31
27/4/2006 UK SuperB Factory Workshop 1 The LHCb Perspective Jim Libby – University of Oxford

The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

  • Upload
    others

  • View
    2

  • Download
    0

Embed Size (px)

Citation preview

Page 1: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 1

The LHCb Perspective

Jim Libby – University of Oxford

Page 2: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 2

Outline� Physics goals of SuperB and LHCb (almost)

identical

� Indirect search for New Physics in heavy flavour decay

� In particular CP violating and rare B decays

� Is there a synergy with a Super B factory?

� Synergy to symbiosis

� LHCb detector and status

� LHCb core programme

� Comparison to SuperB

� An upgraded LHCb

� Conclusions

Page 3: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 3

Symbiosis-living together

� In symbiosis, at least one member of the pair

benefits from the relationship

� The other member may be:

� injured

� relatively unaffected

� may also benefit ( = mutualism)

Page 4: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 4

Page 5: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 5

Requirements for flavour physics at the LHC

� Triggering:

� 6 in 1000 inelastic pp collisions at 14 TeV contain a bb pair

� Average of 1 interaction/bunch crossing (40 MHz)

� Reduce event rate for mass storage at 2 kHz

� Also require standard B physics tools

� Vertexing

� Particle identification

� Good invariant mass resolution

� Neutral reconstruction

� Flavour tagging

� A large number of bb events!

Page 6: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 6

1

10

102

-2 0 2 4 6

eta of B-hadron

pT

of

B-h

adro

n

ATLAS/CMS

LHCb100 µb

230 µb

Pythia production cross section

Acceptance and luminosity� In the forward region at LHC the bb

production cross section is large

� All types of B hadron

� LHCb uses the forward direction

� 4.9 > η >1.9

� Both hadrons containing the b & b quarks are likely to be within the acceptance

� B hadrons are moving with considerable momentum ~100 GeV/c

� Design luminosity L=2×1032 cm-2s-1

� Maximises number of single interactions

� 1012 B hadrons in 107 sec = 1 LHC year

η

pt

Page 7: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 7

LHCb detectorMuon Detector

Tracking

stations

Trigger

Tracking

proton

beam

interaction

region

Page 8: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 8

LHCb cavern snapshotMuon shielding and

electronics tower

HCAL and

ECAL modules RICH 2

Magnet –

mapped

RICH 1 -

photo-detector

magnetic shielding

WILL BE READY FOR

2007 PILOT RUN

Page 9: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 9

LHCb trigger� First level hardware trigger

� High pt hadrons, leptons and photons

� Veto multiple interactions

� If event passes 1st level all sub-detector data readout at 1 MHz to Higher Level Trigger farm

� Adaptable software trigger

� Fast VELO tracking to identify high impact parameter tracks

� Match to high pt objects that fired first level

� 2 kHz output rate

� Inclusive D* (300 Hz) – PID calibration and charm physics

� Dimuon (600 Hz) – B→J/ψX with no impact parameter selection

� Inclusive b→µ (900 Hz) – data mining and calibrations

� Exclusive B decay (200 Hz) – physics channels

Page 10: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 10

Tracking and vertexing

� Proper time resolution στ ~ 40 fs�Bs →Dsh (h=π,K)�Bs → J/ψ φ

� Essential for time dependent Bs measurements

Bs→Dsπ

σ(mB) [MeV/c2]Channel

8Bs → J/ψ φ(mJ/ψ constrained)

16Bs → J/ψ φ

14Bs →Ds π

Bs → µµ 18

Bs→DsπAll performance results with PYTHIA+GEANT4

simulation unless otherwise stated

Page 11: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 11

2GeV/c

5.1 5.15 5.2 5.25 5.3 5.35 5.4 5.45 5.5

Co

un

ts

0

50

100

150

200

250

300

Invariant mass

-π +π → dB-π + K→

dB

- K+ K→ sB

- K+π → sB

- p K→ bΛ

-π p → bΛ

2MeV/c

5100 5150 5200 5250 5300 5350 5400 5450 5500

Co

un

ts

0

200

400

600

800

1000

1200

Invariant mass

-π +π → d

B-π +

K→ dB-

K+

K→ sB-

K+π → sB-

p K→ bΛ-π p → bΛ

Particle IDNo RICH

0 20 40 60 80 100 0

20

40

60

80

100

Momentum (GeV/c)

Eff

icie

ncy

(%

)

Κ → Κ

π → Κ

Kaon ID: ~88%

Pion mis-ID: 3%

� Low momentum – Kaon flavour tag (b→c→s)

� High momentum –Background rejection for exclusive B decay reconstruction

ππ

hypothesis

B→h+h-

Page 12: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 12

Flavour tagging

�Most powerful tag is opposite kaon

(from b→c→s)

� Combined εεεεD2 ~ 6.9% (Bs) or 4.8% (B0)

� Multivariate approach ~9% for Bs

Qvtx

BsB0

D

l-K–

K+PV

SV

2.1%Same side K±(Bs)

1.0%Jet/vertex charge

2.4%K±

0.4%e±

1.0%µ±

εD2 = ε(1–2w)2Tag

Page 13: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 13

LHCb Physics Programme Sampler

� Bs mixing phase and lifetime difference

� Bs→J/ψφ

� Several routes to γ

� Bs→ DsK – tree only

� Bd→ π+π- and Bs→ K+K- – tree and penguin

� B-→D0K- and B0→D0K*0 – tree and D0 mixing

� α with Bd→ ρπ

� Rare decays

� Bs→µ+µ-

� Bd→K *0 µ+µ-

� Bd→ K *0γ and Bs→ φγ

Page 14: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 14

� Bs analogue of Bd →J/ψKs measures the Bs mixing phase

� φs = –arg(Vts2) = –2λη2 ~ –0.04 in SM

� Large CP asymmetry would signal Physics Beyond SM

� J/ψφ is not a pure CP eigenstate� Admixture of 2 CP even and 1 CP odd amplitudes

� Need to fit angular distributions of decay final states as function of proper time

� Requires external ∆ms from Bs→Dsπ

� Exploits excellent proper time resolution

� 1 year predictions with ∆∆∆∆ms = 20 ps-1

� 125k events with B/S~0.5

� σσσσ(sin φφφφs)~0.031

� σσσσ(∆Γ∆Γ∆Γ∆Γs /ΓΓΓΓs)~ 0.011

� 3σ SM sensitivity to sin φs after 5 years

� Also add pure CP states Bs→J/ψη(‘)

φs and ∆Γs from Bs→J/ψφ

Page 15: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 15

γ from Bs → DsK

� 2 amplitudes (b→c and b→u) of same magnitude (~λ3) interfere via

Bs mixing

� insensitive to new physics

� large interference effects expected

� 2 time-dependent asymmetries

� Bs (Bs) → D-s K+ and Bs (Bs) → D+

s K-

� 5400 signal events/year with B/S<1

� PID and mass resolution reduce

contamination from Bs→ Dsπ ~ 10%

Bs→→→→DsK

Bs→→→→Dsππππ

s sb c

us

B s

0 { }D s

}K+

}K–

s sb u

cs

B s

0 {}D s

+

Page 16: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 16

−0.5

−0.25

0

0.25

0.5

Asy

m (

Ds −

K+)

t [ps]

Asy

m (

Ds +

K−)

−0.5

−0.25

0

0.25

0.5

0 0.5 1 1.5 2 2.5 3 3.5 4

DsK asymmetries (5 years, ∆∆∆∆ms =20 ps–1)

Ds–K+

Ds+K–

γ from Bs → DsK

� Fit 2 time-dependent asymmetries� phase of D−

s K+ = ∆ + (γ + φs)

� phase of D+s K− = ∆ −−−− (γ + φs)

� φs from Bs → J/ψφ to extract ∆and γ

� 1 year sensitivity: � Assuming ∆ms = 20 ps-1 and -

20°<∆<20°

� σ(γσ(γσ(γσ(γ)))) ~ 14°

� Statistically limited

� 8-fold ambiguities in γ can be resolved� If ∆Γs large enough, or

� B0→Dπ and U-spin symmetry

Page 17: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 17

γ from B0→π+π− and Bs→K+K−

� Large penguin contributions in both decays

� Sensitive to New Physics

� Measure time-dependent CP asymmetry for B0→π+π− and Bs →K+K−

� ACP(t) = Adir cos(∆mt) + Amixsin(∆mt)

� Adir and Amix depend on γ, mixing phases, and ratio of penguin-to-tree amplitudes (d eiθ)

� Exploit “U-spin” symmetry (d↔s)

� dππ = dKK and θππ = θKK

� Mixing phases from golden modes

� 4 measurements and 3 unknowns,

1 year yields and sensitivity:

� 26k B0000→π→π→π→π++++ππππ−−−− and 37k Bs→→→→K++++K−−−−,

� σ(γσ(γσ(γσ(γ) ∼ 5) ∼ 5) ∼ 5) ∼ 5°

γ (°)

d

Bs → K+K−

(95% CL)

B0 → π+π−

(95% CL)

Bd/s

Bd/s

π/K

π/K

π/K

π/K

R.Fleischer, Phys.Lett. B459, 306 (1999)

Page 18: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 18

� Dunietz variant of Gronau, London and Wyler method

� Exploits interference between two colour-suppressed diagrams

� Measure 6 decay rates: B0 →D0(Kπ,πK,KK)K*0 + CP conjugates

� Allows γ and other parameters to be extracted without flavour tagging or proper time determination

� 80 precision on γ with one year’s data

γ from B0 �D0K*0

d

b

ds uc

B0

}D 0

}K*0

}D0

d

b

ds cu

B0 }K*0

A1 = �A1

A2

�A2 = A2 e−2iγA3

A4

γ∆

γ

A1 = A(B0 → D0K*0): b→c transition, phase 0

A2 = A(B0 → D0K*0): b→u transition, phase ∆+γ

A3 = √2 A(B0 → DCPK*0) = A1+A2, because DCP=(D0+D0)/√2

= strong phase

Page 19: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 19

B± →DK±Similar to B0-two interfering tree processes

Now one diagram colour suppressed

• γ – b→u , b→c interference

• rB – the ratio in magnitude of two diagrams (0.1 – 0.2)

• δB – a CP conserving strong phase difference

Look for decays common to Do and Do to access

interference effects, which depend on 3 parameters:

1. Cabbibo favoured self-conjugate decays e.g. Ksππ, KsKK, KKππ

Preliminary Ksππ studies 6k events/year with B/S ~O(1)

2. Cabbibo favoured/doubly Cabbibo suppressed modes e.g. Kπ, KπππOne year γ sensitivity 50

Two types of D0 decay understudy:

u

bB

0D

u

c

Ku

s

u

b

B−

Ku

s

0D

c

u

Page 20: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 20

Angle α from Bd →π0π–π+ decays

�Dalitz plot analysis (Quinn Snyder method)

�Bd→π0π–π+ selection based on

multivariate analysis

�Use resolved and merged π0

�Expect 14k events per year B/S < 1

� Toy MC study:

� 11-parameter likelihood

fits performed in time-

dependent Dalitz space

� B/S = 0.8

(flat and resonant bkg)

ρ0π0

ρ–π+

ρ+π–

m2(π0π+)

m2(π

0π–

)

Combined discriminant variable

1 year σσσσ(αααα) ~10°

ααααgen=106°

Page 21: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 21

s = (mµµ)2 [GeV2]

AFB(s) for B0→→→→K*0µµµµµµµµ

Rare decays with leptonsBs→µ

+ µ-

� BR ~ 3.5 × 10–9 in SM, can be strongly enhanced in SUSY

� LHCb has prospect for significant measurement� ~30 events/year

� Full simulation: 10M incl. bb events + 10M b→µ, b→µ events (all rejected)

� Sensitivity to SM Bd→µ+ µ- which has SM

BR ~ 8×10-11

s(GeV^2)0 2 4 6 8 10 12 14 16 18 20

FB

A

-0.5

-0.4

-0.3

-0.2

-0.1

-0

0.1

0.2

0.3

0.4

Expt20

B0+B0bar FBA

Fit to FBAB→K*0µ+ µ-

� AFB very sensitive to new physics

� Expect 4.4k events in 1 year� B/S < 2.5

� In 5 years 13% sensitivity to s(AFB=0)

Page 22: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 22

B0→ K0* γ and Bs → φ γ� B→K0* γ expected direct

CP violation Acp<0.01

� 35k/year B/S>0.7

� B→φγ TDCPV zero in SM � Sensitive to same new

physics as TDCPV in B0→ K*0(K0

sπ) γ� Selection optimises proper

time resolution

� 9.49.49.49.4k/year B/S>2.5

� Sensitivity studies in progress

σσσσm~ 64 MeV/c2

B→ Kππππ γγγγ

Bs→ KK γγγγ

σσσσττττ~ 60 fs

mKπ[GeV]

τtrue-τrec [ps]

Page 23: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 23

…and much, much more

� Other CP measurements, for example

� sin 2β with B→J/ψK0S

� sin (2β+γ) with B→D*π

� α with B→ρ0 ρ0

� φ s with Bs → φ φ (gluonic penguin)

� Other rare decays e.g Bs → φ µµ� Other areas to be explored

� B baryons

� Bc physics – 14k/year in Bc → J/ψ π

� Charm physics (300 Hz of D*+→D0(h+h-)π+)

� Control samples for systematic uncertainties i.e. B+→J/ψK+

Page 24: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 24

-0.5 -0.4 -0.3 -0.2 -0.1 -0 0.1 0.2 0.3 0.4 0.5

|ub

|V

K)s

D→s

(Bγ KK)→

s(Bγ

)*

(DKγ

)π ρ(α isospin)ππ(α

βsin 2)ντ D→0BR(B

)ντ D→+BR(B

)νν+ K→+

BR(B

)µµ →s

BR(B

ll)*

K→(BFB

A10

C

ll)*

K→(BFB

A9

C

)γs

X→(BCP

A

)γs

X→BR(B)γ*0

S(K

)s

φsin()

0

S K

0π S(∆)

0

SK

0

SK

0

S S(K∆

)0

S’ Kη S(∆

)0

S K

- K

+ S(K∆

)0

S Kφ S(∆

Comparison to Super B

� This was shown by N.

Katayama at FCPC a

couple of weeks ago

� At first glance I’m

working on the wrong

experiment!

� But:

� LHCb ~2010

� SuperB ~2020

� Some missing LHCb info

SuperB (50 ab-1) LHCb (2 fb-1)

Page 25: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 25

-0.5 -0.4 -0.3 -0.2 -0.1 -0 0.1 0.2 0.3 0.4 0.5

|ub

|V

)γs

X→BR(B)ντ D→0BR(B

)ντ D→+BR(B

)νν+ K→+

BR(B

isospin)ππ(α)γ*0

S(K

)0

S K

0π S(∆)

0

SK

0

SK

0

S S(K∆

)0

S’ Kη S(∆

)0

S K

- K

+ S(K∆

)0

S Kφ S(∆

ll)*

K→(BFB

A10

C

ll)*

K→(BFB

A9

C

)γ)*/Ks

(X→(BCP

A)

*(DKγ

)π ρ(αβsin 2

K)s

D→s

(Bγ KK)→

s(Bγ

)µµ →s

BR(B

)s

φsin(

Comparison to Super B

� Added some

information on

several modes

� Scaled LHCb to

10 fb-1 luminosity

(~2014) and

reordered the

measurements

� Symbiosis!

Incl

usi

ve/ν

No I

PB

sC

om

mon

Page 26: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 26

Possible LHCb upgrades

� Simulation studies indicate we can run at 5×10-32cm-2s-1 and gain in statistics

� Particularly dimuons

Bo→→→→ππππ+ππππ-

BS→→→→φγφγφγφγBS→→→→J/ψφψφψφψφBS→→→→DSK-

� Vertex detector will be replaced because of radiation damage

� Very radiation hard technologies would allow detectors to be closer to the

beam

� Pixels could be used in 1st level of the trigger to improve selection of

hadronic modes-potentially allow running above 5×10-32cm-2s-1

� ECAL inner region replaced by PbWO4 to improve neutral

performance

Hadronic/photonic modessaturate allotted bandwidth

Page 27: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 27

Conclusions

� LHCb will be ready for data taking next year

� A large number of measurements will be made

during the lifetime of the experiment

� Largely complimentary to Super B programme

� Performance might be enhanced with upgrades to

vertexing, triggering and electromagnetic

calorimetry

Page 28: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 28

0 1 2 3 4 5 6 7 8 9 10-0.8

-0.6

-0.4

-0.2

0

0.2

ACP

Proper time (ps)

sin(2β) from B0→J/ψ KS� “gold-plated” decay channel at B-factories for measuring the Bd- Bd mixing phase

� needed for extracting γ from B → π π and Bs → K K, or from B → D*π

� in SM ~0, non-vanishing value O(0.01) could be a signal of Physics Beyond SMdir

CPA

ACP(t) (background subtracted)

LHCbOne of the first CP measurements at LHC:

� demonstrate CP analysis performance

� study tagging systematics

Expected sensitivity:

� LHCb: 240k signal events/year

� σstat(sin(2β)) ~ 0.02 (1year, 2fb-1) (�σ(β)∼0.6°)

Search for direct CP violating term…

Page 29: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 29

B- →D0(K+π-)K-

� Both D0 and D0 → K+π- :

Doubly Cabbibo suppressed Cabbibo favoured

� For these decays the reversed suppression of the D decays relative to the B decays results in much more equal amplitudes → big interference effects

� Counting experiment

� Interference depends on 5 parameters :

� From the B decays γ, rB and δB

� rDKπ – the ratio in magnitude of two D decay processes

� Well measured (PDG value 0.060)

� δDKπ – a CP conserving strong phase difference

B-→D0K- (colour

favoured) then :

B-→D0K- (colour

suppressed) then :

Atwood, Dunietz and Soni

u

cD

0

+

Ks

u

π

u

d

u

cD

0 +

Ku

s

π

u

d

Page 30: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 30

B- →D0(K+π-)K-

� Have 4 B±→D(Kπ)K± rates we can measure:

� Two rates are favoured (1) and (3)

� Two rates are suppressed (2) and (4)

– but suppressed rates have O(1) interference effects as rB ~ rD

� Taking the relative rates have more unknowns than equations –need information from other decays eg. D → Kπππ or the CP eigenstates KK, ππ (rD

KK=1, δDKK=0)

(1)

(2)

(3)

(4)

Page 31: The LHCb Perspective - University of Warwick · Fast VELO tracking to identify high impact parameter tracks Match to high pt objects that fired first level 2 kHz output rate Inclusive

27/4/2006 UK SuperB Factory Workshop 31

ADS 1 year sensitivity studies� Event yields

� 60,000 favoured

� 2,000 suppressed

� B/S = 0.5 for both

� Fit robust over range of strong D decay strong phases

6.906.005.905.605

5.505.305.105.002

5.004.804.804.601

4.104.004.003.900

B/S

Kπππ

5210

B/S Kπ

1000 toy experiments-no background