1 chen jiangchuan (for bes collaboration) institute of high energy physics, beijing 100039, p.r. c....
TRANSCRIPT
1
Chen Jiangchuan(for BES Collaboration)
Institute of High Energy Physics, Beijing 100039, P.R. C.
The International Conference on QCD and Hadronic PhysicsJune 16—20, 2005
Recent Results on (3770) Resonance and D Mesons Production
& Decays from BES
2
D0 & D+ Meson Decays
(3770) production & decays
Outline
Summary
3
~18 pb-1 of data taken at 3.773 GeV
~7 pb-1 of data taken at the region from 3.768 GeV to 3.778 GeV
~8 pb-1 of data taken in the energy region from 3.665 to 3.878 GeV
about 33 pb-1 of data collected around 3.773 GeV in total.
2004 Jan.5 BES completed total (3770) data collection.
BES (3770) data Sample
4
(3770) production & decays
(3770) resonance parameters
DD-bar cross cection at 3.773 GeV
Search for charmless decays of .. ,..)3770( *00* ccK KccKK
/)3770( JψEvidence for
5
Since its mass is above open charm-pair threshold and its width is two order of magnitude larger than that of , (3770) is thought to decay almost entirely to pure DD-bar.
(3770) is believed to be a mixture of and states of
system
131 D 1
32 S
)3686(
nb 8.16.11))3770((12
2)3770(
)3770( eeBFM
prd
(3770) production cross section at peak
MeV 5.29.3769)3770( M 51012.1))3770(( eeBF Using mass and branching fraction (PDG02):
nb 0.50.5)( DDeeobs (Mark-III)
nb 7.01.7)( DDeeprd Non-saturate decay ?
About 39% of (3770) does not decay to DD-bar ?
Puzzle of (3770) production and decays
cc
6
(1991)11 PLB267keV 160)( 13 gggD
Rosner) J.L. ,ph/0105327-(hep keV 620 )χ γΓ(ψ(3770) cJ
)155PRD41(1990 Kuang, Y.P. keV, 200) /)3770(( J
keV 980))3770(( DDnon
4.2%))3770(( DDnonBF Added all above numbers up !
There are some theoretical calculations about non-DD-bar decays
Theoretical predictionThere are some theoretical arguments about decays
Lipkin pointed out that could decay to non-DD-bar final states with a large branching fraction.
(3770)
(3770)
7
(3770) resonance parameters
To understand this long-standing puzzle, (3770) and production cross section should be measured more precisely.
The cross section of (3770) can be obtained based onthe (3770) resonance parameters.
(3770) resonance parameters can be extracted froma fit to the observed hadonic cross sections in the energy range which cover (3770) resonance (-- scan experiment).
DD
8
N0
e+e-e+e-
+
+-
e+
e-e- -
e+ + +
e- e-
e+ e+
e+
e-
Nhad
e- e-
e+ e+
+-
N0
e+e-e+e-
+
+
-e
e +
q-
q
Events Recorded by BESII
Cosmic-ray and beam associated background
Distributions of the vertex of events
physics background could be estimated based on cross sections, luminosities and acceptances
bN
bN
bN
hadn
)1( hadNhad
n
9
/J'
)3770(
GeV 78.3energy c.m. Nominal s
Monte Carlo productionhadronsee
The ISR (Initial State Radiation) return. The histogram show the hadronic eventproduction due to ISR when nominal center-of-mass energy at 3.78 GeV.
10
Monte Carlo productionhadronsee
Shadows are experimental data, lines are MC sample, (Ecm= 3.773 GeV).(Nch, KNO, Thrust, Sphericity, Aplanarity, xp, η, <pTin>, <pTout> distributions)
11
Hadron efficiency vs C.M. energy
[GeV] cmE
trgcmhadcm
hadcm
obshad EEL
nE
)( )()(
1
0
exp ))1(( ),( )( xssxfdxs Becthad
)()(
)(12)(
2222 sMMs
ss
tot
feeB
(Kuraev and Fadin)
functionsampling issxf ),(
had Observed cross section
12When scan over 3.770 G
eV
Just before the scan experiment
Mass [MeV]
PDG02
BEPC
BEPC
BEPC
04.087.3096
05.030.3095
09.096.3685
01.090.3684
02.050.3684
BEPC energy calibration
'
'
'J/
J/
3095.33684.8
MM3095.3)(EME
PDGJ/ψ
PDG
ψBEPCPDG02J/ψ
true '
EBEPC is the energy of BEPC set in the experiment,
Etrue is the true energy
01.070.3684
8.36842
9.36847.3684
13
'
/J
(3770) productionTo get right resonance parameters, the two resonance productions and decays should be considered simultaneously. In this way the “correct” QED background ( ) can be determined correctly !
udsR
quarks) s and du, (from QED
'
)3770(
)3770(
BES-II Preliminary !
[GeV] cmE [GeV] cmE
obshad
obshad
0.010.132.21Ruds
14
(preliminary !)
Experiment
MARK-I
DELCO
MARK-II
PDG02
BES-II
(MeV) Γ tot (eV) Γee
63772
63770
2.53769.9
0.31.03772.3
528
524
90370
60180
50276
40260
130224
388
286
280
(MeV) M
2.483.9
524
2.723.6
53764
Comparison of (3770) Resonance Parameters
0.13.125.5 1.086.8
nb 0.0382..| MeV8.sprd
)( 007937723770
(MeV) )3770(M
15
Comparison of (2s) Resonance Parameters
experiment
This measurement
(preliminary !)
BES-II published
(PLB550(2002)24)
PDG2002
(MeV) M '(keV) '
tot
(keV) 'ee
300063685 ... 3569269 020110252 ...
..AN 27264 21.044.2
09.096.3685 25300 15.019.2
Using a constant for vacuum polarization correction
16
e+
e-
D
D
K-
tag
D-
D+
X
π+
π+
Single tag analysis
Using kinematical fit method to improve momentum resolution and select the singly tagged D meson
1pb 3.17 L
Xfit MM Requiring
PDG02 Br
From Monte Carlo
DD-bar Cross Section at 3.773 GeV
2 BrL
NtagDobs
DD
BES-II: of data @ 3.773 GeV
Single tag method
17
nb 0.260.082.56 obs
DD
nb 0.500.126.14 obsDD
Observed cross sections for DD-bar production at 3.773 GeV
KD0
KD0
KD
nb 0.310.093.58 00 obs
DD
18
Near DD-bar production threshold region
e+
e-
D
D
K-
π+tag
D-
D+
X
e-e+
D
D
K-
tag
D0
D0
0X
Using ‘double tag’ method, pioneered by MARK-III
1pb 3.17 L
DD-bar Cross Section at 3.773 GeV
BES-II: of data @ 3.773 GeV
Singly tagged D sample
Doubly tagged D
π+ π+
Double tag method
19
nb 0.190.333.50 00 obs
DD
nb 0.190.332.49 obs
DD
nb 0.380.475.99 obsDD
绝对测量
Preliminary !
20
)()(
)(12)(
2222 sMMs
ss
tot
feeB
2/41
0|))1((1|))1(( ),( )(
2
xsxssxfdxssM Bobs
DD
D
Assuming that decay exclusively into (3770) DD
Radiative correction
PR D62 (2000)012002-1024.0047.1)1(|))1((1| 2
vpxs
Initial State Radiation correction factorB
obs
g
21
Obtained based on PDG02 (3770) resonance
parameters:
GeV 773.3At s
Radiative correction factor
Due to the uncertainties in resonance parameters and vaccum polarization )1( vp
GeV 773.3@ s
MeV2.53769.9M
MeV2.723.6" tot
eV 40260" ee
nb 0.370.103.29 tree
DD
nb 0.740.157.88 treeDD
nb 0.450.124.60 00 tree
DD
036.0779.0 Tree
obs
g
22
and
12.002.029.1
ee
treeDD
DDR
R
The contribution to R in the charm threshold region from the light quarks is estimated to be , which is obtained by fitting to the R values from 2.0 to 3.0 GeV measured by BES-II. The theoretical expectation is that is approximately independent of center of mass energy in this region.
14.026.2 udsR
udsR
yielding 18.002.055.3 R
R DD
R
The open square is charm counting method of R measurementAssuming that decays
exclusively into DD-bar
GeV) 3.773(at nb 709.6(GeV)
nb 8.8622
cmee E
Squares are the BES-II direct R measurements by counting inclusive hadronic events
(3770)
0.010.132.21Ruds which is obtained in measurement of (3770) resonance parameters
udsDDRRR udsDD
RRR or
DDR
23
4-prong with net charge zero0.85|cos|
(K) 0.001CL (K) π
01.0)4,P( 2 K
ππππ
22 ,4)P(χ)4,P( K
selection Ksatisfy 0S
Selection criteria
..00* ccKK S
.C.L 90%at @ 3.2)( * KKeeN
Data taken around (3770) peak
1pb 727 .Ldt
windowmass K0S
0SKM
8.35.12)( 00* SKKeeN
0)( * KKeeN
Neutral mode Charged mode
Search for charmless decays of .. ,..)3770( *00* ccK KccKK
24
observed signalc.c. KK nt significaNo S* 00
observed signal No KK*
.C.L 90% @ 3.2)( * KKeeN
Data taken off-resonance (@ 3.65 GeV)
7.100*
SKKQEDN
2.4*
KK
QEDN
Normalized to the luminosity and phase space of ψ(3770) production
1pb 4.6 Ldt
.C.L 90% @ 3.9)( 00* SKKeeN
Check if there are continuum
production ?
0SKM
KK *
25
c
c
process photon one onannihilati process continuumphoton one
hadrons hadrons
e e
e e
Resonance productions and decays QED process
Observed in experiment
ga amplitude a amplitude QEDa amplitude
Charmless final states observed
2||)hadrons charmless( QEDgobserved aaaeeN
** *c
c
hadrons
e
e
*g
|a|~|a| and |a||a| gQEDg around 3.77 GeV
Three gluon annihilation process
26
A detailed maximum likelihood analysis based on above observed event numbers gives
69592 .
230.246.1
00* ||86.1))3770(( gS aKKN
2490300
00 4390 |a|.)KKee(N QED..QEDS
*
o.cos 1809990
16162 . χ 0 |a| set g
giving a significance of 2.4
27
Those yield the branching fraction and upper limit to be
pb 4.0)6.04.18()( GeV 3.773
00* KKeeobs
L. C. 90%at 102.1))3770(( 3-00* KKBF
keV 3.3)1.10( 7.120.8)3770(
00*
KK
C.L. 90% @ keV 2900*)3770(
KK
4-5.44.3
00* 101.3)3.4())3770(( KKBF
and partial width to be
(preliminary !)
28
Evidence for Decay
??
it is an interesting question if transitions inside the charmonium system exist.
/Jψ ''
29
Examine the recoil mass of
Projecting the events on to the vertical scale (recoil mass of
), the evidence for is observed
llECMll
EE
5 . 2| |
MeV150| | / JllMM
22 ||)(
PEEM cmREC
/'' J
'
(mainly)
/)3770( J
Due to ISR
Evidence for (cont’d)
/Jψ ''
30
Evidence for (cont’d)
/Jψ ''
/ return ISR ' Jψ
/)3770( J
/' Jand
Data MC
9.55.25 /J MeV3.03103.3M1
signal events
Analysis of the recoil mass
3.11.11 9.55.25
/' J
out of
events in total
/' J
20 times large than the data
31
Evidence for (cont’d)
/Jψ ''
analysis of the fitted dilepton masses ofOpen histogram is for e+e- channel,
histogram in yellow is for mu+mu- channelISR todue production '
mainly
The histogram is psi(3686), while error bars are the psi(3686) + psi(3770)
/Jψ ''
8.48.17 signal events obtained 8.00.6
8.48.17
/)3686( Jψ
/)3686( Jψ out of/J
signal events/J8.48.11)/)3770(( JN
data MC
20 times large than the data
ll
32
It has been quoted 21 times.
e
c
c
e
e
* *
e
(3770)
(3770)It is an interesting question if transitions inside the charmonium system exist.
It is very important in elucidating the exact nature of the (3770) and help us understand why the (3770) does not seem to be saturated by DD-bar decays.
Before BES-II one knows the decays
BES-II established the transition at level ! σ3
Paper published in PLB605 (2005)63
Comments by Referees of the paper
keV )()J)(( 2333803770
)%...()J)((BF 0901403403770
33
D0 & D+ Meson Decays
Exclusive Semileptonic D DecaysExclusive Semileptonic D Decays
Purely Leptonic DPurely Leptonic D+ + DecayDecay
D absolute hadronic decay branching fractions
Singl tag samples
(3770) is a good laboratory for study D meson decays
34Invariant mass distribution for tags0
DInvariant mass distribution for tagsD
19875840 tagD
N 1495321tagD
N
KD0
00 KD
KD0
00SKD
KD 0
SKD
KKD S0
KKD
0SKD
00 SKD
0 KD KD
DSUM
Singly tagged D samples
35
Semileptonic D DecaysSemileptonic D Decays
e+
e-
D
D
tag
D-
D+
0Ke
π+
K-
π+π+
e-e+
D
D
K-
tag
D0
D0
K
Singly tagged D sample
e
36
Branching fractions for eKD0 eD0and
To measure the standard model parameters Vcs, Vcd
Probing the hadronic current
Understand the dynamics of semileptonic decays
HLV
GilXMA
QqF
qqqQ ''
2)(
vluL )1( 5
))(()( '22 ppqfqH
Where is a vector form factor, and are the four momenta of the initial and final mesons, respectively, and is the squared mass of the virtual W.
)(qf 2 p 'p
2 2 2
2 2 21 2
: and
* : , ,
lD Kl f q m f q
D K l A q A q V q
q
As an example
11122 100531 s|)(f||V|.)KeD( K
cse11122 100013
s|)(f||V|.)eD( cde
(“nearest pole dominance”)
Motivation
37
Branching fraction for
To test if the Isospin conservation is still held in D semileptonic decays. Isospin conservation requires
and
2.04.1)(/)(00
ee eKDeKD
From PDG Br
1)(/)(00
ee eKDeKD
It is called “Longstanding puzzel” in Charm decay !
eKD0 )(
0 eKD
Longstanding Puzzle in charm decay
Is isospin conservation held in the D semileptonic decays?
Motivation
38
tags.)D of RECin (found 0
eeK ) tags D of REC. in (found eK -
eS 0
Distribution of the Inv. masses of
Combinations for the events in which the
are observed in the recoil side
Kn
eeKD 0
REC.)in (found ee
Distribution of the momentum of the electronfrom the events of eeKD 0
39
Experiment
BES
MARK III
PDG 04
)( 0eeKDBr
27.040.082.3
)( 0eeDBr )(
0eeKDBr
03.013.033.0
4.05.04.3
18.058.3
04.039.0 23.011.0
06.036.0 9076 ..
7.00.6 2.23.1
670591958 ...
Results
[%] [%] [%]
Phy. Let. B597(2004)39-46 Phy. Let. B608(2005)24-30
40
11.078.0
|)0(| Kf |)0(| f
11.065.0
00.007.0)3(71.0
01.000.0)6(57.0
03.004.078.0
00.007.0)5(64.0
01.000.0)4(66.0
06.014.073.0
QCDSR
LQCD(1)
LQCD(2)
BES
BES
|)0(/)0(| Kff 07.019.093.0
Phys.Rev.D66,114002,2000
Nucl.Phys.Prog.Suppl.83,286,2000
Nucl.Phys.B619,565,2001
111220 10|)0(|||53.1)(
sfVeKD Kcs
111220 10|)0(|||01.3)(
sfVeD cd
Theoretical predictions are in the range from 0.7 to 1.4. See J.D. Richman et al., Rev. Mod. Phys., Vol. 67, No 4, 1995
Different theoretical predictions
Form factors
| |VV cdcs ||PDG04
inserting
Average MARK-III and CLEO gives
41
06013006011 ....
030060290 ...
030040050260 .
...
BES(QCDSR)
BES(LQCD(1)
)
BES(LQCD(2)
)
|| csV || cdV
15005001 ...
090080060181 ....
050050250 ...
BES MARK III
2|/| cscd VV 003.0017.0043.0 005.0057.0 038.0017.0
100 |)(f/)(f| K
Input
CKM matrix elements Input theoretical predictions for the form factors
)0( )0( ff K
42
BES MARK III PDG04
)(
)(0
0
e
e
eKD
eKD
62.044.1 2.04.1
Ratio of partial width
Obtained based on the branching fractions quoted from PDG02
070220081 ...
Solve the longstanding puzzle in Charm decays !
BES-II results support isospin conservation is held in the D semileptonic decays!
43
Purely Leptonic DPurely Leptonic D+ + DecayDecay
e+
e-
D
D
K-
tag
D-
D+
π+
π+
Phy. Let. B610(2005)183-191
44
Motivation
Df
2
2
22
221
8
D
lDlDD
cdF
m
mmmf
|V|GνlD(
)
Df
Lattice gauge, potential models bag model, QCD sum rule …, calculation predict the value of
The fD measurement will allow comparison with the theoretical calculation to improve the theory. Lattice predicts fB/fD with small errors. Precision measurement of fD precision estimate of fB and precision determination of Vtd
Df Bf00 BB Mixing experiment
It is very difficult to measure the fD due to |Vcd| is small D
f
DThe effect of strong interaction can be parameterized by
45
)%08.0()( 17.005.0
DB
D
MeV)300( 8018040150Df
MARK-III set an upper limit of fD < 290 MeV
BES-I observed 1 event for and measured
Physics Letters B 429(1998) 188-194
Previous measurements
GeV 03.4@ S
46
e+
e-
D
D
K+
tag
D+
D-
π-
π-
missmissmiss PEU Neutrino carries energy and momentum away
Should be around zero
1495321tagD
N
Fully reconstruct one D
Require one additional charged track and no additional photons
0sK K
KK 0
KK 0
SK
00 SK
0 K K
Total
47
KD
D KD
0KD
0 KD DVS
p
Monte Carlo sample 150 times more than data
missU
3 events in the signal region
missU
Monte Carlo simulation
missU 3
48
Estimation of background
The main background are 000 K , ,KD
)background continuum possible theas wellas
, ντ,πK,ππD as(such
modes)decay all ( 00
DorDDD ee -
3 X 100 times more Monte Carlo samples for each of the modes Nb = 0.22
Analysis of 320 pb-1 Monte Carlo samp
le Nb = 0.33+/-0.11
13 events in the tagged D- mass region
Method 1
Method 2
Method 3
1 hadronic track in the recoil of the tags
Nb=0.31±0.09
1 muon is fund in the recoil of the tags, and the events satisfied the requirements for selection of
025.0
D
49
Search for the decay
e+
e-
D
D
K+
π-
νe
Singly tagged D-
Candidate
tag
D+
D-
π-
%,)010.0122.0()( 111.0053.0
DBr
2.67±1.74 Events D
2
2
22
22
18
||)(
D
lDlDD
cdF
mm
mmfVG
νlDBr
|| cdV
MeV )25371( 129119 D
f
Df
50
e+
e-
D
D
K-
π+
tag
D-
D+
π+
Double-tag
D absolute hadronic decay branching fractions
0K
π+
e-e+
D
D
K-
tag
D0
D0
K
Singly tagged D sample
51
They are two very important constants to normalize all other branching fractions for the D mesons decays, B mesons and Z0 decays.
They enter into CKM matrix elements determinations. So more precisely measuring the both branching fractions can directly improve the CKM matrix elements:
|| csV
|| cdV
|| cbV
determine from
determine from
)( 0 eKDB
determine from
)( 0 eDB
)(0
lDBB )( 0 lDBBand
Methods of measuring )( 0 πKDB and
• at (3770) ---
• B decay
)( πKDB
DD double tag analysis
Absolute branching fractions for
and
πKD0
πKD
55
D absolute hadronic decay branching fractions
PDG04
(preliminary !)
56
SUMMARYBES measured (3770) resonance parameters
nb 0.030.829.07 prd)( 3770
BES measured the DD-bar Cross Section at 3.773 GeV to be
.
.
Experiment
BES-II
PDG02
)3770(M (MeV) Γ tot (eV) Γee
2.53769.9
0.31.03772.3
40260
130224
(MeV) M
2.723.6
0.13.125.5 1.086.8 (preliminary !)
2.483.9
( ISR based on PDG02 )
nb 0.740.157.88 treeDD
nb 0.760.158.14 treeDD
( ISR based on BES-II parameters )
(preliminary !)
(3770)
0.010.132.21Ruds From 3.66 to 3.87 GeV
57
BES observed the charmless decay events of
measured the partial width of
BES observed hadronic transition of to and measured the partial width to be
(3770) /J
keV )213280()/( '' J
.
.
keV 3.3)1.10( 7.120.8)3770(
00*
KK
..,..)3770( *00* ccK KccKK
C.L. 90% @ keV 2900*)3770(
KK
and set its upper limit to be
(preliminary !)
(preliminary !)
SUMMARY
58
SUMMARYMeasured the form factors & ratio of partial widths
06.014.073.0|)0(f|
07.022.008.1)Γ(/)Γ(00
ee eKDeKD
Observed 3 D+ purely leptonic decay events, and obtained
MeV 25)(371 129119 D
f
.
. πππ, Kππ KKD 00 ,
00000 K,K,K,K,KD
.
03.004.078.0|)0(f| K 07.019.093.0
)0(
)0(
Kf
f Theory: from
0.7 to 1.4
Solve the longstanding puzzle in Charm decays
Measured absolute hadronic branching fractions for
Those would improve the normalization constants used in Charm and B physics !
59
谢 谢!
Thank You !
60
Comparing the BES Results with that from CELO-c
Near DD-bar Threshold Experiments
61
LP03 关于 J/ 的讨论
?ee→ 2S2S→ J
Ecm -Mass recoiling
3770→ J
mainly
BES-II
CLEO-c
BES-II 结果成为热门话题, 被广泛关注,讨论和引用!这是 BES-II 与 CLEO-c 的物理结果第一次被 CLEO 成员所做的对比。 (at LP03)
62
DAPHNE’04 06/08/04 Hanna Mahlke-Krueger, Cornell (RG mdfy)
ee→ 2S2S→ J ?
232 events
Ecm -Mass recoiling
• 5.2±0.2 pb-1, (4.5±0.4)104 ’’decays
• efficiency: 37% < 4.75 events @ 90%CL B
R3770J(1S)) <0.26% @ 90% CL
17.8±4.8 events incl 6.0±0.8 bgd (0 from cont) BR3770→J)
= (0.34±0.14±0.08) % = (80 ±32±21) keV
BESII CLEO-c
T. Skwarnicki, QWG03
ee→ 2S2S→ J
M(ℓ+ℓ) GeV
hep-ex/0307028
已 21次被引用
63
DAPHNE’04 06/08/04 Hanna Mahlke-Krueger, Cornell
J/
ee→ 2S2S→ J ?
232 events
Ecm -Mass recoiling
• 5.2±0.2 pb-1, (4.5±0.4)104 ’’decays
• efficiency: 37% < 4.75 events @ 90%CL BR
3770J(1S)) <0.26% @ 90% CL
• 28 pb-1 (3.783-3.885GeV), 1.85105 ’’decays
• efficiency: 16% 17.8±4.8 events incl 6.0±
0.8 bgd (0 from cont) BR3770→J)
= (0.34±0.14±0.08) % = (80 ±32±21) keV
BESII CLEO-c
T. Skwarnicki, QWG03
ee→ 2S2S→ J
M(ℓ+ℓ) GeVhep-ex/0307028
64
Results given at international conference from BES-II & CLEO-c
Moriond EW04 (2004 年 3 月 )
APS (2004 年 5 月 )
nb 0.370.124.18 00 tree
DD
nb 0.340.093.23 tree
DD
nb 0.670.157.41 treeDD
nb 0.250.093.26 00 obs
DD nb 0.210.143.43 00 obs
DD
nb 0.240.072.52 obs
DD nb 0.160.152.44
obs
DD
nb 0.450.115.78 obsDD
nb 0.360.205.87 obsDD
无报道MeV )(365 32121
28-113-D
f MeV 10)42(230 Df
N/A
18.003.048.3 R
这是 BES-II 的物理结果与 CLEO-c 的第二次对比。
2 个月之后
65
Results given at international conference from BES-II & CLEO-c
BES -- Moriond EW04 (March, 2004)
CLEO-c -- APS (May, 2004) 00
SKD
无报道keV 21)32(80 )/)3770(( J
Dalitz analysis of N./A.
Branching fractions
CLEO-c 原计划要在 Moriond’04 国际会议上正式报道物理结果。 但最后却什么也没讲。
Rosner 主要根据 BES Moriond’04 结果 , 提出 rescattering 模型 , 来解释 衰变 . 他在文章中先后 5 次引用 BES 结果 .
DDnon )3770(
0.0030.0210.052 |/| cscd VV
08.021.004.1)(
)(0
0
eKD
eKD
0.080.201.01 /)0( Kff
0.020.040.74 )0( Kf
0.060.140.77 )0( f
66
nb 0.310.093.58 00 obs
DD
nb 0.260.082.56 obs
DD
nb 0.500.126.14 obsDD
BES-II DD-bar Cross section in good agreement with CLE-c
与 CLEO-c 物理结果的对比及国际反响
在 1.3% 的范围内一致!
67
68
69070220081 ...
BES-II Final result
70
71
Heavy Quarkonia
8 类典型的热点问题 3 大不解之迷 ? 有 2 个主要起源于 BES的 近期研究工作!
QQ-bar 的热点问题和不解之迷?国际反响
(3770)
72
几乎是常数效率,早年的辐射修正, …
MARK-I, DELCO, MARK-II 平滑效率; ( 相对 scale)
BES-II 效率曲线
73
依赖于 ) measured(Only DD B
目前 PDG 采用 MARK-III 的 nb 3.06.02.4 D
依赖于 )( 0 πKDBF
)(
)(0
πKDBF
πKDBF CLEO measured
绝对测量
πDD 0*
πKD0
软 标记π
实验状况
It is important to accurately measure the cross sections for DD-bar production !
)( 0 πKDBF )( πKDBF
74
CKM matrix elements &|| csV || cdV
Form factors & |)0(| f
Branching fractions
*
*
*
0Dc
u)(d
)( D
e
e
s ][d
u)(d
K ][
)( 0K][ || ||VV cdcs
)]0([ )0( ff K
Motivation
Isospin conservation implies
)(/)(0
0
eeeKDeKD
2.04.1)(/)(00
ee eKDeKD longstanding puzzle in Charm decays !
From PDG Br
|)0(| Kf
1)(/)(00
ee eKDeKD
eKDeeKD 00 , ,