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

1. Inclusive Measurement of BR(D X) and The Neutrino Spectrum Michael Weinberger CLEO-c Cornell University Lake Louise Winter Institute

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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)

10. & 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

11. & 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

12. 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

13. Red = signal Blue = background Black = all events that pass cuts: sum of red and blue Missing Energy Spectra D0 MC D± MC Emiss(GeV) Emiss(GeV) Cutoff at 0.1 due to min P cut Michael Weinberger Cornell University Lake Louise Winter Institute

14. Data [57.2 Pb-1] vs. MC Comparisons MC Data Missing Energy (GeV) Missing Energy (GeV) Michael Weinberger Cornell University Lake Louise Winter Institute

15. Data vs. MC points = data red = scaled MC D0 D± Emiss (GeV) Emiss (GeV) Michael Weinberger Cornell University Lake Louise Winter Institute

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) Michael Weinberger Cornell University Lake Louise Winter Institute

17. EXTRA SLIDES Michael Weinberger Cornell University Lake Louise Winter Institute

18. Neutrino and No Neutrino Events Old plots Michael Weinberger Cornell University Lake Louise Winter Institute

19. 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

20. PDG(2004) inclusive D  lX Michael Weinberger Cornell University Lake Louise Winter Institute

21. Left Side Tail Signal only Signal only Missing Energy(GeV) Michael Weinberger Cornell University Lake Louise Winter Institute

22. “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

23. 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

24. Re-Fixed Plot D0 Emiss D± Missing Energy(GeV) Extra background? Michael Weinberger Cornell University Lake Louise Winter Institute Emiss

25. 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

26. 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)