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Inclusive Measurement of BR(D  X) and The Neutrino Spectrum. Michael Weinberger CLEO-c Cornell University. Lake Louise Winter Institute. CLEO-c. CESR: symmetric e + e - accelerator 57.2 Pb -1 data at  (3770) used for this analysis Charm production threshold

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inclusive measurement of br d x and the neutrino spectrum

Inclusive Measurement of BR(D X) and The Neutrino Spectrum

Michael Weinberger

CLEO-c

Cornell University

Lake Louise Winter Institute

cleo c
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

Michael Weinberger Cornell University Lake Louise Winter Institute

motivation to study br d x
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

Michael Weinberger Cornell University Lake Louise Winter Institute

electron and neutrino spectra are different
Electron and Neutrino Spectra are Different

In weak semileptonic decays of quarks, the lepton has the harder spectrum than the anti-lepton

Low Q2

s

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 frame

The same effect will occur for the anti-c.

e+

W+*

Low Q2

s

Q2 = momentum transfer to W

e+

W+*

In B decays electron has harder spectrum than neutrinos, electron is now particle

Michael Weinberger Cornell University Lake Louise Winter Institute

slide5

Method of Analysis

Xl

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

Michael Weinberger Cornell University Lake Louise Winter Institute

e miss vs e 2 p 2
Emiss vs. E2 - P2

Monte Carlo

Not Seen KL

Red = event with neutrino

Blue = no neutrino in event

Neutrinos

Missing Energy(GeV)

Max M2miss: P2=0, E vs E2

Fully Reconstructed Hadronic events

Michael Weinberger Cornell University Lake Louise Winter Institute

slide7

Cuts

  • 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

Michael Weinberger Cornell University Lake Louise Winter Institute

k l suppression cuts

No Hadronic calorimeter for KL reconstruction

KLSuppression Cuts

CC is ~1 nuclear interaction length => about half of KL’s interact in detector

Other half leave some fraction of their energy in EM calorimeter

Half of KL’s leave no energy Peak at Missing Mass2 = (.497GeV)2

Monte Carlo

Monte Carlo

Missing mass squared for events with KL

Energy in showers matched to KL

Eshower(GeV)

Michael Weinberger Cornell University Lake Louise Winter Institute

k l shower distance cut weinberg er angle
KL: Shower Distance Cut(Weinberger angle)

Monte Carlo

  • 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

Closest Shower

Missing Momentum Vector

Keep these events

Missing Momentum Vector

Charged tracks

Charged tracks

Neutrino Event

KL Event

Michael Weinberger Cornell University Lake Louise Winter Institute

Cos(Weinberger angle)

effect of cuts on background

&

Red = neutrino event

Blue = no neutrino in event

Effect of Cuts on Background

Events with good tag

Monte Carlo

Monte Carlo

KL suppression

Missing Energy (GeV)

Clean reconstruction cuts

To make sure that event is fully reconstructed and that missing vector is in detector

Michael Weinberger Cornell University Lake Louise Winter Institute

slide11

&

Red = neutrino event

Blue = no neutrino in event

Effect of Cuts on Background

Events with good tag

Monte Carlo

Monte Carlo

Monte Carlo

KL suppression

Missing Energy (GeV)

Missing Energy (GeV)

Clean reconstruction cuts

To make sure that event is fully reconstructed and that missing vector is in detector

Michael Weinberger Cornell University Lake Louise Winter Institute

v cut on e miss vs e 2 p 2
V Cut on Emiss vs. E2 – P2

“V” cut on E2 – P2

E2 – P2 = (E+P)*(E-P)  2E(E-P)

Monte Carlo

Error on Mass2miss is dominated by error on energy

The “V” cut is then a constant cut on the fractional error of the Mass2miss

Missing Energy(GeV)

Shower distance cut will not eliminate non-interacting KL

Michael Weinberger Cornell University Lake Louise Winter Institute

missing energy spectra

Red = signal

Blue = background

Black = all events that pass cuts: sum of red and blue

Missing Energy Spectra

D0

MC

MC

Emiss(GeV)

Emiss(GeV)

Cutoff at 0.1 due to min P cut

Michael Weinberger Cornell University Lake Louise Winter Institute

data 57 2 pb 1 vs mc comparisons
Data [57.2 Pb-1] vs. MC Comparisons

MC

Data

Missing Energy (GeV)

Missing Energy (GeV)

Michael Weinberger Cornell University Lake Louise Winter Institute

data vs mc
Data vs. MC

points = data

red = scaled MC

D0

Emiss (GeV)

Emiss (GeV)

Michael Weinberger Cornell University Lake Louise Winter Institute

br d x conclusion
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)

Michael Weinberger Cornell University Lake Louise Winter Institute

extra slides
EXTRA SLIDES

Michael Weinberger Cornell University Lake Louise Winter Institute

slide18

Neutrino and No Neutrino Events

Old plots

Michael Weinberger Cornell University Lake Louise Winter Institute

how well code id s particles
How Well Code id’s Particles

Fixed id in code

Particle ided as

1 = kaon

2 = pion

3 = electron

kaon

pion

electron

No muon id means all muons are treated as pions

Michael Weinberger Cornell University Lake Louise Winter Institute

slide20

PDG(2004) inclusive D  lX

Michael Weinberger Cornell University Lake Louise Winter Institute

left side tail
Left Side Tail

Signal only

Signal only

Missing Energy(GeV)

Michael Weinberger Cornell University Lake Louise Winter Institute

slide22

“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

Michael Weinberger Cornell University Lake Louise Winter Institute

slide23

Subtract Out Photon

Dashed – left side events

Solid – photon subtracted out

Left side events

Missing Energy(GeV)

Events with photon subtracted out.

Now in signal region

Michael Weinberger Cornell University Lake Louise Winter Institute

slide24

Re-Fixed Plot

D0

Emiss

Missing Energy(GeV)

Extra background?

Michael Weinberger Cornell University Lake Louise Winter Institute

Emiss

slide25

Spike in D+ Bkg

Signal events

Non spike 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

spike

Number of tracks in event

Bkg pions not in spike

Bkg pions in spike

Michael Weinberger Cornell University Lake Louise Winter Institute

slide26

Comparison of MC Generated vs. Reconstructed Variables

Overlay of MC generated energy spectrum of neutrinos

Scaled down to recontructed spectrum

Black = mc generated(scaled)

Red = reconstructed neutrinos

Michael Weinberger Cornell University Lake Louise Winter Institute

Energy (GeV)