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New Results on (3770) and D Mesons Production and Decays From BES. Gang RONG (for BES Collaboration) Presented by Yi-Fang Wang. Charm07 Cornell University, August 4-8 2007. Outline. Introduction. Inclusive decays of D Mesons. Measurements of R. Parameters of (3770). - PowerPoint PPT Presentation
Citation preview
1
New Results on (3770) and D Mesons Production and Decays From BES
Gang RONG
(for BES Collaboration)
Presented by Yi-Fang Wang
Charm07
Cornell University, August 4-8 2007
2
Measurements of R
Introduction
Inclusive decays of D Mesons
Outline
Summary
B[(3770)non-DD] and Search for Charmless decays of (3770)
Parameters of (3770)
3
BESII (3770) data sample of about 33 pb-1 about 17.3 pb-1 data taken at 3.773 GeV
about 7 pb-1 data taken from 3.768 GeV to 3.778 GeV
0
50
100
150
200
250
300
MARK-I DELCO MARK-II MARK-III BES-II CLEO-c
pb-1
(by summer,2005)
World (3770) Samples (pb-1)
about 8 pb-1 data taken from 3.665 to 3.878 GeV
• about 1 pb-1 data taken at 3.665 GeV
IntroductionData Samples
• about 6.5 pb-1 data taken at 3.650 GeV
5
D+XWith the singly tagged D sample, we can do some absolute measurements of D decays on the side recoiling against the tags .
e+
e-
D
D
K+
π–tag
D+
D-π–
Singly tagged D sample
P+
X=any particles
XD 0 XD
0.52-0.62 GeV
0.62-0.72 GeV
0.72-0.82 GeV
0.82-0.92 GeV
0.92-1.02 GeV
mKnπ(Dtag)
PT
Nμobs
P+ is any charged particle (, e, π and K)
6
obs
kobs
eobs
obs
ke
kekk
ekeeee
ke
true
ktrue
etrue
true
N
N
N
N
N
N
N
N
kk
1
Nobsi =observed particle I; Ntrue
i = true particle iεim= ratio of a particle “i” to b
e identified as “m”
μtrue etrue
Ktrue πtrue
truek
ktruee
etruetrueobs NNNNN
etruekektrueee
etrueetrue
eobs NNNNN
ktruekkktrueek
etruektrue
kobs NNNNN
truek
ktruee
etruetrueobs NNNNN
D+X
First measurementsARGUS 6.0±0.7±1.2 -
CHORUS 6.5±1.2±0.3 -
BES-II 6.8±1.5±0.6 17.6±0.7±1.3
PDG 6.5±0.7 16.1±0.4
)(%)( 0 XDB )(%)( XDB
15.070.059.2)(
)(0
XDB
XDB
02.054.20
D
D
PDG
7
De+X and DKX
06.012.095.0)(
)(0
XeD
XeD
Preliminary CLEO-c 6.46±0.17±0.13 16.13±0.20±0.33
MarkIII 7.5±1.1±0.4 17.0±1.9±0.7
BES-II 6.3±0.7±0.4 15.2±1.0±0.7
PDG2007 6.55±0.17 16.1±0.4
)(%)( 0 XeDB )(%)( XeDB
Comparison of Results
B(De+X) and B(DKX)
BES-II 24.7±1.3±1.2 15.2±1.0±0.7 57.8±1.6±3.4 3.5±0.7±0.3
PDG2007 27.5±2.4 5.5±1.6 53±4 3.4+0.6-0.4
)(%)( XKDB )(%)( XKDB )(%)( 0 XKDB )(%)( 0 XKDB
8
Why are we interested in R(s) ?
• For evaluation of the electromagnetic coupling at the Z mass scale, )( ZQED M
• For determination of of the muon. 2/)2( ga
)()(
3
)0(
24
2
2LOhad, sR
s
sKdsa
m
• Evaluate )(sS• Non-DD decays of (3770)
• Vacuum polarization correction needs the R(s) values, which plays an important role in the precision test of the Standard Model.
The quantity R
• important in open charm region for the understanding of 1-- resonance production, for searching for new states, and for studying dynamics …
9
(3770) production & decays
It is believed to be a mixture of and states of system. It is thought to decay almost entirely to pure DD-bar.
131 D 1
32 S cc
Before BES-II & CLEO-c, previously published data indicate that more than about 35% of (3770) does not decay to DD-bar ? This conflicts with theoretical prediction.
The quantity R
10
New MeasurementsRecently BES and CLEO-c measured the DD and (3770) production at 3.773 GeV based on the data taken below DD threshold and at 3.773 GeV.
A better way to measure the cross sections, the widths of the resonance and the DD branching fractions of (3770) is to analyze the line-shapes of (3770), (3686) and DD production simultaneously.
BES made several fine cross section scans covering both the (3686) and (3770) to measure the resonance parameters, branching fractions and search for non-DD decays …
To uncover the puzzle, a better way is to make cross section scan
The quantity R
11
Precision measurement of the cross sections in this region
The Previously Measured quantity R
Including all hadrons
The quantity R
12
calculateRhad
Ruds
hadrons
hadrons
)()3770()( sR cuds )()( )3770()( sRsR cuds
udsR
above cc-bar threshold
below cc-bar threshold
Rhad(s)=Ruds(c)(s)+ΣRres,i(s),Rres,i(s) is R values due to all 1 -- resonances decay to hadrons except Ψ(3770).
Definition of different R
)( ZQED M
2/)2( ga
)(sSEvaluate
The quantity R
[where q is the light (u,d,s) quarks]
13
2
0
expecthad |))1((1|))1(( ),( )(
max xsxssxFdxsx B
ISR corrections
functionsampling issxF ),(
sections crossorder Born is )(sB
Kuraev & Fadin
HSVxsxF 1),(the electron equivalent radiator thickness
1ln
22em
s
4
372ln
3
1
242
1
34
31 2
2
22
e
SV
m
s
HHH21
211
xH
xx
x
x
xxH 6)1ln(
)1(311ln)2(4
8
1 22
2
s
sx
'
1 Effective c.m. energy
Moninal c.m. energy
The quantity R
14
...)()(1)(1
1 2
sss Vacuum polarization change
the photon propagator
results in
2|)(1| s
BB
Vacuum polarization correction
lh )](
)([
4
''
'
2sids
ss
sPV
s BB
h
llvacl
2
11
)4
()(2
)(2
vac s
mx, xfs lll
)1( ,11
11log
6
)2(1
39
5)(
xx
xxxxxf
)1( ,1
1tan
3
)2(1
39
5)( 1
xx
xxxxf
)(1 222 qq
ig
q
ig
B
expecthad)1( Radiative correction factor
The quantity R
15
Ruds = 2.141±0.025±0.085
RpQCDuds = 2.15±0.03
)()3770()( sR cuds )()( )3770()( sRsR cuds
udsR
above cc-bar threshold
below cc-bar threshold
Results PRL 97, 262001 (2006)
Below DD-bar threshold
The quantity R
Sources ΔSYS (%)Luminosity 1.8
Hadron selection 2.5
M.C. modeling 2.0
ISR 1.5
Ψ(3770) resonance parameters 2.7
Total (off Ψ(3770) region) 3.9
Total(within Ψ(3770) region) 4.9
17
Resonance Parameters of (3770)
The paper is being in press (PLB)
68 energy points
Dec. 2003 data
...) (EichtenMeV 1.20))3770(( DD
...) (HeikkilaMeV 11))3770(( DD
New measurements
18
Resonance Parameters of (3770)
Experiment prd[e+e-(3770)][nb] obs[e+e-(3770)][nb]
This work [Dec. 2003 data] 10.00.30.5 7.20.20.4
BES [PRL 97(2006)121801] 9.60.70.4 6.90.50.3
MARKII 9.31.4
M(3770)(MeV) tot(3770)(MeV) ee
(3770)(eV) Note
3772.40.40.3 28.51.20.2 2771113 PLB in press
3772.20.70.3 26.92.40.3 2512611 PRL 97(2006)121801
Experiment PLB in press PRL 97(2006)121801 PDG
B[(3770)e+e-][10-5]0.970.030.0
50.930.060.03
1.050.14
Ruds=2.121 0.023 0.084
Comparison with those measured by other experiments
[Dec. 2003 data]
[Dec. 2003 data]
New measurements
19
obs)3770( [nb]
Comparison of measurements of the cross section for (3770)
production
What about World Average
Resonance Parameters of (3770)
510 ]))3770([( eeB
PRL 97 (2006) 121801
Preliminary !
)%031.0755.0(])3686([ eeB PDG04
)%033.0122.0704.0(])3686([ eeB PRL 97 (2006) 121801
Leptonic branching fraction
20
)%5.31.19.35())3770(( DDBF )%9.33.11.50())3770(( 00 DDBF
)%0.67.10.86())3770(( DDBF )%0.67.10.14())3770(( DDnonBF
Determined from analysis of R values and DD-bar cross sections
)%5.31.40.37())3770(( DDBF )%2.32.58.46())3770(( 00 DDBF
)%4.68.68.83())3770(( DDBF )%4.68.62.16())3770(( DDnonBF
Obtained by fitting to the inclusive hadron and the DD-bar production cross sections simultaneously.
)%585())3770(( DDBF )%515())3770(( DDnonBF PDG07
B[(3770)non-DD]PLB641 (2006) 145
PRL 97 (2006) 121801
21
ModeMode 3.7733.773[pb][pb] 3.6503.650[pb][pb] BBupup[[1010-3-3]]
00 <3.5<3.5 <8.9<8.9 <0.5<0.5
<12.6<12.6 <18.0<18.0 1.91.9
2(2(++--)) 173.7173.78.48.418.418.4 177.7177.713.313.318.18.88
4.84.8
KK++KK--++-- 131.7131.710.110.114.14.11
161.7161.717.917.917.17.11
4.84.8
++-- <11.1<11.1 <22.9<22.9 1.61.6
2(K2(K++K)K) 19.919.93.63.62.12.1 24.124.16.56.52.62.6 1.71.7
KK++KK 15.815.85.15.11.81.8 17.417.49.29.22.02.0 2.42.4
ppppbarbar++-- 33.233.23.43.43.83.8 42.142.16.16.14.84.8 1.61.6
ppppbarbarKK++KK 7.17.12.02.00.80.8 6.16.13.13.10.70.7 1.11.1
ppppbarbar <5.8<5.8 <9.1<9.1 0.90.9
3(3(++--)) 236.7236.714.714.733.33.44
234.9234.923.823.833.33.11
9.19.1
2(2(++--)) 153.7153.740.140.118.18.44
86.686.640.340.310.410.4 24.324.3
2(2(++--))00 80.980.913.913.910.010.0 124.3124.321.721.714.14.99
6.26.2
KK++KK--++--00 171.6171.626.026.020.20.99
222.8222.837.737.727.27.22
11.111.1
2(K2(K++K)K)00 18.118.17.77.72.12.1 <23.0<23.0 4.64.6
ppppbarbar00 10.110.12.22.21.01.0 9.29.23.43.41.01.0 1.21.2
ppppbarbar++--00 53.153.19.29.26.86.8 29.029.011.111.13.73.7 7.37.3
3(3(++--))00 105.8105.834.434.416.16.99
126.6126.647.147.119.19.22
13.713.7
PLB650(2007)111
Search for Charmless Decays of (3770)
Search for Charmless decays of (3770)
We have searched for more than 40 modes for the light hadron decays.
22
ModeMode 3.7733.773[pb][pb] 3.6503.650[pb][pb] BBupup[[1010-3-3]]
KK++KK--2(2(++--)) 168.0168.018.218.2223.73.7
164.9164.930.330.3223.23.2
<10.3<10.3
2(K2(K++KK--))++-- 11.911.95.85.81.71.7 <49.1<49.1 <3.2<3.2
ppppbarbar2(2(++--)) 23.523.55.05.03.53.5 22.822.88.48.43.43.4 <2.6<2.6
4(4(++--)) 131.8131.819.519.523.23.66
76.276.224.424.413.13.99
<16.7<16.7
KK++KK--2(2(++--))00 231.5231.563.663.637.37.55
<375.2<375.2 <52.0<52.0
4(4(++--))00 <206.9<206.9 <119.4<119.4 <30.6<30.6
00++-- 111.9111.913.113.113.13.11
113.6113.621.321.313.13.11
<6.9<6.9
00KK++KK-- 34.234.211.511.54.44.4 57.657.617.917.96.36.3 <5.0<5.0
00ppppbarbar 13.113.13.23.21.81.8 17.717.76.26.22.82.8 <1.7<1.7
KK*0*0KK--++ 94.794.715.515.510.10.44
85.585.526.326.314.14.44
<9.7<9.7
barbar <2.5<2.5 <6.1<6.1 <0.4<0.4
barbar++-- <26.7<26.7 <42.9<42.9 <4.4<4.4
Preliminary Results Search for light-
hadron decays of (3770)
Search for Charmless Decays of (3770)
23
ModeMode 3.7733.773[pb][pb] 3.6503.650[pb][pb] BBupup[[1010-3-3]]
++-- <37.1<37.1 <50.8<50.8 5.55.5
KK++KK-- <44.4<44.4 <53.2<53.2 6.66.6
ppppbarbar <20.3<20.3 <30.9<30.9 3.03.0
++--00 <25.5<25.5 <66.7<66.7 3.83.8
KK*0*0KK--++00 116.3116.332.732.720.20.00
128.1128.159.559.517.917.9 16.316.3
KK*+*+KK--++-- 173.9173.973.373.326.26.11
189.0189.0116.3116.328.28.22
32.432.4
KK++KK--0000 <5.6<5.6 47.647.633.433.410.710.7 0.80.8
KK++KK--++-- 94.294.231.631.611.711.7 141.9141.953.353.319.719.7 14.614.6
barbar00 <7.9<7.9 <21.4<21.4 1.21.2Upper limits are set at 90% CL
Preliminary Results
Search for light-hadron decays of (3770)
Search for Charmless Decays of (3770)
We searched for (3770)light hadrons over 40 channels, but no significant signals were found. This does not mean that (3770) does not decay into light hadrons. To extract the branching fractions for (3770)light hadrons from the observed cross sections, one need to make finer cross section scan covering both (3686) and (3770) with larger data samples (BES-III can do this well).
24
SUMMARY• Inclusive decays of D mesons
Measured BF(D+ mu+ X)=(17.6+-2.7+-1.3)% for the first time
Measured BF(D+ K- X)=(24.7+-1.3+-1.2)%
Measured BF(D+ K+ X)=(6.1+-0.9+-0.4)% Measured BF(D0 K- X)=(57.8+-1.6+-3.4)%
Improved measurements
• R value
Improved measurements of R in the range from 3.65 to 3.88 GeV
Measured Ruds = 2.121+-0.023+-0.085
Measured Ruds(c)+(3770) for the first time
• (3770) parameters
Precisely measured M(3770) =3772.3+-0.5 MeV; Γtot=28.5+-1.2 MeV; Γee=277+-16 eV
Precisely measured BF(e+e-)=(0.97+-0.08+-0.05)x10-5
σobs(3770) = 7.15+-0.25+-0.25 nb [combined two measurements]
25
SUMMARY
• BF[(3770)non-DDbar]
Measured BF[(3770)non-DDbar] = (15+-5)%
• Light hadron decays of (3770)
No significant signals for (3770)light hadron were found in about 40 channels.
• How to solve this problem ?
Combined 49 energy point cross section scan results and 3 energy point cross section results (inclusive hadron and DD-bar cross sections)
Finer cross section scan over (3686) and (3770) to measure the cross sections for exclusive modes and fitting the cross sections to extract out the branching fractions (My comment only !)
Measured BF[(3770)DDbar] = (85+-5)% PDG07 [BES]
28
Comparison with those measured by CLEO-c
BES-II CLEO-c)%2.42.74.16())3770(( DDnonBF
nb 0.080.01 0.410.30-)3770(
DDnon
nb 0.086.38 0.410.30-)3770(
obs
hadrons
Based on analysis of inclusive hadron and DD-bar cross section scan data.
(hep-ex/0512038); PRL 96 (2006) 092002
nb 0.106.39 0.170.08-
obsDD
Actually, considering the errors, the two results are not in contradiction.
nb 0.280.486.94obs)3770(
nb 0.61.1 )3770(
DDnon
PLB 141 (2006) 145
29
BES-II CLEO-cnb 0.500.126.14 obs
DD nb 0.106.39 0.17
0.08-obs
DD
nb 0.4212.00.95 )3770(
DDnon
nb 0.080.01 0.410.30-)3770(
DDnonnb 0.086.38 0.41
0.30-)3770(
obshadrons
Based on measured R values.
Comparison with those measured by CLEO-c
Method:BES measured near DD-bar threshold and R at 3.773 GeV with traditional method, then calculate the Born order cross section for (3770) production. By comparing the cross sections for DD-bar and (3770) production, BES obtained the branching fraction. BES used an ISR generator to simulate the decay e+e- hadrons and obtain the efficiency for e+e- hadrons.
udsRMethod:CLEO-c directly count the number of hadronic events observed at 3.773 GeV, and subtract the backgrounds from J/, (2S) radiative tails and continuum QED background. CLEO-c used the efficiency for the decay (3770) J/ π+ π- to estimate the efficiency for e+e- hadrons.
nb 0.630.197.09obs)3770(
Use parameter keV 33.2)2( eeS Use parameter keV 54.2)2( ee
S
Assuming that there are interference between the two amplitudes of continuum and resonance
nb 0.4212.00.62 )3770(
DDnonnb 0.620.196.76obs
)3770(
30
BES-II CLEO-c
Comparison with those measured by CLEO-c
Method: Method:
nb 0.080.01 0.410.30-)3770(
DDnon
Discussion
if we use to calculate the ISR & vacuum polarization correction factor, and assuming that there are interference between the two amplitudes of the continuum and the resonance, we would obtain
CLEO-c did not consider the difference of ISR & vacuum polarization corrections for continuum hadron production at the two energy points (3.671 GeV and 3.773 GeV) when subtracting background at 3.773 GeV.)2( S
keV 54.2)2( eeS
nb 42.00.110.48 )3770(
DDnon
)% 4.68.17.3())3770(( DDnonB
PRL 97 (2006) 121801