(3770) and D physics at BESII

Ma HaiLong[For BES Collaboration]

CCAST & IHEP

中国物理学会 2006 年秋季会议（北京）2006.9.15-17

Outline

Purely and semi leptonic decay of D meson

Summary

BF[(3770) → D0D0,D+D-,DD and non-DD]

Motivation

Df

2

2

22

221

8

D

lDlDD

cdF

m

mmmf

|V|GνlD(

)

Df

The effect of strong interaction can be parameterized by

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|

Df

D

Motivation

2041)()/(00 ..eKDeKD ee

PDG04 BF

1)()( 0 ll KlD/KlD The called

“Longstanding puzzle” in Charm decay! 00( ) / ( )l lD K l D K l

0

0

, , D K l l

D K l

The decay rates can be related to the CKM matrix elements and form factors

0Dc

u)(d

)( D

s ][d

)(d

K ][

)( 0K][ || ||VV cdcs

)]0([ )0( ff K

Ratio of partial widths of vector to pseudoscalar semileptonic decays of D mesons

*0 0( ) / ( )D K e D K e

Branching fractions

Isospin conservation implies

There are controversies from both experiment and theoretical prediction

Early theories: 0.9-1.3Measurements: smallerRecent theories:0.5-0.7

Motivation

Motivation

Long-standing puzzle of (3770) production and decays

(3770) is thought to decay almost entirely to pure DDbar, but there is large discrepancy between and )3770( DD

1, Systematic shift in the measured cross sections2, There may be some other effects

3, There may be substantial non-DDbar decays

nb 8.16.11))3770((12

2)3770(

)3770( eeBFM

prd

nb 0.50.5)( DDeeobs (Mark-III)nb 7.01.7)( DDeeprd

before BES-II & CLEO-c

Cross section at peak (PDG04 parameters)

Simultaneously measusing both and )3770(DD

Precisely measuring the energy dependent cross sections for both inclusive hadrons and DDbar events production simutanmeously, directly measure and00[ (3770) , , ]BF D D D D DD [ (3770) ]BF non DD

Motivation Search for some exclusive non-DDbar decays

No final answer from experiments. It is assumed

S-D mixing,

puzzle,

Re-scattering mode,

What is the total branching fraction for non-DDbar decays?

Interference…

BES observed 12 signal events for the decay DD non)3770(measured the branching fraction to be

)%09.014.034.0()/)3770(( JBF

CLEO confirmed BES observation of the decay, and measured the branching fractions to be

)%022.0189.0()/)3770(( 007.0004.0

JBF

PLB 605(2005)63

CLEO also observed some other non-DD-bar decay modes such as , … ( 0,1,2)CJ J

More works is being done……

PRL96(2005)082004

(3770) data sample

~17.3 pb-1 data taken at 3.773 GeV

~7 pb-1 data taken at the region from 3.768 GeV to 3.778 GeV

~8 pb-1 data taken in the energy region from 3.665 to 3.878 GeV

The total Luminosity is about 33 pb-1

Near DD-bar production threshold region

π–

e+

e-

D

D

K+

π–tag

D+

D-π–

e-e+

D

D

K+

tag

Singly tagged D sample

Absolute Measurements

0D

0D

X+ X0

Throughout the talk, charge conjugation is implied

Singly tagged D samples

Singly tagged D- modes: (a)K+π -π -;(b) K0 π -; (c) K0 K-; (d) K+K-π -;(e) K0π -π -π+; (f) K+π -π -π0;(g) K0π -π0;(h) K+π -π -π -π+;(i) π -π -π+; (j) Sum

Singly tagged D0 modes: (a)K+π -; (b) K+

π -π -π +; (c) K0 π -π +; (d) K+ π -π 0

ND-Tag=5321±125±160 ND

0Tag=7584±198±241

Singly tagged D samples

Mass[mKnπ]

e+0.1110.053( ) (0.122 0.010)%,BF D

D

129119(371 25) MeV

Df

Purely leptonic decay

e-

D+

K+

D+

D-

missmissmiss PEU

Neutrino carries energy and momentum away

Should be around zero

5321 125 160TagD

N

Fully reconstruct one D-

Require one additional charged track and no additional photons

tagπ-

π-D-

0.33±0.11 background events is estimated from 3 candidate events, 2.67±1.74 is

retained

background estimation

Theory Comparison[from Matt Shepherd’s Meson06 Talk]

PLB610(2005)283

PRL95(2005)251801

Should be around zero due to the mass of the missing neutrino is zero

Semileptonic DecaysSemileptonic Decays

Umiss=Emiss-pmiss

|Umiss|<2[3]σ Umiss

No surplus charged track and good photon on the recoiling side

π–

e-e+

D

D

K+

tag

Singly tagged D sample

0D

0D

Ke

e

0 (found in REC of D tags.)eK e

0 (found in REC of D tags.)ee

CKM matrix elments

Form factors

PLB597(2004)39

)( 0eeKDBr

)( 0eeDBr

BESII(%) CLEO(%)

3.83±0.40±0.27 3.44±0.10±0.10

0.33±0.13±0.03 0.262±0.025±0.008PRL95(2005)181802

0 (found in REC of D tags.)K 0

(found in REC of D tags.)

Preliminary Results The first error is statistical, the second systematic, and the third arises from PDG branching fractions for the normalizing modes

030100110)(

)(0

0

...KDBr

DBr

606063 ... 100310380 ... CLEO

E687-1

E687-2

E653

FOCUS

PDG06

BESII

0 -e (found in REC of D tags.)K e

Preliminary Results

0

0

( )1.08 0.22 0.07

( )

e

e

D K e

D K e

0

0

( )0.87 0.24 0.15

( )

D K

D K

Support isospin conservation holds in the D semileptonic decays!

040050001)(

)(0

0

...eKD

eKD

e

e

PLB608(2005)24

PRL95(2005)181801

0BF( ) 8.95 1.59 0.67eD K e

0 - (found in REC of D tags.)K

0BF( ) 10.3 2.3 0.8eD K e

Candidates for

eeKD 0*eeKD

eeKD 00eeKD *0

Mass[mKn] Mass[Kπ]

*00 0 *, , ,e e e eD K e K e D K e K e

Branching fractions

Decay modes

BES MARKIII PDG04

*0

0

( )0.57 0.17 0.02

( )

D K e

D K e

support smaller ratio of D to V/P semileptonic decay of D mesons

EPJC47(2006)31

eeD

D

No signal event is observed

90%CL

Candidates for

EPJC47(2006)39

Measurement of R

BornhadR

had

hadobshad L

N

)1(

obshadBorn

had

R -

e+

e-

+

h a d ro n s-e

e+

q-

q

f la v o rc o lo r

= Qf2

lowestorder

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

: # of hadronic hadN

: Luminosity L

: Eff.had

events

: radiative correction factor

)1(

22 (GeV)

nb 8.86

cmee E

)( & hadrons)( DDeeee

ECM [GeV]

σobshad(nb) σ0

had(nb) R

3.650

3.665

3.773

18.983 0.087 0.182

18.299 0.199 0.176

27.680 0.056 0.266

14.578 0.067 0.141 0.588

14.128 0.158 0.139 0.580

22.855 0.046 0.220 1.144

2.236 0.010 0.022 0.089

2.185 0.024 0.022 0.087

3.746 0.008 0.036 0.187

3.746 0.008 0.036 0.187@ 3.773 GeVR

WA| 2.218 0.019 0.089udsR

(3686) (3770)fit to &| 2.262 0.054 0.109uds σR

PRL in press, hep/0605107

Obtaining by fitting to the R values measured by BES in the range from 2.0 to 3.0 GeV

14.026.2| GeV 3.0 to 2.0 udsR

PLB641(2006)145, hep-ex/0605105

Born σ )3770((3770) & R

udsRRR )3770(

Taking the R for light hadron production to be a constant, then

(3770) 1.528 0.042 0.131R We obtain

(3770) 9.323 0.253 0 801 nbBorn .

nb 74.108.11))3770(()1(

122

)3770(VP)3770(

eeBF

MBorn

)024.0047.1()1( VP obtained based on PDG04 (3770) resonance parametersPLB 603(2004)130

My

calc

ula

tio

n It is consistent with

(3770) cross section

e+

e-

D

D

K-

tag

D-

D+

X

π+

π+

Using Kinematic fit method to improve momentum resolution and select the singly tagged D meson

Xfit MM Requiring

2 BrL

NtagDobs

DD

of data @ 3.773 GeV Single tag method

DD cross section

KD0

KD0

KD

nb 0.260.082.56 obs

DD

nb 0.500.126.14 obsDD

Observed cross sections for DD-bar production at 3.773 GeV

nb 0.310.093.58 00 obs

DD

PLB 603(2004)130

1pb 3.17 L

Near DD-bar production threshold region

e+

e-

D

D

K-

π+tag

D-

D+X

e-e+

D

D

K-

tag

D0

D0

Using ‘double tag’ method, pioneered by MARK-III, to identified DD-bar pair

tagged one D meson

tagged another D

π+ π+

Double tag method

K+π- -

π- -

K+π- -

π- -

π+

Absolute measurement, does not depend on branching fractions of D meson decays

117.3 pbL of data

DD cross section

nb 0.210.323.47 00 obs

DD

nb 0.200.332.46 obs

DD

nb 0.350.465.93 obsDD

An

ab

solu

te

mea

sure

men

t

KvsK ..

KvsK ..

0.. KvsK

00 .. KvsK

KvsK ..0 KvsK ..

KvsK ..

0.. KvsK

0.. SKvsK

KKvsK S0..

0.. SKvsK

00.. SKvsK

KKvsK ..

00 KD

KD0

KD0

0SKD

KD

0SKD

KKD KKD S0

0 KD00 SKD

NPB727(2005)395

D0D0(nb) D+D-(nb) DD(nb)

BES single

3.58±0.09±0.31 2.56±0.08±0.26 6.14±0.12±0.50

BES double

3.47±0.32±0.21 2.46±0.33±0.20 5.93±0.46±0.35

MARKIII 2.90±0.25±0.30 2.10±0.30±0.15 5.00±0.39±0.34

CLEO

Comparison of observed cross sections

+0.07-0.053.60 0.07 +0.10

-0.042.79 0.07 +0.17-0.086.39 0.10

Radiative correction factor B

obs

g

Born

obsDD

Born

BornDDDD

σgN

NDDBF

)3770(IIBES)3770(prd

(3770)

prd

))3770((

Obtained from analysis of R

Determination of

BES II 0.770 0.014g

Some systematic uncertainties can be canceled out

Radiative correction factor obtained based on new (3770) resonance parameters measured by BES-II, hep/0605107.

BF[(3770) → D0D0,D+D-,DD and non-DD]

( (3770) ) (35.7 1.1 3.4)%BF D D

0 0( (3770) ) (49.9 1.3 3.8)%BF D D

( (3770) ) (85.5 1.7 5.8)%BF DD ( (3770) ) (14.5 1.7 5.8)%BF non DD

PLB641(2006)145, hep-ex/0605105

Measurement of branching fractions for DDDDDD ,,)3770(

00 DD non)3770(and

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 .

Cross section scan experiment

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

Integrated luminosities

Luminosities were measured by using large angle Bhabha scattering eventsAbout 5.4 pb-1 of data were collected for the experiment (for hadron events)

Monte CarloDeveloped 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

When scan over 3.770 GeV

Just before the scan experiment

Mass [MeV]

PDG04

BEPC

BEPC

BEPC

011.0916.3096

05.030.3095

034.0093.3686

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

MC generator & simulationFull energy range ISR Generatorhadronsee

GeV 783.s )3770(

)3686(

/J

)1700(

[GeV] energy Effective

Nch KNOφ

Thrust Oblatenesscosθ

Sphericity

Aplanarity

Jet axis cosθ

x η Y

Pt <PTin2>

<PTout2>

Den

sity

[n

b/G

eV]

D.Zhang,G.Rong,J.C.Chen, PRD74(2006)054012

trgcmhadcm

hadcm

obshad EEL

nE

)( )()(

1

0

exp ))1(( ),( )( xssxfdxs Becthad

)()(

)(12)(

2222 sMMs

ss

tot

feeB

(Kuraev and Fadin)

functionsampling issxf ),(

Hadron efficiency vs C.M. energy

Energy dependent hadron cross sections

had

hadobshad L

N

: # of hadronic

: Luminosity L: Eff.had

eventshadN

Inclusive hadrons

Inclusive hadrons

Ob

serv

ed c

ross

sec

tio

n f

or

had

ron

pro

du

ctio

n [

nb

]

)mode(2

)()(

tag single

tag single

D

D

DBL

ENE

cm

cmobs

DD

KD0

KD

Distributions of invariant masses of combinations at different c.m.energyies

mKn

Energy dependent DDbar cross sections

KD0

00DD

DD

DD

Line shape of the cross sections for hadron and DD-bar production

( (3770) ) (36.9 3.7 3.1)%BF D D

0 0( (3770) ) (46.7 4.7 2.3)%BF D D

( (3770) ) (83.6 7.3 4.7)%BF DD ( (3770) ) (16.4 7.3 4.7)%BF non DD

Branching fractions

Simultaneously.fitting to the inclusive hadron and the DD-bar production cross sections

00DD

DD

Inclusive hadrons

Inclusive hadrons

Inclusive hadrons

PRL in press, hep/0605107

Experiment

MARK-I

DELCO

MARK-II

PDG06

BES-II

(MeV) Γ tot (eV) Γee

63772

63770

3771.1 2.4

3772.2 0.7 0.3

528

524

90370

60180

50276+27-24242

251 26 11

388

286

280

(MeV) M

85.0 2.4

524

23.0 2.7

53764

Comparison of (3770) resonance parameters

26.9 2.4 0.3 86.7 0.7

(MeV) )3770(M

(3686) (3770)fit to &| 2.263 0.058 0.091uds σR

(3770) 9.63 0.66 0 35 nbBorn .

PRL in press, hep/0605107

Comparison of (3686) Resonance Parameters

Experiment

This measurement

BES-II published

(PLB550(2002)24)

PDG2006

(MeV) M '(keV) '

tot

(keV) 'ee

3685.5 0.0 0.3 331 58 2 2.330 0.036 0.110

..AN 27264 21.044.2

034.0093.3686 337 13 2.48 0.06

The measured partial width is consistent with PDG06 partial width of (3686).

PRL in press, hep/0605107

CKM matrix elments and form factors

SummarySummary

The ratio of

0

0

( )0.87 0.24 0.15

( )

D K

D K

0

0

( )1.08 0.22 0.07

( )

e

e

D K e

D K e

Support isospin conservation holds in the D semileptonic decays.

support smaller ratio of D to V/P semileptonic decay of D mesons

*0

0

( )0.57 0.17 0.02

( )

D K e

D K e

BES measured branching fractions of exclusive semileptonic decays of D mesons

The ratio of

Preliminary

BES search for and eeD

D

BES measured branching fraction for pure leptonic decay D

129119(371 25) MeV

Df

0.1110.053( ) (0.122 0.010)%,BF D

nb 0.500.126.14 obsDD

nb 0.350.465.93 obsDD

Singly tagged D analysis

Doubly tagged D analysis

BES measured DDbar cross sections at 3.773 GeV

BES measured R at 3.773 GeV and Ruds around 3.65 and 3.6648 GeV

(3686) (3770)fit to &| 2.262 0.054 0.109uds σR

3.746 0.008 0.036 0.187@ 3.773 GeVR

WA| 2.218 0.019 0.089udsR

In the range from 3.67 to 3.89 GeV, obtained from fitting to (3686) and (3770)

SummarySummary

SummarySummary BES measured the branching frations for inclusive non-DDbar decays of (3770) using two different data sample and two different methods

( (3770) ) (36.9 3.7 3.1)%BF D D

0 0( (3770) ) (46.7 4.7 2.3)%BF D D

( (3770) ) (83.6 7.3 4.7)%BF DD ( (3770) ) (16.4 7.3 4.7)%BF non DD

( (3770) ) (35.7 1.1 3.4)%BF D D

0 0( (3770) ) (49.9 1.3 3.8)%BF D D

( (3770) ) (85.5 1.7 5.8)%BF DD ( (3770) ) (14.5 1.7 5.8)%BF non DD

These are first measurements.

Determined from analysis of R values and DD-bar cross sections

Obtained from fitting to the inclusive hadron and the DD-bar production cross sections simultaneously.

Thank You ！