1 Absolute Hadronic D 0 and D + Branching Fractions at CLEO-c Werner Sun, Cornell University for the CLEO-c Collaboration CKM 2005 Workshop on the Unitarity Triangle March 2005, San Diego, CA Introduction to CLEO-c Branching fraction measurement technique Results Future directions

CKM 2005 Workshop, March 2005, San Diego, CAWerner Sun, Cornell University 2 The CLEO-c Program  Run CESR at √s = 3—5 GeV to study D and D s at threshold, search for exotics at .  Precise measurements of:  D, D s hadronic branching fractions:  Input to V cb, 5% error.  For CLEO V cb, 1.4% from  ( B ), total syst 4.3%  D semileptonic B ’s and form factors:  V cs, V cd to ~ 1% (current errs. 16% and 7%).  c  ul FFs to test LQCD  V ub (25% err.  5%).  D and D s decay constants:  Validate LQCD, use to predict f B & f Bs  V td & V ts (40% error  5%).  Improve understanding of strong and weak interactions (6 of 9 CKM matrix elements).  Currently running at  (3770)  DD, no D s.  (3770) ’’ E beam Current analysis based on 60 pb -1 pilot run from fall ’03—spring ‘04

CKM 2005 Workshop, March 2005, San Diego, CAWerner Sun, Cornell University 3 CLEO-c and CESR-c  Experimental features:  Low multiplicity, bkgs.  Simple initial state: e + e -   (3770)  DD, no extra fragmentation.  D tagging—this analysis reconstructs 10% of all D decays.  CESR III  CESR-c:  Added 12 SC wiggler magnets to decrease emittance, damping time.  Only 6 were in place for the present dataset.  CLEO III  CLEO-c:  Silicon vertex detector  stereo drift chamber.  B field 1.5  1.0 T  Tracking: 93% of 4   53 layers.   p /p ~ 0.6% at 1 GeV.  CsI calorimeter: 93% of 4   7800 crystals.   E /E ~ 2.2% at 1 GeV.  2 sources of particle ID:  dE/dx in drift chamber.  RICH: 80% of 4   Combined  (K or  ) > 90%.  Fake rate < 5%. Inner Drift Chamber CLEO-c

CKM 2005 Workshop, March 2005, San Diego, CAWerner Sun, Cornell University 4 Overview of Technique  Single tag (ST) = one D reconstructed: n i = N DD B i  i  Identifies charge and flavor of other D.  Establishes well-defined subsample to search for other D.  Double tag (DT) = both reconstructed: n ij = N DD B i B j  ij  When all information combined, statistical  ( B ) ~  (N DD ).  Independent of L and cross sections.  Correlated systematic uncertainties cancel.  Kinematics analogous to  (4S)  BB: identify D with   (M BC ) ~ 1.3 MeV, x2 with  0   (  E) ~ 7—10 MeV, x2 with  0  Reference modes D  K   + and K   +  + normalize other B measurements from other experiments.  Same dataset as ICHEP04, but analysis updated. e+e+ e-e- D D D0D0 K+K+ K+K+ K++K++ D+D+ K++K++ K++0K++0 KS+KS+ K0S+0K0S+0 K0S+-+K0S+-+ K+K+K+K+

CKM 2005 Workshop, March 2005, San Diego, CAWerner Sun, Cornell University 5 M BC (log scale) for ST modes: D+D Yield Fits  Unbinned ML fits to M BC (1D for ST, 2D for DT)  Signal function includes ISR,  (3770) line shape, beam energy smearing, and detector resolution.  Signal parameters from DT fits, then apply to ST.  Background: phase space (“ARGUS function”).  D and D yields and efficiencies separated. ISR & beam energy DT signal shape Detector resolution ModeN D (10 3 )  D  (%) KK 5.11± ± ±0.2 K   9.51± ± ±0.1 K  7.44± ± ±0.1 K  7.56± ±0.1 K   2.45± ± ±0.1 K0sK0s 1.10± ± ±0.3 K 0 s   2.59± ± ±0.1 K 0 s  1.63± ± ±0.1 KK  0.64± ± ±0.4 All D 0 DT 2484 ± 51 All D + DT 1650 ± 42

CKM 2005 Workshop, March 2005, San Diego, CAWerner Sun, Cornell University 6 Branching Fraction Fitter  B and N DD extracted from  2 fit.  Include both statistical and systematic errors (with correlations):  All experimental inputs treated consistently.  B (D 0 ) and B (D + ) statistically independent, but correlated by common systematics.  Efficiency, crossfeed, background corrections performed directly in fit.  Predicted DCSD explicitly removed as background.  See arXiv:physics/ for more details. Yields n(n)n(n) V n (n x n) Bkgnds b(b)b(b) V b (b x b) Signal effs E (n x n) V E (n 2 x n 2 ) Bkgnd effs F (n x b) V F (nbxnb) Fit Inputs: c = E -1 ( n – Fb )

CKM 2005 Workshop, March 2005, San Diego, CAWerner Sun, Cornell University 7 Systematic Uncertainties  Dominant error: MC simulation of tracking, K 0 S, and  0 efficiencies.  Correlated among all particles of a given type—adds up quickly.  Missing mass technique to compare data and MC.  Fully reconstruct entire event, but deliberately leave out one particle.  Fraction of MM peak where the last particle is found = efficiency.  Depends on event cleanliness. K found (MC) K not found (MC) Example: K  efficiency from D 0  K   +  ≈ 91% in fiducial volume SourceUncertainty (%) Tracking/K 0 s /  0 0.7/3.0/2.0 Particle ID 0.3  /1.3 K Trigger  < 0.2  E cut 1.0—2.5 per D FSR0.5 ST / 1.0 DT  (3770) width 0.6 Resonant substructure0.4—1.5 Event environment0.0—1.3 Yield fit functions0.5 Data processing0.3 Double DCSD0.8 Neutral DT: interference between Cabibbo-favored and DCSD on both sides.  K -  +  0, etc.

CKM 2005 Workshop, March 2005, San Diego, CAWerner Sun, Cornell University 8 Fit Results  Precision comparable to PDG WA.  Statistical errors: ~2.0% neutral, ~2.5% charged from total DT yields.   (systematic) ~  (statistical).  Many systematics measured in data, will improve with time.  Simulation includes FSR, so we measure B (final state + n  ).  Using efficiencies without FSR correction would lower B.  N DD includes continuum and resonant production.  L determination being updated; no new cross sections since ICHEP, yet.  N D + D - /N D  D  = 0.78 ± 0.02 ± ParameterValue no  FSR NDDNDD (2.01±0.04±0.02)x % R 0 = K   + (3.91±0.08±0.09)%-2.0% K+K+ (14.9±0.3±0.5)%-0.8% K++K++ (8.3±0.2±0.3)%-1.7% ND+D-ND+D- (1.56±0.04±0.01)x % R + = K   +  + (9.5±0.2±0.3)%-2.2% K++0K++0 (6.0±0.2±0.2)%-0.6% KS+KS+ (1.55±0.05±0.06)%-1.8% K0S+0K0S+0 (7.2±0.2±0.4)%-0.8% K0S+-+K0S+-+ (3.2±0.1±0.2)%-1.4% K+K+K+K+ (0.97±0.04±0.04)%-0.9% K+/R0K+/R0 3.65±0.05± % K++/R0K++/R0 2.10±0.03± % K++0/R+K++0/R+ 0.61±0.01± % KS+/R+KS+/R ±0.004± % K0S+0/R+K0S+0/R+ 0.75±0.02± % K0S+-+/R+K0S+-+/R+ 0.34±0.009± % K+K+/R+K+K+/R ±0.004± %

CKM 2005 Workshop, March 2005, San Diego, CAWerner Sun, Cornell University 9 Comparison with PDG 2004  Measurements and errors normalized to PDG.  PDG global fit includes ratios to K -  + or K -  +  +.  No FSR corrections in PDG measurements.  Our measurements also correlated (statistics and efficiency systematics). B(D0  K-+)B(D0  K-+) B (D +  K -  +  + ) Other direct meas. Overall C.L 25.9%

CKM 2005 Workshop, March 2005, San Diego, CAWerner Sun, Cornell University 10 Future Directions  Improve measurements with more data (goal 3 fb -1 ).  275 pb -1 projected for this summer.  Will lower both statistical and systematic uncertainties.  With 1 fb -1, < 2% errors on K -  + and K -  +  + —systematics limited.  D 0 D 0 quantum coherence negligible: only flavored final states.  But with CP eigenstates, exploit coherence to probe mixing.  x =  M/ , y =  /2 , r = DCS-CF amp. ratio,  = DCS-CF phase diff.  Time-integrated yields sensitive to mixing, e.g.  (D  CP ± )~1+y.  Mixing entangled with DCSD, separate with semileptonics.  Simultaneous fit for hadronic and semileptonic B s + x, y, r, .  With 1 fb -1 :  (y)~1% (same as current WA)  (x sin  )~1.5% (current: xcos  +ysin  < 1.8% at 95% C.L.).  CLEO-c also sensitive to new physics through rare phenomena.  See also D. Asner in WG5.

CKM 2005 Workshop, March 2005, San Diego, CAWerner Sun, Cornell University 11 Summary  One major goal of CLEO-c: measure hadronic D branching fractions (preprint to appear as CLNS , CLEO 05-6).  Three more years of data taking.  Branching fractions in 60 pb -1 competitive with world averages.  B (D 0  K -  + ) measured to 3.1% (PDG 2.4%).  B (D +  K -  +  + ) measured to 3.9% (PDG 6.5%).  Over 4x more data for this summer.  Will lower statistical and systematic errors.  D s branching fractions with √s ~ 4.14 GeV running.  Reduce error on V cb.  Contribute to stringent test of CKM unitarity.