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Charm Physics at CLEO. Centennial APS Meeting Mats Selen, University of Illinois (speaking for the CLEO collaboration) March 23, 1999. This Presentation:. New D 0 mixing results K p mixing analysis (including lifetime) (David Asner) CP-even KK and pp lifetime results (Tony Hill)
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Charm Physics at CLEO Centennial APS Meeting Mats Selen, University of Illinois(speaking for the CLEO collaboration) March 23, 1999 APS Centennial
This Presentation: • New D0 mixing results • Kp mixing analysis (including lifetime)(David Asner) • CP-even KK and pp lifetime results(Tony Hill) • Charmed Meson Spectroscopy • First observation of broad D1(j=1/2)(Tim Nelson, Harry Nelson) • B(Lc pKp ) absolute measurement • New method described • Preliminary results presented(Dave Besson, Russ Stutz) (Charge conjugation implied throughout) APS Centennial
Our Detector:(CLEO-II & II.V) Svx + HePr APS Centennial
1996 1997 1998 Our Accelerator(CESR) 9 fb-1 CLEO II.VIntegratedLuminosity CLEO IItook 4.7 fb-1prior to this 32.3 pb-1 DailyLuminosity APS Centennial
Our Data: On(2/3) Off(1/3) This Presentation: Mixing Analysis: 5.7 fb-1 CLEO-II.V (SVX) DJ & Lc Analyses: 4.7 fb-1 CLEO-II APS Centennial
Mixing Analysis: Time evolution of D & D0 mesons Decay eigenstates Define Where APS Centennial
on shell off shell D0 D0 D0 D0 pp,KK… can be relatively large in S.M. small in S.M. Window on New Physics What we are sensitive to in the Kp mixing analysis: Where It will eventually be very important to disentangle “x” and “y” CP eigenstate lifetime analysis will tell us about “y” independent of “x” APS Centennial
p+ D*+ p- D0 D0 K+ p+ D*+ p+ D0 K- Mixing in D0 Kp decays: “wrong-sign” RMIX = “right-sign” But “wrong-sign” events can also come fromDoubly Cabibbo Supressed Decays (DCSD): p+ “wrong-sign” D*+ p- D0 K+ APS Centennial
p+ D*+ p- D0 D0 K+ p+ D*+ p- D0 K+ Mixing vs DCSD: Mixing DCSD • Same initial & final states ! • Bad news if this is all the info available • But theres more... 1) Amplitudes evolve differently in time. 2) Amplitudes can interfere. Can use timing information to help untangle Mixing from DCSD APS Centennial
(Where t is measured in D0 lifetimes) 100% mixed 100% DCSD N(t) RMIX = RDCSD cosf = 1 cosf = 0 cosf =-1 D0 lifetimes t(WS)t(D0) RMIX / (RMIX+RDCSD) The total “wrong-sign” rate is given by: APS Centennial
5.7 MeV Analysis uses excellent kinematic resolution to stop K-p+ feedthrough, and relies on good Particle-ID to suppress backgrounds. APS Centennial
Systematic Errors RWS = (0.31 0.09 0.07) % APS Centennial
Aleph: RDCSD 1 RMIX95% CL CLEO-II 1 E791 Klv 90% CL E691 90% CL E791 1 CLEO-II.5 1 Preliminary Results: APS Centennial
Using Lifetime Info: 100% mixed 100% DCSD RMIX = RDCSD N(t) cosf = 1 cosf = 0 cosf =-1 D0 lifetimes t(ws) = ( 0.650.4 (stat+sys) )x t(D0) Exploit this info to limit RMIX APS Centennial
Mixing Results: Aleph: RDCSD 1 RMIX95% CL CLEO-II 1 E791 Klv 90% CL E691 90% CL E791 1 CLEO-II.V 90% CL Preliminary Limits have been calculated for all cosf (ask me after) APS Centennial
on shell off shell D0 D0 D0 D0 pp,KK… can be relatively large in S.M. small in S.M. Window on New Physics What we are sensitive to in the Kp mixing analysis: Where It will eventually be very important to disentangle “x” and “y” CP eigenstate lifetime analysis will tell us about “y” independent of “x” APS Centennial
CP-even Lifetime Analysis: Look for G(D0K-p+) G(D0p-p+, K- K+) This is a direct measure of DG !(i.e. measure “y” independent of “x”) Plan: Measure t(D0K-p+) t(D0p-p+) t(D0K- K+) Both CP=+1 Should have the same lifetimes D0K-p+ , D0p-p+, andD0K- K+ are easy to distinguish kinematically Don’t need particle-ID APS Centennial
CP-even Yields: APS Centennial
Lifetime Fits: Use unbinned maximum likelihood fit to extract signal lifetimes: APS Centennial
Extracting “y”: Look for G(D0K-p+) G(D0p-p+, K- K+) Where t+ (t-) are the CP even (odd) lifetimes, and tKp = (t+ + t- )/2 Based on our present measurement: y = -0.032 0.034 or -0.076 y 0.012 (90% CL) CLEO II.V Preliminary APS Centennial
Putting it all together y x CLEO II.V Preliminary APS Centennial
Future mixing prospects CP odd eigenstate lifetime analysis sneak preview Lots more data to analyze APS Centennial
Charm Meson Spectroscopy j=1/2 j=3/2 j=3/2 j=1/2 We search for D1(j=1/2) D1(j=3/2) D2*(j=3/2) Previously not seen B- p- Previously seen D*+p- D0p+ APS Centennial
Analysis Technique • Partial reconstruction: B- DJ0p-; DJ0 D*+p-; D*+ D0p+ • Measure 4-momenta of p-p-p+. • Extract signal via 4-D Max Likelihood Fit • Fitting Technique • 4 independent variables: • helicity q2,helicity q3,azimuth ,M(D*p) • Fit parameters: • Yields (3 resonant, 1 non-resonant) • Mass and width of broad D1(j=1/2) • Mixing and interference between resonances. • Strong phases relative to D1(2420) APS Centennial
1+ d-wave 1+ s-wave 2+ d-wave cos q3vscos q2 cvscos q2 cvscos q1 Total Background cvscos q2 cvscos q1 cos q3vscos q2 APS Centennial
Total background (see below) D1(2420)0 D2*(2460)0 D01(j=1/2) Fit Results APS Centennial
Weighted Fit Components 1+ s-wave Weighted 1+ d-wave Weighted 2+ d-wave Weighted Background Weighted APS Centennial
With 5.7s significance Preliminary Results • Properties of D1(j=1/2) • (second systematic error due to • uncertainty modeling strong phases) • Spin-Parity assigned to 1+ • Tests of JP favor 1+ over 0- • (closest alternative). • Quark Model: APS Centennial
e+e- Tag charm with one of these cc Baryon tag p D*- Dp-s Lc Xe- ne pK-p+ B(Lc pKp) Absolute • Why? • One of the 4 measured quantities used to normalize all charm analyses B(D0K-p+),B(D+K-p+p+),B(Dsfp+), B(LcpK-p+) • Not well determined at present B(LcpK-p+) = (51.3)% PDG • Our Technique (NEW): Divide event into hemispheres APS Centennial
p p Two versions: Triple correlation analysis (x2): cc D*- or Dp-s pK-p+ Lc Xe- ne cc D*- or Dp-s Lc anything Xe- ne Double correlation analysis: p cc anything pK-p+ Lc p cc D*- Dp-s Lc anything Kp... APS Centennial
Yield examples: (Double correlation analysis) “numerator” LcpK-p+ (same hemisphere as anti-proton tag) “denominator” D0K-p+ (opposite hemisphere from anti-proton tag) Apply efficiency correction and get answer... APS Centennial
p p cc D N D Fake p tag Sounds easy, but... Biggest Backgrounds/Corrections: Falsely increased denominator cc anything Count and correct D cc D D p+ K- Falsely increased denominator Study Kaon fake rate as a function proton momentum and correct (15% effect): After correction, p momentum spectrum looks OK. APS Centennial
Preliminary Results • Make the physics corrections mentioned on previous page (and other smaller ones): • Make appropriate efficiency corrections. B(LcpK-p+ ) Double correlation (4.9 0.5)% Triple correlation (ps tag) (5.2 1.3)% Triple correlation (e tag) (5.6 2.5)% Weighted average: B(LcpK-p+ ) = (5.0 0.5 1.5) % APS Centennial
Future Prospects CLEO-III • Several New Detector Components • RICH, Drift Chamber, Silicon • New CESR cavities & IR • Lots more luminosity APS Centennial