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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

New Results on (3770) and D Mesons Production and Decays From BES

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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

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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

4

Absolute measurements

Double tag analysis

D- and D0 tags

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

16

Comparison of R measurements from different experiments

PLB 641 (2006) 145

The quantity R

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]

26

Thank You !

27

Backup slides

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