Recent Results from CLEO

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1 Ryan Mitchell Indiana University MENU June 1,

2 Overview of the CLEO Experiment CESR at Cornell University: symmetric e + e collisions at bottomonium (III) and charmonium (c) energies Inner Tracking: Silicon (III) Drift Chamber (c) CLEO III ( ) Select Data Samples: ϒ(4S) 15.5 fb 1 ϒ(3S) 6M events ϒ(2S) 9M events ϒ(1S) 22M events CLEO-c ( ) Select Data Samples: 4.17 GeV ~ 586 pb -1 ψ(3770) ~ 818 pb -1 ψ(2s) ~ 26M (+1.5M CLEO-III) : > 500 publications (weak, em, strong, exotic, etc. physics) 2

3 Recent News from CLEO from Light to Heavy (lightest) (heavy decaying to light) 1. Observation of η π + π π 0 and η π + π e + e 2. J/ψ and ψ(2s) Radiative Decays to η and η (half heavy) (heavy) 3. D and D s Decay Constants: f D and f Ds 4. Higher-Order Multipoles in ψ(2s) γχ c1,2 and χ c1,2 γj/ψ (heaviest) 5. Confirming Evidence for ϒ(3S) γη b (many other results are available but not covered...) 3

4 1. Observation of η π + π π 0 and η π + π e + e (lightest) PRL 102, (2009) 4

5 Observation of η π + π π 0 and η π + π e + e Look for: ψ(2s) π + π J/ψ J/ψ γη η X π + π π 0 Both have significance > 6σ. Use π + π to select the J/ψ Perform a kinematic fit of all decay products to the ψ(2s) 4-momentum Measure rates relative to η π + π η; η γγ Backgrounds: Linear backgrounds: Use sidebands in M(X) Peaking backgrounds: Estimate η cross-feed from MC π + π e + e signal MC η cross-feed 5

6 Observation of η π + π π 0 and η π + π e + e η π + π π 0 24 events observed bg from sidebands bg from MC events π + π π 0 Both have significance > 6σ. BF = ( ± 4) 10 4 η π + π e + e 8 events observed - 0 bg from sidebands bg from MC events π + π e + e signal MC η cross-feed BF = ( ± 5)

7 Observation of η π + π π 0 and η π + π e + e B(η π + π π 0 ) is the last piece needed for the ratio r ± /r 0 : Predictions for r ± /r 0 range from: 0.37 (η-π 0 mixing, (mu-md)) to 5 (π + π π 0 rescattering through ρ, with non-trivial Dalitz structure). PLB 643, 41 (2006) R = BF relative to η π + π η[γγ]; B = B(η X); P = previous measurement of B also many upper limits 7

8 2. J/ψ and ψ(2s) Radiative Decays to η and η (heavy decaying to light) PRD 79, (R) (2009) 8

9 J/ψ and ψ(2s) Radiative Decays to η and η Look for: ψ(2s) π + π J/ψ and J/ψ γη ( ) η ( ) X ψ(2s) γη ( ) η ( ) X Use π + π to select the J/ψ Use many different decay modes of the η and η ( ) Perform a kinematic fit of all decay products to the ψ(2s) 4-momentum Count events in the signal regions. (only representative η and η decay modes are shown) 9

10 J/ψ and ψ(2s) Radiative Decays to η and η There is a strange depletion in ψ(2s) γη!?! but Why are these ratios so different? (only representative η and η decay modes are shown) 10

11 J/ψ and ψ(2s) Radiative Decays to η and η There must be something beyond this simple picture: J/ψ or ψ(2s) η or η Perhaps this is related to the classic ρπ puzzle: J/ψ or ψ(2s) ρπ 11

12 3. D and Ds Decay Constants: fd and fds (half heavy) will show plots from this one... PRD 78, (2008) PRD 79, (2009) PRD 79, (2009) PRD 80, (2009) [D μν] [D s μν, τ(πν)ν] [D s τ(eνν)ν] [D s τ(ρν)ν] 12

13 D and D s Decay Constants Leptonic decay of the D s + (for D +, swap s for d): The QCD part of the rate can be factored into a constant, f Ds (f D for D + ): Since f D and f Ds can be calculated in lattice QCD, leptonic decays allow comparison between theory and experiment. With ~1/2 of the final CLEO-c data set there were hints of disagreement with lattice QCD (>2σ) for f Ds, but good agreement for f D. CLEO-c now has results with the final data sets (586 pb 1 at 4170 MeV and 818 pb 1 at ψ(3770)) 13

14 D and D s Decay Constants Look at one set of measurements of f Ds as an example... PRD 79, (2009) e + e (at 4170 MeV) D s +* D s (or D s * Ds + ) γd s+ D s γ(d s )(μν or τν (τ πν)) Mass (D s Tag Modes) Missing Mass Squared Against D s Tag Modes and γ 1. Fully reconstruct one D s using 9 different tag modes 2. Require a second D s using the first D s and a photon 14

15 D and D s Decay Constants 3. Now look for the second D s decaying to μν or τν (in πνν) using the first D s, the photon, and a μ or π candidate. D s μν 4. Separate the μ and the π using energy deposited in the calorimeter. case i: E calorimeter < 300 MeV case ii: E calorimeter > 300 MeV D s τν (πνν) 5. Find branching fractions: Missing Mass Squared Against D s Tag Modes and γ and μ or π 15

16 D and D s Decay Constants Tabulation of final measurements of D s leptonic decays from CLEO-c: PRD 80, (2009) PRD 79, (2009) PRD 79, (2009) AVERAGE for τν PRD 79, (2009) FINAL AVERAGE Compare to lattice calculations of f Ds : f Ds = 241 ± 3 MeV (HPQCD, UKQCD) PRL 100, (2008) 2010 Update: f Ds = 247 ± 2 MeV f Ds = 249 ± 3 ± 16 MeV (FNAL, MILC, HPQCD) PRL 95, (2005), arxiv: Update: f Ds = ± 7.7 ± 5.0 MeV For f Ds, lattice calculations have risen and experimental values have fallen: discrepancy now < 2σ. Notes: There is no disagreement for f D. Belle, BaBar measurements are consistent with CLEO (with larger errors) for f Ds. 16

17 4. Higher-Order Multipoles in ψ(2s) γχc1,2 and χc1,2 γj/ψ (heavy) PRD 80, (2009) 17

18 Higher-Order Multipoles in ψ(2s) γχ c1,2 ; χ c1,2 γj/ψ 3.8 "(1 3 D1) CHARMONIUM E1 amplitudes are dominant, but M2 amplitudes are expected: 2MD "(2 3 S1) b J=2 MASS [GeV/c 2 ] !c(2 1 S0) hc(1 1 P1) aj=1 b J=1 #c1(1 3 P1) #c0(1 3 P0) a J=2 #c2(1 3 P2) 3.2 Note that: 3.0!c(1 1 S0) J/"(1 3 S1) E1-Dominated Transitions M1-Dominated Transitions M2 has sensitivity to the anomalous magnetic moment of the charm quark (κ c ) E3 is expected to be zero, but is allowed if there is S-D (ψ(2s)) or P-F (χ(1p)) mixing 0 $+ 1 $$ 1 +$ J PC There are also recent lattice calculations: (Dudek et al., PRD73, (2006), PRD79, (2009)) 18

19 Higher-Order Multipoles in ψ(2s) γχ c1,2 ; χ c1,2 γj/ψ Procedure: χ c1 (0.23% background) χ c2 40k events 20k events Select samples of: ψ(2s) γχ cj ; χ cj γj/ψ; J/ψ e + e, μ + μ clean samples well-described by MC Use 5-dimensional angular distributions to differentiate multipole amplitudes. (0.29% background) Fit the χ c1 and χ c2 decay chains separately. 19

20 Higher-Order Multipoles in ψ(2s) γχ c1,2 ; χ c1,2 γj/ψ χ c1 Sample Fit Projections (projection of cosine of angle between l + and γ from χ cj decay in J/ψ frame) χ c2 Fits are poor when only E1 amplitudes are used. There is clear evidence for non-zero M2 amplitudes. E3 amplitudes are consistent with zero. 20

21 Higher-Order Multipoles in ψ(2s) γχ c1,2 ; χ c1,2 γj/ψ χ c1 γj/ψ ψ(2s) γχ c1 χ c2 γj/ψ There is good agreement with theory when: m c = 1.5 GeV/c 2 and κ c = 0 i.e., there is no evidence for a non-zero anomalous magnetic moment of the charm quark. ψ(2s) γχ c2 Old apparent theoryexperiment discrepancies are resolved. (see PRD 80, (2009) for numerical results) 21

22 5. Confirming Evidence for ϒ(3S) γηb (heaviest) PRD 81, (R) (2010) 22

23 Confirming Evidence for ϒ(3S) γη b The η b is the ground state of bottomonium. (Bottomonium was discovered >30 years ago.) BOTTOMONIUM The η b was recently discovered by BaBar in ϒ(3S) γη b and has since also been reported in ϒ(2S) γη b. The η b mass provides a first look at hyperfine splitting in bottomonium (recently calculated in lattice QCD). The ϒ(nS) γη b decays are the only observed M1 radiative transitions in bottomonium. E1 Transitions M1 Transitions CLEO recently reanalyzed ϒ(3S) data to search for ϒ(3S) γη b... 23

24 Confirming Evidence for ϒ(3S) γη b Use the angle between the photon and the thrust axis of the rest of the event to form three bins with different levels of continuum background. Simultaneously fit the thrust bins with four components: A. Non-peaking background * different polynomial for each thrust bin B. χ bj (2P) γϒ(1s) lines B C D * shapes fixed from independent studies * normalization, energy resolution, and energy offset floated C. Initial State Radiation (ISR) to ϒ(1S) * fixed using ϒ(4S) data D. ϒ(3S) γη b signal * shape constrained by χ bj (2P) lines * width fixed at 10 MeV 24

25 Confirming Evidence for ϒ(3S) γη b BaBar M ϒ(3S) CLEO -- 6M ϒ(3S) PRL 101, (2008) χ bj (2P) ISR η b χ bj (2P) γϒ(1s) ~4σ sig ISR ηb 25

26 Confirming Evidence for ϒ(3S) γη b CLEO s new ϒ(3S) γη b branching fraction measurement is: B(ϒ(3S) γηb) = (7.1 ± 1.8(stat) ± 1.3(syst)) 10 4 (assuming the η b width is 10 MeV), compared to BaBar s (4.8 ± 0.5 ± 0.6) 10 4 and replaces CLEO s old UL: < The η b signal has a mass of: M(η b ) = ± 6.6 ± 2.0 MeV/c 2, or a hyperfine splitting of: M(ϒ(1S)) M(η b ) = 68.5 ± 6.6 ± 2.0 MeV/c 2 which is consistent with BaBar s mass of ± 3.1 MeV/c 2. A new upper limit for ϒ(2S) γη b is found: B(ϒ(2S) γη b ) < , compared to BaBar s ( ± 0.9) 10 4 and replaces CLEO s UL: <

27 Summary of News from CLEO from Light to Heavy (lightest) (heavy decaying to light) 1. Observation of η π + π π 0 and η π + π e + e 2. J/ψ and ψ(2s) Radiative Decays to η and η (half heavy) (heavy) 3. D and D s Decay Constants: f D and f Ds 4. Higher-Order Multipoles in ψ(2s) γχ c1,2 and χ c1,2 γj/ψ (heaviest) 5. Confirming Evidence for ϒ(3S) γη b (many other results are available but not covered...) 27