Recent Results from BaBar Fabrizio Bianchi University of Torino and INFN-Torino 5 th International Conference on Flavor Physics Hanoi, September 24-30, 2009 F. Bianchi1

Outline Will cover results from BaBar and Belle on: – D 0 Mixing. – “Charmonium”: X, Y, Z states. – Bottomonium. – Searches for New Physics in Bottomonium decays. Related talks: – G. Mohanty: Unitarity Triangle. – A. Luisiani:  Decays. – E. Manoni: Rare B Decays. F. Bianchi2

D 0 -D 0 Mixing F. Bianchi3

D 0 Mixing: Formalism Neutral D mesons are produced as flavor eigenstates D 0 and D 0 and decay via : as mass eigenstates D 1, D 2 of mass M 1, M 2 and width  1,  2 where : Mixing requires non zero or And it is expressed in term of : Where: F. Bianchi4

Two types of WS Decays: – Doubly Cabibbo-supressed (DCS) – Mixing followed by Cabibbo-Favored (CF) decay Discriminate between DCS and Mixing decays by their proper time evolution (assuming CP-conservation and |x|«1, |y|«1) :  K   strong phase difference between CF and DCS decay amplitudes measured by CLEO-c PRD 78, , (2008) D 0 Mixing in “Wrong Sign” Decays (D 0 → K +  - ) DCS DecayInterferenceMixing D 0D 0 f D 0 ~ D 0 D 0 ~ f F. Bianchi5

Identify the D 0 flavor at production using the decays D 0 Mixing: Analysis Technique select events around the expected The charge of the soft pion determines the flavor of the D 0 Identify the D 0 flavor at decay using the charge of the Kaon Vertexing with beam spot constraint determines  m, M(K  ), decay time t, and decay time error  t right-sign (RS) wrong-sign (WS) mm M(K  ) F. Bianchi6

“Wrong Sign” Decay Time Fit with Mixing R D : (3.03±0.16±0.10)x10 -3 x’ 2 : (-0.22±0.30±0.21)x10 -3 y’: (9.7±4.4±3.1)x10 -3 x' 2, y' correlation:  384 fb -1 PRL 98, (2007) BaBar: 384 fb -1 PRL 98, (2007) CDF: 1.5 fb -1 PRL 100, (2008) Belle: 400 fb-1 PRL 96:151801,2006 F. Bianchi7

D 0 Mixing from WS D 0 → K + π − π 0 arXiv: Analysis similar to WS D 0 → K + π - analysis, but now mixing depends on position in Dalitz plot. Final state f = K + π - π 0 can be reached either through DCS decays (A DCS ) or mixing+CF decays (A CF ) decays: Phase difference between DCS and CF reference amplitudes (cannot be determined in this analysis) ≠ δ Kπ Probability for no mixing 0.1% (3.2σ). No evidence for CPV F. Bianchi8 384 fb -1

D 0 Mixing: Lifetime Ratio Observables D* tagged analysis Measure: Construct: Untagged analysis In the limit of CP conservation, y CP = y and  y = 0 F. Bianchi9

Y CP Tagged Analysis Results PRL (2007) 540 fb -1, 3.2  evidence PRD (R) (2008) 384 fb -1, 3.0  evidence No evidence of CP Violation F. Bianchi10

Y CP Untagged Analysis Results KK KK  KK (fs) = ± 1.00 (stat.)  K  (fs) = ± 0.38 (stat.) y CP (untagged) = [ 1.12 ± 0.26 (stat) ± 0.22 (syst) ]% y CP (tagged+untagged) = [ 1.16 ± 0.22 (stat) ± 0.18 (syst) ]% y CP (untagged) = [ 0.11 ± 0.61(stat) ± 0.52 (syst) ]% arXiv: arXiv: F. Bianchi11 From lifetime comparison of D 0 ->  K s (CP=odd) and D 0 ->K s K + K (CP-even) 384 fb fb -1

D 0 Mixing: Summary Mixing established at 10.2σ combining all measurements. No observation (yet) in a single channel (measurements ~4σ). No evidence for CPV in mixing. Data consistent with q/p = 1 F. Bianchi12

“Charmonium” Spectroscopy F. Bianchi13

Introduction to Charmonium Bound State of charm and anti- charm quarks. Relevant quantum numbers: n, L, S, J. Relationships with parity and charge conjugation: P = (-1) L+1, C = (-1) L+S Below open-charm threshold: mostly narrow states. Above open-charm threshold: mostly broad states. Basically all states below threshold are observed and explained. But many new states discovered since F. Bianchi14

Beyond Charmonium ? Many of the new states do not seem to correspond to expected charmonium mass AND some of them are narrow. Should we look beyond mesons for more exotic states ? – Hybrids States with excited gluonic degrees of freedom Lattice and model predictions for the lowest-mass hybrid M ~ 4.2 GeV/c 2 Dominant decay into DD* – Tetraquarks Bound states of 4 quarks Large number of states expected Small widths above threshold – Molecular States Loosely bound states of a pair of mesons Small number of states Small widths above threshold Exotic signature would be – non-charmonium J PC – unnaturally small width – non-null charge D0D0 D*0D*0 π F. Bianchi15

Charmonium Production at the B-factories F. Bianchi16

X(3872) Observed by Belle as a narrow peak in J/ψ π + π − invariant mass in B → K J/ψ π + π − decays. Soon confirmed by CDF/D0 in inclusive pp and by Babar in B decays. Mass close to D 0 D* 0 threshold: m(D 0 ) + m(D* 0 ) = ( ± 0.4) MeV/c 2 Angular distribution studied by Belle (1 ++ ) and CDF (1 ++ or 2 -+ ) PRL 91 (2003) hep-ex/ PRL 98 (2007) F. Bianchi17

X(3872) → DD ( * ) Belle updated its first measurement and find mass compatible to J/ψππ. Babar studies also DD (finds no signal) and finds a mass ~3MeV higher F. Bianchi18

X(3872) Radiative Decays Radiative decay to  J/ψ (Belle/Babar) and  ψ(2S) (Babar) too large for  c1 (2P)? too large for D 0 D 0 * molecule? F. Bianchi fb -1

The states near 3940 MeV F. Bianchi20

Y(3940) confirmed by BaBar F. Bianchi fb -1

Peak in γγ  ωJ/ψ Is it the Y(3940) found in B  K ωJ/ψ ? Good agreement with Babar mass measurement F. Bianchi22

Y(4260): 1 -- family in J/ψππ decays Observed by Babar in ISR production Soon confirmed by CLEO (ISR and on-peak running) Confirmed by Belle arXiv (2008) 454 fb -1 Y(4008) ? F. Bianchi23

Y(4350) and Y(4660): 1 -- with ψ(2S)π + π - decays No evidence for Y(4260)... Y(4350) observed by BaBar in ISR ψ(2S)π + π - Confirmed by Belle, which finds a significant excess also at 4660 MeV Why are there states decaying to 2 3 S 1 and not to 1 3 S 1 ? F. Bianchi fb fb -1

Open charm cross sections from ISR F. Bianchi25

Open charm cross sections from ISR D*D*D*D* DD *  (4040)  (4160) Y(4008)  (4415) Y(466 0) Y(4260) Y(4350) DD DDπ Λc+Λc–Λc+Λc– ? PRD77,011103(2008) PRL100,062001(2008) PRL98, (2007) PRL101, (2008) [hep-ex] DD*π Y(4260) ψ(4415) Y(4008), Y(4260), Y(4360), Y(4660) don’t match the peaks in D (*) D (*) x-sections Not all are conventional cc: only one empty 1 – slot and widths for ψππ transition seems too large Y(4260) is DD 1 molecule, ccg hybrid? DD 1 [ → DD*π] decay should dominate but no signal found F. Bianchi fb fb fb -1

Z(4430) ±   ±  ’ F. Bianchi27

Search for Z(4430) Search for the Z(4430) - in the decay modes B - → J/  - K 0 B 0 → J/  - K + B - →  (2S)  - K 0 B 0 →  (2S)  - K + Describe the K  - system in detail, since structure in the K  - mass and angular distributions dominates each Dalitz plot Correct the data for efficiency event-by-event across the Dalitz plot, and describe using only K  - S-, P-, and D-wave intensity contributions Project each K  - description onto the relevant  - mass distribution to investigate the need for Z(4430) - signal above this “K  - background” Good descriptions of the m(K  - ) distributions are obtained. The K  - reflections reproduce the data no significant evidence for additional structure PRD 79, (2009) 413 fb -1 F. Bianchi28

Search for Z(4430) m J/ψπ - (GeV/c 2 )m ψ(2S)π - (GeV/c 2 ) M=4476±8 Γ=32±16 2.7σ M=4483±3 Γ=17±12 2.5σ M=4439±8 Γ=41±33 1.9σ F. Bianchi29

Dalitz Plot analysis of B  Kπψ’ Mass shift and larger width. Lower BF. Published Belle results: arXiv: (2009) F. Bianchi fb -1

Two Z ± →  c1 π ±  Dalitz-plot analysis of B 0 →  c1 π + K -  c1 → J/ψγ with 657M BB  Dalitz plot models: known K* → Kπ only K*’s + one Z → χ c1 π ± K*’s + two Z ± states favored by data significance 5.7  PRD 78, (2008) Projection with K* veto F. Bianchi31

The X Y Z puzzle: outlook Many charmonium-like states have been discovered at the B-factories. Many of them cannot be accommodated in charmonium spectrum, not enough empty slots. X(3872) mass keeps getting closer & closer to M(D 0 ) + M(D* 0 ). Is it a D 0 D* 0 molecule ? The X(3940) & Y(3940) seem to be distinct states. – Is the Y(3940) the state at 3915 MeV decaying to ωJ/ψ ? Neutral XY may be exotic, but charged Z indeed are exotic: – Belle has confirmed the Z(4430) +   + y’ with a more refined analysis and has observed Z 1 (4050) + & Z 2 (4250) +     c1. Most XYZ states have large partial widths to hidden charm final states. F. Bianchi32

Bottomonium Spectroscopy F. Bianchi33

Bottomoniummissingstates  Hadronic transitions via π 0, η, ππ, ω emission via π 0, η, ππ, ω emission  Electric dipole transitions  Magnetic dipole transitions BaBar Data sample: 120 M  (3S) decays 100 M  (2S) decays Belle data sample 100 M  (1S) decays 46 M  (2S) decays Goals: Find missing η b (nS), h b (nP) states below open bottom threshold. Find bottomonium analogue of X, Y, Z. F. Bianchi34

Search of  b (1S) Decays of  b not known Search for  b signal in inclusive photon spectrum Search for the radiative transition  (3S),  (2S) →  b (1S) In c.m. frame: For  b mass m = 9.4 GeV/c 2 monochromatic line in E g spectrum at 915 (604) MeV. Look for a bump near 900 (600) MeV in inclusive photon energy spectrum from data taken at the  (3S) and  (2S). F. Bianchi35

Discovery of  b (1S) Non-peaking Background subtracted χ bJ 19K ± 2K (10σ) η b η b 120M Y(3S) γ ISR 100M Y(2S) χ bJ 14K ± 3.5K (>3.5σ) η b η b γ ISR PRL 100, (2008)arXiv: Combined mass is m(  b (1S)) = ± 3.1 MeV/c 2 resulting in a hyperfine splitting of 69.9 ± 3.1 MeV/c 2 F. Bianchi36

Energy Scan above the  (4S) s s Structures corresponding to the bb opening thresholds PRL 102, (2009) Search for bottomonium states that do not behave as two-quark states; such states would have a mass above the  (4S) and below 11.2 GeV. Precision scan in √s from to GeV 5 MeV steps collecting ~25 pb -1 at each step (3.3 fb -1 total) 600 pb -1 scan in energy range to GeV in 8 steps with unequal energy spacing (investigation of  (6S)) F. Bianchi37

Di-pion transitions above the  (4S) Di-pion transitions above the  (4S) arXiv: Inclusive and exclusive dipion x-sections inconsistent with PDG Y(5,6S) parameters. arXiv: S Y  yields peak 25 MeV above 5S is this a bottom partner of Y(4260)? 7.9 fb -1 F. Bianchi38

Search for New Physics in Bottomonium decays F. Bianchi39

Light Higgs Search in  (nS) Decays Narrow initial state  (1S) M= 9,469.3 ± 0.3 MeV Γ = ± 1.25 KeV  (2S) M=10,0233 ± 0.3 MeV Γ = ± 2.63 KeV  (3S) M=10,355.2± 0.5 MeV Γ = ± 1.85 KeV Radiative Y(nS) Decays:  (nS) → A 0  with –A 0 → μ + μ - –A 0 →  +  - –A 0 → invisible (hint for light dark matter) F. Bianchi40

Search for A 0 →  +  - PRL 103, (2009) Search for three decays modes  → ee,  → eμ, and  → μμ (  → ℓυ ℓ υ τ ) Selection optimized in 5 E  regions. Main background from ee →  Peaking background expected at ~760 MeV:  (3S) →  bJ (2P),  bJ (2P) →  (1S,2S),  (1S,2S) →  No evidence for an enhancement at ~921 MeV for  (3S) →  η b, η b →  F. Bianchi41

Search for A 0 →  +  - Exclude regions around J/ψ and ψ(2S) Y(2S) Y(3S) Combined B A B AR preliminary Search for narrow enhancement. ML fit in 1955 mass intervals of 2-5 MeV, covering the range ≤ m(A 0 ) ≤ 9.3 GeV. No evidence for A 0 → μ + μ - structure beyond the null hypothesis. Upper limit at 90% C.L.: arXiv: F. Bianchi42

Search for A 0 → invisible arXiv: Select events with single photon E  >2.2 GeV and LARGE missing energy. Search for a peak in E  spectrum. No evidence for a signal was observed F. Bianchi43

NMSSM Predictions for  (nS) → A 0  vs BaBar Limits NMSSM models with light CP-odd Higgs: R. Dermisek et al. PRD76,051105(2007) F. Bianchi44

Search for  (3S) →  (1S)  (1S) → invisible F. Bianchi45

 (1S) → invisible: Results Fit Results: N peak = 2326 ± 105 (stat.) events. Peaking background estimate, calibrated against control sample data: N bkg = 2444 ± 123 (syst.) events.  (1S) → invisible yield: –118 ± 105(stat.) ± 124(syst.) BR(  (1S) → invisible) < 90% C.L. arXiv: F. Bianchi46

Lepton Flavor Violation in  Decays Unobservably small in the Standard Model: BF< Unambiguous signature of new physics Sensitivity to multi-TeV mass scales far beyond the reach of direct searches F. Bianchi47

LFV in  Decays: Strategy Search for events with an energetic lepton (e or μ), a second charged particle of different flavor, and missing energy. p/E F. Bianchi48

 3S  → e  and  3S  →  Limits arXiv: Best limit for  →  First limit for  → e  F. Bianchi49

New Physics in Bottomonium Decays: Outlook No signal of a light scalar particle (e.g. CP-odd Higgs) in radiative decays of  (2S) and  (3S) in    ,    , or invisible final states. – Set upper limits that rule out much of available parameter space; most stringent constraints to date. Set a limit on    ,and     BF of  b. No evidence for invisible decays of  (1S). – Constrain models with light dark matter. No evidence for LFV in  (3S) decays. F. Bianchi50

Summary A lot of exciting physics is still coming from the B-factories: – D 0 mixing has been established at > 10 . No evidence of CPV in D 0 decays so far. – Many new “charmonium like” new states have been observed. Still many open questions: What are they ? Why are they observed in some decay channels and not in others ? – After a 30 years long quest the  b has been discovered. – No evidence of light Higgs or DM in Bottomonium decays. Set limit on models. To do: – Update analyses with full statistics when applicable. – Add new channels. – Stay tuned for LHCb results. – Many measurement will still be statistically limited: a lot to do for the super-B factories. F. Bianchi51