¢o -+ ~r+Tr- ) Br(x¢2 ---*a'+Tr- ) Br(xeo Br(xe2 Br(xeo Br(xel Br(Xc2 Br(xco Br(Xcl Br(xc2
-+ K + K - ) ---* K + K - ) --+ p~) "* p~) ~ p~) --+ ~r+Tr-~r+lr - ) --+ ~r+Tr-rc+lr - ) --+ ~r+lr-lr+ Ir- )
B~(x~o -* K f K°, ) Br(x~2 Br(x~o Br(x~I Br(x¢2
~ K ° K °) --+ ~r+~r-K+ K - ) --+ ~r+Tr- K + K - ) ~ ~r+Tr-K+ K - )
B~(X,0 -~ r + ~ - # ) Br(Xcl Br(x,2 Br(xeo Br(xcl Br(xc2 B,'(Xoo B,'(Xo= Br(x~o Br(x~I Br(xe2
---, ~r+Tr-pff) --* ~r%r-pp) "* K + K - K + K - ) --* K + K - K + K - ) --~ K + K - K + K - ) --+ ¢¢) --, ¢¢) --+ KO~K+~r ~ + ~.~.) --+ K°K+rr - + e.c.) --+ KOK+Tr- + c.c.)
Br(x~0 - . 3(~+,r)) Br(Xel .--+3(,/r+¢r-)) B~(xo~ --+ 3(,~+,r)) *Br(x¢o -+ 7r%r°) *Br(xe2 --+ 7r°TrO)
*B~(xoo ~ ,7,7) *B r ( x ~ ~ '7'7)
BES ( x l 0 -z) 4.68 4- 0.26 4- 0.65 1.49 4- 0.14 -4- 0.22 5.68 4- 0.35 4- 0.85 0.79 4- 0.14 4- 0.13 0.159 4- 0.043 4- 0:053 0.042 4- 0.022 4- 0.028 0.058 4- 0.031 4-0.032 15.4 4- 0.5 4- 3.7 4.9 4- 0.4 4- 1.2 9.6 4- 0.5 4- 2.4 1.96 4- 0.28 4- 0.52 0.61 4- 0.17 4- 0.16 14.7 4- 0.7 4- 3.8 4.5 4- 0.4 4- 1.1 7.9 4- 0.6 4- 2.1 1.57 4- 0.21 4- 0.54 0.49 4- 0.13 4- 0.17 1.23 4- 0.20 4- 0.35 2.14 4- 0.26 4- 0.40 0.42 4- 0.15 4-0.12 1.48 4- 0.26 4- 0.32 0.92 4- 0.34 4- 0.38 2.00 4- 0.55 4- 0.61 < 0.71 2.46 4- 0.44 4- 0.65 < 1.06 11.7 4- 1.0 4- 2.3 5.8-t-0.74-1.2 9.0-t-1.04-2.0 2.80 4- 0.32 4- 0.51 0.92 4- 0.27 + 0.52 2.03 4- 0.84 4- 0.58 < 2£
PDG(×10 -a) 7.5 4- 2.1 1.9 4- 1.0 7.1 4- 2.4 1.5 4- 1.1 < 0.9 0.086 4- 0.012 0.10 4- 0.01 374-7 164-5 22 4- 5
30 4-7 9 -t-4 19 4-5 5.0 4-2.0 1.4 4-0.9
15 4- 5 224-8 124-8 3.1 4- 0.6 1.1-4- 0.3 2.5 4- 1.1 0.8 4- 0.5
T h e m a s s differences b e t w e e n Xco,1,2 and b e t w e e n 7/c and J/~b reflect t h e hyperfine s t r u c t u r e of t h e spin-spin interactions, t h e X~1,2 and J / ¢ masses h a v e b e e n precisely d e t e r m i n e d . B E S i m p r o v e s [13] t h e X~o mass w i t h (3414.1 4- 0.6 4- 0.8) M e V over P D G 9 8 value w i t h an error of 2.8 M e V , and Xco decay w i d t h w i t h P×~0 = (14.3 5: 3.6) M e V over P D G 9 8 value (13.5 4- 5.3 M e V ) . Fig. 2 shows Xc3 h a d r o n i c decays [13,14]. F r o m ¢ ' r a d i a t i v e t r a n s i t i o n to r/c, B E S gives t h e qc mass w i t h (2975.8 + 3.9 4- 1.2) M e V [14].
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E L i u / N u c l e a r Physics A 6 7 5 (2000) 7 1 c - 7 5 c
3. C O M P A R I S O N W I T H N R Q C D Recent years, non-relativistic QCD (NRQCD) [15] are successfully applied int o description of the production and decays of heavy quarkonia. Its key idea is that heavy quark Q(~ pairs are produced at short distances in color-octet states and subsequently evolve into physical (eolor-singlet) quarkonia by nonperturbative emission of soft gluons. Using the total decay widths of J / ¢ , ¢~ and X~0,1,~ from PDG98 and the BES measured branching fractions, the corresponding partial decay widths are extracted, see Table 3. From Table 3, it is shown that the experimental results accord with NRQCD predictions [16] within errors. But for some decay modes, the errors are large due to the low statistic. Table 3 Charmonium Partial Decay Decay Widths. Channels J/¢ J/¢ J/¢ 3/¢ 3/¢
~ ~ ~ ~ ~
Eo:~o ih ~-_~+ A++A E*-:~*+
¢, _~ 2o~o ¢' --* Ah ¢, -~ ~-~+ ¢, --, A++A Ct __+~.,-~,+ Xc2 --> Pfi
Xco ~ K + K Xcu --~ K + K Xeo ~
~+'lr-
Xc2 ~ ql'+'/l'-~cO......+~O~ o Xc2---+~0~ 0
X~o --+ ~
NRQCD 174 eV 113 eV 117 eV 62.5 eV 65.1 eV 40.8 eV 76.8 eV 55.0 eV 54.6 eV 33.9 eV 32.1 eV 24.4 eV 56.2 eV 154.2 eV 38.6 keV 2.89 keV 45.4 keV 3.64 keY 23.5 keV 1.93 keV 24.0 keV 1.91 keV
PDG (186 ± 14) eV (110 -4-16) eV (117 ± 14) eV (78 ± 18) ~v (96 ± 26) eV (45 -4-6) eV (52.6 -4-15.1) eV
(75.7 ± 16.0) eV (200.0 -4-27.0) eV (99 ± 49) keV (3.0 ± 2.2) k~V (lO5 -4-48) keY (3.8 ± 2.0) keY (43 -4-18) keV (2.2 ± 0.6) keY (35.0 -4-20.2) keV (1.6 4- 1.0) keV
BES
(72.6 ± 18.0) eV (33.2 -4-14.3) eV (52.4 ± 10.2) eV (27.7 -4-9.4) ev (37.2 ± 10.5) eV (30.5 ± 12.1) eV (37.0 ± 32.2) eV (116.0± 90.6) eV (79.5 -4-31.2) keV (1.58 ± 0.41) keV (65.5 ± 25.4) keV (2.98 -4-0.59) keY (39.2 ± 16.3) keV (1.84 ± 1.20) kev (28.4 ± 17.5) keV <5 keV
4. S U M M A R Y Using the (3.79 ± 0.31) × 106 ¢ ' data sets at BES, a large number of ¢ ' and XcJ results have been presented, many of them for the first measurements and/or with the unprecedented precision. BES has observed new suppressed decay modes and first observed enhanced decay from ¢~ among a large number of the normal hadronic decays. Some results are also compared with NRQCD calculations. ACKNOWLEDGEMENTS We acknowledge the strong efforts of the B E P C staff and the helpful service from the IHEP computing center. The work of the BES Collaboration is supported in part by the National Natural Science Foundation of China under Contract No. 19991480
75c
E Liu/Nuclear Physics A675 (2000) 71c-75c
and the Chinese Academy of Sciences under contract KJ95T-03, and by the Department of Energy under Contract Nos. DE-FG03-92ER40701 (Caltech), DE-FG03-93ER40788 (Colorado State University), DE-AC03-76SF00515 (SLAC), DE-FG03-91ER40679 (UC Irvine), DE-FG03-94ER40833 (U Hawaii), DE-FG03-95ER40925 (UT Dallas). ®30,~
[e
I
•
¢
. . . . . . . . .
1
1.05
1.1
1o15
1,2
1,25
0.6
'
0.8
• I,'l,
1
.t'llIlI|,ll
1-2
1.4
2~¢mass against ¢ (GeV/C2)
K+IC Mass(GeV/C2)
Figure 1. K + K - and 7r+Tr- masses for ¢' --+ ;r+Tr- and ¢f0(980) (preliminary).
m= (GeVl~)
v~n
~,., ~.T i ,
i,
i,
"° a,v,$"
"' ; 7 . . . . . . . . .
,.,
Figure 2. X~J decays into 7r+Tr- [13], 7r%r° (preliminary), 2(Tr%r-) and 7 r % r - K + K - [14] respectively. REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
11. 12. 13. 14. 15. 16.
J . Z . Bat et al., BES Coll., Nuclear Instruments and Methods A344, 319 (1994). M . E . B . Franklin et al., Physical Review Letters 51,963 (1983). T. Applequist and D. Politzer Physical Review Letters 34, 43 (1975). Particle Data Group, R. M. Barnet et al., Euro. Phys. J. C3 1998. J . Z . Bat et al., BES Coll., Physical Review Letters 81, 5080 (1998). J . Z . Bat et al., BES Coll., Physical Review Letters 83, 1918 (1999). J.Z. Bat et al., BES Coll., ¢' ratiative decays into two pseudoscalars, to be submitted. J . Z . Bat et al., BES Coll.,Physical Review D58, 097101 (1998). J . Z . Bat et al., BES Coll., ¢' decays into baryon-antibaryon pairs, to be submitted. for example, W. S. Hou and A. Soni, Phys. Rev. Lett 50, 569(1983); S. J. Brodsky et al., Phys. Rev. Left 59, 631(1987); X.Q. Li et al., Phys. Rev. D55, 1241(1997) S. J. Brodsky and M. Karliner, Phys. Rev. Lett 78,468(1997); Y. Q. Chen and E. Braaten, Phys. Rev. Lett 80,5060(1998). J. Z. Bat et al., BES Coll., ¢' hadronic decays involving w / ¢ , to be submitted. J. Z. Bat et al., BES Coll.,Physical Review D58, 092006 (1998). J. Z. Bat et al., BES Coll., Physical Review Letters 81, 3091 (1998) J. Z. Bat et al., BES Coll., Physical Review D60, 072001 (1999). G. T. Bodwin, E. Braaten and G. P. Lepage Phys. Rev.D46, 1914(1992); ibid D51, 1125(1995). J. Bolz and P. Kroll, Physics Letters B392, 198 (1997), Eur. Phys. J. C2, 705 (1998); P. Kroll, hep-ph/9709393; S. M. H. Wong, hep-ph/9903236.
ELSEVIER
Nuclear Physics A675 (2000) 71c-75c
A
www.elsevier.nl/locate/npe:
R e c e n t ¢ ' r e s u l t s at B E S F. Liu ~ * On behalf of the BES Collaboration Inst. of High Energy Physics, P.O. Box 918(1), Beijing 100039 Based on (3.79 4- 0.31) × 106 ¢ / d a t a sets collected with the BES detector at BEPC, the recent ¢i, XcJ and y~ results from BES are presented. 1. S T U D I E S O F ¢ ' D E C A Y S Charmonium physics is always one of the interesting and intriguing fields of particle physics. Charmonium provides us an excellent and simple system to study QCD, the production and decay mechanisms of heavy quarkonia and light hadron spectra from its decays, and can be treated nonreIativistically and perturbatively. Using (3.79 4- 0.31) × 106 ¢ ' sample collected with the BEijing Spectrometer (BES) at BEPC, the recent ¢', Xc and y~ results are presented. The BES detector is described in detail in Ref. [1]. Out of the charmonium decays, there exists a mysterious and longstanding plr puzzle of J / ¢ and ¢ ' decays [2]~ first revealed by Mark-II Collaboration. In QCD, both ¢ ' and J / ¢ decays are expected to be dominated by annihilations into three gluons. Based on the similarity between the ¢ ' and J / ¢ wave functions and the slow running of the strong interaction coupling constant as, the non-relativistic perturbative QCD predicts [3]: the ratios of the decays widths of ¢ / i n t o hadrons to those of J / ¢ into hadrons are:
Br(¢'-~ h) Qh -- B r ( J / ¢ --+ h) -
Br(¢l-~ ~+~-) B r ( ¢ ~ e+e-) = (14.7 4- 2.3)%
named as the "14%" rule. Mark II first observed the vector-pseudoscalar (V for vector, P pseudoscalar, B baryon, A axial-vector and T tensor) p~r and K*~- channels are highly suppressed w.r.t, the "14%" expectation - known as the p~r puzzle. BES has confirmed the puzzle with much lower upper limit by a suppression factor of ~ 60 and observed new highly suppressed decay modes, meanwhile BES presents many observations (Table 1). From Table 1, a large number of ¢' decay branching ratios have been measured, and most for the first time [4]. And it is found that some VP, VPP, VT, PBB and AP decay modes are suppressed w.r.t, the "14%" rule, where VT modes [5] is the first evidence for suppression other than VP. While for ¢ ' decays into AP modes [6], the normal decay blur, enhanced mode Kl(1270)R and suppressed decay KI(1400)Kare observed. The "14%" rule holds for the radiative decays into V T modes [7] within errors, but it is suppressed for the decays into VP modes[8]. Now the suppressed decays also extend to the 3-body *E-mail: [email protected], Web Site: http://hpwsl.ihep.ae.cn/~lfeng 0375-9474/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII S0375-9474(00)00216-5
72c
E L i u / N u c l e a r P h y s i c s A 6 7 5 (2000) 7 1 c - 7 5 c
decays, but the "14%" rule holds for the baryonic decays [9]. Quite a few models [10] have been put forward to explain the puzzle, but none of them is satisfactory. From the measured results, it has also been observed that the s t r o n g d o u b l e O Z I ( D O Z I ) violation in ¢ ' --+ ¢~r+~r- and the isospin violation in the decays between ¢ ' --+ w~r° and the isospin-conserving and SU(3)-allowed decay ¢1 __~ p~r, and between the charged and neutral decays ¢ ' --+ K * + K - + c.c and ¢ ' --+ K*°/~ ° + c.c. Fig. 1 shows the K + K and ~r%r- invariant masses for ¢ ' --+ ¢~r+Tr- and ¢f0(980) [11]. Also BES first measures B r ( ¢ ' --+ T+~- ) = (2.82 ± 0.45 ± 0.56) × 10 -3 (preliminary) and has precisely determined B r ( J / ~ b - + / + Z - ) = (5.87 ± 0.04 ± 0.09)% [12] with errors half of those in PDG98. Table 1 ¢ ' decay branching ratios (the unpublished results indicated by * are preliminary). Channels p~r * K + K * ( 8 9 2 ) - + c.c. * K ° ~ * ( 8 9 2 ) ° + c.c. *
BrpDa(xlO -4)
BrBES(×IO -4)
< 0.83 < 0.54
< 0.28 < 0.30 0.81 4- 0.24 4- 0.16 0.38 4- 0.17 4- 0.11 < 0.33 1.06 4- 0.11 4- 0.16 1.25 4- 0.18 4- 0.26
~ * ' (%) = Brv#, < 0.22 < 0.6 1.9 4- 0.7 9.14-5.0 <2.1 7.1 4- 1.6 2.1 4- 0.6
-
0.53 4- 0.31 4- 0.08 1.54 4-0.31 4- 0.20 < 1.7 < 2.3 < 1.2 < 0.45 5.2 4- 0.8 4- 1.0 10.0 4- 1.8 4- 2.1 < 3.1
6.2 4- 3.8 3.6 4- 0.9 < 3.9 < 2.1 < 1.8 < 3.66 17.3 4- 5.2 > 33.4 < 8.2 17.1 4- 2.9 12.8 4- 3.4 7.3 4- 3.0 22.0 4- 5.3 20.5 4- 8.1 6.3 4- 1.4 17.0 4- 9.6 4.64-2.2 18.9 4- 13.4 16.74-7.1
1.94-0.5 < 4.0
2.36 4- 0.24 4- 0.32 1.24 4- 0.20 4- 0.16 0.61 4- 0.18 4- 0.15 1.76 4- 0.22 4-0.24 0.66 4-0.17 4- 0.07 4.47 4-0.57 4- 0.54 1.26 4-0.43 4- 0.39 0.60 4-0.23 4- 0.14 0.86 4-0.50 4- 0.20 3.85 4-0.37 4- 0.56 2.58 4-0.68 -4- 0.73 0.84 =1=0.48 4- 0.48 2.62 ± 0.17 4- 0.55 1.89 4-0.21 4- 0.21
* 097f0 * ~or]
* ,Kd-.K--7~0
0.94-0.5
* KKTr
7z] 7rf(958) w f2 pa2 K*(S92)°K-~2(1430) ° 4- c.c. ¢f~(1525) b1~r Kl(1270)K KI(1400)K * -~A(1270) * -/fj(1710) * ¢K+K * (9,7£+,]r-
* ¢f0(980) * ¢ a T r + ./r -
* wK+K * (Mpp *
Cpp
* ,ff-bTf--TcOp~
* rpr+Tc-pp * ypp * AX * ~0~
0
QhBES
4.004-4.00 12.3 4- 2.8 14.0 4- 2.7
1.20 4-0.40 4- 0.30
9.2±4.1
1.00 4-0.30 4- 0.10
11.14-4.3
* A++A
1.34 4-0.11 4- 0.33
12.2 4- 4.5
. E.+~-*-
1.10 4-0.30 4- 0.30
10.7 4- 4.3
,
~-~+
< 2.0
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E L i u / N u c l e a r Physics A675 (2000) 71c-75c
2.
HADRONIC
X~J D E C A Y S
T h e (3.79 4- 0.31) × 10 ~ ¢ ' s a m p l e p e r m i t s studies of X~J w i t h u n p r e c e d e n t e d precision ( ~ 1.0 × l O S x ' s ) . T a b l e 2 shows t h e results of X~J decays [13,14]. F r o m t h e table, t h e m e a s u r e m e n t precision is i m p r o v e d m u c h , and m a n y decay m o d e s are p r e s e n t e d first t i m e , like X¢0 --+ p/5 [13]. T h e results of t h e n e u t r a l decays are preliminary. Table 2 R e s u l t s on X~J H a d r o n i c Decays (the u n p u b l i s h e d results i n d i c a t e d by * are p r e l i m i n a r y ) . decay channels Br(X¢o -+ ~r+Tr- ) Br(x¢2 ---*a'+Tr- ) Br(xeo Br(xe2 Br(xeo Br(xel Br(Xc2 Br(xco Br(Xcl Br(xc2
-+ K + K - ) ---* K + K - ) --+ p~) "* p~) ~ p~) --+ ~r+Tr-~r+lr - ) --+ ~r+Tr-rc+lr - ) --+ ~r+lr-lr+ Ir- )
B~(x~o -* K f K°, ) Br(x~2 Br(x~o Br(x~I Br(x¢2
~ K ° K °) --+ ~r+~r-K+ K - ) --+ ~r+Tr- K + K - ) ~ ~r+Tr-K+ K - )
B~(X,0 -~ r + ~ - # ) Br(Xcl Br(x,2 Br(xeo Br(xcl Br(xc2 B,'(Xoo B,'(Xo= Br(x~o Br(x~I Br(xe2
---, ~r+Tr-pff) --* ~r%r-pp) "* K + K - K + K - ) --* K + K - K + K - ) --~ K + K - K + K - ) --+ ¢¢) --, ¢¢) --+ KO~K+~r ~ + ~.~.) --+ K°K+rr - + e.c.) --+ KOK+Tr- + c.c.)
Br(x~0 - . 3(~+,r)) Br(Xel .--+3(,/r+¢r-)) B~(xo~ --+ 3(,~+,r)) *Br(x¢o -+ 7r%r°) *Br(xe2 --+ 7r°TrO)
*B~(xoo ~ ,7,7) *B r ( x ~ ~ '7'7)
BES ( x l 0 -z) 4.68 4- 0.26 4- 0.65 1.49 4- 0.14 -4- 0.22 5.68 4- 0.35 4- 0.85 0.79 4- 0.14 4- 0.13 0.159 4- 0.043 4- 0:053 0.042 4- 0.022 4- 0.028 0.058 4- 0.031 4-0.032 15.4 4- 0.5 4- 3.7 4.9 4- 0.4 4- 1.2 9.6 4- 0.5 4- 2.4 1.96 4- 0.28 4- 0.52 0.61 4- 0.17 4- 0.16 14.7 4- 0.7 4- 3.8 4.5 4- 0.4 4- 1.1 7.9 4- 0.6 4- 2.1 1.57 4- 0.21 4- 0.54 0.49 4- 0.13 4- 0.17 1.23 4- 0.20 4- 0.35 2.14 4- 0.26 4- 0.40 0.42 4- 0.15 4-0.12 1.48 4- 0.26 4- 0.32 0.92 4- 0.34 4- 0.38 2.00 4- 0.55 4- 0.61 < 0.71 2.46 4- 0.44 4- 0.65 < 1.06 11.7 4- 1.0 4- 2.3 5.8-t-0.74-1.2 9.0-t-1.04-2.0 2.80 4- 0.32 4- 0.51 0.92 4- 0.27 + 0.52 2.03 4- 0.84 4- 0.58 < 2£
PDG(×10 -a) 7.5 4- 2.1 1.9 4- 1.0 7.1 4- 2.4 1.5 4- 1.1 < 0.9 0.086 4- 0.012 0.10 4- 0.01 374-7 164-5 22 4- 5
30 4-7 9 -t-4 19 4-5 5.0 4-2.0 1.4 4-0.9
15 4- 5 224-8 124-8 3.1 4- 0.6 1.1-4- 0.3 2.5 4- 1.1 0.8 4- 0.5
T h e m a s s differences b e t w e e n Xco,1,2 and b e t w e e n 7/c and J/~b reflect t h e hyperfine s t r u c t u r e of t h e spin-spin interactions, t h e X~1,2 and J / ¢ masses h a v e b e e n precisely d e t e r m i n e d . B E S i m p r o v e s [13] t h e X~o mass w i t h (3414.1 4- 0.6 4- 0.8) M e V over P D G 9 8 value w i t h an error of 2.8 M e V , and Xco decay w i d t h w i t h P×~0 = (14.3 5: 3.6) M e V over P D G 9 8 value (13.5 4- 5.3 M e V ) . Fig. 2 shows Xc3 h a d r o n i c decays [13,14]. F r o m ¢ ' r a d i a t i v e t r a n s i t i o n to r/c, B E S gives t h e qc mass w i t h (2975.8 + 3.9 4- 1.2) M e V [14].
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3. C O M P A R I S O N W I T H N R Q C D Recent years, non-relativistic QCD (NRQCD) [15] are successfully applied int o description of the production and decays of heavy quarkonia. Its key idea is that heavy quark Q(~ pairs are produced at short distances in color-octet states and subsequently evolve into physical (eolor-singlet) quarkonia by nonperturbative emission of soft gluons. Using the total decay widths of J / ¢ , ¢~ and X~0,1,~ from PDG98 and the BES measured branching fractions, the corresponding partial decay widths are extracted, see Table 3. From Table 3, it is shown that the experimental results accord with NRQCD predictions [16] within errors. But for some decay modes, the errors are large due to the low statistic. Table 3 Charmonium Partial Decay Decay Widths. Channels J/¢ J/¢ J/¢ 3/¢ 3/¢
~ ~ ~ ~ ~
Eo:~o ih ~-_~+ A++A E*-:~*+
¢, _~ 2o~o ¢' --* Ah ¢, -~ ~-~+ ¢, --, A++A Ct __+~.,-~,+ Xc2 --> Pfi
Xco ~ K + K Xcu --~ K + K Xeo ~
~+'lr-
Xc2 ~ ql'+'/l'-~cO......+~O~ o Xc2---+~0~ 0
X~o --+ ~
NRQCD 174 eV 113 eV 117 eV 62.5 eV 65.1 eV 40.8 eV 76.8 eV 55.0 eV 54.6 eV 33.9 eV 32.1 eV 24.4 eV 56.2 eV 154.2 eV 38.6 keV 2.89 keV 45.4 keV 3.64 keY 23.5 keV 1.93 keV 24.0 keV 1.91 keV
PDG (186 ± 14) eV (110 -4-16) eV (117 ± 14) eV (78 ± 18) ~v (96 ± 26) eV (45 -4-6) eV (52.6 -4-15.1) eV
(75.7 ± 16.0) eV (200.0 -4-27.0) eV (99 ± 49) keV (3.0 ± 2.2) k~V (lO5 -4-48) keY (3.8 ± 2.0) keY (43 -4-18) keV (2.2 ± 0.6) keY (35.0 -4-20.2) keV (1.6 4- 1.0) keV
BES
(72.6 ± 18.0) eV (33.2 -4-14.3) eV (52.4 ± 10.2) eV (27.7 -4-9.4) ev (37.2 ± 10.5) eV (30.5 ± 12.1) eV (37.0 ± 32.2) eV (116.0± 90.6) eV (79.5 -4-31.2) keV (1.58 ± 0.41) keV (65.5 ± 25.4) keV (2.98 -4-0.59) keY (39.2 ± 16.3) keV (1.84 ± 1.20) kev (28.4 ± 17.5) keV <5 keV
4. S U M M A R Y Using the (3.79 ± 0.31) × 106 ¢ ' data sets at BES, a large number of ¢ ' and XcJ results have been presented, many of them for the first measurements and/or with the unprecedented precision. BES has observed new suppressed decay modes and first observed enhanced decay from ¢~ among a large number of the normal hadronic decays. Some results are also compared with NRQCD calculations. ACKNOWLEDGEMENTS We acknowledge the strong efforts of the B E P C staff and the helpful service from the IHEP computing center. The work of the BES Collaboration is supported in part by the National Natural Science Foundation of China under Contract No. 19991480
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and the Chinese Academy of Sciences under contract KJ95T-03, and by the Department of Energy under Contract Nos. DE-FG03-92ER40701 (Caltech), DE-FG03-93ER40788 (Colorado State University), DE-AC03-76SF00515 (SLAC), DE-FG03-91ER40679 (UC Irvine), DE-FG03-94ER40833 (U Hawaii), DE-FG03-95ER40925 (UT Dallas). ®30,~
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Figure 1. K + K - and 7r+Tr- masses for ¢' --+ ;r+Tr- and ¢f0(980) (preliminary).
m= (GeVl~)
v~n
~,., ~.T i ,
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Figure 2. X~J decays into 7r+Tr- [13], 7r%r° (preliminary), 2(Tr%r-) and 7 r % r - K + K - [14] respectively. REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.
11. 12. 13. 14. 15. 16.
J . Z . Bat et al., BES Coll., Nuclear Instruments and Methods A344, 319 (1994). M . E . B . Franklin et al., Physical Review Letters 51,963 (1983). T. Applequist and D. Politzer Physical Review Letters 34, 43 (1975). Particle Data Group, R. M. Barnet et al., Euro. Phys. J. C3 1998. J . Z . Bat et al., BES Coll., Physical Review Letters 81, 5080 (1998). J . Z . Bat et al., BES Coll., Physical Review Letters 83, 1918 (1999). J.Z. Bat et al., BES Coll., ¢' ratiative decays into two pseudoscalars, to be submitted. J . Z . Bat et al., BES Coll.,Physical Review D58, 097101 (1998). J . Z . Bat et al., BES Coll., ¢' decays into baryon-antibaryon pairs, to be submitted. for example, W. S. Hou and A. Soni, Phys. Rev. Lett 50, 569(1983); S. J. Brodsky et al., Phys. Rev. Left 59, 631(1987); X.Q. Li et al., Phys. Rev. D55, 1241(1997) S. J. Brodsky and M. Karliner, Phys. Rev. Lett 78,468(1997); Y. Q. Chen and E. Braaten, Phys. Rev. Lett 80,5060(1998). J. Z. Bat et al., BES Coll., ¢' hadronic decays involving w / ¢ , to be submitted. J. Z. Bat et al., BES Coll.,Physical Review D58, 092006 (1998). J. Z. Bat et al., BES Coll., Physical Review Letters 81, 3091 (1998) J. Z. Bat et al., BES Coll., Physical Review D60, 072001 (1999). G. T. Bodwin, E. Braaten and G. P. Lepage Phys. Rev.D46, 1914(1992); ibid D51, 1125(1995). J. Bolz and P. Kroll, Physics Letters B392, 198 (1997), Eur. Phys. J. C2, 705 (1998); P. Kroll, hep-ph/9709393; S. M. H. Wong, hep-ph/9903236.