1 / 36

FIRST RESULTS from the CLEO-c DETECTOR

FIRST RESULTS from the CLEO-c DETECTOR. John Yelton University of Florida Gainesville, FL yelton@phys.ufl.edu. The CLEO-c Physics Program The CLEO-c Detector The CLEO-c Run Plan Preliminary Results on the(3770) Preliminary Results on D decays at threshold Conclusions.

hshank
Download Presentation

FIRST RESULTS from the CLEO-c DETECTOR

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. FIRST RESULTS from the CLEO-c DETECTOR John Yelton University of Florida Gainesville, FL yelton@phys.ufl.edu • The CLEO-c Physics Program • The CLEO-c Detector • The CLEO-c Run Plan • Preliminary Results on the(3770) • Preliminary Results on D decays at threshold • Conclusions

  2. The CLEO-c Physics Program The CLEO collaboration: Carleton, Carnegie Mellon, Cornell, Florida, George Mason, Illinois, Kansas, Northwestern, Minnesota, Pittsburgh, Puerto Rico, Purdue, Rochester, RPI, SMU, Syracuse, Vanderbilt and Wayne State. • Charm Measurements: Precise charm absolute branching ratio measurements Hadronic decays: measure strong phases Leptonic decays: decay constants fD and fDs Semi-leptonic decays: form factors Vcs, Vcd • QCD Studies Precise measurements of quarkonia spectroscopy Searches for glue-rich exotic states • Studies Beyond the Standard Model D-mixing, CP violation, rare D decays

  3. “ZD” – Inner Drift Chamber • 6 stereo layers: • r=5.3 cm – 10.5 cm • 12-15o stereo angle • |cos q| < 0.93 • 300, 10 mm cells • 1% X0, .8mm Al inner tube • 60:40 Helium-Propane • 20 mm Au-W sense wires • 110 mm Au-Al field wires • Outer Al-mylar skin

  4. CLEO-c Run Plan Main change for CESR to become CESR-c is the installation of 12 wigglers (6 completed, 6 more being installed). __________________________________________________ Spring and Fall 2004, we hope for 3 fb-1 at and around the (3770). This corresponds to ~18,000,000 decays, and maybe 3,600,000 tagged D decays (310 x MARKIII, 170xBES) ____________________________________________________ Fall 2005, E=4140 MeV, we hope for 3 fb-1 giving 1,500,000 DsDs events, 300 ,000 tagged Ds decays (480 x MARK III, 130 x BES) ___________________________________________________ Fall 2006 we may run at E=3100 MeV, 1 fb-1, giving 1,000,000,000 J/  decays (170 x MARKIII, 20 x BES II) Run plan subject to change, in particular it is dependent on the physics results from the early running.

  5. CLEO-c Run Plan 6 CESR Wigglers installed Summer 2003 Winter 2003 took data on the (3770), (2S), and continuum ~3 pb-1 (2s) ~55 pb-1 (3770) ~20 pb-1 continuum a h Cross-Section Log Scale Ebeam(GeV) 6 Wiggler Running L ~ 5x1031 cm-2 s-1On target! Design Luminosity, 12 Wigglers, ~3x1032 cm-2s-1

  6. Physics at the (3770) The (3770) is known to decay into mesons. The total cross section at E=3.77 GeV has been measured to be 26.2+/-1.0 nb (preliminary), this includes a large, and not well understood continuum component, the radiative tail of the (2S), ,and maybe some other processes as yet unexplored. Decays of the (2S), and thus the nature of the (2S) events at E=3770 are being investigated (see next talk). The continuum below the (2S) is also being studied. To know how many D’s we will reconstruct, we need to know at E=3.77 GeV.

  7. Measurement of • The value of cross section is required to make predictions of the sensitivity of charm threshold e+e- experiments such as CLEO-c and BESII. Mark III (PRL 60 89 (1988) with 9.4 pb-1 measured the observed cross section at GeV to be Recently BES II (Moriond '04) using 17 pb-1 measured • In the BES measurement the cross section was determined using a single tag method, where the charm branching fraction to the final state under study is taken from the PDG. • Here, we use a double tag method to find a value of independent of any branching fraction measurement.

  8. General Analysis Techniques Good K- separation by dE/dx up to 600 MeV/c For p > 600 MeV/c, RICH combined with dE/dx. K0s are found from two tracks with a displaced vertex. 0’s found from 2 gammas in the CsI To find D’s from the (3770), we first calculate the E(D) and compare with the beam energy. If E(D)=Ebeam then we calculate the beam constrained mass

  9. Measurement of at 3770 K- + e- e- e+ e+ p- p- K+ K+ Double tagged D Single tagged D ( independent on B and  in the approximation)

  10. D0K  - in DDMonte Carlo MC D0→K-π+  = 6.4 MeV MC D0→K-π+  = 1.6 MeV E(GeV) Mbc(GeV)

  11. D0 single tag -Data Luminosity = 55.81pb-1 • Require –40 MeV < E < 30 MeV Data D0→K-π+ =8.2 MeV Data D0→K-π+ =1.7 MeV S =9460 E(GeV) Mbc(GeV)

  12. Double Tag Monte Carlo • We search for events where the AND • We use a scatter plot of two beam constrained masses to measure the double tag efficiency. MC Double tag 2 =34.8% M2(GeV) M1(GeV) • We find the double tag efficiency is the square of single tag efficiency with an uncertainty of 3% for

  13. D0Double Tags – Data DATA Double tag Signal =102±11 M2(GeV) M1(GeV) (ee→D0D0)=(3.930.42(stat) 0.23(syst)) nb

  14. D+ Single Tags -Data • Search for • delE cut : E (-31MeV,25MeV) Data D-→K-π+ π+ S=13950±132 Data D-→K-π+ π+ Mbc(GeV) E(GeV)

  15. D+ Double Tags - Data • Use the Decays Double tags Signal=338±19 M2(GeV) M1(GeV) (e+e-→D+D-)=(2.580.15(stat) 0.16(syst))nb

  16. Summary for (DD) • Our result, which is independent of charm branching ratios, is in agreement with the BES. The BES experiment used a single tag method which depends on the PDG values for the branching fractions. The largest systematic uncertainty arises from the luminosity measurement All CLEO-c numbers are preliminary!

  17. An initial D state can be tagged by the “other-side” D Several good tagging decay modes Many large branching fractions High reconstruction efficiency Net tagging efficiency ~20% Expectations from full dataset: 3,600,000 D’s Tagging can be used to find absolute branching fractions of not only hadronic decays, but semi-leptonic and even purely leptonic decays. D-Tagging

  18. Measurement of In the decay of a scalar meson, M, into a lepton plus neutrino, the width is given by: We know the D+ lifetime, thus a measurement of this branching fraction can give a model-free measurement of fD, This is of vital check of LQCD, and can be used to extrapolate to fB, which can enhance our understanding of B decays.

  19. 4 More D+ Modes Ks+ ~ 1800 events Ks+ 0 ~ 2800 events Ks+  +0 ~ 4300 events Ks+ - + ~ 3700 events

  20. Overview of the technique Reconstruct one of the two D’s in a hadronic decay channel. Make use of the neutrino MM2 observable to separate signal and background: Muon candidate consistent with minimum ionizing particle, deposited energy < 0.4 GeV in the CsI. (Too low a momentum for the muon detector).

  21. MM2 Distribution Data Preliminary K0p- DATA Preliminary! ~55 pb-1 K0 MC Candidates/0.01 GeV2 Signal Region Signal region Signal Region

  22. Backgrounds D Background: • D+  +  0: Used max. shower energy cut. • D+ K0+: No reconstructed K0. • D+ 0+ : negligibly small, higher MM2 . • D+ + : negligibly small, higher MM2 . D0D0 Background: • D0D0 can look like D+D-: ex:D0K-+,D0 +- ContinuumBackground Estimated backgrounds from MC

  23. Signal 9 events within 2 (-0.056<MM2<0.056 GeV2) 0.67 0.24 estimated background events. SIGNIFICANT SIGNAL! Reconstruction efficiency ~70% B = Signal / (Tags x Efficiency) PRELIMINARY! Statistically Limited! Soon we will have 60 x the dataset! Systematic errors on Bestimated to be: a) m detection efficiency (5%) b) background, taken as 100% uncertainty (7.4%) c) D+ sample size (1%)

  24. Inclusive Electron Spectrum from D Semi-Leptonic Decays Object: To make improved measurements of the shape of the lepton spectra in This, leads to measurements of the semi-leptonic branching fractions. Electron identification, optimized by studying radiative Bhabha events, a combination of E/p in the CsI calorimeter, dE/dx and RICH information.

  25. D Meson Samples DD D0 D0 Y(3770) Only use one mode for each state now, more will be added later D+ D- X e- n K-p+ p+ K-p+ D+tagged D0 tagged X e- n +Charge conjugate mode +Charge conjugate mode

  26. The Corrected Electron Spectra PRELIMINARY! DATA DATA Number Of event /(50MeV/c) Number Of event /(50MeV/c) Electron Momentum (GeV/c) from D+ Electron Momentum (GeV/c) from D0 Statistical Uncertainty ~0.5% PDG: BR = (6.750.29)% Statistical Uncertainty ~ 0.6% PDG: BR = (17.21.9)% Systematic Uncertainties not Fully Evaluated The dataset should increase by a factor of 60!

  27. Exclusive Semi-Leptonic Decays of D’s Measurements of the absolute branching fractions for semi-leptonic decays in the D system provide: a) A stringent test of theoretical form factor models b) Input calibration of LQCD c) Direct Measurements of Vcs and Vcd d) Input of semi-leptonic form factor models in the B system, and thus Vub Method a) Reconstruct as many D’s as possible (62K D0 and 30K D+ Tags) b) Identify the remaining tracks in the event and define the parameter U=Emiss-|Pmiss| and look for a peak at zero.

  28. Excess of around 100 events in data Data (prelim) MC (prelim) ALL PRELIMINARY!

  29. Excess of around 1.1K events MC (prelim) Data (prelim) ALL PRELIMINARY!

  30. Other D0 Semileptonic Modes Excess ~ 80 events Data (prelim) Data (prelim) Data (prelim) Excess ~120 events. Excess ~ 25 events First Observation of this Mode! Signals are inclusive of non-resonant contributions ALL PRELIMINARY!

  31. D+ Semileptonic Modes (1) Excess of around 400 events Data (prelim) Data (prelim) Data (prelim) Excess of around 300 events The nonresonant contribution is included in the yield Excess of around 50 events ALL PRELIMINARY!

  32. D+ semileptonic modes (2) Excess of around 35 signal events The nonresonant contribution is included in the yield Data (prelim) Data (prelim) A Hint of a Signal ALL PRELIMINARY!

  33. The CLEO-c Reach for Semi-Leptonics The 55/pb data sample collected in fall-2003/winter-2004 by the CLEO-c detector already allows measurements of BRs for most or all of the modes considered today with statistical uncertainties comparable or smaller thanthose in PDG-2002. CLEO-c is expected to collect 60 timesmore (~3/fb) data on (3770) as well as ~3/fb of data at Ecm ~ 4140 MeV for studies of Ds mesons in the coming 2 years. The CLEO-c data will dramatically improve knowledge of the BRs of charm mesons:

  34. Summary and Conclusions • The CLEO-c Detector is working well, and has accumulated ~55fb-1 at the  (3770), together with data at the (2S) and continuum below the (2S) • With this dataset, we have new preliminary results for the cross section at the (3770) of (D+D-) =2.580.15 0.16 nb and (D0D0) = 3.930.420.23 nb We have new preliminary results for the branching fraction of the purely leptonic mode of We hope to collect 60 times more data on the (3770) and then same amount of data at Ecm ~ 4140 MeV. These data samples will play an extremely important role in particle physics, making the definitive measurements of charm hadronic, semi-leptonic and leptonic decays. These will validate and calibrate data for LQCD, and increase the physics potential of B-factories and other experiments. • CLEO-c running resumes in September.

More Related