rare ew penguin decays tom ziegler win05 2005 delphi, greece 6-11 th june 2005 1 b -> s b...
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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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 2
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 3
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 4
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 5
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 6
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 7
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 8
Extract BR(b -> Xs )
Measurements and SM calculations agree very well, theoretical uncertainties are already of same order
than statistical errors of measurement!
[B9]
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 9
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 10
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 11
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 12
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 13
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 14
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 15
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]
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 16
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]
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 17
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 18
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)
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 19
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]
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 20
|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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 21
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 22
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 23
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 24
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 25
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 26
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 27
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)
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 28
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!
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 29
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 30
... a lot of work lies still ahead!
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 31
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 32
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 33
[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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 34
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)
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 35
[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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 36
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.
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 37
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
Mbc = E*2beam – |p*
B|2
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 38
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 39
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()
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 40
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|
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 41
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
Rare EW Penguin Decays Tom Ziegler WIN05 2005 Delphi, Greece 6-11th June 2005 42
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:
Mbc = E*2beam – |p*
B|2