Upload
harmony-houser
View
217
Download
3
Embed Size (px)
Citation preview
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