BESIII CsI Calorimeter

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BESIII CsI Calorimeter Powered By Docstoc
					Recent Results from BES
          Weiguo Li
        IHEP, Beijing
Representing BES collaboration
          ICFP2005
   NCU, Chungli, Taiwan
         Oct. 5, 2005
                    BESII Detector




VC: xy = 100 m    TOF: T = 180 ps     counter: r= 3 cm
MDC: xy = 250 m   BSC: E/E= 22 %              z = 5.5 cm
    dE/dx= 8.4 %         = 7.9 mr    B field: 0.4 T
    p/p=1.8(1+p2)      z = 2.3 cm Dead time/event: 〈10 ms
             Data from BESI and BESII
     Ecm (GeV)       Physics       BES Data      Other Lab.

         3.10           J/         7.8106        8.6106

         3.69          (2S)        3.9106        1.8106

         4.03                      1.0105         LEP

         4.03          DS, D        22.3 pb-1      CLEO
     3.55 m scan       m           5 pb-1

     2-5 R scan      R value,      6+85 points   2, MarkI
                    QED, (g-2)                 Crystal Ball
2.   2.2,2.6,3.0                                 Pluto……
                       QCD
          3.1          J/          5.8107
         3.69         (2S)         1.46107
         3.78        (3770)        ~27 pb-1
    Recent J/ Results from BESII
• Multiquark candidates study at BES

 * pp threshold enhancement in       J/ψ  γpp
 * observation of X(1835) in       J /   '   

 * p threshold enhancement in        J/ψ  pKΛ
 * K threshold enhancement in        J/ψ  pKΛ
 *  enhancement in                 J /  
• Light scalar mesons -- , , f0(980), f0(1370), f0(1500) …

• Excited baryon states

• Measurements of J/ and c decays
During the past two years, a lot of surprising
experimental evidences, including some BES
results showed the existence of hadrons that
      cannot (easily) be explained in the
          conventional quark model.

J/ decay is a good place to search for the new form
                    of hadrons.
  Observation of an anomalous enhancement near
  the threshold of pp mass spectrum at BES II

acceptance
                              BES II J/pp
weighted BW                      M=1859 +3 +5 MeV/c2
                                             10 25      0-+
                                 G < 30 MeV/c2 (90% CL)




                         c2/dof=56/56


                 0           0.1         0.2           0.3
      3-body phase space M(pp)-2mp (GeV)    acceptance
                   Phys. Rev. Lett., 91 (2003) 022001
 Observation of X(1835) in J /  ' 
                                          

                                           X(1835)
                                           5.1 
                      '
J /   '   
   '    


                                           X(1835)
                      '                   6.0 
J /  '  
                 


   '  


hep-ex/0508025
Accepted by PRL
Combine two channels
    J                        7.7
  Statistical Significance 7.7 


X(1835)
                                                BESII Preliminary




         BESII Preliminary         N obs  264  54
                                   M  1833.7  6.1  2.7 MeV/c 2
                                   G  67.7  20.3  7.7 MeV/c 2


 B( J   X ) B( X    )  (2.2  0.4  0.4)  104
c. f . : B( J   X ) B( X  pp )  (7.0  0.41..9 )  105
                                               0 8
Refit to J/  pp including FSI
M = 1830.6  6.7 MeV             Include FSI curve from
                                 A.Sirbirtsev et al.(hep-ph/
G = 0  93 MeV                   0411386) in the fit (I=0)

    BES II Preliminary




                         In good agreement with X(1835)
       X(1860) from BES has large BR to pp
 • BES measured:
     BR ( J /  X (1860 ))  BR ( X (1860 )  pp ) ~ 7  10 5

 • For a 0-+ meson:
         BR ( J /  X (1860 )) ~ 0.5  2  10 3
 • So we would have:
         BR( X (1860)  pp) ~ 4  14%

Considering that decaying into pp is only from
the tail of X(1860) and the phase space is very small,
such a BR indicates X(1860) has large coupling to pp !
• X(1835) could be the same structure as pp mass
  threshold enhancement.

• It is likely to be a pp bound state since it
  dominantly decays to pp when its mass is above
  pp mass threshold.

• ’ mode is expected to be the most favorable
  decay mode for a pp bound state below pp mass
  threshold
        G.J. Ding and M.L. Yan, PRC 72 (2005) 015208
  Observation of an anomalous enhancement near the
     threshold of p  mass spectrum at BES II

            BES II
         J /  pK




                   3-body phase space




Phys. Rev. Lett. 93, 112002 (2004)
         For a S-wave BW fit: M = 2075 12  5 MeV
                              Γ = 90  35  9 MeV
Similar enhancement also observed in
              '  pK




        4 away from phase space.
Observation of a strong enhancement near the
 threshold of K   mass spectrum at BES II

 NX*


           BES II
                                J /  pK


                                        M K  Λ (GeV/c2 )

                              PS, eff. corrected
                              (Arbitrary normalization)




                             M KΛ  M K  M 
• A strong enhancement is observed near the mass threshold of
  MK at BES II.

• Preliminary PWA with various combinations of possible N*
  and Λ* in the fits —— The structure Nx*has:
  Mass 1500~1650MeV
  Width 70~110MeV                  BES II Preliminary
  JP    favors 1/2-

The most important is:

  It has large BR(J/ψ  pNX*) BR(NX* KΛ) 2 X 10-4 ,
  suggesting NX* has strong coupling to KΛ.
    Observation of  threshold
     enhancement in J/  

         DOZI process
                               | M KK  M  | 15MeV



        MKK                                  M3
                        

        BES II Preliminary




                             20MeV | M KK  M  | 35MeV
BES II
Preliminary
   A clear threshold enhancement is observed

                                          Eff. curve
                 Phase Space




                                    Side-band




S wave fit:   M  181019  13 MeV, G  105  20  11 MeV
                       26
        Study of the scalars

 There have been hot debates on the
  existence of  and  .

 Lattice QCD predicts the 0++ scalar glueball
  mass in the range 1.5 - 1.7 GeV.

  f0(1500) and f0(1710) are good candidates.
       study  in   J /          



         study  in J /  K K and KK
                                *

0++
       study f0(980), f0(1370), f0(1500), f0(1710)
      and f0(1790) in

          J /   , ,     , KK
                                             
               The study of 
• evidence for a low mass pole in the early DM2
  and BESI data on J/   .
• huge event concentration in the I=0 S-wave 
  channel seen in M ~ 500 – 600 MeV in the pp
  central production exp.
• to explain  scattering phase shift data,
  should be introduced in chiral perturbative
  theory.
• FNAL E791 exp. D+ +-+ data
       M  478 23  17 MeV, G  324 40  21 MeV
               
                 24
                                     
                                       42
The  pole in J /     at BESII

          0
                       M(+-0)   
          M()



    
                                   
           M(+-)
    Fit to J/→+ (whole mass region)

Method I:                                 b1(1235)


Channels fitted to
the data:
J/f2(1270)               preliminary
    
    f0(980)                               f2 contribution
    b1(1235)
    ’(1450)
    f2(1565)
    f2(2240)
                     f0 contribution
  Fit to J/→+ (M < 1.5 GeV)
                                       f2 contribution
Method II:           f0 contribution


Channels fitted to
the data:

J/f2(1270)
    
    f0(980)
    b1(1235)
    phase space
Breit-Wigner for :
       Fit results:
        BW form                           Pole position (MeV)
        Const. G                       542  7  20  i(269  15  25)
I
        G with                         570  7  19  i(274  14  22)
     Adler zero form      542  7  15  30(extrap.)  i(249  15  20  30(extrap.))

     BW form           Mass(MeV)         Width(MeV)         Pole position(MeV)
      Const. G          446 11 30               
                                          578 36 114           16 36               40
                                                           (512 13 31 )  i(252 1433 )
II                          9 32             23 86                            9
       G with          530 10  35
                                  28
                                           448  27 89
                                                 22 119
                                                           (558 17 46 )  i (2311458 )
                                                                 14 42             12
                            8                                                  45
     G with  (HQ)           10  76
                        752 10 77              36 348
                                           984 39  258        19  44
                                                           (52118 49 )  i(237 7 36 )
                                                                                  6 33
                                                                               



Averaged pole position:                (541  39)  i(252  42) MeV

                  Phys. Lett. B 598 (2004) 149
                   The study of 
    A possible  pole is controversial.
 Some analyses of LASS K scattering data need (800), some
  don’t.
 Scadron et al. favors a nonet made up of , (800), f0(980) and
   a0(980).
 Julich group used t-channel exchanges to explain K scattering
   data.
 evidence of  in FNAL E791 data on D+ K-++
      M  797  19  43 MeV, G  410  43  87 MeV
 slightly lower statistics of CLEO D0 K-+0 data find no
  evidence of 
 FOCUS data on K+K-++ require K*0 interfere with either
  a constant amplitude or a broad 0+ resonance in K
                           κ




            81                      48                  hep-ex/0506055
(841  30    73   )  i (309  45    72   ) MeV/c   2
                                                          Submitted to PLB
    K*0(1430)





  Pentaquark searches


                +(1540)
 not forbidden by QCD:
  definite evidence of pentaquark states would be an
  important addition to our understanding of QCD.


 a baryon with S=+1 is a natural candidate
         Need more experimental facts
             (through different processes)

       BES: e+ e- collision; has relatively clean
          data samples with less backgrounds

            investigate the pentaquark state  in
            the hadronic decays of charmonium

 (2S ) & J /    ( K s p)(K  n ) & ( K s p )( K  n)
                  K s p or K  n
                  K  n or K s p
         (2S)                       J/

No pentaquark state (1540) (or ) is observed.
Upper limits @ 90% C.L.




      B( J /  K s p  K s pK  n)  1.6 10 5


              PRD70 (2004) 012004
        Study of other scalars

Lattice QCD:

the lightest scalar glueball in the region of 1.5- 1.7 GeV

   Glueball searches should be performed in
    J /  X , X ,X        simultaneously.
  I will skip the other parts of J/ decay results to
  save time, please refer to the BES talks at
  Hadron05.
                                                       BES preliminary
(2S) and cCJ Decays                                   cc0→+K+K
                         Different way for scalar study:
                            1. Start from JPC=0++, 1++, 2++
                            2. Start from gluon+gluon
                            3. Pair production of scalars,
                               very different information
                               than in J/ decays
                                Can study different
            cc0                    kinds of resonances:
1371 evts                       •   (            )( K           K )
             cc1
                                •   (K              )(K             )
                   cc2
                                •   (K   ) K
                                     hep-ex/0508050
                                    Submitted to PRD
                        BES preliminary, cc0→+K+K
                        ( + ) ( K+K )                        f0(980)
             f0(2200)                                            f0(980)
f0(1710)

                                                                 f0(1370)


                                                        (770)




Q. Zhao, hep-ph/0508086, try to understand these data and the scalars …
(K  )(K  )                BES preliminary
                                 cc0→+K+K




    With           K*(892)0
 kappa-kappa
                              K*0/2(1430)

                                            K*0(1950)
   Without
 kappa-kappa
   S=39.
(K   )K                      BES preliminary, cc0→+K+K

        1371 events                            K1(1270)
                 K1(1400)
      K1(1270)




                                         M(K ) [896±60]



                                                 K1(1270)




 The mixing angle between
 K1A and K1B >57 degrees,
  while in ’ decays to K1K,
                                         M( ) [700,850]
 the angle is <29 degrees.
            Why?
      “12% rule” and “ puzzle”

MARK-II    Violation found by Mark-II , confirmed
             by BESI at higher sensitivity.
           Extensively studied by BESII/CLEOc

            VP mode:  , K*+K-+c.c., K*0K0+c.c., 0,…
            PP mode: KSKL

            BB mode: pp, , …

K*K         VT mode: K*K*2, f2’, a2, f2

ρπ          3-body: pp0, pp, +-0, …
            Multi-body: KSKShh, +-0 K+K- , 3(+-), …
     Extension of the “12% rule”
 In Potential model, if J/, ’, and ’’ are pure 1S,
 2S, and 1D states, one expects

        Bψ' X        Bψ'  e  e 
Qh                                    (12.7  0.6)%
       BJ/ψX         BJ/ψe  e 

        Bψ'' X       Bψ''  e  e 
Q' 
 h                                     (1.9  0.3)  10 -4
       BJ/ψX         BJ/ψe  e 

but ’ and ’’ are known not pure 2S and 1D states,
PRD17, 3090 (1978); 21, 203 (1980); 41,
155(1990); …
Let’s look at data … (and first, the story of )
’   + - 0       BESII: PLB619, 247 (2005)
                     CLEOc: PRL94, 012005 (2005)

                    229 0s                             196 0s
                    BESII                              CLEOc




       BESII : B( '     0 )  (18.1  1.8  1.9) 105
      CLEOc : B( '     0 )  (18.81..5  2.8) 105
                                         
                                          16


         BES and CLEOc in good agreement!
’ + - 0        Dalitz plots after applying 0 mass cut!

                                                 Very different
           BESII                     CLEOc       from J/ 3!

                                                            J/




Similar Dalitz plots,
different data        BESII : B( '   )  (5.1  0.7  1.1) 105
handling techniques:
                    CLEOc : B( '   )  (2.40.7  0.2) 10
                                                   0.8          5

PWA vs counting!

      ’ is observed, it is not completely
                  missing, BR is at 10-5 level!
J/ + - 0              Make  mass cut,
PWA analysis               and count events
assuming 
interferes with
excited  states
L. P. Chen and
W. Dunwoodie,
Hadron’91, MRK3 data
                                                  PDG: 1.270.09%
  B( J /    )
                    1.17 (1  10 % ?)
B( J /      )
              0




                          B( J /     0 )           Very
                                                       different!
                           (2.00  0.09)%

                       B(J/ψ  ρπ)  2.34  0.26%
’’ + - 0                          Very small in ’’ decays


                                  φ

                               phase


  interference                                            interference




                  Continuum contribution is crucial in ’’ analysis:
                  1. Total ’’ charmless decays (<2nb) is much
                     less than total continuum process (~16nb),
      BESII
    preliminary
                  2. Interference between amplitudes
’’   + - 0          BESII: hep-ex/0507092
                         CLEOc: CLEO-CONF 05-01
             BESII preliminary              CLEOc preliminary

       3.773GeV              3.650GeV                    3.773GeV
                                                         3.670GeV




  (e e     ) @ 3.773 GeV : @ continuum :
   B                 0


  BESII : (8.6  3.3  2.1) pb           (19.3  7.3  3.7) pb
 CLEOc : (7.4  0.4  1.2) pb            (13.11..7  2.1) pb
                                              
                                               18



  BES and CLEOc are in good agreement!
  X-section at ’’ peak is smaller than at continuum!
                            BESII: hep-ex/0507092
’’      + - 0          CLEOc: CLEO-CONF 05-01
                BESII preliminary              CLEOc preliminary

             3.773             3.65                3.773            3.67




 (e e   ) @ 3.773GeV : @ continuum :
  B     
                                                          Subtle difference
 BESII : 6.0 pb                       25 pb             in handling
                                                          efficiency and
CLEOc : (4.4  0.3  0.5) pb          (8.0 1.7  0.9) pb ISR correction.
                                          1.4

      BES and CLEOc are in good agreement!
      X-section at ’’ peak is smaller than at continuum!
                           non-zero ’’ amplitude.
                                           BESII: hep-ex/0507092
             ’’                        CLEOc: CLEO-CONF 05-01
       Wang, Yuan and Mo:PLB574,41(2003)
                                           on  resoance  peak :
                                                                                        2
                                             a '' ggg  a '' *  ae e
                                               B
Total cross section




                                                                            
                                               on                                 *

                                           off  resonance  peak :
                                                                       2
                                              B
                                               off    ae  e   *
                                                                                        2
                                           B( ' '   )  a '' ggg  a '' *
                                Three unknowns with two equations ---
       n obs                        One can plot the BR versus phase .
B 
     L 1               B depends on efficiency and ISR correction,
                               efficiency and ISR correction depends on B(s) !
                                            Iteration is necessary!
                        BESII: hep-ex/0507092
 ’’                 CLEOc: CLEO-CONF 05-01
                                            BES data restrict BR
                                            and phase in a wide
                                            range (@90% C.L.):
                                                  
                                            BR  6 10 6 ,2.4 10 3       
                                                 150 ,20 
                                                                


                                            CLEOc data further
                                            restrict BR and phase
                                            in a ring*. At =-90:

                                             BR  2.1  0.3 10 3
                                                  or
                                                    
                                             BR  2.4    3.4
                                                         2.0   10   5


*Toy MC is used to get BR from CLEOc data (not CLEO official results)!
J/ , ’ , ’’  ρπ               G( J /    )  2.1keV
•Partial width of ψ’’ρπ is           G( '   )  0.014keV
larger than that of ψ’ρπ!           G( ' '   )  50keV
•hard to understand if ψ’’ is
pure 1D state, also hard if ψ’’              or
is 2S and 1D mixture.                G( ' '   )  0.6keV
  B(ψ '  ρπ)                        Q e  12.7%
               ( 0.20  0.06 )%
 B(J/ψ  ρπ)
 B(ψ ' '  ρπ)
                ( 9.0  1.6 )%
                                     Q  0.019%
                                        '
                                        e
 B(J/ψ  ρπ)                        In S-D mixing model, using
                                    mixing angle θ=12°, using
               or                   Rosner’s assumption (12% rule
                                    for 1S and 2S), one predicts
 B(ψ ' '  ρπ)                      Q’ρπ =(2.7-5.3)% !
                ( 0.100 ..15 )%
                        0
                        09
 B(J/ψ  ρπ)                   -90 or imperfect model?
Other ’ decay modes


  ’    is suppressed by a factor of 60!

  ’’    is enhanced!

  Other modes may supply more information!




    We list a few new measurements
                   using BESII/CLEOc
    data …
             BESII : PLB614, 37 (2005)
’ VP                                   K*(892)K+c.c.
  Br0=(13.3±2.7     ±1.7)10–5                 K*   BESII

  Br±=(2.9±1.7 ±0.4)10–5
                                                     K*0
Br0=(9.2±2.7 ±0.9)10–5
Br±=(1.3±1.0 ±0.3)10–5




                                   Good agreement!
                                   Large Isospin violation!
 CLEOc: PRL94, 012005 (2005)       Both modes suppressed!
’ VP




                                   Some modes are suppressed,
                                      while some others obey
                                      the 12% rule!


 CLEOc: PRL94, 012005 (2005)   BESII : PRD70, 112007 (2004)
                                       PRD70, 112003 (2004)
Multi-body ’ decays             BESII: PRD71, 072006 (2005)




                                        BESII, preliminary




                                 CLEOc
                                 preliminary:
                                 hep-ex/
                                 0505057


                                 Some modes are suppressed, some are
                                 enhanced, while some others obey the
   CLEOc: PRL95, 062001 (2005)   12% rule!
Search for ’’ decays to light hadrons
CLEOc preliminary: LP2005-439




                                 BR(’’final state)   Same operation as for
                                                          ’’ should done for
                                                          all the modes to extract
                                                          the BRs of ’’ decays.

Some x-sections agree,    =-90 degrees as in J/ and ’ decays?
some very different.      Any way to choose one solution?
  “12%” rule and “0.02%” rule
’ VP suppressed               Seems no obvious rule to categorize
’ PP enhanced
                                 the suppressed, the enhanced, and the
                                 normal decay modes of J/ and ’.
’ VT suppressed
                                 The models developed for interpreting
’ BB obey/enhan.
                                 specific mode may hard to find
Multi-body –obey/sup.           solution for other (all) modes.
The ’’ decays into light hadrons may be large --- more data and more
sophisticated analysis are needed to extract the branching fractions
from the observed cross sections. Why D-wave decay width so large?
Model to explain J/, ’ and ’’ decays naturally and simultaneously?
   •S-D mixing in ’ and ’’ [J. L. Rosner, PRD64, 094002 (2001)]
   •DD-bar reannihilation in ’’ (J. L. Rosner, hep-ph/0405196)
   •Four-quark component in ’’ [M. Voloshin, PRD71, 114003 (2005)]
   •Survival cc-bar in ’ (P. Artoisenet et al., hep-ph/0506325)
   •Other model(s)?
Measurements of (e+e-hadrons)
         and BF for
  (3770) D0D0, D+D-, DD and
       (3770)  non DD
                                     PLB605(2005)63-71


 BF(((3770) J/ ) =             Before BES-II one knows the decays


 (0.34 0.14 0.09)%
                                    (3770)
 G(((3770) J/ ) =
 (80 3323)KeV                                                      e
                                         e
  BES was the first to report the                 * c        *
  non DD Decay of (3770)                    
                                                       c
                                         e          (3770)
                                                                     e

Now study non-DD decay by R           BES-II established the transition
measurement and energy peak scan      at 3 σ level !
 (e e  hadrons) &  (e e  D D )
                                                                    


Measurement of R
R is one of the most fundamental quantities in particle physics,
which counts directly the charges, the flavors and the colors of
quarks involved .
  pQCD calculates the R ratio                   Experimentally, one measures
                                                                           N had : # of hadronic
            -
           e        - hadrons                               N had                       events
                    q                             obs
                                                                          L           : Luminosity
                                                           L   had
                                                   had
                               lowest                                      had : Eff.
           e+       q            order

  Rº       e-                    =S      Qf2
                                                             had
                                                               obs
                           -
                                   flavor       had
                                                 Born
                                                                          (1   ) : radiative
                                   color
                                                           (1   )        correction factor
       
                +                                  had
                                                    Born
                                                                                                      86.8 nb
           e            
                        +                      R                           e    
                                                                                  e        
                                                                                               E cm (GeV) 2
                                                                                                      2
                                                                                          R tot and R uds
            Including the contribution        Including J/ψ and
            from high order processes         ψ’ contribution


      ECM [GeV]           σobshad             σ Bornhad             B (e  e   hadrons )      R
       3.650            19.16  0.08 15.20  0.06 15.10  0.06 2.31  0.01
       3.665            18.59  0.19 15.15  0.15 14.79  0.15 2.29  0.02
       3.671            17.13  0.41 14.37  0.34 13.66  0.34 2.12  0.05
       3.773            27.97  0.05 23.23  0.04 23.21  0.04 3.81  0.01
        R  3.81  0.01  0.19 @ 3.773 GeV

        Ruds |WA  2.30  0.01  0.10                             Ruds |2.0    to 3.0 GeV      2.26  0.14

        Ruds |fit to  ( 3686) & σ ( 3770)  2.21 0.13                   Obtaining by fitting to
                                                                            the R values measured
              BES contribution paper                                        by BES in the range
see below                                                                   from 2.0 to 3.0 GeV
              to Lepton-photon 2005
                   BF ( ( 3770)  non  D D ) determined                               with R & σ D D

                  R (3770) & σ ( 3770)
                                Born



                   Taking the R for light hadron production to be a constant, then
                                                  R ( 3770)  R  Ruds
                   We obtain
                                          R ( 3770 )  1.51  0.01  0.12

                                    ( 3770)  9.21  0.06  0.73 nb
                                    Born


                    It is consistent with
My calculation




                                               12
                         ( 3770) 
                         Born
                                                               BF ( ( 3770)  e  e  )  11.08  1.74 nb
                                       (1   VP ) M ( 3770)
                                                    2



                         (1   VP )  (1.047  0.024)
                                                                   obtained based on PDG04 (3770)
                          PLB 603(2004)130                         resonance parameters
 (e e  D D )
        
                       L  17 .3 pb 1of data @ 3.773 GeV
                                             N Dtag      From Monte
                                obs
                                                        Carlo
  D K 
    0                          DD
                                           2 L Br       PDG04 Br
                            Observed cross sections for DD-bar
                            production at 3.773 GeV


  D0  K    
                              D D  3.58 0.09  0.31nb
                               obs
                                   0   0



                                obs
                                 D D
                                            2.56  0.08 0.26 nb

  D   K   
                                obs
                                 DD
                                        6.14  0.12  0.50 nb

                                                      PLB 603(2004) 130
                 Checked by double tagging method (33pb-1 data)
  D0  K                                                               K   .vs. K                            K   .vs. K   0
                                               D 0  K    0

D 0  K                                D   K    

                                                                                                                   K   0 .vs. K   0
    D K 
            0   
                                               D K   
                                                       0             K   .vs. K    
             S                                          S



                                               D  K S K 
                                                      0
  D   K  K  
                                                                         K   0 .vs. K             K     .vs. K    

    D   K      0                      D   K S   0
                                                      0




                                                                          K    .vs. K              K    .vs . K S  
                                                                                                                               0




                                                                          K    .vs. K S    
                                                                                           0
                                                                                                           K    .vs. K  K  

                        D D  3.47  0.32  0.21nb
                         obs
                           0   0                                                                         K    .vs. K    0
                                                                          K    .vs . K S K 
                                                                                            0



                        D D  2.46  0.33  0.20 nb
                         obs
                              
                                                                           K    .vs. K S   0
                                                                                            0



                        D D  5.93  0.46  0.35 nb
                         obs


                                      Preliminary !
 Contribution paper to LP05
 Determination of branching fractions with
           DD
            obs
                          and  ( 3770)
                               Born

                                                                                    Obtained from analysis of R

                                                          prd
                                                        N DD           DD
                                                                         Born
                                                                                       DD
                                                                                         obs

BF ( ( 3770)  D D)                                                Born 
                                                       prd
                                                      N (3770)        ( 3770) gBES II σ ( 3770)
                                                                                             Born




Radiative correction                                                                           Some systematic
                                                                                               uncertainties can
Assuming that (3770) decay exclusively into D D                                               be canceled out
                     1 4 M D / s
                            2

   obs
    DD
          ( s)                    dx f ( x, s)  B ( s(1  x )) | 1  ( s(1  x )) | 2
                  0


 | 1  ( s(1  x)) |2  (1   vp )  1.047  0.024
                                                                            PR D62             Radiative correction factor
                                                                            (2000)012002-1     obtained based on new
                                                                                               (3770) resonance
                                12GeeG f ( s )
  ( s) 
     B                                                                                         parameters measured by
                     ( s  M 2 )2  M 2Gtot ( s )
                                         2                                                     BES-II.

                                    obs
    Radiative correction factor g  B                                          gBES II  0.768  0.020
                                   
 Results of branching fractions

   BF ( ( 3770)  D 0 D 0 )  (50.6  1.2  3.7)%
   BF ( ( 3770)  D  D  )  ( 36.2  1.1  3.5)%
    BF ( ( 3770)  DD )  (86.8  1.6  5.1)%
   BF ( ( 3770)  non  DD )  (13.2  1.6  5.1)%

                                           Uncertainties due
                                           to luminosity,
These results are preliminary !            trigger, radiative
                                           corrections are
                                           canceled out.
  Measurement of branching fractions for
 (3770)  D D , D D , D D and  ( 3770)  non  D D
            0 0




                                               (3770)
 Cross section scan experiment             production

 The data were collected at 49 energy points from
 3.66 to 3.89 GeV, which begin from off-resonance,
 cover (2S), (3770) and stop at DD* threshold .

 Separated beam collision data at 3 energy points
 were collected to study beam associated background.

 Some J/, (2S) data were also taken to calibrate
 BEPC energy and determine trg
 Observed cross section                             Hadron efficiency vs C.M. energy


                       nhad
 ( Ecm ) 
    obs

            L( Ecm )  had ( Ecm )  trg
    had



                    1
   expect
    had      ( s)   dx f ( x, s)  B ( s(1  x))
                    0

                        12GeeGf ( s)
 ( s) 
     B

                  ( s  M 2 ) 2  M 2Gtot ( s)
                                       2



 f ( x, s) is sampling function
      (Kuraev and Fadin)
                                              BEPC energy calibration

    Just before the scan experiment                                                                  M PDG  M PDG
                                                                                                       ψ'      J/ψ
                                              E   true
                                                         M   PDG02
                                                                       (E   BEPC
                                                                                     3095.3)
                                                                                                 3684.8 3095.3
                                                              J/ψ



                                               EBEPC is the energy of BEPC
   J/                     '
                                               set in the experiment,
                                               Etrue is the true energy
                                                                         3684.7  3684.9
                                                                                          3684.8
                                                                                2
                                Mass [MeV]               J/                                    '
       '


                                PDG04 3096.916  0.0113686.093  0.034
                                BEPC         3095.30  0.05                          3684.70  0.01

                                BEPC                                                 3684.90  0.01
When scan over 3.770 GeV        BEPC                                                3684.50  0.02
                                      (3770) Resonance parameters


          
                  To get right resonance
   obs
    had
              '
                  parameters, the two
                  resonance
                                               obs
                                                had
                                                                (3770)
                  production and
                  decays should be
                  considered
                  simultaneously. In this
                  way the “correct” QED
                  background ( Ruds )
                  can be determined
                  correctly !


                                                      QED (from u, d and s quarks)
                      (3770)

                                                      '

                               R uds  2.21  0.13      J /

                  Ecm      [GeV] BES-II Preliminary !            Ecm      [GeV]
  Comparison of (3770) Resonance Parameters
Experiment
                  M  ( 3770) (MeV)   Γto t (MeV) Γee (eV) M (MeV)
MARK-I              3772 6            28  5   370 90   88  3
DELCO               3770 6            24  5   180 60   86  2
MARK-II
                     3764 5           24  5   276 50   80  2
PDG04             3770.0 2.4 23.6 2.7 260  40 83.9 2.4
 BES-II
(preliminary !)
                  3772.3 1.0 25.5 3.1 224  30 86.8 1.0


      prd
       ( 3770)      |   s  3772.3 MeV
                                         9.07  0.82 nb
   Comparison of (3686) Resonance Parameters
experiment      M (MeV)  '
                            Gtot (keV)
                             
                                       G ee (keV)
                                          '                  '



This measurement
  (preliminary !)   3685.6  0.1  0.3   269  69  35   2.25  0.11  0.02

BES-II published
(PLB550(2002)24)          N.A.            264  27           2.44  0.21

PDG2004             3686.093  0.034 281 17             2.12  0.12

  Using a constant for vacuum
  polarization correction

                                         The measured partial width is
                                         consistent with PDG04 partial
                                         width of (3686).
Line shape of the cross sections for hadron and DD-bar production

               Inclusive hadrons                    Inclusive hadrons




                                                            D0 D 0



                                                            D D
                 Red: inclusive had.

                 Black: D0D0-bar

                 Blue: D+D-




   obs




          E cm                [GeV]
 Branching fractions
                                        Obtained from fitting to the inclusive
                                        hadron and the DD-bar production
                                        cross sections simultaneously.

  BF ( ( 3770)  D 0 D 0 )  ( 51.1  4.2  3.5)%            Considered the

  BF ( ( 3770)  D  D  )  ( 33.7  2.9  3.2)%
                                                              correlation
                                                              between the two
  BF ( ( 3770)  DD )  (84.8  6.8  6.4)%                  branching
                                                              fractions for the
  BF ( ( 3770)  non  DD )  (15.2  6.8  6.4)%            two modes

  BF ( ( 3770)  non  DD )  30.1% @ at 90% C.L.



 where the first error is statistical and second systematic, which
 arises from the un-canceled systematic uncertainties in hadron
 cross sections (~3.4 %), neutral DD-bar cross sections (~6.2 %)
 and charged DD-bar cross sections (~8.6 %).

 These results are preliminary !
               Summary
Lots of new results from J/, (2S), cCJ and (3770)
decays.
X(1835) observed in J/+(’) decays, could be
the same state observed in J/pp, could be a
baryonium. Other threshold enhancements.
 Parameters of  and  are given.
Vector charmonia (J/, ’, and ’’) hadronic decays
are studied extensively and simultaneously to
understand charmonium decay dynamics.
“ puzzle” remains a puzzle.
Inclusive and exclusive (3770) non DD decay
reported.
           Status of BEPCII/BESIII
Two ring machine, design luminosity 3  10 
1032cm-2s-1 .
Detector design: SC magnet 1 tesla field;
small cell MDC; CsI crystal calorimeter;
Time of flight ~100ps; RPC as muon detector 9 layers.
Schedule: Summer of 2006, machine to be
commissioned.
Detector moved to beam line early of 2007, and
started to commission detector with machine together.
Expect to have test run in 2007.
Thanks
 谢谢
BES, PRL91, 022001(2003)
                           Old fit
                           w/o FSI

M  1859 10 25 MeV/c 2
           3 5
          

 G  30 MeV/c 2



                            New fit
                            with FSI
’ + - 0
  PWA




                                           C is incoherent
                                           background term


               Gounaris-Sakurai’s parametrization
S- and D-wave mixing                     A prediction of ’’ charmless decays
                                         Wang, Mo and Yuan, PRD70, 114014(2004)

                                          B((2S)  ggg)/B(J/  ggg) = 0.26 ± 0.04




                    G( ' '  f )                            G( '  f )
            RG                                      RG 
                                                      '

                   G( J /   f )                           G( J /   f )


                               Phase=0



                                                                    Average
                        Non-zero phase btwn                         enhancement
                        matrix elements
                                                                    factor



 Prediction on ψ(3770) charmless decay branching fraction: 16% (or 3.8MeV)
0++ states:
f0(980), f0(1370), f0(1500), f0(1710), f0(1790)

PDG 2004 values:
f0(980): M = 980 10 MeV, G = 40 – 100 MeV
           , KK
f0(1370): M = 1200 – 1500 MeV, G = 200 – 500 MeV
           2, 4, KK …
f0(1500): M = 1507  5 MeV, G = 109  7 MeV
           2, 4, , ’, KK …
f0(1710): M = 1714  5 MeV, G = 140  10 MeV
          2, 2K, 4, , ’ …
                             f0(980)
                                   • Important parameters from
                         f0(980)     PWA fit:
J /   
             
                                       M  965  8  6 MeV
                                       g  165  10  15 MeV
                                       g KK
                                             4.21  0.25  0.21
                                       g
                   f0(980)
J /   K K
              

                                   • Large coupling with KK
                                     indicates big strange quark
                                     component in f0(980)

              Phys. Lett. B 607 (2005) 243
                       f0(1370)
                                      • There has been debate
                                        whether f0(1370) exists or not.
                      f0(1370)
J /    
                                      • f0(1370) clearly seen in
                                        J/  , but not seen in
                                        J/  .

J /              NO f0(1370)

PWA 0++ components
                                         M  1350  50 MeV
                                         G  265  40 MeV

                 Phys. Lett. B 607 (2005) 243
                   f0(1710)
                                      • Clear f0(1710) peak in J/
                                         KK.
                         f0(1710)
 J /  K  K 
                                           M  1740  30 MeV
                                           G  125  20 MeV


                                      • No f0(1710) observed in J/
                     NO f0(1710)          !
J /    
                                    BR ( f 0 (1710 )   )
                                                             0.13 @ 95 %CL
                                    BR ( f 0 (1710 )  KK )



                   Phys. Lett. B 603 (2004) 138
J /  K  K 
                                 PWA analysis shows
                  f 0 (1710 )    one scalar in 1.7 GeV region.


                                   M  1740  4 10 MeV
                                                 25
                                             515
                                   G  166 810 MeV
                                           
J /  K s K s f (1710 )
          0 0
                 0

                                Phys. Rev. D 68 (2003) 052003
                   New f0(1790)??
                                  • A clear peak around 1790 MeV is
                                    observed in J/  .
                                       M  179040 MeV
                                               30

                       f0(1790)        G  27030 MeV
                                              
                                                60


J /    
                                  • No evident peak in J/  KK. If
                                    f0(1790) were the same as f0(1710),
                                    we would have:
                                       BR ( f 0 (1790 )   )
                                                               ~ 1.5
                                       BR ( f 0 (1710 )  KK )

                           ?        Inconsistent with what we observed
                                    in J/   , KK
J /   K  K                        BR ( f 0 (1710 )   )
                                                                0.13 @ 95 %CL
                                       BR ( f 0 (1710 )  KK )


                                   f0(1790) is a new scalar ??
            Scalars in J/  
J /    
                                            Two scalars in J/  :
            f 0 (1500 ) ?   f 0 (1710 ) ?


                                              – One is around 1470 MeV,
                                                may be f0(1500)?
                                              – The other is around 1765
J /   0 0                                  MeV, is it f0(1790) or f0(1710)
                                                or a mixture of f0(1710) and
                                                f0(1790)?
           Excited baryon states

 Probe the internal structure of light quark baryons
 Search for missing baryons predicted by quark
  model
                         J/ decays

   relatively large branching ratios
      processes       branching ratios(10-3)    N* decays
    J /  pp    0
                              2.00.1          N *  N
J /  pp                 6.00.5          N*    N
                                                        

    J /  p  n             2.00.1          N *  N
J /  pp                    2.10.2           N *  N
J /  pp '                  0.90.4          N *  ' N
J /  pp                    1.30.3          N *  N
                Pure isospin 1/2




        Feynman diagram of the production
        of pN *, *, S S*,   *
For J /  NN
             and     J /  NN N
                                ,
and Nsystems are limited to be pure isospin
1/2.
 The evidence of 2 new N* peaks
J /  pn   c.c.  
                                             N*(1520)   N*(1650)
                                 N*(1440)?   N*(1535)   N*(1675)
                                                        N*(1680)


                                                                   ?




Missing mass spectrum (GeV/c2)
• Fitting formula
         q 2l 1k
  (M 2  M 0 )  M 0 G0
            2      2 2




 k : momentum of n
 q : proton momentum in
   Mx frame
   ► Possible new N* resonance
  M = 2065  3-30 MeV/c 2 G=175  12  40MeV/c 2
              +15


   ► preliminary PWA shows: this N* favors 3/2+

                     hep-ex/0405030
Measurements of J/ and c decays
First observation of J/  f2(1270)f2(1270)4

                                    fit with:
J/anything MC BG       signal     BW: 0(770), f2(1270)
                                    BG: 2nd order polynomial
                                        + f2

                                  Br ( J /  f 2 (1270 ) f 2 (1270 )   4 )
                                   (9.45  0.65  1.56) 10  4
           M(GeV/c2)



        P. R. D. 70 (2004) 112008
Measurement of J/ decays to Vector + Pseudoscalar
                 --- Brs. of J /   0 ,  ,  '

channels measured:

     J /   0
     J /   ,   K  K  ,   
     J /   ,   K  K  ,     
     J /   ,   K  K  ,      0
     J /   ',   K  K  ,  '  
     J /   ',   K  K  ,  '    
     J /   ',   K  K  ,  '    
The measured branching ratios




Phys. Rev. D 71 (2005) 032003
First measurements of J/ 2(+-) and 3(+-)

     J/ 2(+-)                 J/ 3(+-)

                                                        




         M() GeV                        M() GeV

   Br ( J /  2(   ) )     Br ( J /  4(   ) ) 
    (1.88  0.06  0.25) 103    (7.24  0.96  1.23) 104

         Phys. Lett. B 610 (2005) 192
Measurement of J/ decays to  + Pseudoscalar
                 --- Brs. of J /   0 ,  ,  '
       J /        0


       J /   ,   
       J /   ,                    


       J /   ,                       0


       J /   ,  '  
       J /   ,  '                 


       J /   ,  '                 
preliminary
First observation of cK+K-2(+-) and 3(+-)

    J /   c ,  c  K  K     


                                               Ndata=100 26
                                                  (1.43  0.04)%
                                                 G  17.3MeV
                                                 significance: 4.0




B( J /  c )  B(c  K  K      )  (1.21  0.32  0.23) 104
B( J /  c )  B(c       )  6.03 105 at 90% C.L.
       J /   c ,  c       
                                                    




                                                    Ndata=427 64
                                                      (3.21  0.06)%

                                                        G  17.3MeV
                                                    significance: 6.9




B( J /  c )  B(c         )  (2.59  0.32  0.48) 104
      Submitted to Phys. Lett. B (hep-ex/0505093)
Search for Lepton flavor violation (LFV)

  • In SM, lepton flavor symmetries are conserved.
  • neutrinos having mass and flavor oscillation
    indicates the existence of LVF
  • J/  e,  and e are LVF processes
   Decay modes       Nsignal   Nbackground    Upper limit
                                             (@90%C.L.)
       J/→e           4          2           1.110-6

       J/→e           1          0           8.310-6

       J/→           0           0          2.010-6

           Phys. Lett. B 555 (2003) 174
           Phys. Lett. B 598 (2004) 172
                                                                          Radiative correction could
                                                                          remove the effects of high
                                                                          order processes from the
                                                                          cross section, and gives
                                                                             B (e  e   hadrons )

                                                                         Events Recorded by BESII
                                                                        n    N
                 e-                                                      had    b
                            -
                            q
                                       Nhad                                                n  N had (1   )
                             q                                                              had
                 e+
                                                  Pri
                                                cos rimary
                                                  P
                                                cosmmary
                                                   miic ray
                                           N          c ra
  e-        e-    e-        e- - -       N               y
                                               0 +
                                               0 +
         l+l-
         qq
                      e+               e-- e+ -- +        
                                                          
  e+        e+             e+ + +    e e+ e +
                                            e
                 e-              e-
                                            e e
                                                     +
                                                     +                     Cosmic-ray and beam
                 e+              e+                                         associated background
                 e-              
 N
     b           e+                                           The distributions of the averaged Z of events

N could be estimated based on cross sections, luminosity and acceptance
 b
                                                           MC generator & simulation
                   Full energy range ISR e  e   hadrons Generator
                                                                    Nch           KNO
                                                ( 3770)                                        φ
                            s  3.78 GeV

                                            ( 3686)
                                                                                              cosθ
Density [nb/GeV]




                                                                Thrust        Oblateness
                                        J /

                                                                            Aplanarity


                      
                                                             Sphericity                    Jet axis cosθ


                              (1700)                                     x        η                Y


                                                                    Pt           <PTin2>
                                                                                             <PTout2>




                       Effectiveenergy [GeV]
                                                                               ISR corrections
                       ( s)  
                                  xmax
             expect
              had                        dx F ( x , s )  B ( s(1  x )) | 1   ( s(1  x )) | 2
                                 0
                                                                                                 Effective
           (s ) is Born order cross sections
              B                                                                                  c.m. energy
                                                                                 s'
                                                                          x  1
          F ( x, s ) is sampling function                                        s            Moninal c.m.
Kuraev                                                                                        energy
& Fadin                        F ( x , s )   x  1 V  S                  H


                                               2      s                          the electron equivalent
                                                 ln       1
                                                    me 2    
                                                               
                                                                                    radiator thickness


                                          3    2 1       2 9    2 
                              V S
                                       1    3  2     32  12 
                                                                      
                                          4                         
                                                  H   1H   2H
                                                                   x
                                                  1H     1     
                                                                   2
                            1 2             1 1  3(1  x ) 2                                  
                      H
                       2     4( 2  x ) ln                 ln(1  x )  6                 x
                            8               x       x                                          
                                                    Vacuum polarization
    1
           1   ( s )   2 ( s )  ...           correction
1  ( s)
                                                        Vacuum polarization change
  h  l                                             the photon propagator
            s            B ( s' )
h             [PV               ds'  i B ( s )]        ig                ig 
       4               ss                                          
                                                                                            
            2                  '
                                                              q2          q 2 1   (q 2 )
            1 ll
 l  1   vac                                                       results in
            2
            2                      4m l2                                  B
 vac ( s ) 
   l l
                 f ( x),       (x          )                      B 
                                       s                               | 1   ( s ) |2
           5 x     1  x (2  x )  1  1  x 
 f ( x)                      log          ,       ( x  1)
           9 3          6           1  1  x 
           5 x  1  x (2  x )                1
f ( x)                      tan1              ,     ( x  1)
           9 3       3                       x 1

                                         had
                                          expect
                             (1   ) 
                                         B
 Integrated luminosities
  Luminosities were measured by using large angle
  Bhabha scattering

   About 5.4 pb-1 of data were collected for the
   experiment (for hadron events)
                                      Using more cross section
                                      scan data to reconstruct
 Monte Carlo                         DD-bar events


   Developed a inclusive hadronic event generator
   with high order ISR corrections to simulate the
   hadronic event production (including Lorentz boost
   due to initial state photon emission) in the full
   energy region
                                     DD-bar
 Energy dependent cross sections production




               D0  K  
                                                                          D0  K    

                                Distributions of invariant masses of mKn
                                combinations at different c.m. energies


                                                            N Dsingletag ( Ecm )
                                   obs
                                          ( Ecm ) 
                                    DD
                                                      2 L Dsingle tag B( D  mode)

              D   K   
                                                                Observed cross sections


                                                              Inclusive hadrons




          Observed cross section for hadron production [nb]
  0   0
DD




D D

                                                              Inclusive hadrons



DD
     Fit to the observed cross sections
     Fitting the observed inclusive hadron and DD-bar production cross
     sections to the theoretical cross sections, one obtains the branching
     fractions             0
                             12GeeGtot ( s )
                                                                    0
                                                                                                 12GeeGD D ( s )
        B
          ( 3770 )                                                             B
                                                                                       
                        ( s  M 2 )  M 2Gtot ( s )
                                             2                                    DD
                                                                                            ( s  M 2 )  M 2 Gtot ( s )
                                                                                                                2


     Gtot ( s)  G            0   ( s)  GD D ( s)  Gnon  D D ( s)                 momentum of D at peak
                       D0 D

                                                             1  ( rp D 0 ) 2 ( pD 0 ) 3
                                                                      0
                                                                                                                          0
     G          0 ( s )  G0 ( E cm  2 M    )                                             B( ( 3770)  D 0 D )
         D0 D                              D0
                                                             1  ( rp D 0 ) 2 ( pD 0 ) 3
                                                                                 0

                                              threshold                                        momentum of D
(3770) total width                           function
                                                             1  ( rp D  ) 2 ( pD  ) 3
                                                                      0

     GD  D  ( s )  G0 ( Ecm  2 M D  )                                                 B( ( 3770)  D  D  )
                                                             1  ( rp D  ) 2 ( pD  ) 3
                                                                                 0



                                                                              0
     Gnon  D D ( s )  G0 (1  B( ( 3770)  D 0 D  B( ( 3770)  D  D  )
                                                                                        2
                                                          obs 0 ( j )   exp 0 ( j ) 
                                                                                                                                2
                                                                                              D D ( j )   D D ( j ) 
                                                 2
                           (i )   (i ) 
                       obs              exp                                                     obs             exp

     c 2                                           D D                             
                                                                                                                          
                                                             0               0
                       had              had                                 D D
                             had ( i )                        0 0 ( j)                          D D ( j )          
                                                                 D D                                                   
                                                   Independent hadron and
                                                   DD-bar data sample

                net                                        net
              N had                                      nhad
 had ( i ) 
  obs
                                             had (i ) 
                                              exp

              L had                                     L had    Branching
                                                                   fraction for

                                            nhad  nhad  nD D
                                             net    exp    exp     the singly
N   net
    had   N   obs
               had   N    obs
                           DD
                                                                   tagged D
                                                                   channel

 nhad   had L had
  exp     exp


n   exp
    DD
              prd
                ( 3770)   (1   ISR ) LB0 ( B1 1  B2 2 )  B B3 3 
                                       0
B0  B( ( 3770)  D D )           0


B  B( ( 3770)  D  D  )

 These relations remove those hadronic events which also
 appear in the DD-bar samples, so that the inclusive hadronic
 and DD-bar samples are independent.
                       SUMMARY
 .BESmeasured R at 3.773 GeV and around 3.666 GeV
 with average uncertainties of ~ 5%    (preliminary !)
     R  3.81  0.01  0.19       @   s  3.773 GeV
     R uds  2.30  0.01  0.10   @     s  3.66 GeV
     R uds  2.21  0.13      @ in the range from 3.67 to 3.89 GeV
                                  Obtained from fitting to (3686) and (3770)

      ( 3770)  9.21 0.06  0.73 nb
      Born


.
 BES  measured the energy dependent DD-bar cross
 sections, and the cross section at 3.773 GeV
                  D D  6.14  0.12  0.50 nb
                   obs
                                                         Singly tagged D analysis


                  D D  5.93  0.46  0.35 nb
                   obs
                                                         Doubly tagged D analysis
                       SUMMARY
                                                       (preliminary !)
.
 BES measured the branching fractions for inclusive non-DD-bar
  decays of (3770) using two different data sample and two
  different methods

    BF ( ( 3770)  D 0 D 0 )  (50.6  1.2  3.7)%         Determined
                                                            from analysis
   BF ( ( 3770)  D  D  )  ( 36.2  1.1  3.5)%         of R values
   BF ( ( 3770)  DD )  (86.8  1.6  5.1)%               and DD-bar
                                                            cross sections
    BF ( ( 3770)  non  DD )  (13.2  1.6  5.1)%




                                                             Obtained from
   BF ( ( 3770)  D D )  ( 51.1  4.2  3.5)%
                          0   0
                                                             fitting to the
   BF ( ( 3770)  D  D  )  ( 33.7  2.9  3.2)%          inclusive
                                                             hadron and the
   BF ( ( 3770)  DD )  (84.8  6.8  6.4)%                DD-bar
   BF ( ( 3770)  non  DD )  (15.2  6.8  6.4)%          production
   BF ( ( 3770)  non  DD )  30.1% @ at 90% C.L.
                                                             cross sections
                                                             simultaneously.

  These are first measurements.

				
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