b s signal selection
DESCRIPTION
B s signal selection. Donatella Lucchesi University and INFN Padova for B s Mixing group. CDF Collaboration Meeting June 7, 2006. The Blessed Selections: hadronic decays. Signal B s D s D s . B s D s D s KK D s K *0 K K *0 K D s 3 B s D s 3 - PowerPoint PPT PresentationTRANSCRIPT
Bs signal selection
Donatella Lucchesi University and INFN Padova
forBs Mixing group
CDF Collaboration MeetingJune 7, 2006
June 7,2006 Donatella Lucchesi 2
The Blessed Selections: hadronic decays
BsDs Ds KK Ds K*0K K*0 K Ds 3BsDs3 Ds Ds K*0K
Signal BsDs Ds
Partially reconstructed B mesons
Combinatorial backgroundB0 D-
June 7,2006 Donatella Lucchesi 3
Hadronic Bs decays summary
Decay channel Yield
BsDs Ds 1587
BsDs Ds K*0K 762
BsDs Ds 3 627
BsDs3 Ds 428
BsDs3 Ds K*0K 200
Total 3604
B+ D0 ~ 26,000
B0 D- ~ 22,000
June 7,2006 Donatella Lucchesi 4
Blessed selection Bs semileptonic Decays
BsDsX Ds KK Ds K*0K K*0 K Ds 3
Total yield: Dsl ~37,000 events
June 7,2006 Donatella Lucchesi 5
What can we do to improve it?
Include PID in the selection
Use NN to discriminate signal from background
Add new decay modes
June 7,2006 Donatella Lucchesi 6
Including PID in the selections
BsDs Ds K*0K K*0 K has reflection from B0D D K when you give K mass to
A. Heijboer Standard analysis useD+ veto: |MK– MD+|>24 MeV
June 7,2006 Donatella Lucchesi 7
Including PID in the selections
Aart proposal:|MK– MD+|>18 MeV OR CCL0 19.223.0Give this to NN
A. Heijboer
LR cut event by eventincreases Ds 1640In progress the Bs
significance evaluation
J. Mulmestadt
BSS/
Johannes idea:
BSS/
June 7,2006 Donatella Lucchesi 8
Neural Network selectionsB. Casal, K. Anikeev
Use ROOTSNNS v3.0 Train NN to separate signal from bckg (side bands) Optimize to maximize Fit mass distribution using the actual mixing fitter
Rectangular cuts NN cuts
Increase 33% like adding 78% of more data
BSS/
BSS/
June 7,2006 Donatella Lucchesi 9
Neural Network selections summary
B. Casal, K. Anikeev
Use wrong charge events as background in the future?
57.78/43.30=1.3 improvement A
June 7,2006 Donatella Lucchesi 10
Partially Reconstructed B
BD, D*D*D/ treated as hadronic? Large yields (same order of fully reconstructed)
High k-factor, lose soft /
Lower S/B
Different K def. investigatedfinally use the standard one
Jeff Miles
Kp
MLct reco
T
PDGxy
Depend on mass
June 7,2006 Donatella Lucchesi 11
Partially Reconstructed B
B0D* -[D0 -] +
Kp
mLct
T
Bxy
*
***
**
*
xy
xy
B
B
T
T
L
L
m
m
p
pK
Above 5.17 GeV D* and D*K
Low combinatorial background
5.00 <mass<5.35 GeV/c2
c 2= 464.6 +14.2 –13.5
m
Amanda Deisher
June 7,2006 Donatella Lucchesi 12
New Decay Modes
BsDs Ds KsK Ks has reflection from
B0D D 3 as for Ds K*0K K*0 K Different topology easy to separate
Simone Pagan Griso
16% increase
~270 events 1fb-1
BSS/
Using PID
June 7,2006 Donatella Lucchesi 13
Semileptonic decay modesV. Tiwari, G. Gomez-Ceballos
Improve event selection including PID BsDslx:
Dscombinatorial bck reduce by factor
2 Ds K*K yield increased by factor ~2.5
and combinatorial bck reduced by factor 2 Include l+SVT dataset Remove the ct* cut Noticeable
gain
June 7,2006 Donatella Lucchesi 14
Summary
The number of events can be increased by includingnew decay modes, partially reconstructed eventsand by optimizing cuts.
Plan for the summer:Include partially reconstructed modes and optimize cuts.The actual gain on ms significance will be the combination of all the effect. Expected improvements on A:o 1.3 for the hadronic decay modes cuts optimizationo “Something” for semileptonic decayso Under evaluation for adding partially reconstructed hadronic decay