D0 and D+ Hadronic Decays at CLEO

Transcription

1 and + Hadronic ecays at CLEO K π π Cornell University K π π + CLEO collaboration and branching fractions oubly Cabibbo suppressed branching fractions: K and K S vs. K L alitz analyses: K K and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 1

2 and at Ψ(377) We collide e and e at the 377 resonance (81 pb 1 so far). or This energy is just above threshold for production, with no additional massive particles. e Identify 's from beam constrained mass ( M BC ) and E. + M BC E beam p (peaks at E E E beam (peaks at zero) mass) e + K π+π+ K+π π Three ways to analyze an event: ( single tag ). Fully reconstruct one or ( double tag ). Fully reconstruct both and as a tag, then look for Reconstruct one a particular decay of the. This is useful when one particle can't be detected (e.g. K L ). and + Hadronic ecays at CLEO PF/JPS 6 1/31/6

3 The CLEO c etector Good momentum resolution:.6% at 1 GeV Good photon detection: Good particle I: RICH (Cherenkov) & de/dx Run primarily at ECM = 3.77 GeV for ECM = 4.17 GeV for s mass resolution ~ 6 MeV excellent / K separation production (this talk) and at production. CESR Cornell Electron Storage Ring and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 3

4 Hadronic BFs: Overview environment at CLEO c is ideal for measurement of absolute The hadronic branching fractions. and Results do not depend on the luminosity or cross section. These branching fractions are an important input for B physics. We measure 3 and 6 decay modes, including the two reference modes K and K. We previously published* results based on 56 pb 1, and we are now updating with ~5x more data: 81 pb 1. Both statistical and systematic uncertainties have improved. Modes: K K K K K S K KS K K K S * Q. He et al., Phys. Rev. Let. 95, 1181 (5). and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 4

5 Hadronic BFs: Method Reconstruct single candidates (single tags) and candidates (double tags) from the final state particles. Require E consistent with zero. Extract single and double tag yields by fitting M BC plots. Using single and double tag yields, do a fit for branching fractions and N. single tags M BC (GeV) ATA double tags ATA m Note log scale! m m and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 m M BC (GeV) 5

6 Hadronic BFs: Yield Extraction We fit single and double tag peaks with a theoretically derived M BC peak shape that includes the effects of initial state radiation, beam energy spread, momentum m resolution, and the 377 line shape. All ouble tag yields are obtained from a dimensional. fit of M BC vs. M BC ouble Tags m Single tag yields are obtained from a 1 dimensional M yields are extracted fit of M BC. and (GeV) separately. M BC (GeV) BC ATA ATA All ouble Tags m Note log scale! m m ATA m and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 ATA M BC (GeV) 6

7 Hadronic BFs: ouble Tag Yields Fit components: M BC (GeV) Signal peak One Mispartitioning Both 's incorrect ouble Tags ATA etector resolution correct, one incorrect All m Beam energy and initial state radiation smearing Projections ATA Note log scale! K K vs. One bad Mispartitioning Total yields: 136 double tags 89 double tags m and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 M BC (GeV) 7

8 Hadronic BFs: Single Tag Yields K 56 signal events ATA K 61 signal events ATA K 4 signal events ATA K 44 signal events ATA Note log scale! Total yields: 3 and 167 and and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 single tags single tags 8

9 Hadronic BFs: Branching Fraction Fit We are determining 9 branching fractions, as well as the number of and pairs, from 18 single tag yields and 45 double tag yields, so we do a fit. N i = i B i N j = j B j N N N = N ij = ij B i B j N N i N j ij Bi = N ij i j This fit includes background subtractions on the yields and cross feeds between modes. N ij j N j ij Systematic errors are included in the fit. When appropriate, they are correlated between tag modes (ex. tracking efficiencies). Many systematics in N cancel, as do systematics on the other side branching fraction calculations. and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 in 9

10 Hadronic BFs: Preliminary Results Mode K K K K K K S K S K S K K Branching Fraction (3.876 ±.35 ±.85)% (14.57 ±.1 ±.4)% (8.6 ±.7 ±.9)% (9.18 ±.1 ±.5)% (5.98 ±.8 ±.1)% (1.549 ±. ±.47)% (7. ±.9 ±.3)% (3.134 ±.5 ±.14)% (.98 ±.16 ±.9)% K Our results are consistent with our previous measurements and those of other experiments. We are systematics limited (stat. precision ~ 1%), but we expect to improve some systematics. 3 single tags 167 single tags double tags double tags PRELIMINARY K and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 1

11 K Reconstruct K single tags, measure rate relative to K : B K B K = Y K / K Y K / K We find B K = (.8 ±.36 ±.15 ±.8)x1 4 * BABAR: (.5 ±.47 ±.5 ±.8)x1 4 ** first measurement Test isospin symmetry: Expect K K 148 ± 3 signal events efficiency = 44.5% =.5 With our result and PG values, K K =.64 ±.1 ** B. Aubert et al., Phys. Rev. 74, 1117(R) (6). * S.A. ytman et al., Phys. Rev. 74, 711(R) (6). and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 11

12 L S K vs. K To first order, B K S B K L (from K ). Interference from doubly Cabibbo suppressed process for K S 1/ K K and K L 1/ K K. K has opposite sign This produces an asymmetry between the decay rates (Bigi & Yamamoto): R K c W u K c W u s K u u d K s u u B K S B K L c W u SU(3) prediction K s K d W c W ~ tan C s K u u c d d K s W s K c W K R =? tan C R = tan C c u B K S B K L d c K s u and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 W s d K u 1

13 Quantum Correlation for and Since is produced through a virtual photon (C= 1), decays of and are correlated. (For example, they can't decay to states with the same CP.) Apparent branching fraction for a decay depends on how the decayed, especially for CP eigenstates like K S and K L. What we can measure: 1 ~ % S y Untagged K gives B K 1y S 1, rfe = K S, tagged by f, gives B K S 1 r f cos f r f K L, tagged by f, gives B K L 1 r f cos f r f i f f f ~.3 % (Untagged K L would give B K L 1y, but our technique for finding K requires a tag.) L f =K, K, K Strategy: Measure untagged K S, and K S and K tagged by 3 modes. L Use these, with y and r f, to calculate B K S, r f cos f, and B K L. and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 13

14 S K Measurements Take B K S from the hadronic BF analysis (described earlier). Measure B K S 1y from untagged direct reconstruction via K S, Subtract M BC E and M sidebands. Result: due to efficiency, cancels in asymmetry B KS = (1.6 ±.17 ±.41 ±.48)% E PG 6: (1.14 ±.1)% f f Measure B K S 1 r f cos r f decay. for each tag mode f by also requiring a found K Result: Mode f K K K r f cos f.181 ± ± ±.63 M BC 7487 ± 99 signal events efficiency = 3.5% PRELIMINARY K M BC and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 K M BC 14

15 L K Analysis Technique Reconstruct all particles except the K. L Form missing mass squared: M miss p event p p peaks an the kaon mass squared for K L and K S. K L e Remove K S by vetoing events with extra tracks or 's. e some tag mode candidates, etermine number of tags from M BC and E of tag and number of signal events from peak in missing mass squared. L B K = Y signal Y tags R (R 1) ~ few % accounts for easier tag reconstruction when the other decays to K L efficiency for finding signal given that tag was found and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 15

16 L K Results 3 ± 54 signal events efficiency = 81.6% 165, tags 1116 ± 37 signal events efficiency = 53% 183, tags KL S K KS PRELIMINARY B K L KL due to input value of B K S = (1.46 ±.4 ±.35 ±.6)% K Measure B K L 1 r f cos f r f, then calculate B K L. B K L due to efficiency, cancels in asymmetry = (.987 ±.48 ±.34 ±.38)% primary systematics: signal peak shapes and veto efficiencies and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 16

17 L S K vs. K Asymmetry Compare rates by calculating asymmetry: R B K S B K L PRELIMINARY B K S B K L Comparing B K S and B K L, R =.1 ±.4 ±.3 (Expect R = tan C =.19±.1 from U spin symmetry.*) * J.L. Rosner, Phys. Rev. 74, 575 (6). Comparing B K S and B K L, R =.3 ±.16 ±.1 (No simple prediction.) and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 Final results will be submitted to PRL. 17

18 alitz Analysis E791 and FOCUS have analyzed. Fit by E791 finds enhancement (low mass S wave) in the alitz plot. FOCUS uses K matrix approach. CLEO reconstructs this decay in events, without tagging. alitz plot background boxes signal box candidate selection E KS M BC N(KS +) ~ 4 Nbackground ~ 15 N( + + -) ~ 6 and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 18

19 alitz Results vs. Likelihood Fit including: Amplitude, phase, spin dependent PW (ie. BW), angular distribution, Blatt Weiskopf angular momentum penetration factor. m 1 m Mode Fit Values Relative Amplitude KS Phase (degrees) removed Fit Fraction (%) ρ(77)π+ 1..±.3±.9 f(98)π+ 1.4±.±. 1±1±5 4.1±.9±.3 f(17)π+.1±.±.1 37±6±3 18.±.6±.7 f(137)π+ 1.3±.4±. 1±15±14.6±1.8±.6 f(15)π+ 1.1±.3±. 44±13±16 3.4±1.±.8 σ pole 3.7±.3±. 3±4± 41.8±1.4±.5 Limits on Other Contributing Modes Consistent with E791: E791 BW σ Fit Fraction = (46.3±9.±.1)% Also try two S wave models to replace σ and f(98). ata are consistent with both. ρ (145)π+.9±.5 51± <.4 f(171)π+ 1.±1.5 17±9 <3.5 f(179)π+ 1.±1.1 3±58 <. Non resonant.17±.14 17±9 <3.5 I= π+π+ S wave.17±.14 3±58 <3.7 CLEO preliminary: hep ex/6769 and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 19

20 K K alitz Analysis Motivation: Measurement of CKM angle ( 3) from B decays requires input values of r and : A K K i = r e A K K r and can be determined from the K K alitz plot. Method: 9 fb 1 collected near (4S) with CLEO III detector Consider 's from, tagging flavor of the by the pion's charge. 735 candidates and + Hadronic ecays at CLEO PF/JPS 6 1/31/6

21 K K alitz Results alitz plot and projections K Mode Fit Values Relative Amplitude K K K Phase (degrees) Fit Fraction (%) Κ +Κ ±3.1 Κ Κ+.5±.5±.4 33±8±11 1.3±. φπ.64 ±.4 36±9 14.9±1.6 NR 5.6±.45 ±5 36.±3.7 Read off the values from the P fit: r=.5±.5±.4 δ = (33±8±11)o C. Cawlfield et al., Phys. Rev. 74, 3118(R) (6). First measurement of δ. Significant improvement on r over previous value using K*K BF s and + Hadronic ecays at CLEO PF/JPS 6 1/31/6 1

22 Summary CLEO continues to generate measurements of and decays. Absolute hadronic branching fractions set the scale for decays. Measurements of K and K S vs. K L provide a complete set of measurements for the doubly Cabibbo suppressed K decays. alitz analyses measure substructure of decays, including input for measurement of CKM angle from B decays. We will approximately triple our results will be coming. 377 dataset over the next year, so more and + Hadronic ecays at CLEO PF/JPS 6 1/31/6