Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11 th June 2005 1 b -> s b -> s l + l - and other rare B decays with the Belle

Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 1

b -> s b -> s l+l- and other rare B decayswith the Belle Detector

Tom Ziegler

WIN 2005

Delphi, Greece 6-11th June 2005

Motivationb -> s b -> d

b -> s l+l-

Summary &

Perspective


Flavor Changing Neutral Current

=> Test SM and search for new physics!

Branching fractions Direct CP violation CP violation phase CKM elements Vtd, Vts

Wilson coefficients Energy/mass spectra, moments, …

Decays in this talk proceed viaFlavour Changing Neutral Currents (FCNC)

=> penguin and box diagrams


The KEK-B collider

3.5 GeV e+ on 8 GeV e-

L = (1.6 x 1034)/cm2/sec

L dt > 450 fb-1Y(4S)

Currents: 1.8 A x 1.3 A=>

18-may-2005

31-may-2005


The Belle Detector

3/4 layerSilicon Vertex Detector

Central Drift Chamber

8 GeV e-

3.5 GeV e+

Aerogel Cherenkov Counter

ToF counter

Electromagnetic. Cal.(CsI crystals)

1.5T SC solenoid

and KL detection system


Continuum suppression

BB and qq have different topologies!

Typical variables for Bkg suppression:- Modified Fox Wolfram moments- Sphericity cossph)- Thrust, cos(thr)- …

=> Build Fisher discriminant F for correlated variables=> Form Likelihood for uncorrelated variables: L(F,cosB)

=> Build Likelihood ratio: LR = LB / (LB+Lqq)Kinematic Variables: *

beam*B EEE

2*B

2*beambc p)E(M


b -> s

BR(b->s3.5 10-4

Not so rare actually…

=> Test SM and search for new physics!

Pure penguin diagram in leading order

Investigate - inclusive - exclusivedecays => extract observables

Wilson coefficient

)m/1.(corrCVV32

mGsb b

27eff

2

tb*

ts4

5bem

2F


Inclusive b -> Xs

Select photons with E* > 1.5 GeV

(analysis done with E* > 1.8 GeV)

Veto photons from 0 and decays Subtract background<E> = 2.289 ± 0.026 ± 0.034 GeV

<E2> - <E>2 =

0.0311 ± 0.0073 ± 0.0063 GeV2

Smeared by motion of b quarkinside the B meson and gluon emission => dynamics of B meson

important for Vub measurementfrom inclusive charmless semileptonic decays [B18,B19]

[B9]

based on 140 fb-1


Extract BR(b -> Xs )

Measurements and SM calculations agree very well, theoretical uncertainties are already of same order

than statistical errors of measurement!

[B9]


B -> K*

•K*(892) reconstructed in 4 final states:

K+-, K0s0, K+0, K0

s+ with

|M(K) – M(K*)r| < 75 MeV/c2

[B8]

Based on 78 fb-1


BR(B -> K*)

BR(B0 -> K*0) = (40.1 2.1 1.7) 10-6 NLO calc = (71 23)

10-6

BR(B+ -> K*+) = (42.5 3.1 2.4) 10-6 NLO calc = (75

23 ) 10-6

[B8]

*beam

*B EEE

2*B

2*beambc p)E(M

Ali, Parkhomenko [T2]Bosch,Buchalla [T3]

Based on 78 fb-1


0+(B -> K*)

Investigate Isospin asymmetry between B0 and B+:

0+ = (+1.2 4.4

2.6)%

SM predicts +(5-10)%!

B0

B+ = 1.083 0.017 [PDG2002]

Assumes f+/f0 = 1!

f+/f0 = 1.072 0.057

[PDG2002]

)KB()KB(

)KB()KB(**00

**00

0

0B

B

0B

B

BRBR

BRBR

[B8]

Kagan, Neubert [T4]

Based on 78 fb-1


ACP(B -> K*)

ACP = (-1.5 4.4

1.2)%

In SM ACP should be

smaller than 1% !ACP = 1/(1-2w)

N(B->K*) - N(B->K*)

N(B->K*) + N(B-

>K*)

Mbc = E*2beam – |p*

B|2

[B8]

Bosch,Buchalla [T3]

Based on 78 fb-1


Time-dependent CPV

tmcosAtmsinS

K)t(BK)t(B

K)t(BK)t(BA

00S

00

0S

0

00S

00

0S

0

CP

Use K0S0 final state for time-dependent CP analysi:

11.058.0)K(S38.0

46.000S

11.034.003.0)K(A 00S

[B17]

Based on 253 fb-1

Atwood et al [T5]Gronau et al [T6]

SM <0.1

SM <0.01


B -> K

Reconstruct -> and -> + - 0

K0S -> + -

|M(K)| < 2.4 GeV/c2 (EB > 2.1 GeV, about 84% of b-

>s)

B+

-> K

+

B0

-> K

0

No hint for B -> K*3(1780)

6.8 3.4

6

9.0

2.1 105.14.8)KB(

BR 6

6.1

9.1

7.2

1.30S

0 107.8)KB(

BR

[B11]

Good candidate for time-dependent CPV!Atwood et al [T5]

Based on 253 fb-1


B -> K1(1270)

Reconstruct K++- and K0+- Search for resonant structure in M(K+-)

Based on 140 fb-1

=> prediction: 0.5-2.0 10-5

51 109.09.03.4))1270(KB( BR (7.3 ) (large!)

501

0 108.5))1270(KB( BR 5105.1))1400(KB( BR @90% CL

first observation!

of axial-vector resonance

radiative B-decay

[B12]

[T8]

Interesting: time-dependent CPV, photon-helicityAtwood et al [T5]


B+ -> p

Reconstruct -> p +

Based on 140 fb-1

653.0

58.0 1020.016.2)pB(

BR (8.6 )

600 106.4)pB( BR @90% CL

[B14]

first observation

of hyperonic radiative decay!

SM expectation: 10-6 Cheng, Yang [T11] Geng, Hsiao [T12]


Summary of b -> s

o Many neutral exclusive b -> s modes for time-dependent CPV!

o K0 final state should help forphoton polarization

o useful to reduce inclusive b -> s systematic errors

o isospin in B and K(*) decays is assumed

59 6 %missing


b –> d

Look for the exclusive modes:

B- -> -, B0 -> 0 , B0 ->

The b -> d transition should be suppressed by|Vtd/Vts|2 0.04 (large uncertainties on Vtd)=> BR 0.9-2.7 10-6 expected

+

(where - -> - 0, 0 -> + -, -> + - 0)


B -> and B0 ->

Simultaneous fit to B+ -> +, B0 -> 0 and B0 –> From isospin relations:BR(B+ -> +) = 2 ((B+)/(B0)) BR(B0 -> 0) = 2 ((B+)/(B0)) BR(B0 -> ) (B+)/B0) = 1.086 ± 0.017)

Based on 253 fb-1

Limit:BR((,)) < 1.4 · 10-6 @ 90% CL

[B15]


|Vtd/Vts| from B -> (,)

Significance: 1.2

SM predictions: Ali-Parkhomenko[T2]: BR(B+ -> +) = (0.90 ± 0.34) 10-6

Bosch-Buchalla[T3]: BR(B+ -> +) = (1.50 ± 0.50) 10-6

Constraint on Vtd:

R1)m/m1(

)m/m1(

VV

)KB()),(B( 2

32B

2

K

32B

2),(

2

ts

td*

2

BRBR

22.0V

V

ts

td @ 90% CL

[B15]

6

39.0

43.0 10)28.072.0()),(( BR

Based on 253 fb-1


B -> Xs l+l-

+BR(b->sl

+l-emBR(b->s) 10-6 !!!

Again: New particles can/will contribute significantly to the decay rates and various asymmetries via the loops!

=> Testing ground for SM and extensions (2HDM, MSSM, GUT, …?)

b -> sl+l- penguin: b -> sl+l- box:

)m/1.(corrCCRe,C,C,CVV~sd

)sb(db

9eff

7eff

210eff

29eff

27eff

2

tb*

ts2em

2

b)m/M(s


Inclusive b -> s l+l-

Select oppositely charged leptons (e±,±) Reconstruct hadronic system semi-inclusively (K(n)) M(l+l-) > 0.2 GeV/c2

687.083.0s 1030.104.4)eeXB(

BR

685.081.0s 1005.113.4)XB(

BR

685.081.0s 1083.011.4)XB(

BR

6s 1070.02.4)XB( BR

Ali et al

[B13]

[T13-T15]

Based on 140 fb-1


Dynamics of b->s l+l- transition

M(Xs): test model fragmentation

q2 = M2(l+l-): check for non-SM effects

No surprises so farwith available statistics!

[B13]

Based on 140 fb-1


exclusive B -> K(*) l+l-[B13]

770.0

75.0 1002.027.050.5)KB(

BR

72.2

3.2* 104.09.05.16)KB(

BR

q2 distribution in comparison with SM pred.

[T13,T16,T17]

Based on 253 fb-1


AFB in B -> K* l+l-[B13]

)0(cos)0(cos

)0(cos)0(cosA

BB

BBFB

AFB(K l+l-) = 0 (control sample)

AFB(K* l+l-)AFB in q2 bins from Mbc fit

and Z interference in SM:sensitive to C7, C9 and C10 => errors still too large!

Based on 253 fb-1


Super KEK-B

1.6x1034

450 fb-1

5x1034

~1 ab-1

2.5x1035

~10 ab-1

Lpeak (cm-2s-1)Lint

Crabcavities

Major upgrade ofKEKB & Belle detector

~1010 BB/year !!~108 BB/year x 100


AFB in B -> K* l+l-

Precise determination of C9 and C10 is possible=> C9/C9 10%, C10/C10 13% at 5 ab-1, C7 fixed from b -> sNeed fit to 2-dim q2 vs. angular distribution(systematic error neglected here)


What have we achieved?

What did we know before the B-factories?Radiative B-Decays in PDG 2000:

charged modes neutral modes

--------------------------------------------------------------------------------

K*(892) (5.7±3.3) • 10-5 (4.0±1.9) • 10-5 PDG

2000

K1(1270) < 7.3 • 10-3 < 7.0 • 10-3

PDG 2000

K*2(1400) < 2.2 • 10-3 < 4.3 • 10-3

PDG 2000

K*2(1430) < 1.4 • 10-3 < 4.0 • 10-4

PDG 2000

K*(1680) < 1.9 • 10-3 < 2.0 • 10-3

PDG 2000

K*3(1780) < 5.5 • 10-3 < 1.0 • 10-2

PDG 2000

K*4(2045) < 9.9 • 10-3 < 4.3 • 10-3

PDG 2000

Dramatic improvement of our knowledge of radiative B-decays!


Summary

Radiative B decays are rich field with interesting physics Knowledge increased dramatically since start ofB-factories Measurements of BR have already very small errors B -> s

many decay modes seen, time-dependent CPV,constraint on Vts, a lot of useful observables fortest of SM and its extensions

B -> d not yet seen, but should be available soon,constraint on Vtd

B -> s l+l-

established, important to pin down Wilson coefficients


... a lot of work lies still ahead!


References I, Belle

[B1] K. Abe, et al, A Measurement of the Branching Fraction for the Inclusive B -> Xs Decays with Belle, PLB 511, 151 (2001), hep-ex/0103042

[B2] K. Abe, et al, Observation of the Decay B -> K l+l-, PRL 88, 021801 (2002), hep-ex/0109026

[B3] S. Nishida, et al, Radiative B Meson Decays into K and K Final States, PRL 89, 231801 (2002), hep-ex/0205025

[B4] J. Kaneko, et al, Measurement of the Electroweak Penguin Process B-> Xs l+l-, PRL 90, 021801 (2003), hep-ex/0208029

[B5] A. Drutskoy, et al, Observation of radiative B -> φ K decays, PRL 92, 051801 (2004)

[B6] A. Ishikawa, et al, Observation of B -> K* l+l-, PRL 91, 261601 (2003), hep-ex/0308044

[B7] M.-C. Chang, et al, Search for B0 -> l+l- at Belle, PRD 68, 111101 (2003), hep-ex/0309069

[B8] M. Nakao, et al, Measurement of the B -> K* Branching Fractions and Asymmetries, PRD 69, 112001 (2004), hep-ex/0402042


References II, Belle

[B9] P. Koppenburg, et al, An inclusive measurement of the photon energy spectrum in b -> s decays, PRL 93, 061803 (2004), hep-ex/0403004

[B10]S. Nishida, et al, Measurement of the CP Asymmetry in B -> Xs , PLB 93, 0218038 (2004), hep-ex/0308038

[B11]S. Nishida, et al, Observation of B+ -> K+ , PLB 610, 23 (2005), hep-ex/0411065

[B12]H. Yang, et al, Observation of B+ -> K1(1270) , PRL 94, 091601(2005), hep-ex/0412039

[B13]M. Iwasaki et al, Improved Measurement of the Electroweak Penguin Process B -> Xs ll, submitted to PRD, hep-ex/0503044

[B14]Y.-J. Lee, et al, Observation of B+ -> p , submitted to PRL, hep-ex/0503046

[B15]D. Mohapatra, et al, Search for the b -> d process, submitted to PRD, hep-ex/0505097

[B16] K. Abe, et al, Measurement of the Differential q2 Spectrum and Forward-Backward Asymmetry for B -> K(*) l+l-, hep-ex/0410006

[B17]Y. Ushiroda, et al, New Measurement of Time-Dependent CP-Violating Asymmetry in B0 -> K0

S 0 Decay, hep-ex/0503008


[B18]I. Bizjak, et al, Measurement of the Inclusive Charmless Semileptonic Partial Branching Fraction of B Mesons and Determination of |Vub| using the Full Reconstruction Tag, hep-ex/0505088

[B19]A. Limosani, T. Nozaki, Extraction of the b quark shape function parameters using the Belle B -> Xs photon energy spectrum, hep-ex/0407052

References III, Belle


References I, Theory

[T1] A.L. Kagan, M. Neubert, QCD anatomy of B -> Xs decays, EPJC 7, 5 (1999)

[T2] A. Ali, A.Y. Parkhomenko, Branching ratios for B -> K* and B -> decays in next-to-leading order in the Large Energy Effective Theory, EPJC 23, 89 (2002)

[T3] S.W. Bosch, G. Buchalla, The radiative decays B -> V at next-to-leading order in QCD, NPB 621, 459 (2002)

[T4] A.L. Kagan, M. Neubert, Isospin Breaking in B -> K* decays, PLB 539, 227 (2002)

[T5] D. Atwood, M. Gronau, A. Soni, Mixing-Induced CP-Asymmetries in Radiative B-Decays in and beyond the Standard Model, PRL 79, 185 (1997)\

[T6] B. Grinstein, et al, Photon polarization in B -> X in the standard model, PRD 71, 011504 (2005)

[T7] S. Veseli, M.G. Olsson, Radiative rare B decays revisited, PLB 367, 309 (1996)

[T8] D. Ebert, et al, Rare radiative B decays to orbitally excited K mesons, PRD 64, 054001 (2001)

[T9] A. Safir, The radiative rare decays B -> K** in the light cone QCD sum rule approach, EPJC 3, 15 (2001), hep-ex/0109232

[T10] H.Y. Cheng, C.K. Chua, Covariant light-front approach for B -> K* , K1 , K*2

decays, PRD 69, 094007 (2004)


[T11] H.-Y. Cheng, K.-C. Yang, Penguin-induced radiative baryonic B decays, PLB 533, 271 (2002)

[T12] C.Q. Geng, Y.K. Hsiao, Radiative baryonic B decays, PLB 610, 67 (2005)[T13] A. Ali, et al, Improved model-independent analysis of semileptonic and

radiative rare B decays, PRD 66, 034002 (2002)[T14] A. Ali, Next-to-leading Order Calculations of the Radiative and Semileptonic

Rare B Decays in the Standard Model and Comparison with Data, hep-ex/0210183

[T15] A. Ghinculov, et al, The rare decay B -> Xs l+l- to NNLL precision for arbitrary dilepton invariant mass, NPB 685, 351 (2004)

[T16] D. Melikhov, N. Nikitin, S. Simula, PLB 410, 290 (1997)[T17] P. Colangelo et al. PRD 53, 3672 (1998), Erratum-ibid.D 57, 3186 (1998)

References II, Theory


B0 l+l-

=> Helicity suppressed 2-body decay in SM

+

BR in SM: B->: (1.00 0.14) 10-10

B->ee : (2.34 0.33) 10-15

B->eforbidden in SM, but possible in SUSY or Lepto-Quark models!

Not observable, but enhancement by 2-3 orders of magnitude in 2HDM or Z mediated FCNC models.


B0 l+l-

•Tight cut on leptons (e/): L > 0.9

•BKG suppression with LR(F,cos(*B))

•Signal box: 5.27<Mbc<5.29 GeV/c2, |E|

<0.05GeV

E = E*B –

E*beam


B|2


Channel BR (@90% C.L.) Ldt

===================================================

B->ee < 1.9 10-7 78 fb-1 Belle

B->< 1.6 10-7 78 fb-1 Belle

B->e< 1.7 10-7 78 fb-1 Belle

Channel BR (@90% C.L.) Ldt

===================================================

B->ee < 1.9 10-7 78 fb-1 Belle

B->< 1.6 10-7 78 fb-1 Belle

B->e< 1.7 10-7 78 fb-1 Belle

B->< 2.5 10-7 113 pb-1 CDF

Bs->< 9.5 10-7 113 pb-1 CDF

Bs->< 16 10-7 100 pb-1 D0

---------------------------------------------------

B->e< 5.4 10-6 60 fb-1 Belle

B->< 6.8 10-6 60 fb-1 Belle

B->< 6.6 10-6 81 fb-1 Babar

B->< 4.1 10-4 81 fb-1 Babar

Status of B ll


SM prediction for purely leptonic/radiative B-decays:

B->: 3 10-8 B->: > 3 10-8

B->: 1 10-10 B->: few 10-10

B->ee : 3 10-15 B->ee: few 10-10

B->: 7 10-5 B->: > 7 10-5

B->: 3 10-7 B->: few 10-6

B->e: 7 10-12 B->e: few 10-6

Any significant increase in these BR might give hint for new physics

Some of these modes should be accessible with the B-factories!

Future? B ll()


Low energy eff. Hamiltonian

Heff 10i=1 Ci()Oi()

(b -> s) = 1/324 G2F em m5

b |V*tsVtb|2 (|C7

eff|2 + O(1/mb,1/mc)))

=> Access to |C7|


Low energy eff. Hamiltonian

Heff 10i=1 Ci()Oi()

(b -> s) |V*tsVtb|2 |C7

eff|2

=> Access to |C7|Interesting observables: BR, ACP, spectrum

(b -> s+-)/ds |V*tsVtb|

2 O(s, |C7eff|2, |C9

eff|2 ,|C10eff|2 , C7

effRRe(C9eff))

=> Access to |C7|, |C9|, |C10|, sgn(C7)Interesting observables: BR, AFB, q

2 distribution

s = q2/m2b = (M(+-)/mb)

2


Particle ID & Kinematic Variables

E = E*B –

E*beam

K/ separation:- dE/dx from CDC- light yield from ACC- t from ToF

e ID:- dE/dx from CDC- light yield from ACC- t from ToF- CsI (ECL)

ID:- hits in KLM

ID:- 16X0 CsI (ECL)

Kinematic Variables:


B|2

Documents

Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11 th June 2005 1 b -> s b -> s l + l - and other rare B decays with the Belle