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

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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

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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

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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.

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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:

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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

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Test (2): Test (2): DD//’/’/ e e - Generic MC - Generic MC

Procedure tested with Generic Monte Carlo

Input BFs reproduced successfully

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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

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Results (2): Results (2): DD’e’e, , ee (DATA – 281/pb) (DATA – 281/pb)

Feldman & CousinsPhys.Rev.D57:3873-3889,1998 Preliminary

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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

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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.