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
Final Results from FOCUS ),()( KD S
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
Final Results from FOCUS ),()( KD S
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)
CLEO Form Factors and CP eC0
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)
CLEO Form Factors and CP eC0
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