Inclusive Measurement of BR(D X) and The Neutrino Spectrum
Michael Weinberger
CLEO-c
Cornell University
Lake Louise Winter Institute
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
2/16
CLEO-c•CESR: symmetric e+e- accelerator•57.2 Pb-1 data at (3770) used for this analysis
•Charm production threshold•2X data has been taken and is being processed for analysis•Plan to take 3 fb-1 total
•CLEO-c: •CLEO III detector with silicon vertex replaced by drift chamber•Covers 93% of solid angle•dE/dx from drift chamber•Ring Imaging Cherenkov Detector (RICH) for particle ID•Track resolution of ~ 0.6%•Solenoid field 1 T
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
3/16
Motivation to study BR(D X)
Physics Branching fractions and form
factors by different method Branching ratio not
previously measured for neutrinos
Unique opportunity at CLEOc
Produced at threshold Clean events
Tagged D fully reconstructed
Lepton flavor blind Electrons and muons on
equal footing
Data Event
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
4/16Electron and Neutrino Spectra are Different
s
e+
se+
esec
Can look at spins to determine favorable and suppressed directions for neutrino
The top diagram is favored, the neutrino will get a boost from the W+* compared to the electron in the lab frameThe same effect will occur for the anti-c.
W+*
W+*
Low Q2
Low Q2
eEE Low ,High
EEe Low ,High
In B decays electron has harder spectrum than neutrinos, electron is now particle ceb
In weak semileptonic decays of quarks, the lepton has the harder spectrum than the anti-lepton
Q2 = momentum transfer to W
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
5/16
DD)3770(
Simple Hadronic Modes
Fully reconstructed tags
Use tag to eliminate half of each event for neutrino reconstruction
•Add up all signal side tracks and unmatched showers
•Use RICH and dE/dx for particle ID
•Get missing 4-momentum
•Cut to eliminate non neutrino events
•KL suppression
•Clean reconstruction cuts
0222 missmissmiss PEMass
SK
KD
K
K
K
D 00
Method of Analysis
Xl
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
6/16Emiss vs. E2 - P2
Fully Reconstructed Hadronic events
Not Seen KL
Neutrinos
Red = event with neutrino
Blue = no neutrino in event M
issi
ng
En
erg
y(G
eV
)
222 )(GeVPE missmiss
Monte Carlo
Max M2miss:
P2=0, E vs E2
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
7/16
Good Tag Cuts Only 1 tag per mode per event Good Tag
Delta E cut Beam constrained mass cut
Clean Reconstruction Cuts No tracks lost to quality cuts Showers are not matched to track Charge of event is = 0 Costheta of missing momentum is inside detector At least one track in event – no ID performed
KL Suppression Cuts Single Track Cut [event with single kaon]
Track Shower Matching Cut
Cuts
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
8/16
KL Suppression Cuts
Missing mass squared for events with KL
Monte Carlo
Energy in showers matched to KL
Monte Carlo
Half of KL’s leave no energy Peak at Missing Mass2 = (.497GeV)2
Other half leave some fraction of their energy in EM calorimeter
No Hadronic calorimeter for KL reconstruction
CC is ~1 nuclear interaction length => about half of KL’s interact in detector
Eshower(GeV)222 )(GeVPE missmiss
2
LKM
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
9/16
KL: Shower Distance Cut (Weinberger angle)
Angle of missing momentum vector to closest unmatched shower
20% of events with neutrinos have no shower to measure angle to, this cut is then skipped
Black = KL and no neutrino
Red = Neutrino events with a shower to compare to
Cos(Weinberger angle)
Monte Carlo
Keep these events
Missing Momentum Vector
Closest Shower
Charged tracks
Neutrino Event
Missing Momentum Vector
Charged tracks
KL Event
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
10/16
Effect of Cuts on Background
Monte Carlo
222 )(GeVPE missmiss
Red = neutrino event
Blue = no neutrino in event
Events with good tag
Clean reconstruction cutsTo make sure that event is fully reconstructed and that missing vector is in detector
KL suppression
Mis
sing E
nerg
y (
GeV
)
&
Monte Carlo
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
11/16
Effect of Cuts on Background
Mis
sing E
nerg
y (
GeV
)
Monte CarloMonte Carlo
222 )(GeVPE missmiss 222 )(GeVPE missmiss
Red = neutrino event
Blue = no neutrino in event
Events with good tag
Clean reconstruction cutsTo make sure that event is fully reconstructed and that missing vector is in detector
KL suppression
Mis
sing E
nerg
y (
GeV
)
&
Monte Carlo
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
12/16
V Cut on Emiss vs. E2 – P2
“V” cut on E2 – P2
E2 – P2 = (E+P)*(E-P) 2E(E-P)
Monte Carlo
222 )(GeVPE missmiss
Mis
sing E
nerg
y(G
eV
)
Error on Mass2miss is
dominated by error on energy
The “V” cut is then a constant cut on the fractional error of the Mass2
miss
Shower distance cut will not eliminate non-interacting KL
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
13/16
Missing Energy Spectra
Emiss(GeV) Emiss(GeV)
D0 D±
Red = signal
Blue = background
Black = all events that pass cuts: sum of red and blue
MCMC
Cutoff at 0.1 due to min P cut
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
14/16
Data [57.2 Pb-1] vs. MC Comparisons
MC Data
222 )(GeVPE missmiss
Mis
sing E
nerg
y (
GeV
)
Mis
sing E
nerg
y (
GeV
)
222 )(GeVPE missmiss
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
15/16
Data vs. MC
D0 D±
Emiss (GeV)
points = data
red = scaled MC
Emiss (GeV)
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
16/16
BR(D X): Conclusion
CLEOc allows first opportunity to make measurement of Branching Ratio in this inclusive mode
Fully inclusive as to: Lepton flavor Semileptonic decay mode
This approach is completely orthogonal to all existing measurements of BR(D Xl)
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
17/16
EXTRA SLIDES
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
18/16Neutrino and No Neutrino EventsOld plots
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
19/16
How Well Code id’s Particles
Fixed id in code
Particle ided as
1 = kaon
2 = pion
3 = electron
kaon
electron
pion
No muon id means all muons are treated as pions
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
20/16
PDG Fit D0 Average D+ D+ D0PDG BR(D->eX) 17.2 1.9 6.87 0.28PDG BR(D->muX) XXX XXX 6.5 0.8Sum (or e*2 if nu not available) 34.4 3.8 13.37 1.73
PDG(2004) inclusive D lX
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
21/16
Left Side Tail
Signal only
222 )(GeVPE missmiss 222 )(GeVPE missmiss
Signal only
Mis
sing E
nerg
y(G
eV
)
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
22/16
“Left” Event properties
Look at properties of events in “left tail”
Most have one photon
Dashed – left
Solid - good
Photon’s angle is anti-corrolated to MissVec
Appears that photon is double counted
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
23/16
Subtract Out Photon
Dashed – left side events
Solid – photon subtracted out
Left side events
Events with photon subtracted out.
Now in signal region
222 )(GeVPE missmiss 222 )(GeVPE missmiss
Mis
sing E
nerg
y(G
eV
)
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
24/16Re-Fixed Plot
Extra background?
222 )(GeVPE missmiss
D±
D0
Emiss
Emiss
Mis
sing E
nerg
y(G
eV
)
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
25/16
Spike in D+ Bkg
Looking at spike events [no nu, Emiss > 0.72] properties show only one track in event
Decay tree shows events are
D->KLPi, with the Pi missided as a kaon
Bkg pions not in spike
Bkg pions in spike
Signal events
spike
Non spike bkg
Number of tracks in event
February 22, 2004 Michael Weinberger Cornell University Lake Louise Winter
Institute
26/16Comparison of MC Generated vs. Reconstructed Variables
Overlay of MC generated energy spectrum of neutrinos
Scaled down to recontructed spectrumBlack = mc generated(scaled)
Red = reconstructed neutrinos
Energy (GeV)
e
Trueee
obs ESESmod
modmod )()(