1
HADRONIC BRANCHING FRACTIONS OF D0 AND D+ AND THE PRODUCTION CROSS SECTION AT
THE (3770) RESONANCE
Outline Introduction and Motivation Method Event Selection Fitting Yield Extractions Systematics Results Conclusion and Summary
Batbold Sanghi, Purdue Universityfor the CLEO collaboration
DD
2
Introduction
CLEO-c, in a pilot run, has accumulated 57.2 pb-1. with this data, we present a preliminary measurement of absolute branching fractions and cross section. We use double tagging technique pioneered by MARK III.
branching fractions: and are reference branching fractions. Determine other branching fractions Reduce systematics when extracting CKM matrix elements
cross section
Precise measurement since many systematic errors canceled.
DD
RESULTS ARE PRELIMINARY
KDB 0 KDB
DD
3
Using double tags to measure and
ijjiDDij BBND
2
2
42 i
ii
ii
iDD
ji
ij
ij
jiDD D
SNor
D
SSN
e+ e
0D
0D
K+
+
K-
iiDDi BNS 2
XSingle tagged D
Double tagged D
e+ e
0D
0D
K+
DD B
ii
i
i
iii
ij
j
j
iji S
DBor
S
DB
2
Single and double tags give and
Use 3 modes : , ,
Use 2 modes : ,
DDNB0DD
KD0 00 KD KD0
KsD KD
4
Using double tags to measure and DD B
and yields fitted separately.
10 single tag yields and 13 double tag yields.
Perform fits
Parameters: 5 branching ratio and and
Yields corrected by backgrounds and crossfeeds
The fit includes statistical and systematic uncertainties. Statistical errors for efficiencies, yields, and background subtractions Correlated and uncorrelated systematic errors
Some systematic errors for and completely cancelled
and in this approximation,
D D
2
DDN
00DDN
1/ jiij ijjiDD DSSN /~
00DDN DD
N
5
Selection criteria Two key variables(D0K-+ as an example)
22PPEM Kbeambc
EEEE Kbeam
0
3.0 σ mass cut for 0 mass Shower energy > 30MeV
Track selection criteria: Track quality criteria Hadronic PID criteria are based on
the dE/dX information the RICH information
0
3.0 σ mass cut for 0 mass Shower energy > 30MeV
Ks 3.0 σ mass cut for Ks mass
Additional cuts Mode dependent cuts Lepton veto to reject cosmics, radiative bhabhas and pairs when an event
has two tracks.
Best candidate selection for single tag modes Choose the entry with the smallest
Best candidate selection for double tag modes Choose the entry with the smallest
E
E
Dbcbc mDmDm 2
6
Single tag fitting
Mbc(GeV)
Signal MC without ISR: fit with Argus+Gaus+wide bif. Gaus
Ratio between widths of Gaus and wide bif. Gauss
Ratio between areas of Gaus and wide bif. Gaus
Generic MC(no ISR) fit with Argus+Gau+wide bif. Gaus
Fix the above parameters
Signal MC with ISR: fit with Argus+Crys.Ball+ wide bif.
Gau Data
fit with Argus+Crys.Ball+ wide bif. Gau
Mbc(GeV)
Signal MC with ISR
Signal MC without ISR
DD bar MC
Data
DD
KD0
7
Double tag fitting Double tag sample
. Signal components
A a diagonal Crys.BallGau : a wide Gaussian
Background components A diagonal Argus function two Argus functions.
00 KD 00 KD
M2(
GeV
)
M1(GeV)
M2(
GeV
)
M1(GeV)
M1(GeV)
8
Single and Double tag efficiency
within statistical uncertainty
Eff(%)
single tag 62.5 32.0 40.4
61.4 37.8 20.6 24.8
31.7 20.0 10.7 12.7
40.1 24.8 13.0 16.4
Eff(%)
single tag 47.5 42.0
47.8 22.4 19.8
41.7 20.0 17.3
K 0 K K
Ks
K
0D
0D
K0 K
K
D K
Ks
D
jiij
PRELIMINARY
9
Generic MC Yields
All *1000
singletag 47.5±0.2 87.9±0.3 65.0 ±0.3
47.1±0.2 1.12±0.03 2.06±0.05 1.53±0.04
87.0±0.3 2.19±0.05 4.11±0.07 2.86±0.05
64.0±0.2 1.55±0.04 2.90±0.05 2.10±0.05
All *1000
singletag 65.0 ±0.3 9.42 ±0.10
64.7 ±0.3 2.82±0.05 0.38 ±0.02
9.33 ±0.1 0.41 ±0.02 0.07 ±0.01
0D K 0 K K
K
0D
0 K K
D K KsD
KKs
Check the technique for yield extraction and branching ratio fit Samples : (10data),CONT and RR MC.
Statistical errors (3 times smaller than for data) crossfeed and background contributions
DD
PRELIMINARY
10
Generic Monte Carlo Fit Result
The yields corrected by crossfeed and background contributions. Statistical errors for yields(3 times smaller than for data) Systematic errors (substantially smaller than for data) Fitted values reproduced input variables.
Fitted 2.08106 0.0377 0.1373 0.0786 1.55106 0.0901 0.0147
Input 2.04106 0.0383 0.1390 0.0790 1.52106 0.0900 0.0145
Error 0.02106
1.1%
0.0004
1.1%
0.0013
1.0%
0.0008
1.0%
0.03106
2.1%
0.0017
1.9%
0.0003
2.3%
Input +1.6 -1.4 -1.3 -0.5 +1.1 +0.1 +0.6
00DDN K 0 K K DD
N K Ks
PRELIMINARY
11
Data Yields
All *1000
single 5.16±0.08 9.58±0.12 7.39 ±0.10
5.14±0.07 0.11±0.01 0.25±0.02 0.21±0.01
9.62±0.12 0.26±0.02 0.48±0.02 0.36±0.02
7.39±0.10 0.20±0.01 0.34±0.02 0.28±0.02
All *1000
single 7.57 ±0.09 1.12 ±0.04
7.58 ±0.09 0.38±0.02 0.06 ±0.01
1.09 ±0.04 0.41 ±0.02 0.009±0.003
K0D 0 K K0D
K0 K K
D K KsD
KKs
PRELIMINARY
Single tag 44260 neutral single tags and 17360 charged single tags
Double tag Poor statistics for some double tag modes 2480 neutral double tags and 502 charged double tags
12
Systematics
Source Systematic Uncertainty(%)
Data processing 0.3
Yield fit functions 0.1-2.9
Background bias 2.5
Double DCSD interference 0.8
Tracking efficiency 3.0
Ks efficiency 3.0
0 efficiency 4.4
PID 0.3
K PID 1.0
Trigger efficiency 0.3
FSR 0.5
E cut 1.0
Resonant substructure 1.5 in K3
PRELIMINARY
Currently dominated by tracking efficiency systematics. Most systematics will improve with further study.
13
Data Fit Result
All branching fractions consistent with PDG averages(higher than) Better agreement for ratio of branching fractions. Statistical errors for branching fractions : 20-40% of total error(systematics limited) Precise measurement for and (some systematic errors cancelled)
*Our branching fractions are corrected by FSR. PDG values are not
Parameter Fitted Value PDG2004*
(1.980.04 0.03) 105
0.0392 0.0008 0.0023 0.0380 0.0009
0.143 0.003 0.010
0.0810.0020.009
(1.480.060.04) 105
0.098 0.004 0.008 0.092 0.006
0.01610.0008 0.0015
00DDN
KB
0 KB
KB
DDN
KB
KsB
3.64 0.05 0.17 3.42 0.22
2.05 0.03 0.14 1.96 0.06
0.164 0.004 0.006 0.1530.003
KBKB /0
KBKB /
KBKsB /
00DDN DD
N
14
Cross Sections Luminosity collected on : 57.2pb-1
Cross section :
nb
nb
nb
3770
PRELIMINARY
LN DD /
15.007.047.300 DDee
11.011.059.2 DDee
22.013.006.6 DDee
02.004.075.0/ 00 DDeeDDee
reference
MARK III 2.10.3 2.9 0.4 5.0 0.5 PRL 60,89(1988)
BES 3.260.090.25
2.520.070.24
5.71 0.110.11
Hep-ex/0604027
00DD DD DD
15
Summary Cross sections :
nb
nb
nb
PRELIMINARY
The preliminary results for reference branching fractions :
Many systematic uncertainties will be improved with further study. more results from CLEO-c in the near future
15.007.047.300 DDee
11.011.059.2 DDee
22.013.006.6 DDee
02.004.075.0/ 00 DDeeDDee
%23.008.092.30 KDB
%8.04.08.9 KDB