Hadronic Decays of Charm Mesons

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1 Hadronic Decays of Charm Mesons Roy A. Briere Carnegie Mellon University ( & CLEO Collaboration ) Lepton Photon 2007 Daegu, Korea 14 Aug 2007 R.A. Briere Lepton Photon

2 Outline Introduction 1) Absolute Hadronic Branching Fractions 2) Dalitz Plot Analyses 3) Kπ Strong Phase 4) Higher Resonances, D 0 Mass 5) R had & Production Cross-Sections Future & Conclusions Very recent Charm Workshop: Aug 5-8 CHARM 2007 Ithaca, NY more details on many results can be found here: R.A. Briere Lepton Photon

3 Many Other Charm Talks Here Charm is very active: D Mixing -- Monday: W. Lockman & B. Golob D Semileptonic & Leptonic -- Today: E. Barberio Rare D Decays Spectroscopy -- Today: M. Nakao -- Today: R. Faccini & R. Mizuk Production studies are also ongoing. Let s look inside the Charm Hadronic sector R.A. Briere Lepton Photon

4 Charm Hadronic Landscape Seven weakly-decaying ground states: D + D 0 D + s Λ c Ξ 0 c Ξ + c Ω c This talk covers mesons (w/ a few comments on baryons where appropriate ) Many interesting hadronic decays of charmonium -- New sample of ~27M ψ(2s) from CLEO-c; results soon -- Extensive work from BES II; and BES III is starting in 2008 Charmonium will be de-emphasized in this talk Many excellent reviews exist elsewhere Some interesting transitions from excited states: ( not simply isospin-constrained pion emission ) -- Mixtures of relative angular momenta (e.g., S + D waves) -- Multi-body decays R.A. Briere Lepton Photon

5 Techniques & Players D D threshold: Mark III, BES II CLEO-c ( and soon BES III ) -- Very clean samples with tags ( = reconstruct one D, study other ) -- No fragmentation particles: ~clean even without tags -- Unique aspects of data: CP tags & Quantum Correlations! Charm at B factories: -- VERY high statistics ( 10 9 charm hadrons ) -- Continuum tagging & other clever ideas in use -- D* tags: still key for mixing! Initial-state radiation at B factories: -- Good for spectroscopy, and also exclusive cross-sections Fixed Target / Tevatron Collider: -- FOCUS, SELEX still publish -- CDF can access hadronic modes (non-hadronic at both CDF & DØ) R.A. Briere Lepton Photon

6 D Hadronic Branching Ratios Normalizations for D, B decays in Weak studies D 0 K π + D + K π + π + D S K + K π + Tagging at CLEO-c vs. high statistics at BaBar & Belle Issues: Final-state radiation (FSR); D s golden-mode (what is φπ BF?) Note: I will need to omit lots of good work on singly & doubly Cabibbo-suppressed decays, inclusive yields (D s incl. useful for B s studies) R.A. Briere Lepton Photon

7 D Tags at CLEO-c + D, D0 D0 ψ(3770) D π K+ π K+ (no extra particles) ν K π+ K+ π π+ π π K π+ K π+ K π+ π+ vs. K+ π π Double Tag R.A. Briere e+ K e+ ν vs. K+ π Tag = fully-recon. Hadronic decay Lepton Photon 2007 Single Tag ( yellow boxes are trigger cells ) 7

8 D 0, D + : Clean Tag Samples D + K - π + π + Single Tags linear scale square-root scale to PRD, arxiv soon! PRELIMINARY 281 pb -1 ~80k events ISR Tail ~52k ~80k ~26k M BC 2 = E beam 2 - p D 2 D + K - π + π + vs. D - K + π - π - Double Tags ~101k ~26k ~16k 2002 events (~8600 D + D - tags in total) ~78k ~11k ~7k R.A. Briere Lepton Photon

9 D 0, D + Branching Fractions Single Tags: N j = N DD B j ε j Double Tags: N ij = N DD B i B j ε ij to PRD, arxiv soon! PRELIMINARY 281 pb -1 B i = N ij ε j / N j ε ij N DD = N i N j ε ij / N ij ε i ε j Key points: B independent of N DD ε j / ε ij ~ ε i : ~ independent of tag j (usual Achilles heel) Systematics: -- Study efficiencies with tag data Golden Normalization Modes: B(D 0 K π + ) = (3.891 ± ± ± 0.035)% B(D + K π + π + ) = (9.15 ± 0.10 ± 0.16 ± 0.07 )% errors: stat syst FSR Ratio of CLEO-c to PDG ( PDG04 here, since PDG06 includes prior 56 pb -1 CLEO-c ) R.A. Briere Lepton Photon

D 0 K π + Partial reconstruction B 0 D* + X l ν D* + D 0 π

BaBar: B ( D 0 K π + ) = ( 4.007 ± 0.037 ± 0.

10 D 0 K π + Partial reconstruction B 0 D* + X l ν D* + D 0 π + (l = µ,e) arxiv: sub. to PRL 210 fb -1 M ν 2 = ( E beam E D* E l ) 2 ( p D* + p l ) 2 Exclusive D 0 K π + ΔM = m(d 0 π + ) - m(d 0 ) BaBar: B ( D 0 K π + ) = ( ± ± )% Recall CLEO-c: B(D 0 K π + ) = ( ± ± ± 0.035)% R.A. Briere Lepton Photon

11 D s Tags E cm = 4170 MeV ~1 nb of D s * D s CHARM2007 PRELIM 298 pb -1 M(D s - ) Have 976±33 double tags Sets the scale of stat. error: ~3.5% Double tags M(D s+ ) ~13.9k ~3.1k Single tags ~3.5k ~2.0k ~1.7k All modes ~3.2k ~1.8k ~1.1k Projected M(D s+ ) - M(D s- ) R.A. Briere Lepton Photon

12 D s Branching Fractions CHARM2007 PRELIM 298 pb -1 No CLEO-c in PDG07 Often statistics limited: Plan to take double data by end of CLEO-c run (31 Mar 2008) Key normalizing mode: B ( D S K + K π + ) = ( 5.67 ± 0.24 ± 0.18 ) % CLEO-c also quotes B( D S K + K π + ) with various M(K + K ) windows (see A. Ryd, CHARM2007) Working on Dalitz analysis. R.A. Briere Lepton Photon

13 D s Continuum Tagging Use exclusive e + e D s * + D s1 (2536) arxiv: PRELIM 552 fb -1 Compare two partial reconstructions: 1) D s1 D* K only γ from D s * + use recoil mass against D s1 γ for D s * + M(D*K) D s1 D* 0 K D s1 D* + K S 2) D s * + (K + K π + ) γ only K from D s1 use recoil mass against D s * + K for D s1 (plots omitted) Ratio gives B(D s K + K π + ) ( given the well-known D*, D s * branching ratios ) ΔM recoil (D s1 γ) D s1 D* 0 K D s1 D* + K S B ( D S K + K π + ) = ( 4.0 ± 0.4 ± 0.4 ) % R.A. Briere Lepton Photon

14 Final-State Radiation Accuracy in BF s now demands special care! -- FSR matters: CLEO-c uses Photos v BaBar relative FSR syst. for Kπ is 0.07%; CLEO-c is 0.90% -- Need to give clear information to PDG, users of BFs, etc. Photos for FSR: many versions & settings exist! -- No interference between radiation off final-state hadrons -- Interference only between identical particles -- `Full interference (v2.15) D s Normalization Many nice new numbers (including older Babar), but: -- Likely hard to correct many old results using D s φπ ( φ-region mass cuts, helicity cuts, matter! ) -- But, new results will supersede these in any case Need to take care that new ones are sensibly normalized and thus updatable ( See BaBar Dalitz analysis a bit later in this talk ) R.A. Briere Lepton Photon

15 Interference in K L π, K S π D Decay diagrams source both K 0 and K 0 bar These interfere in physical K L, K S final states: K S, K L asymmetry R(D) = [ B(D K S π) B(D K L π) ] / [ B(D K S π) + B(D K L π) ] Bigi & Yamamoto [ PLB 349, 363 (1995) ] D 0 : expect BF asymmetry of: R(D 0 ) = 2 tan 2 θ C ~ 10% D + : more diagrams to consider R(D+) see next page c w + s d K 0 D0 u u u p0 Cabibbo-favored c d w + D0 u u u p0 Cabibbo-suppressed s K 0 R.A. Briere Lepton Photon

16 Interference in K L π, K S π arxiv: pb -1 PRELIMINARY D 0 Κ L0 π 0 D O : R D = ± ± ( consistent with 2 tan 2 θ C ) Missing Mass Squared D + Κ L0 π + D + : R D = ± ± D + Κ S0 π + (leakage) D + π 0 π +, µ + ν D + ηπ + Dao-Neng Gao predicts: R(D + ) = to ( arxiv:hep-ph/ v2 ) Missing Mass Squared J. Rosner, CHARM2007: R(D + ) = ± R.A. Briere Lepton Photon

17 Dalitz Plot Analyses A booming industry: -- Improved techniques ( but more to do ) -- Low-E spectroscopy ( Kπ, ππ S-waves, etc. ) -- Exploitable for better S/N ( e.g., D mixing ) -- Connections to B physics ( CKM angle γ) -- New: CP-tags at CLEO-c Nice review: G. Cavoto, FPCP 2007 arxiv: R.A. Briere Lepton Photon

18 101K events 95% pure f 0 (980) broad & near φ φ(1020) D S K + K π + (ampl & phase removed to save space ) FPCP2007 PRELIM 240 fb -1 K * (892) φ(1020) Perhaps large interference? K * (892) P-wave dominates here f 0 (980) is large, but with large systematics as well Crucial addition to precise BFs R.A. Briere Lepton Photon

ents; 97% pure Low M Kπ arxiv:0705.2248 ( sub. To PLB ) High M Kπ Isobar fit: i.e., sum of interfering Breit-Wigners ~22% κ

19 Folded plot D + K π + π + 54K events; 97% pure Low M Kπ arxiv: ( sub. To PLB ) High M Kπ Isobar fit: i.e., sum of interfering Breit-Wigners ~22% κ (broad low-mass S-wave Kπ resonance) Such fits violate unitary due to B-W overlaps κ pole unreliable! K-matrix fit which can describe LASS & other Kπ scattering data: Respects 2-body unitarity ~82% S-wave but large I = 1/2, 3/2 interference! A careful, technical tour-de-force Also have nice D 0 4π analysis: arxiv: R.A. Briere Lepton Photon

D 0 K S π + π + from D Mixing paper arxiv.0701.4000 sub.

20 D 0 K S π + π + from D Mixing paper arxiv sub. To PRL 540 fb -1 Necessary to reduce error on CKM angle γ But can improve even more with phase information Isobar results here, but S-wave K-matrix done for comparison R.A. Briere Lepton Photon

21 D 0 K S,L π + π : Flavor Tags Interference effects as with K S,L! earlier... CHARM2007 PRELIM 281 pb -1 The K S,L!! Dalitz plots are not exactly equal K L!! There is a clear difference in the DCS K* + peak Appears constructively in K L!!, and destructively in K S!! M 2 (K S! - ) K S!! Can flavor-tag w/ D*: B factories Why CLEO-c? CP-tags! M 2 (K S! + ) R.A. Briere Lepton Photon

22 D 0 K S π + π : CP Tags CP Tags give information on phase between D and D amplitudes CHARM2007 PRELIM 281 pb -1 K S ρ 0 K S ρ 0 resonance enhanced in CP-odd Dalitz plot CP-odd K S ρ 0 resonance absent in CP-even Dalitz plot M 2 (K S! + ) R.A. Briere Lepton Photon

23 J/ψ K + K π 0 Decay Concrete example of Dalitz analysis yielding spectroscopy PRL 97, (2006) 58M J/ψ C-Parity: X should be 1, 3, etc. PWA prefers 1 Unusually wide! 4-quark state? R.A. Briere Lepton Photon

24 Four-Body χ cj Decays PRD 72, (2005) 14M ψ(2s) R.A. Briere Lepton Photon

25 Four-Body χ cj Decays Teaser Plots R.A. Briere Lepton Photon

26 Dalitz Plot Future D mesons: -- High statistics: continue to explore technical issues -- Pursue connections to B physics -- CP-tags will be more exciting with BESIII luminosity! ( though CLEO-c already helps a lot ) Charmonium: -- Expect a great J/ψ & ψ(2s) resurgence soon at BESIII Glueballs? Multi-quark? Hybrids? -- Excellent χ cj data from CLEO-c ready to analyze now Access to different initial J PC Once again, more at BESIII! R.A. Briere Lepton Photon

27 Kπ Strong Phase CP-tagging allows a clean measurement: very topical due to D mixing R.A. Briere Lepton Photon

Kπ Strong Phase See D mixing talks by: Lockman, Golob Mixing: long-distance in SM, but still constrains new physics well! Golowich, Hewitt, Pakvasa, Petrov: arxiv:0705.

28 Kπ Strong Phase See D mixing talks by: Lockman, Golob Mixing: long-distance in SM, but still constrains new physics well! Golowich, Hewitt, Pakvasa, Petrov: arxiv: CLEO-c contribution: Kπ phase shift: cos δ Relates x, y to x, y Use D Kπ vs. CP-tags ( CP tags = K + K, π + π, K S π + π, etc. ) Definite CP = coherent D 0, D 0 sum: Effect due to DCSD amplitude: r = A(D 0 K + π )/A(D 0 K π + ) Interference flips for CP+ vs. CP : ±2r cos δ ~ 2 λ 2 ~ 10% rate Yield / No-QC prediction 1+ re (1 + 2r cosδ + r R.A. Briere Lepton Photon = B B K Kπ Kπ π + D 0 iδ 2 + K π 2 ) + D 0 2

29 Parameter N D 0 D 0 (10 6 ) y (10-3 ) r 2 (10-3 ) cosδ x 2 (10-3 ) B(K π + ) (%) B(K K + ) (10-3 ) B(π π + ) (10-3 ) B(K 0 S π0 π 0 )(10-3 ) B(K 0 S π0 ) (%) B(K 0 S η) (10-3 ) B(K 0 Sω) (%) B(X e + ν) (%) B(K 0 L π0 ) (%) χ 2 /ndof [ ] = with external input Standard Fit 1.046±0.019± ± 16 ± 10 [6.6 ± 1.9 ± 0.8] 1.03 ± 0.19 ± 0.08 [ 0.6 ± 1.3 ± 0.7] [3.77 ± 0.07 ± 0.03] [3.81 ± 0.09 ± 0.03] [1.35 ± 0.03 ± 0.01] 8.08 ± 0.34 ± 0.51 [1.18 ± 0.03 ± 0.03] [4.56 ± 0.21 ± 0.25] [1.16 ± 0.04 ± 0.06] 6.55 ± 0.16 ± 0.17 [0.98 ± 0.03 ± 0.02] 27.8/46 Kπ Strong Phase Extended Fit 1.044±0.019±0.012 [4.3 ± 1.3 ± 0.7] [3.39 ± 0.08 ± 0.00] 0.93 ± 0.32 ± 0.04 [0.05 ± 0.05 ± 0.00] [3.77 ± 0.07 ± 0.03] [3.88 ± 0.08 ± 0.03] [1.36 ± 0.03 ± 0.01] 8.35 ± 0.32 ± 0.52 [1.14 ± 0.03 ± 0.03] [4.41 ± 0.19 ± 0.25] [1.11 ± 0.03 ± 0.05] 6.59 ± 0.16 ± 0.17 [1.02 ± 0.03 ± 0.02] 58.1/58 B results do NOT supersede other CLEO-c results! Likelihood curves +95% CL ULs Standard fit: CHARM pb -1 PRELIMINARY cosδ > 0.54 sinδ < 0.72 Extended fit (w/ external y data): cosδ > 0.38 sinδ < 0.84 R.A. Briere Lepton Photon

30 Higher Resonances, D 0 mass Higher resonances: -- Two interesting new results D 0 Mass: -- High-precision -- Useful to understand X(3872) R.A. Briere Lepton Photon

31 D s1 Angular Analysis First full analysis for a P-wave charmed meson D s1 (2536) D* + K S S-wave fraction: Γ S / Γ tot = 0.72 ± 0.05 EPS 2007 V. Balagura Fit Projections S-wave dominates, contradicts HQET Ds1(2460) Ds1(2536) mixing j l = 1/2 j l = 3/2 Longitudinal polarization fraction: ρ 00 = ± Ds1 s helicity = 0 preferred, agrees with HQET (aligned prod n of jq=3/2 states predicted) R.A. Briere Lepton Photon

32 Multi-Body D s1 Decay Known: Ds1(2536) D* + K S D* 0 K + D s +π + π D* 0 cannot go to D + π (phase space) But substantial Ds1(2536) D + π K + found EPS 2007 V. Balagura NEW Norm n Mode B( D + π K + ) /B( D* + K S ) = ( 3.17 ± 0.17± 0.36 ) % Data similar to phase-space MC R.A. Briere Lepton Photon

33 Precision D 0 Mass PRL 98, (2007) 281 pb -1 Can X(3872) be a D*D bound state? Need precise masses to get binding E 319 ± 18 events Use D 0 K S φ K S π + π φ K+ K φ & K S masses well known; sum to 81% of D0 mass M( D 0 ) = ± ± MeV gives E B = 0.6 ± 0.6 MeV ( E B < 0 is bound ) Need better X(3872) mass now! Previous PDG Ave: ± 0.4 (fit to several experiments + a-posteriori SPEAR energy tweak ) R.A. Briere Lepton Photon

34 R had & Exclusive Cross-Sections R had needed for muon g-2, many measurements -- Charm rate is now studied exclusively R.A. Briere Lepton Photon

35 BES II R had Data Fit New analysis: Allows interference of B-W amplitudes for first time arxiv: ( sub. To PLB ) Still not unitary but a big step forward R.A. Briere Lepton Photon

36 Open Charm Rates via ISR PRL 98, (2007) 548 fb -1 D* + D* D 0 D 0 + D + D arxiv: fb -1 D + D* + c.c arxiv: fb -1 D 0 D 0 + D + D Belle: ~large ψ(3770)? BaBar: only relative rates now, need normalization! Belle also has nice D 0 Dπ + analysis R.A. Briere Lepton Photon

37 CLEO-c Scan Results D CHARM2007 PRELIMINARY Center-of-Mass energy scan: Reconstruct one D (s) : D momentum = missing mass This separates modes Multi-body! D s CLEO-c Ds run E cm R.A. Briere Lepton Photon

38 Comments on Exclusive Cross-Sections R had studied for years exclusive breakdown is relatively new Results of fits tell us about spectroscopy: -- Exclusive data gives much more information But beware thresholds & coupled channel effects: -- Not every bump is a new resonance!!! (see Eicthen, CHARM2007) If we can fit data well, we show that we understand strong interactions issues, regardless of what comes out of the fit (the spectroscopy, etc.) Good wholesome strong-interaction physics R.A. Briere Lepton Photon

39 Future & Conclusions R.A. Briere Lepton Photon

Beam energy: 1.0-2.3 GeV Luminosity: 1 x10 33 cm -2 s -1 Optimum energy: 1.89 GeV Energy spread: 5.16 x 10-4 No. of bunches: 93 Bunch length: 1.5 cm Total current: 0.

40 Beam energy: GeV Luminosity: 1 x10 33 cm -2 s -1 Optimum energy: 1.89 GeV Energy spread: 5.16 x 10-4 No. of bunches: 93 Bunch length: 1.5 cm Total current: 0.91 A Charm Hadronic at BES III Luminosity for fullest exploitation of CP-tags & Quantum Correlations 1/2008: Cosmic-ray tests 3/2008: BESIII detector in place 5/2008: Start data taking Physics Channel J/ψ τ ψ(2s) Energy (GeV) Luminosity (10 33 cm 2 s 1 ) 1.2 x 10 7 R.A. Briere Lepton Photon Events/year 1.0 x x 10 9 D* x 10 7 D S x 10 6 D S x 10 6

41 Orphans and Beggars More searches for CP & T violation in charm needed (see G. Mancinelli talk at CHARM2007) -- Dalitz analyses: avoid partially integrating out effects! -- Extend pioneering FOCUS triple-product T-violation work -- CDF can do hadronic modes: how are detector CP-asymmetries compared to lower E? Key baryon topics if they want to keep up with mesons: Λ c pkπ Absolute BF ( Special high-e BES III run??? ) Λ c pkπ Dalitz plot analysis R.A. Briere Lepton Photon

42 A Charm Renaissance is Underway Charm Hadronic Decays: -- Precision measurements of key branching fractions ( charm threshold + clever use of B-factory statistics ) -- Dalitz plot analyses inform light spectroscopy, B physics -- Strong Kπ FSI phase measured now; untangles D mixing -- Some progress with decays of higher-mass states -- Much charmonium work in past, more to come soon -- e + e scans and ISR give exclusive cross-sections -- More to come from B Factories, CLEO-c, Tevatron -- New facilities: BES III soon, also LHC-b PANDA at GSI Super B? Fermilab proposals? Relates to other Charm work: -- Tests of Lattice QCD ( decay constants, form-factors ) Absolute hadronic BFs help by normalizing weak physics -- Much excitement with mixing and spectroscopy Strong Kπ phase helps untangle measurements R.A. Briere Lepton Photon

43 Acknowledgments Many thanks to Charm speakers at EPS Manchester and CHARM 2007 & the Lepton-Photon organizers R.A. Briere Lepton Photon

44 Backup Slides R.A. Briere Lepton Photon

45 Comments on cos δ Information in inputs: observe change in parameter errors when removed from fit. y: [Info: 50% KK ST+B ext, 20% ππ ST+B ext, 15% e ± /CP DTs] 2.1σ discrepancy between CLEO-c and world average. Checked extensively for bias; none found statistical fluctuation. cosδ: [Info: 45% Kπ/CP+ DTs, 45% Kπ/CP DTs] Strong nonlinearity introduced by R WS ~= r 2 + 2yrcosδ: Standard fit y not incl. Standard fit 1-σ likelihood contours in y vs. cosδ (excludes xsinδ error) Extended fit Error on cosδ depends on value of y from W. R.A. Briere Lepton Photon

46 CLEO-c D BF Data D 0 ΔFSR is full effect of omitting FSR in MC used for ε D + D s R.A. Briere Lepton Photon

47 Exp t: Charm vs. Beauty λ = sinθ C ~ 0.22 Cabibbo quark-mixing angle Decay rate: O(1) O(λ 4 ) Cabibbo -suppression of b decay compensates Γ ~ m 5 behavior Long B life inspired Wolfenstein s famous CKM parameterization Advent of silicon revolutionizes b physics, as well as c Mixing Ampl. : O(λ 2 ) O(λ 6 ) x f( m t ) Charm decays too fast to mix B mixing enhanced by top mass ( actually, B s enhanced too much! ) Fully Reconstruct: 13% ~ 0.1% At factories producing meson pairs: Can use full-recon. Tag : Study rest of event after full reconstruction of one hadronic decay -- get direction of other meson -- lower background (less combinatorics, reject continuum) Similar numbers of single tags for charm & beauty, but: -- x-section: 6x for charm; integrated lumi: 1000x for beauty -- useful # of Double Tags (reconstruct both D s) for charm! since N Double ~ (εb) 2 : MUCH smaller for B s than D s R.A. Briere Lepton Photon

Outline: Absolute Charm Branching Fractions D0 and D+ Rare and inclusive modes Final states with KS or KL. Anders Ryd Cornell University Presented at

Determination of Hadronic Branching Ratios and New Modes Anders Ryd Cornell University Presented at FPCP Bled, Slovenia May 12-16, 2007 Outline: Absolute Charm Branching Fractions D0 and D+ Ds Rare and