Recent results on D meson decays from BES

Ma HaiLong[For BES Collaboration]

Institute of High Energy Physics, Beijing China

CHARM06Beijing China

2006-6-5

Outline

Introduction

Semileptonic decays

Summary

Inclusive decays

Singly tagged D samples

BEPC collider

L ~ 11031 /cm2s @3.773GeVEcm~2-5 GeV

BESII detector

VC: xy = 100 m TOF: T = 180 ps counter: r= 3 cm MDC: xy = 220 m BSC: E/E= 22 % z = 5.5 cm dE/dx= 8.5 % = 7.9 mr B field: 0.4 T p/p=1.7%(1+p2) z = 3.1 cm

μ identification can be done by the μ Counter for the charged track with momentum of greater than 0.55 GeV/c

dE/dx

TOF

dE/dx and TOF information

(3770) data sample

~18 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

Motivation Isospin conservation implies

2041)()/(00 ..eKDeKD ee

PDG04 BF

1)()( 0 ll KlD/KlD

The called “Longstanding puzzle” in Charm decay!

Is isospin conservation held in the D semileptonic decays?

070220081)(

)(0

0

...eKD

eKD

e

e

040050001)(

)(0

0

...eKD

eKD

e

e

BESII [Phys. Lett. B608(2005)24]

CLEO [Phys. Rev. Lett. 95(2005)181801]

The puzzle has been solved!

Branching fractions

)()(00

KD/KD

0

0 , ,

KD

KD

CKM matrix elements and form factors

0D

c

u)(d

)( D

e

e

s

u ][d

)( * KK

0 *0[ ( )]K K

|| csV

eKDeKD

eKDeKD0**0

00

,

, ,

Form factor

)0(),0(),0( 21 VAA)(/)(

* eKDeKD

E691 0.45±0.11

MARKIII 1.00±0.25(absolute)

CLEO 0.51±0.18±0.06

CLEO 0.60±0.09±0.07

CLEO 0.65±0.09±0.10

E687 0.59±0.10±0.13

E687 0.62±0.07±0.09

CLEO 0.99±0.06±0.07±0.06

FOCUS 0.594±0.043±0.030

CLEO-c 0.63±0.03±0.02

)(/)(*

eKDeKD

Early theories: 0.9-1.3Measurements:

Recent theories:0.5-0.7

MARKIII use a lower BF(D+→K0e+ve )

Shift in form factor prediction of early theory

Branching fractions

Motivation

serve as check on the sum of the branching fractions for the exclusive D decays provide information about the relative strength of Cabibbo-favored and Cabibbo-suppressed D decays.

Up to now, PDG has not summarized the branching fractions for some inclusive decays of D mesons

Measurements of branching fractions for the inclusive decays of D mesons

XK/KD ** XK/KD ** 00

Motivation

XK/KD 00XK/KD ** XK/KD ** 00

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

Semileptonic decays Inclusive decays

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]

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

K

0 0 vs D K D K ν

0 vs. D K D K ν

Umiss (GeV)

Monte Carlo simulation

|Umiss|<2σ Umiss

Candidates for KD0

0

KD

Candidates for KD0

0KDCandidates for Candidates for

The yellow parts are from background events

Mass[mKnπ]

Branching fractions

Experiment

BES

MARKIII

E687(93)

E687(95)

PDG04

)( 0 KDBF

606063 ... )( 0

DBF )(0

KDBF

100310380 ...

500490123 ...

170193 .. 030207 .

..

8032310 ...

Preliminary Results

[%] [%] [%]

130130243 ...

21030207 ....

An upper limit at 90% C.Lis set to be <0.89%

0

0

( )0.89 0.24 0.15

( )

D K

D K

030100110)(

)(0

0

...KDBr

DBr

The ratio of BFs

Ratio of partial width

Umiss (GeV)

eeKD.vs.KD

eeKD.vs.KD 0

eeKD.vs.KD 0000

eeKD.vs.KD 000

e*

e

e*

e

eK ,eKD

eK ,eKD

0

00

|Umiss|<3σ Umiss

Monte Carlo simulation

Candidates for

e*

e

e*

e

eK ,eKD

eK ,eKD

0

00

Candidates for

eeKD 0*eeKD

eeKD 00eeKD *0

Mass[mKnπ] Mass[Kπ]

Results

Tend to support a smaller ratio

Branching fractions(%)

Ratio of partial width

Accepted by EPJC: hep-ex 0605103

eeD

D

No signal event is observed

90%CL

Accepted by EPJC: hep-ex 0604033

Candidates for

Results

(%) (%) (%)

Inclusive DecaysInclusive Decays

XK/KD 00

XK/KD **

XK/KD ** 00

Measurements of branching fractions for the inclusive decays of D mesons

π–

e-

D

D

K+

tag

Singly tagged D sample

0D

0D

X0

e+

D0 signal region

Cabibbo favored decay Cabibbo suppressed decay

Mass[K-π+] Mass[K+π -]

D0 sideband

D- signal region

D- sideband

D- signal region

D- sideband

D0 signal region

D0 sideband

XK/KD ** 00Candidates for

Results

%...XKDBF * 210478)( 00

Cabibbo favored decay:

%...XKDBF * )035423(2)( 0

Cabibbo suppressed decay:

%...XKDBF * 402182)( 00

C.L. 90%at 66)( 0 %.XKDBF *

Phys. Lett. B625(2005)196

*0 2.9-1.0[ ( ) (1.5 0.2) % ]BF D K X

Candidates for XK/KD 00

D0 signal region

D0 sideband

D- signal region

D- sideband

Candidates for XK/KD ** Cabibbo favored decay Cabibbo suppressed decay

D0 signal region

D0 sideband

D- signal region

D- sideband

D- signal region

D- sideband

D0 signal region

D0 sideband

Preliminary results

90%CL

BES measured branching fractions of D semileptonic decay0

0

( )0.89 0.24 0.15

( )

D K

D K

The ratio of

SummarySummary

The ratio of

BES search for and eeD

D

BES measured branching fractions for inclusive decays

Thank You！XK/KD 00XK/KD ** XK/KD ** 00