Impact of Charm Physics on CKM David Asner Carleton University
Outline 1) Review Benefits of Threshold Running 2) Discuss Two Roles of Charm Physics Precision Decay Rates, Spectra Leptonic, Semileptonic, Hadronic Decays Standard Model suppressed processes D Mixing, CPV and Rare Decays 3) Review results from CLEO-c, B-factories Emphasis on CKM relevant measurements 4) Consider future prospects 2
Dsig Charm at Threshold e + e + e - ψ(3770) DD e! D tag Pure DD, no additional particles (E D = E beam ) σ(dd) = 6.4 nb (Y(4S)->BB ~ 1 nb) Low multiplicity ~ 5-6 charged particles/event high tagging efficiency:~22% of D s Compared to ~0.1% of B s at Y(4S)! + ψ(3770) is to charm what ϒ(4S) is to beauty! " K + A little luminosity goes a long way: # events in 100 pb -1 @ charm factory with 2D s reconstructed ~ # events in 500 fb -1 @ ϒ(4S) with 2B s reconstructed! "! +! (3770) $ D Increased statistics is NOT an advantage of threshold running. Cross section is 3x D $ higher than 10 GeV but luminosity is more than 100x lower K " + + # + + D # 3 K! CLEO-c DATA ", D $ K " " # + # #
Two Roles of Charm Physics 1) Precision CKM physics - desire % level Leptonic Decays Decay Constants, f D, f Ds, f D /f Ds Enables precision V td, V ts Semileptonic Decays Measure V cd, V cs Form Factor analysis enables precision V ub Inclusive spectra important for V cb Hadronic Decays Normalizes scale of B physics Important for V cb 2) Standard Model suppressed processes D mixing CP Violation Rare Decays Benefit from low bkgd at threshold Threshold Data Essential Benefits from statistics at 10 GeV Quantum correlated threshold data important 4
Exploiting Quantum Correlation For CKM physics Measure relative strong phase between D 0 K-π+ and D 0 K-π+ Impacts charm mixing at B-factories/LHCb Charm hadronic BF at Threshold Needed for γ/φ 3 measurement with ADS method CP asymmetry in B DK, D Kπ etc. Reduce systematic error on γ /φ 3 CP tagged Dalitz plots Additionally Time integrated sensitivity to D mixing Unique sensitivity to CP violation 5
Precision CKM 6
Precision CKM:Why Do We Measure ρ,η?? We don t really care what ρ,η are we care if results from different measurements of them are the same! -- Is the theory internally consistent? -- Or is there a hint of new physics For several measurements theoretical precision is the limiting factor: Charm physics can help! 7
! Precision Quark Flavor Physics The discovery potential of B physics At BABAR/Belle/CDF/D0/ LHC-b is limited by systematic errors from QCD: l ν B π! B d B d 8
! Precision Quark Flavor Physics The discovery potential of B physics At BABAR/Belle/CDF/D0/ LHC-b is limited by systematic errors from QCD: l ν B π! B d B d D system- CKM elements known to <1% by unitarity l ν DB π measurements of absolute rates for D leptonic & a wide variety of semileptonic decays yield decay constants & form factors to test and hone QCD techniques into precision theory which can then be applied to the B system. D l ν + Br(B D)~100% absolute D hadronic rates normalize B physics important for Vcb (scale of triangle) - also normalize D physics 9
Leptonic Charm Decays & Decay Constants D+ µν CLEO Phys.Rev. Lett. 95 (2005) 251801 D s + µν, τν CLEO hep-ex/0607074 ICHEP06 (preliminary) D s + µν BABAR hep-ex/0607094 submitted to PRL See also talk tomorrow in WG 2/3 by S. Stone Semileptonic + Leptonic D Decays CLEO 10
Leptonic Decays: D (s) l + ν Introduction: Pseudoscalar decay constants _ c and q can annihilate, probability is to wave function overlap Example : (s) or cs In general for all pseudoscalars: 2 2 + 1 2 2 2 m 2! GF fp m M # $ + l l l P ( V 2 ) Qq 8" M P %(P & ) = 1 ' * + Calculate, or measure if V Qq is known 11
BABAR: D s µν + µ! "# Select e+e- cc events with high momentum D 0, D+, D s, D* + close to B kinematic end-point Search for D s * γ Ds γµν in the recoil Measure B(Ds µν)/b(ds φπ)=0.143±0.018 Use B(D s φπ) = (4.71±0.46)% BABAR PRD71 (2005) 091104 Find B(D s µν) = (6.74 ± 0.83 ± 0.26 ± 0.66)x10-3 + ) ) 0.018 ± 0.006 f Ds = (281 ± 17 ± 6 ± 14) MeV BABAR 230 fb -1 12
D s Data at CLEO-c σ(d S D S *) = 0.9 nb at E cm ~4.17 GeV 13
D S+ µ + ν + τ + ν, τ + π + ν: Distinguish by energy deposition in calorimeter: (i) Clear D S+ µ + ν at zero missing mass (ii) events <0.2 GeV 2 are mostly D S τ + ν, τ π + ν (iii) No D S + ν seen 64 events <0.3GeV in CC 24 events D S+ µ + ν and τ + ν (200pb -1, D Tagged) D S+ τ + ν, τ + e + νν: BR product ~1.3%; large compared with expected B(D S + Xe + ν) 8% Signal candidates: 1) e + opposite D S - tag 2) no other tracks 3) Σ calorimeter energy < 400 MeV 400 MeV Signal >0.3GeV in CC 12 events Xe + ν Sum both µν and τν, τ πν: B eff (D S+ µ + ν) = (0.664±0.076±0.028)% B(D S + τ + ν) =(7.1±1.4±0.03)% B(D S+ τ + ν) = (6.29±0.78±0.52)% 14
Decay Constants, Combined Results CLEO combined result (preliminary) f Ds = (280.1±11.6±6.0) MeV Γ(D S+ τ + ν)/γ (D S+ µ + ν): CLEO: 9.9±1.7±0.7, Standard Model: 9.72 consistent with lepton universality D + µ + ν D + 0 + " K! Signal CLEO published from D µν f D+ =(222.6±16.7 +2.3-3.4 )MeV: f Ds /f D +=1.26±0.11±0.03 Or using Unquenched Lattice Gauge prediction of 1.24±0.07 find V cd /V cs =0.22±0.03 15
Hadronic Charm Decays D 0, D + Hadronic BF CLEO presented at HQL06 D s Hadronic BF CLEO hep-ex/0607079 ICHEP06 B(D s φπ) BABAR PRD71 091104 (2005) D s Kππ Dalitz Plot Analysis BABAR presented at DPF06 16
D 0 K - π +,D + K - π + π + at the ψ" (CLEO-c) 281 pb -1 D 0 or D 0 230,225 D 0 & D 0 13,575±120 D + or D - 167,086 D + & D - 8,867±97 Double Tags B(D + K - π + π + ) (%) Error(%) Source B(D 0 K - π + ) (%) Error(%) Source 9.2±0.1±0.2 2.4 CLEO-c (281 pb -1 ) 3.87±0.04 ±0.08 2.3 CLEO-c (281 pb -1 ) 9.2±0.6 6.5 PDG04 3.81±0.09 2.4 PDG04 9.51±0.34 3.6 PDG06 3.80 ±0.07 1.8 PDG06 17
D s Single Tag Yields 18
D s Double Tag Yields 19
Absolute B Results for D S + 195 pb -1 About ±6% error Compare with BABAR B(D s φπ)=(4.71± 0.46)% 20
Comparison of BABAR & CLEO-c 123 M BB pairs B D*D* s Fully reconstruct D*+γ Shown above is the denominator in BF Normalization of D s important for B-factories B-factories measure B(D s µν)/b(d s φπ) Measurements at threshold & 10 GeV very different 21
D s+ K + K - π + (BABAR) 22
The Real B(D S φπ + ) You can use a Dalitz plot fit (i.e. BABAR) to get the fraction of φπ. This is not the same procedure that was done in the past of merely cutting on the K + K - invariant mass about the φ. The BABAR Dalitz plot analysis has the φπ + fraction of K + K - π + =0.379±0.018 Dividing the CLEO number for B(D S K + K - π + ) by B(φ K + K - )=.491, gives B(D S φπ + )=(4.3±0.5)% This is the branching ratio that is most appropriate to compare with theoretical calculations 23
Semileptonic Charm Decays Form Factors, V cs & V cd D 0 /D + Xev D 0 πe/µν, Ke/µν Belle PRL 97:061804,2006 D 0/+ πeν, Keν D 0 Keν D 0 πµν, Kµν BES hep-ex/0610019 D+ Kµν BES hep-ex/0610020 CLEO accepted by PRL hep-ex/0604044 CLEO - presented at ICHEP06 BABAR hep-ex/0607077 - ICHEP06 See also talk tomorrow in WG 2/3 by S. Stone Semileptonic + Leptonic D Decays CLEO And Talk on Friday in WG 1 by M. Artuso Status + Future Perspectives on V cs and V cd 24
Inclusive Semileptonic Results mode D 0 Xe + ν Σ i Β i (D 0 Xe + ν) D + Xe + ν Σ i Β i (D + Xe + ν) Branching Fraction (6.46 ± 0.17 ± 0.13)% (6.1 ± 0.2 ± 0.2)% (16.13 ± 0.20 ± 0.33)% (15.1 ± 0.5 ± 0.5)% CLEO-c 281pb -1 " " SL Consistent with the known exclusive modes saturating the inclusive branching fractions. B SL + + 0 = # = ± ± D D D SL SL B 0 0!! D D D + 0.985 0.028 0.015 Extrapolated below 0.2 GeV Consistent with isospin symmetry Electron vs D Tag D 0 Kπ, D + Kππ 25
Exclusive Semileptonic Decays Either take V cq from other information & test theory, or use theory & measure V cq V cs use D K(K*)lν to measure form-factor shapes to distinguish among models & test lattice QCD predictions V cd use D π(ρ)lν Use D πlν (& ρlν) to get form-factor for B πlν (& ρlν) and use HQET to get V ub See WG2 Session on Exclusive V ub later today 26
D 0 /D + K/πeν CLEO-c (281 pb -1 ) With D tagging Untagged: Neutrino Reconstruction 40% common samples! 1347±49 14397±132 699±28 6796±84 295±20 2910±55 450±29 5846±88 U = E miss P miss (GeV) Plots Integrated over all q 2 27
D 0 K/π e/µν Belle (282 fb -1 ) Fully recontruct e + e - cc D 0 Κeν 1318 ± 37 stat ± 7 syst data data remaining signal fake-d 0 bkg D 0 πeν 126 ± 12 stat ± 3 syst D 0 Κµν data hadronic bkg D 0 πµν 1249 ± 37 stat ± 25 syst data MC Klν bkg Κ /ρlν bkg 106 ± 12 stat ± 6 syst m ν ² / GeV² 1/7 statistics of CLEO-c with 1000x Luminosity 28
Exclusive Branching Ratio Summary 29
Form Factor Fit (CLEO-c & Belle) CLEO-c Belle σ(q²) = 0.012 GeV²/c² σ(q²) = 0.0145 GeV²/c² 30
Form Factors D Ke + ν D πe + ν Decay Mode CLEO-c (av. D 0 & D + ) tagged untagged Belle (D 0 ) BABAR (D 0 ) D Κeν 1.96±0.03±0.01 1.98±0.03±0.02 1.82±0.04 ±0.03 1.854±0.016 ±0.020 D πeν 1.95±0.04±0.02 1.88±0.03±0.02 1.97±0.08±0.04 31
Form Factors & Tests of LQCD D 0 " + # K e! Assuming V cs =0.9745 Use independent measure of V cx Compare data & lattice determination of f + (0). Belle D 0 $ " # e +! Assuming V cd =0.2238 Belle. 32
Use Lattice to extract V cs & V cd Preliminary CLEO-c semileptonic widths Γ(D Keν e ) =(8.7±0.16) x10-2 ps-1 Γ(D πeν e )= (0.76 ±0.03)x10-2 ps-1 FNAL-MILC-HRQCD (PRL 94, 011601 (2005)) Γ(D Keν e )/ V cs 2 and Γ(D πeν e )/ V cd 2 Uncertainties Expt:<2% ~4% LQCD: 10% CLEO-c Preliminary D πeν V cx ± (stat) ± (syst) 0.225 ± 0.004 ± 0.022 PDG06 0.230 ± 0.011 (ν ν interactions) D Keν 0.996 ± 0.008 ± 0.093 0.957 ± 0.017 ± 0.093 (charm exclusive sl width, smaller data sample) Best direct determination of V cs See talk on Friday in WG 1 by M. Artuso Status + Future Perspectives on V cs and V cd 33
Charm Impact on γ/φ 3 Charm Mixing Doubly-Cabibbo Suppressed Decay Strong Phases CP Tagged Dalitz Plots 34
Mixing & Strong Phase at Threshold C = 1 e + e γ* D 0 D 0 Not all final states allowed. Apparent Bs different from incoherent (isolated) decay. interference forbidden in absence of mixing maximal constructive interference forbidden by CP conservation K π + K π + CP+ K l + ν CP+ CP+ K + π K + π K π + K π + K π + K + l ν K + l ν K + l ν K + l ν CP- CP- CP- CP+ CP- Interf. of D 0 and D 0 to same f: DCSD: <D 0 K π + >/<D 0 K π + > = re iδ Κπ Mixing: y = (Γ 2 -Γ 1 )/2Γ Time-integrated rates probe r, cos δ, and y (at first order!). SL decays tag flavor (if no mixing) other D decays as if isolated. Disentangle DCSD and mixing. See PRD 73 034024 (2006) Goals: first measurement of cosδ Kπ, constrain y. 35
Previous Results (Oct 2005) PANIC 05 prelim. results: 281 pb -1. No systematics. Only one CP- mode. With r 2 constrained to world average, cosδ Κπ =1.08±0.66. Use BF constraints then σ(y)~0.03 & σ(cosδ Κπ )~0.5 In progress: Added 70% more CP K 0 S η, K0 S ω Added K 0 L π0. Technique tested with Quantum Correlated MC. Expect in 281 pb -1 σ(y)~0.015 & σ(cosδ Κπ )~0.3 Expect in 281 pb -1 σ(y)~0.01 & σ(cosδ Κπ )~0.1-0.2 Param. N D 0 D 0 y r 2 rz R M B(K π + ) B(K K + ) B(π π + ) B(K 0 S π0 π 0 ) B(K 0 S π0 ) B(X e + ν) Value (1.09 ± 0.04)x10 6-0.057 ± 0.066-0.028 ± 0.069 0.130 ± 0.082 (1.74 ± 1.47)x10-3 (3.80 ± 0.29)% (0.357 ± 0.029)% (0.125 ± 0.011)% (0.932 ± 0.087)% (1.27 ± 0.09)% (6.21 ± 0.42)% <D 0 K π + >/<D 0 K π + > = re iδ Κπ z = 2cosδ Κπ PDG04 or CLEO-c (1.01 ± 0.02)x10 6 0.008 ± 0.005 (3.74 ± 0.18)x10-3 PDG + Belle + FOCUS < ~1x10-3 (3.91 ± 0.12)% (0.389 ± 0.012)% (0.138 ± 0.005)% (0.89 ± 0.41)% (1.55 ± 0.12)% (6.87 ± 0.28)% 36
Determing γ/φ 3 with Direct CPV 1) B +- D ( * ) CP K( * )+ Gronau-London-Wyler 2) B + D 0 Kπ h+ Atwood-Dunietz-Soni 3) B + D 0( * ) CP K( * )+, D 0 K S π + π - Dalitz Method Giri et al., Bondar et al. D mixing is fortunately small enough to ignore ADS requires δ Kπ - phase between D 0 Kπ & D 0 Kπ Dalitz method requires proper amplitude/phase description of D 0 K S π + π -. Benefits from CP tagged Dalitz plots 37
CP Tagged Dalitz Plots CP tagged Dalitz plots can reduce systematic uncertainty on γ/φ 3. CLEO-c data is a source of CP tagged Dalitz plots Preliminary yields for CP tagged D0 K S π + π - in 281 pb -1 Extrapolate to 750 pb -1 expected New! Use kinematic constraints to reconstruct K L π + π - c i = 1 2 ( M ( M! i! i! + M M + i + i ) ) ( K i + K K i K! i! i ) -i i CLEO-c will detemine c i by counting yields in bin i for flavor and CP tags K i - flavor tag yield in bin i M i ± - CP± yield in bin i 38
CP Tagged K S ππ (CLEO-c Data) K S π 0 cuts: -0.071 < ΔE < 0.041 GeV/c 2 1.8589 < M BC < 1.8701 GeV/c 2 ΔE (K S ππ) M bc (K S ππ) KK, ππ,, K S ππ cuts: -0.03 < ΔE < 0.03 GeV/c 2 1.8603 < M BC < 1.8687 GeV/c 2 Slide 9 Very low background ΔE (K S ππ) M bc (K S ππ) 39
CP Tagged K S ππ Dalitz Plots (CLEO-c Data) K S ππ yields by tag: K S π = 95 KK = 66 ππ = 27 no ρ 0 ρ 0 Clearly statistics starved! Use kinematic constraints to add modes with K L K L π + π - K L π 0 K L π 0 π 0 40
Reconstructing K L Kπ vs K L ππ Motivation is clear - more statistics Method straight forward Reconstruct D (Tag) on one side Bkgd ~5% Compute (missing mass) 2 on other Additional CP tags - shown today K L π 0 vs K S π + π - K L π 0 vs K S ππ KK vs K L ππ K S π 0 vs K L π + π - K + K - vs K L π + π - π + π - vs K L π + π - Modes with 2π 0 s also promising K L π 0 π 0 vs K S π + π - K S π 0 vs K L ππ ππ vs K L ππ K S π 0 π 0 vs K L π + π - MM 2 (GeV) 2 41
CP Tagged K L π + π - Dalitz Plots CP+ Tags CP- Tags M(K L π + ) 2 no ρ 0 M(K L π + ) 2 ρ 0 M(K L π - ) 2 M(π+ π - ) 2 M(K L π - ) 2 M(π + π - ) 2 CP- tagged K L ππ Dalitz plots have enhanced K L ρ 0 (CP+) CP+ tagged K L ππ Dalitz plots have no K L ρ 0 42
Double Dalitz Tags K S π + π - vs K L π + π - (CLEO-c Data) M(K S π + ) 2 M(K L π + ) 2 M(π + π - ) 2 M(π + π - ) 2 43
Impact of CLEO-c Φ 3 error vs. D CP statistics [1] # of events (CLEO-c) KK K S π+π - 281 pb -1 66 180 K S π+π- 750 pb -1 281 pb -1 175 ππ 27 75 62 K S π 0 95 250 103 K L π 0 93 250-500 134 457 K L π+π- 750 pb -1 350 150 275-1200 Sys. Error on γ/φ 3 Stat. Error on γ/φ 3 570 CP tags in 281 pb -1 6-7 o sys. err. ~1500 CP tags expected in 750 pb -1 ~4 o sys. err. ~1700 double Dalitz tags expected in 750 pb -1 Impact on sys. err under study # of B+ DK+, D K S π+π- # of CP tagged D K S π+π- [1] Bondar, Poluektov [hep-ph/0510246] 44
CKM Impact of Charm Measurements Leptonic Charm Decays D+ µ+ν, D s + µ+ν,τ+ν Measure decay constants f D, f Ds Improved f B possible from f D measurement + LQCD Important for V td and V ts Semileptonic Charm Decays Measurements of V cs and V cd Test theoretical form factor models Impacts prediction of form factors for B meson decays Important for V ub and V cb Hadronic Charm Decays D 0 Kπ, D + Kππ, D s+ φπ Important for V cb Multibody Charm Decays D 0 K S,L ππ, Important for γ/φ 3 f D :CLEO-c ~8% 4-5% BESIII expect ~1-2% f Ds: CLEO-c ~6% (200 pb-1) BABAR ~8% (230 fb-1) Expect 3% each BESIII expect ~1-2% CLEO-c Vcs <2%, Vcd <4%, Expect<2% BESIII improvement depends on sys err. B-factories contribute to Klν, πlν FF Expect CLEO-c 1-2% D,D + BF Cosδ ±0.3 0.1-0.2 CLEO-c 4% Ds Currently BABAR 10% on φπ CLEO-c 6% on KKπ 4% CP tagged K S ππ + K L ππ: improve γ/φ 3 6 o <4 o at CLEO-c 45
Closing Provacative Thoughts How much more charm data do we need? How precisely do we need to measure CKM parameters? Want to measure f D /f Ds to 1% use double ratio (f B /f Bs )/(f D /f Ds ) from LQCD to get f B /f Bs and interpret Δm d /Δm s Needs O(100 fb -1 ) at threshold BESIII will accumulate 0(10 fb -1 ) Same level of FF analyses as Ke 3, Ke 4 For Ke 4 Na48/2, E685 400K each Charm phase space is larger, perhaps need 1M events Needs O(10 2 to 10 3 fb -1 ) at threshold Sys. Err on γ/φ 3 to 1 o Needs ~20 fb -1 for K S,L ππ - okay for BESIII Other modes (πππ 0, KKπ 0 etc.) will require more threshold data We should consider seriously the option of running SuperB at charm threshold Requires ~(5-10)% of running time distraction from ϒ(4S) 46
The End 47
A Tribute to Bernie Gittelman 1936-Nov. 25, 2006 A hero of flavor physics Pioneered e- storage rings at SLAC First to measure B semileptonic decays Led CLEO II project 48
BABAR & FOCUS Form Factors LQCD CLEO-c Belle Unquenched LQCD Quenched LQCD Simple pole model DATA FIT LQCD DATA FIT 49