bo xinrare d semileptonic decays 14/23/2006 studies of rare semileptonic d meson decays ...
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Bo XinRare D Semileptonic Decays 1 4/23/2006
Studies of Rare Semileptonic D Meson Studies of Rare Semileptonic D Meson DecaysDecays
Introduction Analysis Technique Testing the procedure Results (e, ’e, e) Systematics Summary
Bo Xin
Purdue University – CLEO collaboration
APS April MeetingApr 22-Apr 25, 2006
Bo XinRare D Semileptonic Decays 2 4/23/2006
IntroductionIntroduction
The results with 55.8pb-1 CLEO-c data have been published:
Phys.Rev.Lett.95:181801,2005
Phys.Rev.Lett.95:181802,2005
Summing up all exclusive semileptonic branching fractions measured in this analysis we find:
These are consistent within errors but somewhat smaller than CLEO-c inclusive semileptonic branching fractions (281/pb):
There is room left for new semileptonic modes with small branching fractions, e.g.
)%2.02.01.6()( 0 semilexclDB
)%6.05.02.15()( semilexclDB
)%4.01.16()()%2.05.6()( 0 semilinclsemilincl DBandDB
•D e, ’e, e
Bo XinRare D Semileptonic Decays 3 4/23/2006
The CLEO-c detector and data sampleThe CLEO-c detector and data sample
SVX
CLEO III p/p = 0.6% at 1 GeV/c
E/E = 2% at 1 GeV,
5% at 100 MeV
Excellent electron and particle ID
CLEO-c
)3770(
Pilot run starting in the fall of
2003
Note
: Log
Scale
Beam Energy (GeV)
Over 20 years of data taking at
Y(4S)
Beam Energy (GeV)
• Advantages at (3770)– Pure , no additional
particle – Low multiplicity– High tagging efficiency
• Data sample ~281/pb at (3770)
• The generic MC sample (40X luminosity of the data).
DD
Bo XinRare D Semileptonic Decays 4 4/23/2006
Analysis TechniqueAnalysis Technique Candidate events are selected by reconstructing a D, called a tag, in several
hadronic modes
Then we reconstruct the semileptonic
decay in the system recoiling from the tag.
Two key variables in the reconstruction
of a tag:
Define U Emiss |Pmiss|
The absolute branching fraction is
where is the efficiency of finding a signal
in events with reconstructed tags.
Bo XinRare D Semileptonic Decays 5 4/23/2006
Reconstruction of tagsReconstruction of tags
One D tag candidate per D tag flavor per mode is chosen.
Examples of fits to Mbc for the following tag modes in 281 pb-1data:
Bo XinRare D Semileptonic Decays 6 4/23/2006
Test (1): Test (1): DDK/K//Ks//Ks/00 e e - Generic MC & Data - Generic MC & Data
• Same tests were made using the data, the results agree with other CLEO-c analyses very well.
Test the analysis method using semileptonic modes with large yields for each tag separately and for all tags combined
Bo XinRare D Semileptonic Decays 7 4/23/2006
Test (2): Test (2): DD//’/’/ e e - Generic MC - Generic MC
Procedure tested with Generic Monte Carlo
Input BFs reproduced successfully
Bo XinRare D Semileptonic Decays 8 4/23/2006
Two submodes give consistent results
Results (1): Results (1): DDee (DATA – 281/pb) (DATA – 281/pb)
First observation of DDee !!
eventsYield 7.66.32:
eventsYield 0.48.13:
Preliminary
Bo XinRare D Semileptonic Decays 9 4/23/2006
Results (2): Results (2): DD’e’e, , ee (DATA – 281/pb) (DATA – 281/pb)
Feldman & CousinsPhys.Rev.D57:3873-3889,1998 Preliminary
Bo XinRare D Semileptonic Decays 10 4/23/2006
Systematic Uncertainties and Results
.).%90(106.1)(
.).%90(100.2)(
10)07.019.029.1()(
4
4
3
LCeD
LCeD
eD
.).%90%(09.2)(
.).%90%(1.1)'(
.).%90(105)( 3
LCeD
LCD
LClD
OUR PRELIMINARY PDG-2004
Systematic
Uncertainties
Bo XinRare D Semileptonic Decays 11 4/23/2006
SummarySummaryRare D semileptonic modes: De, ’e, e,
have been studied using 281/pb of data at the (3770)
D e is observed for the first time in two submodes: and +-0
No signal candidates are observed for D ’e and D e. Upper limits are set for these modes.
CLEO-c is going to collect a much larger sample at the (3770). This sample will improve statistical precision of existing measurements and allow observations of new modes.