semileptonic & rare charm decays

Semileptonic & Rare Charm Decays

Will E. Johns

Vanderbilt University

FPCP 2003, June 4

Rare Charm Decays Potential FCNC Decays are Suppressed

10-19

10-16 γγ)( oDBR

)( oDBR

10-8 )( DBR

Short Distance

Rare Charm Decays

10-13

10-8 γγ)( oDBR

)( oDBR

10-6 )( DBR

Long Distance

Enhancement from Long Distance Effects

Even More room for decays:

X eX

New Result from CDF oD

Use D* tagged Do’s

Use Similar Normalization Mode Very Similar Kinematics Keep cuts “same”

Need Anyway: - Background from Normalization ~(MISID)2 = (0.013)2 or (1/5 ev.)

The “MISID ZONE”

Back of the Envelope:

1.5E-3 (2.2/1371) = 2.4E-6

)()( 00 DBReff

eff

N

NDBR

RARE

NORM

NORM

RARE

)5.1/( BS Optimal:

)5.2cut( M

KSideband + (MISID)2

•Expected background– events•Fake: •Combinatorial:

• 0 events in window

•New best limitBr < 2.4 x 10-6 at 90% CLBr < 3.1 x 10-6 at 95% CL

New Result from CDF oD

Background Sideband(Combinatorial Estimate)

Previous Bests: 4.1 x 10-6 at 90% CL (BEATRICE)4.2 x 10-6 at 90% CL (E771)

7.07.1 2.022.0

7.05.1

New Result from CLEO oD

13.8 fb-1

Form D0 mass from 2 photons

(Cuts optimized on )oooD

MoM 3)(

Mass must be within of M(D0)M5.2

Veto candidate when extra photons form mass:

(reduces bkgnd from 4 to 1)oo

Find soft pion consistent with D momentum cuts and Particle ID

Form )()*( oDMDMQ

Fit data to Gaussian and threshold function

Gaussian width and center fixed from Monte Carlo

)(8.310.628 eventsoooD

)(3.92.19 eventsoD

0094.00194.0)(

)(0

0

RARE

NORM

NORM

RARE

eff

eff

N

NooDBR

DBR

New Result from CLEO oD

Systematic error 13.1% from finding efficiencies, fits, MC stats, D selection, Event selection (added in quadrature with stat error for upper limit estimate)

90% ofProbability is above 0.0194

0.033

0.0194

(stat)

Sigma is total error

My toyexplanation

..%[email protected])(

)(0

0

LCooDBR

DBR

40 10)2.24.8()( Using ooDBR

..%[email protected])( 50 LCDBR

Phys. Rev. Lett. 90:101801, 2003hep-ex/0212045

Final Results from FOCUS ),()( KD S

Look for 3 bodies with 2 muonsCut Grid, based on vertexing, Particle ID

L/ – vary from >5-21 Lp

s

ISO1 – CL DK’s in prim (vary <0.1 –0.001)

DCL – CL of DK vertex (>1 -- 4%)MuCL – CL for Muon ID (>1 – 10%)

Cuts on P( for ’s, Cerenkov for ’s and K’s

Loosest Cuts

Tightest cuts


Systematic Check uses a single cut

(makes better plots!)

- First Bootstrap sets cuts for optimal Sensitivity (Blind)

- Second Bootstrap calculates quoted Sensitivity and Branching Ratio

Signal Excluded

D SD

Final Results from FOCUS

Decay

Mode

Dual

Bootstrap

Sensitivity Sys.

Error

Result

W/sys

Single

Cut(w/sys)

Previous

(E791)

D+ ++- 9.1x10-6 7.5x10-6 7.5% 9.2x10-6 12x10-6 44x10-6

D+ -++ 13x10-6 4.8x10-6 7.5% 13x10-6 12x10-6 120x10-6

D+ ++- 8.8x10-6 7.6x10-6 7.5% 8.8x10-6 7.4x10-6 15x10-6

D+ -++ 4.9x10-6 5.6x10-6 7.5% 4.8x10-6 5.2x10-6 17x10-6

Ds+ ++- 3.3x10-5 3.3x10-5 27.5% 3.6x10-5 3.8x10-5 1.4x10-4

Ds+ -++ 1.3x10-5 2.1x10-5 27.5% 1.3x10-5 2.0x10-5 1.8x10-4

Ds+ ++- 2.4x10-5 3.1x10-5 27.5% 2.6x10-5 1.8x10-5 1.4x10-4

Ds+ -++ 2.6x10-5 2.3x10-5 27.5% 2.9x10-5 2.2x10-5 0.8x10-4

(E687)Dominated by PDG rate to normalizing mode


Rare Decay Round-Up

OD

Closing in on Long rangeSM predictions

Sets MSSM constraint

Close to Long Distance Predictions

A 1st !

Lots of RoomAt the bottom!

Semileptonic Charm Decays

022222

2

cossin4sin})cos1()cos1{(coscos

VVVdd

d

(D decay, No form factors, V decays to spin 0 particles)

Neutrino is left handed

Prefers W spin along muon,e

V products spinless

Prefer LZ=0

Form FactorsBaryons (spin ½)Scalar Resonance?

CP?

More than just CKM measurement tools…

)Asymmetry CP(

)M Factors, Form(

Factors) Form(

)(

)(,

)(

)(

ce)Interferen()(

0

Pole0

0*

0*

e

e

KD

D

D

KD

KD

KD

C

C

S

S

FOCUS saw discrepancies in the data

2

20

2

2

2

5

0*

)(sincos2

)()cos1(sin

)()cos1(sin

coscos

obey) NOT Did(

0*

0*

0*

qHB

qHBe

qHBe

ddddqdm

d

KD

KV

K

iV

K

iV

Vk

Phys.Lett.B535:43-51, 2002hep-ex/0203031

FOCUS added a term, things got better

2

20

2

2

2

5

)()(cossin2

)(sin)cos1(

)(sin)cos1(

coscos

0*

0*

0*

qHAeB

qHBe

qHBe

ddddqdm

d

i

KV

K

iV

K

iV

Vk

L=0 ansatz

Clean

The data(error bars)preferred theL=0 ansatz(solid) overno extra term(dashed)

Bkgnd

FOCUS BR MeasurementsCuts similar to rare search:

even

ts /

5 M

eV/c

2

ISO1 ISO2 – No unused tracks consistent with charm vertex (CL < 0.1%)OoM – Charm vertex outside of target and silicon by Vertex3

)(

)(,

)(

)(0*

S

S

D

D

KD

KD

) cuts(/18.0}){(}){( 0*2 DDcGeVKMKM

KD 0*KD

SDSD

0*KD Includes S-wave interference

)(048.0)(033.054.0

)(

)(

sysstat

D

D

S

S

(1.5) 2.2,e)(quadratur Total

(0.94) 1.57, ff) (Bk,fit Vary

(1.12) 1.57, Samples Splitting

(1.06) 0.71, CutsVary

:)( for

offraction a as expressed

:errors Systematic

stat

SDD

(add in if > 1)

Phys.Lett.B540:25-32, 2002hep-ex/0206013

)(021.0)(010.0602.0

)(

)(0*

sysstat

KD

KD

FOCUS Form Factors

and ,parameters waveS and)0(

)0(

)0(

)0( Fit to

)/1.2(,/1

)0()()/5.2(,

/1

)0()(

)(4)())((2

1)(

0set factor, has )()(2)()()(

1

22

1

222

2222

2

22

222

1222

2

20

22221

2

AA

Ar

A

Vr

cGeVMMq

VqVcGeVM

Mq

AqA

qAmM

KMqAmMqmM

qmqH

mqHqVmM

KMqAmMqH

v

VV

AA

ii

KD

DKDKD

K

tKD

DKD

Tried in fit,no sensitivity (E791?)

(common – vary generated parameters in Montecarloby using agreement with reconstructed distributions and data)

Pioneered by D.M. Schmidt for E691 K*ev analysis: NIM A 328 (1993)

0*KD

2max

2V /in 3 and in 3 ,cosin 5 ,cosin bins 5 qq

Kmin 4 and in 3 ,cosin 3 ,cosin bins 3 V

S-wave termBreaks symmetry

S-wave term andr’s essentially decouple

FOCUS Form Factors 0*KD

Cuts similar to previous, some change to get uniform acceptance, one extra

OoM – Charm vertex outside of target and silicon by Vertex1Cut on q2 < 0.2 GeV2/c2 r’s are flat, feeling mμ? Goodness of fit issue

Right sign – Wrong sign

Charm Background

Systematic ChecksS-wave – varied cuts35 fits – Sample VarianceForm Factor (3 sources)1) Varied Cuts2) Split sample

3) Vary MC input Charm Backgrounds

)/9.0(2,, cGeVKD mDDP

2)0(

)0(2

1

3 A

A 064.0049.0875.02

039.0057.0504.1

)()(

05.007.068.0

015.0022.0330.0

r

r

sysstat

A

V

Phys.Lett.B544:89-96, 2002hep-ex/0207049

CLEO Form Factors and CP eC0

Spin ½ Λ baryon adds a new wrinkle…

Körner and Krämer use supplementary definitions for X and the lepton angle

0,1,1,0,1,12

1

2

1

2

1

2

1

2

1

2

1

)}cos1(sinsincos)Re(

)cos1(sinsincos)Re(

)cos1(sin||

)cos1(sin||

)cos1()cos1((||

)cos1()cos1((|{|

coscos

22

3*

22

3*

24

32

24

32

28

32

28

32

2

4

12

102

1

12

102

1

02

1

02

1

12

1

12

1

WW

WW

W

W

W

W

W

HH

HH

H

H

H

H

ddddq

d

eC0

One pole mass describes the decay222

22

22 )/1(

/1

)()( PoleMax

Pole

Max MqMq

qfqf

Helicty H’s made from 2 form factors:

)0,( isspin

|)(||)(|expect

2

22

21

fsticky

qfqf

CBIntegrate over variables and look at asymmetries:

)cos1(cos2

2

Cddq

d(other choices possible)

(no sign change for particle and anti-particle)


2

12

/)(10.0)(07.013.2

)(04.0)(05.031.0/

cGeVsysstatM

sysstatffR

pole

(To be sent to PRL)

Systematics: -Background Normalizations-Kinematic Closing-Fitting simulation-Efficiencies

KK

13.4 fb-1 from CLEO II and II.5

Look for Λe+ pairs where Λ→p π –

directionPFindP C )(?)( - Event thrust axis for direction- Try to close kinematics:

22

)( PPPP eC

(use fragmentation to break ambg)

(again the Schmidt meth)

Semileptonic Round-up

(From K. Stenson’s APS review)

0*KD

Interference effectsNeed other experiments to look Probably more in there…

Lowers by 5.5%

Semileptonic Round-up

We all seem to agree!)(

)(

S

S

D

D eC0

No CP violation

expected toclose/ 12 ff

C Expect ~-1 from HQET

Good agreementin the Distributions

I didn’t miss ‘em!

y)prelininar (Too CLEO

y)preliminar (Too CLEO

y)prelininar (Too CLEO *

py)Spectroscoin cover willChistov(Ruslan BELLE

0

0

0

S

eC

C

D

e

eKD

Would be nice to measure:

BARBARandBELLECDFfromDecaysRare

VDPD

KD

eKDeD ee

,

/

confirmed effects ceInterferen

,0*

00

semileptonic & rare charm decays

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