Transcript Document
D-meson results from CLEO • “Rumors of my death are exaggerated”. – 2003: CLEO re-incarnated (phoenix-like) into 3-4 GeV electronpositron collider. – First “CLEO-class” detector at charmonium energies – Continuing nearly 30 year physics program • Longevity>U2 (but <Rolling Stones) – Scheduled to take data into 2008; expect active physics analysis program for additional five yrs. • Focus here on updated D+mn (2005 pub.) plus recent results on semileptonic+hadronic D modes. • THANKS TO DAVID ASNER, WERNER SUN AND ALEX SMITH, FROM WHOM I SHAMELESSLY LIFTED SLIDES WHOLESALE! CLEO-c Detector/CESR-c Accelerator • Ability to run at cms energies from Mini Drift J/y up to U(5S) SVX SVX CLEO III CLEO-III CLEO-c Chamber y’ y(3770) Beam Energy (GeV) Simple conversion of detector from U(4S) to y(3770) running; CESR reconfiguration now prohibits return to Upsilon system. Silow-mass tracking Running at the y(3770) Ecm ~ U(4S) Ecm ~ y(3770) CLEO III • No extra energy for fragmentation particles CLEO-c – Known/coherent initial state – Clean neutrino reconstruction – Simple combinatorics • Large cross section • Good kinematic particle ID Overview of D-tagging techniques • e+e- y(3770) DD • Kinematics analogous to U(4S)"BB: s(MBC) ~ 1.3 MeV, x2 with p0 s(DE) ~ 7—10 MeV, x2 with p0 • Single tag (ST): ni = NDDBiei • Double tag (DT) : nij = NDDBiBjeij – Ratio + algebra allows extraction of BR; eff cancels to 1st order • Take advantage of low multiplicity, low backgrounds. K found (MC) MM allows extraction of efficiency from data! (Same tracking eff technique in earlier CLEO-II DKpi analysis) DKXX DKp Dpp K not found (MC) Example: K- eff from D0 " K-p+ e ≈ 91% Leptonic Decays: + + D →μ ν 2 ml G 2 2 + + D l n f D + ml M D + 1 - 2 M + 8p D 2 F Compare with lattice QCD predictions! 2 2 Vcd fD+ from Absolute Br(D+ m+n) Tag D fully reconstructed 1 additional track (m) Compute missing mass2: peaks at 0 for signal B ( D + mn ) 10-4 MkIII f D MeV 7.2 BESII 12.211.1 -53 0.11 290 ~9 pb-1 2390 tags 371+-129 119 25 Mark III PRL 60, 1375 (1988) BESII Phys.Lett.B610:183-191, (2005) ~33pb-1 5321 tags D Leptonic Decays: + + D m n Getting the ABSOLUTE branching fractions... “Other side D” tag Tag D e+ e- m+ Signal D n • Tag D decay modes: – • Many large BR tag modes – ~25% efficiency for reconstructing a tag • Signal is very pure after tagging • Roughly 30x BES sample • (281/pb) D - K +p -p D - K +p -p -p 0 D - K S0p D - K S0p -p -p + D - K S0p -p 0 • Fit for (“missing mass”)2: MM 2 Ebeam - Em + - - p 2 D - - pm + 2 TAG SAMPLE Compare with previous results & Lattice Calcs 222.6(16.7)(3.4) Since fD measures w.f. overlap at origin, expect comparable (slightly smaller than) fDs Phys.Rev.Lett. 95 (2005) 251801 Semileptonic Decays D Pln 2 2 F G Vcq p 3 24p 3 f+ q 2 2 c Test LQCD on shape of f+(q2) ne |Vcs| , |Vcd| u,d Use tested Lattice for norm. Extract |Vcd| Extract B(DXen) Dp FF related to Bp FF by HQS Precise Dp FF’s can lead to reduced stheory in |Vub| at B factories Same holds for DVln, except 3 FF’s enter W+ e+ s,d u,d Exclusive Semileptonic D Meson Decays Signal component from fit to variable U Technique: • Reconstruct one D meson in hadronic tagging channel – – M bc E 2 beam -P 2 candidate 0 + B( D + K e n ) D E Ebeam - Ecandidate • Reconstruct the remaining observable tracks • Use the missing energy (Emiss) and missing momentum (|Pmiss|) in the event to form kinematic fit variable for the neutrino U Emiss - Pmiss From Monte Carlo/Data 0 + N (K e n ) 0 + e (K e n )N (D- ) From fit of Mbc and DE for number of tags Both flavors combined: B 0 + N ( K e n ) + N ( K 0 e -n ) 0 + e ( K e n ) ( N ( D - ) + N ( D + )) Semileptonic Decays Semileptonic decays are reconstructed with no kinematic ambiguity Hadronic Tags: 32K D+ 60K D0 K+ pe+ Tagging creates a single D beam of known 4-momentum Events / ( 10 MeV ) n K- D0 K -e +n (~1300 events) U = Emiss– |Pmiss| (GeV) D+ semileptonic results (including omega!) D0 semileptonic results – note wrt PDG Compare CLEO-c to PDG 2004 Double Tag Analysis gives Had BR’s All D+ DT 1650±42 All D0 DT 2484±51 Mode MBC (log scale) for ST modes: D+D ND (103) ND (103) eD(%) Kp 5.11±0.07 5.15±0.07 65.1±0.2 Kpp0 9.51±0.11 9.47±0.11 31.6±0.1 Kppp 7.44±0.09 7.43±0.09 43.8±0.1 Kpp 7.56±0.09 7.56±0.09 51.0±0.1 Kppp0 2.45±0.07 2.39±0.07 25.7±0.1 K0sp 1.10±0.04 1.13±0.04 45.7±0.3 K0spp0 2.59±0.07 2.50±0.07 22.4±0.1 K0sppp 1.63±0.06 1.58±0.06 31.2±0.1 0.64±0.03 0.61±0.03 41.1±0.4 KKp Double Tag Analysis: Fit Results • Fit includes both statistical and systematic errors (with correlations) [arXiv:physics/0503050]. • Precision comparable to PDG WA. s(systematic) ~ s(statistical). – Many systematics measured in data, will improve w/time. • Simulation includes FSR, so we measure B (final state + ng). – Using efficiencies without FSR correction would lower B. • NDD includes continuum and resonant production. Value no FSR (2.01±0.04±0.02)x105 -0.2% (3.91±0.08±0.09)% -2.0% B(K-p+p0) (14.9±0.3±0.5)% -0.8% B(K-p+p+p-) (8.3±0.2±0.3)% -1.7% (1.56±0.04±0.01)x105 -0.2% B(K-p+p+) (9.5±0.2±0.3)% -2.2% B(K-p+p+p0) (6.0±0.2±0.2)% -0.6% (1.55±0.05±0.06)% -1.8% B(K0Sp+p0) (7.2±0.2±0.4)% -0.8% B(K0Sp+p-p+) (3.2±0.1±0.2)% -1.4% (0.97±0.04±0.04)% -0.9% s(D0D0) (3.60±0.07+0.07-0.05) nb -0.2% s(D+D-) (2.79±0.07+0.10-0.04) nb -0.2% s(+-)/s(00) 0.776±0.024+0.014-0.008 +0.0% Parameter ND0D0 B(K-p+) ND+D- B(KS0p+) B(K+K-p+) Comparison with PDG 2004 B(D0 " K-p+) B(D+ " K- p+p+) • Measurements and errors normalized to PDG. • PDG global fit includes ratios to K-p+ or K-p+p+. • No FSR corrections in PDG measurements. Overall • Our measurements also correlated C.L (statistics and25.9% efficiency systematics). Other direct meas. D→ + n(p ) 0 m(p ) • Study Cabibbo-suppressed D decays with single tags only. – Double tag technique not as profitable—statistics too low. – Normalize Bs to ref. modes. • MC tuned to match pp mass spectra in data. • Bkgnd from Cabibbo-favored decays with K0S → p+p-, p0p0. – Veto M(pp) near K0S mass. D0 Reference modes D+ M(p+p-) M(p0p0) MBC distributions in DE signal region and DE sidebands X-checked with search including hgg What’s coming? • Results on CP-modes, • Dalitz analyses & rare decay modes, • Via scan, have found “optimal” run energy for production of Ds mesons…beginning to accumulate tag sample; apply D-reconstruction machinery to Ds, • Immediate Ds goals: high-precision msrmnt of normalizing mode (fp, tn, semileptonic modes (CF and CS), rare modes “tailored” for threshold msmrnts (p-nbar, e.g.) Tags Invariant Masses from the 4160 & the 4180 MeV DATA fp- hr- 23316 22753 KsK- hp- 15018 7010 hp- hr- 9719 K * K- 5615 fr- Total # of Tags = 1219 ± 67(stat) 30422 8215 Impact of CLEO-c Measurements Electroweak Physics n W+ e+ Strong Physics • Calibration and validation of Lattice QCD • Test theoretical form factor calcs. and models – Impacts prediction of form factors for B meson decays • Measurements of |Vcs| and |Vcd| • Improved decay constants fB possible from CLEO-c fD measurement + LQCD • Improved measurement of many important normalization modes CLEO-c Impact on Unitarity Triangle Now: Theory uncertainties dominate With few % theory errors made possible by CLEO-c and 500 fb-1 each from the B factories: Future of Precision Flavor Physics Goal: Measure all CKM matrix elements and associated phases in order to over-constrain the unitary triangles Vud/Vud~0.1% e n n p Vcd/Vcd~71.1% D l n p Vtd/Vtd~365% Bd CLEO-c Vus/Vus~1% K Vub/Vub~155% l n l B p n p Vcs/Vcs~161.4% Vcb/Vcb~53% D l n K Vts/Vts~395% Bd Bs CLEO-c + Lattice QCD +B factories Bs l B n D Vtb/Vtb~29% t W b CLEO-c + Lattice QCD +B factories + ppbar