Radiative and Rare B-Decays Fabrizio Salvatore IoP Meeting Manchester, 19 th November, 2003 Introduction Radiative Decays B->K * X s Limits

Radiative and Rare B-Decays

Fabrizio Salvatore

IoP Meeting

Manchester, 19th November, 2003

Introduction Radiative Decays B-

>K*Xs

Limits on b->d decaysB->K(*)ll DecaysB->K Decays

B->Xsll Decays

Many thanks to:

Tom Ziegler – Belle

Jeff Berryhill - BaBar

Mark Convery -BaBar

Eugeni Grauges –

BaBar

Carsten Hast – BaBar

Radiative and Rare B-Decays Fabrizio Salvatore IoP Meeting Manchester 19th Nov 2003 2

Introduction and Motivation

b -> s and b -> sl+l- decays proceed via

flavor changing neutral current (FCNC) box and

penguin diagrams

b -> s penguin:

b -> sl+l- penguin:

+

b -> sl+l- box:


New particles can/will contribute quite significantly to the decay rates and various asymmetries

via the loops!=> Ideal testing ground for SM and extensions

(2HDM, MSSM, GUT, …?)

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

BR(b->s3.5 10-4 Not so rare actually…

Study of such decay modes of the B meson are of extreme

interest in B-Factory experiments (BaBar/Belle)


PEP-II ColliderPeak luminosity: 6.58 x 1033cm-2s-1

(exceeded design goal 3.0 x 1033)

PEP-II delivered 143 fb-1

BaBar recorded 136 fb-1

For analysis:On peak 82 fb-1

~90M BB pairsOff peak 10 fb-1

Peak luminosity: 6.58 x 1033cm-2s-1 (exceeded design goal 3.0 x 1033)

PEP-II delivered 143 fb-1

BaBar recorded 136 fb-1

For analysis:On peak 82 fb-1

~90M BB pairsOff peak 10 fb-1


The BaBar Detector

DIRC (PID)144 quartz

bars11000 PMs

1.5 T solenoid

Drift Chamber40 stereo layers

Silicon Vertex Tracker

5 layers, double sided strips

e+ (3.1 GeV)e- (9 GeV)

EMC6580 CsI(Tl) crystals

Instrumented Flux Returniron / RPCs

(muon / neutral hadrons)


The KEK-B collider

3.5 GeV e+ on 8 GeV e-

L > (1.0 x 1034) cm-2sec-

1 L dt = 158 fb-1

140 fb-1 on resonance

Y(4S)


The Belle Detector

3 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 and Signal selection

BB and qq have different topologies!

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

Signal candidates are selected using two Kinematic Variables:

Build Fisher discriminant F or Neural Network N from event shape variables Form Likelihood for uncorrelated variables: L(F,cosB) Build Likelihood ratio:

LR = LB / (LB+Lqq)

VS

**beamB EEE

2*2*BbeamES pEm

BaBar


B -> K*in BaBar

•Photon with 2.30 < E* < 2.85 GeV, 0/ veto

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

K+-, K0s0, K+0, K0

s+

K+-

2GeV/c 29.527.5 ESm

75.0cos

80.0cos

80.0cos

*

*

H

B

TH

• Continuum suppression:

|M(K) – M(K*)| < 100

MeV/c2

-200<E *<100 MeV


BR(B -> K*) in BaBar

B(B0K*0) = (42.3 ± 4.0 (stat) ± 2.2 (syst))·10-6

B(B±K*±) = (38.3 ± 6.2 (stat) ± 2.2 (syst))·10-6

B0K0*K0* K+-

B±K±*K±*K±

B0K0*K0*Ks

0B±K±*K±*Ks

0±

20.7 fb-1 of data

~22.7 M

BB

BR(K0*)SM (69 21) 10-6

BR(K+*)SM (74 23) 10-6

PRL 88 101805 (2002)


B -> K*in Belle


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

K+-, K0s0, K+0, K0

s+ with

|M(K) – M(K*)r| < 75 MeV/c2

•BKG suppression against e+e- -> qq() ->

LR(F,cos(*B))


BR(B -> K*) in Belle

BR(B0 -> K*0) = (40.9 2.1 1.9)

10-6BR(B+ -> K*+) = (44.0 3.3 2.4)

10-6

Based on 78 fb-1 ( 85 M BB-pairs)

Belle-Conf-0319 (preliminary)


ACP(B -> K*)

In SM ACP should

be

smaller than 1% !

)()(

)()()21/(1

**

**

KBNKBN

KBNKBNACP

Belle

ACP = (-0.1 4.4

0.8)%

Belle

ACP = (-4.4 7.6

1.2)%

BaBar

K00 mode not used for Acp


B0 K2*0(1430) and B+ K2*+(1430)

BaBar Preliminary BaBar Preliminary

Br(B0 K2*0(1430) ) Br(B+ K2

*+(1430) )

BaBar (12.2 + 2.5 + 1.1)x10-6 (14.4 + 4.0 + 1.3)x10-6 Belle (13.0 + 5.0 + 1.0)x10-6 Cleo (16.6 + 5.9 + 1.3)x10-6

81.4 fb-1hep-ex/0308021

K2*0 -> K+-

onlyK2*+ -> K+0,

K0+ +-


B -> K from Belle


•Select 2 charged K + charged/neutral K

• ID: |M(KK) – M()r| < 10 MeV/c2

•BKG suppression against e+e- -> qq() ->

LR(F,cos(*B)) BR(B+ -> K+) =

(3.4 0.9 0.4)x10-

6

-> 5.5

BR(B0 -> K0) =

(4.6 2.4 0.6)x10-6

(-> 3.3)

< 8.3x10-6 @90% C.L.

|E|<400MeV

B+ -> K+

B+ -> K+yield = 21.65.6

90fb-1 ( 96 M BB-

pairs)

hep-ex/0309006


known at 10% level at NLO

BXsanalysis

HQET: Quark-Hadron Duality B(b -> s) = B(B -> Xs)

• Model dependent assumptions on E result from the confinement of b quark in B meson Better to impose as few requirements as possible on Xs

Inclusive approach

Large Background

s

B -> Xs BB

qq

BaBar


BXsresults (BaBar)

• Data sample 54.6 fb-1

• Significant component of bg removed by making requirements

on the other B meson• Lepton tag: pe(

*>1.3 (1.55) GeV/c

• Signal events in the region: 2.1 < E

< 2.7 GeV• ~6fb-1 off-resonance used for

continuum subtraction• Dominant Syst error from BB

bkgnd subtraction • BXd events subtracted using

SM prediction:22

)04.020.0(/)(/)( tstdds VVXBXB BB

Data

Total expected bg

Preliminary

543 signal events

64323- 10)3736388()( sXBB

hep-ex/0207076

From PDG


Penguin B decays: A leading indicator of new physics at the EW scale

CLEO B → Xs

LEP 2 direct limit

Gambino and Misiak, hep-ph/0104034

b → s provides a very powerful constraint on two-Higgs doublet models

W H

t t t~

Neubert, hep-ph/0212360

CMSSM


Banalysis

• Experimentally very challenging: Low branching ratios: ~10-6

• Large continuum background contribution from ISR and 0/

use veto

Continuum BG Use NN trained with event shape variables

• BB bkgnd from B decays resonance wider (149 MeV) than K*

Use MC simulation

• Large background from B K*


78 fb-1

BresultsB00, 0+-

B±±, ±+

B0, +-

BaBar (preliminary): (hep-ex/0306038 submitted to PRL)

Use a multi-dimensional maximum likelihood fit to mES and E to extract yields:

No Evidence found

B(B00) < 1.2·10-6 @ 90%CLB(B±) < 2.1·10-6 @ 90% CLB(B0) < 1.0·10-6 @ 90% CL


|Vtd/Vts| from B

BaBar (preliminary)

-1 -0.5 0 0.5 10

0.2

0.4

0.6

0.8

1

ksa

VubVcb

k

ksa

B limit

Isospin symmetry: (B) = (B±) =

2x(B0)

B(B) < 1.9x 10-6 @ 90% CL

Using Ali & Parkhomenko (Eur. Phys. J. C.23, 89 (2002))

|Vtd /Vts|<0.34 @ 90% CL

B(B)/B(BK*) = |Vtd/Vts|2 2 |1+R| (1-m

2/MB2)3/(1-mK*

2/MB2)3

=0.76±0.10

R=0.0±0.2< 0.047

B+/B0 = 1.083±0.017


Future of b->s,d

Large theoretical uncertainties on BR !

•Quite dramatic improvement of our knowledge on radiative decays in the last few years, thanks to the results from B-Facotry experiments;

•Current measurements are still statistically limited !

•More modes could be accessible with more data !• B0 -> K0

S promising candidate for time-dependent CPV analysis

•b->d transitions may have contribution from physics beyond the SM (SUSY) and still have to be observed


B -> K l+l- & B -> K*l+l-

•Reconstruct: K+, Ks +-, K*0 K+ -, K*+ Ks +

• For B -> K*l+l- 0.7 < M(K) < 1.1 GeV/c2

•Lepton pair: e or with p(e)>0.5 GeV/c, p()>1.0

GeV/c

• Veto on J/, (2S)

b->sll penguin

diagrams

b->sll box

diagramBaBar

In SM:B(B->K l+l-)~5x10-7

B(B->K*l+l-)~3xB(B->K l+l-)with th~35%

+


B -> K l+l- & B -> K*l+l-

2-D unbinned maximum LH fit to mES and E on all 4 decays K+ee/ and Ks

0ee/

8.4 excess over background

3-D unbinned maximum LH fit to mES, E and mK

Br(BK* ll) = (8.8 +3.3-2.9 +/- 1.0 ) 10-7

3.3 excess over background

Br(BK ll) = (6.5 +1.4-1.3 +/- 0.4 ) 10-7

BaBar

hep-ex/0308042(sub. to PRL)

113 fb-1


B -> K l+l- & B -> K*l+l-

•K: charged or neutral

• K*: K+-, K0s

+, K+0 with

• |M(K)-M(K*)r|<75 MeV/c2

•Lepton pair: e or p(e)>0.4 GeV/c, p()>0.7 GeV/c

veto on J/, (2S)

+7.6+1.0-6.9-1.1yield = 37.9

yield = 35.8+8.0+1.7-7.3-1.7BR(B -> Kl+l-)=(4.8 +1.0/-0.9 0.3 0.1)

10-7

BR(B -> K*l+l-)=(11.5 +2.6/-2.4 0.8 0.2)

10-7

Based on 140 fb-1 ( 152 M BB-

pairs)

Belle

hep-ex/0308044(sub. to PRL)

binned ML fit


B+ -> K+

A rare flavor changing neutral current SM prediction: Br (BK) 410–6

(summed over all neutrino species)The best upper limits (@90% CL): CLEO: Br (BK) 2.410–4

BaBar: Br (BK) 9.410–5

(Semi-Leptonic B-tags: BDlX (X , 0 or nothing))

(50.7 fb-1)hep-ex/0207069

PRL 86 2950 (2001)

• New search (80 fb-1) with hadronic B-tags B D0(*) () (K) (K0

s) (0)

(D* D0 and D0 K , K0, K3, Ks)

• Use kinematic variables E and mES

BaBar


B+ -> K+

BR(B -> K)<1.0510 4 @

90% CL

BaBar

• Identify tag B in E and mES

region• All remaining tracks and neutrals belong to the recoiling signal-side B

• One well identified Kaon with pK > 1.5 GeV/c• Missing momentum within the detector acceptance• no 0; “extra” neutral Energy < 300 MeV

Data

BK MC

B+B MC B0B0 MC cc MC u,d,s MC

Selected events: 3Exp. Bg events: 2.7

0.8

hep-ex/0304020BR(B -> K)<7.010 5 @

90% CLcombined

with

previous

Sub. to PRL

Signal region:-1.8<E<0.6 GeV5.273<mES<5.288 GeV/c2


B -> Xs l+l- analysis Semi-Inclusive analysis: 10 modes: 1 K± or K0

s ( ), ( + 0) 2, 0 1, ~50% of BR(B Xs l+l-)

Same analysis procedure as B -> K l+l-, but higher combinatorial bkgnd → mXs < 1.8 GeV/c2

B Xs e+e- B Xs +-

=2.5% =1.2%

82 fb-1 on-reso

Recent calculations:B(B->Xs e+e-)=6.9±1.0x10-6

B(B->Xs )=4.2±0.7x10-6

(A.Ali et al. PRD66 034002(2002)

m(e+e-) > 0.2 GeV/C2

BaBar

preliminary


B -> Xs l+l- analysis

Br(B Xs e+e-) = (6.6 ± 1.9 ± 1.91.6) 10-6

Br(B Xs ) = (5.7 ± 2.8 ± 1.71.4) 10-6

Br(B Xs l+l-) = (6.3 ± 1.6 ± 1.81.5) 10-6

Mode Nsig ( stat) Significance

(stat)

B

Xs ee

29.0 8.3

4.0

B

Xs 12.4 6.2

2.2

Sum 41.410.3

4.6


Status and Perspective: b -> s

l+l-

Next target:• precise measurement of Xsl

+l-

• q2 distribution

• AFB measurement


Summary

• Many new (and updated) results have become available during the last year from B-Factory experiments:• new measurement of B -> Xs and B -> Xsl+l-

• updated results on B -> K(*)l+l- B -> K and B -> Xsl+l-

• updated results on B -> K* and first observation of B -> K • limits on b->dg transitions (B -> ) and |Vtd/Vts|

• BR and asymmetries are in good agreement with SM• many results are still statistically limited

• We are entering the exciting phase of precision

measurements

• AFB, q2 dependence in K(*)ll, E distribution in B -> K B ->

Xs

• Radiative Penguin decays are ideal testing ground for

SM and new physics …

• Need more data to fix some of the important parameters

in

EW/radiative penguin transitions

Many interesting discoveries are still ahead…


Stay tuned !


Backup slides


What have we achieved?

Radiative B-Decays in PDG 2000:charged modes neutral modes

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

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

K1(1270) < 7.3 • 10-3 < 7.0 • 10-3

K*2(1400) < 2.2 • 10-3 < 4.3 • 10-3

K*2(1430) < 1.4 • 10-3 < 4.0 • 10-4

K*(1680) < 1.9 • 10-3 < 2.0 • 10-3

K*3(1780) < 5.5 • 10-3 < 1.0 • 10-2

K*4(2045) < 9.9 • 10-3 < 4.3 • 10-3

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


BaBa

r

Status of b->s,d

Channel BR (10-6) Ldt

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

========

B -> Xs 388 36 37 +43/-23 54.6 fb-1

B0 -> K*0 42.3 4.0 2.2 20.7 fb-1

B+ -> K*+ 38.3 6.2 2.2 20.7 fb-1

B0 -> K*02(1430) 12.2 2.5 + 1.1 81.4 fb-1

B+ -> K*+2(1430) 14.4 4.0 1.3 81.4 fb-1

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

B+ -> + < 2.1 (@ 90% C.L.) 78 fb-1

B0 -> 0 < 1.2 (@ 90% C.L.) 78 fb-1

B0 -> (783) < 1.0 (@ 90% C.L.) 78 fb-1


BelleStatus of b->s,d


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

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

B -> Xs 336 53 42 +50/-54 6 fb-1

B0 -> K*0 40.9 2.1 1.9 78 fb-1

B+ -> K*+ 44.0 3.3 2.4 78 fb-1

B+ -> K+ 3.4 0.9 0.4 90 fb-1

B+ -> K++- 24 5 +4/-2 29 fb-1

B0 -> K*02(1430) 13 5 1 29 fb-1

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

B+ -> + < 2.7 (@ 90% C.L.) 78 fb-1

B0 -> 0 < 2.6 (@ 90% C.L.) 78 fb-1

B0 -> (783) < 4.4 (@ 90% C.L.) 78 fb-1


Status of BR(b->s)


BaBar

Belle

Status of b -> s l+l-


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

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

B -> Xsll 61 14 +14/-11 60 fb-1

B -> Kll4.8 +1.0/-0.9 0.3 0.1 140 fb-1

B -> K*ll 11.5 +2.6/-2.4 0.8 0.2 140 fb-1

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

B -> Xsll 63 16 +18/-15 82 fb-1

B -> Kll6.5 +1.4/-1.3 0.4 113 fb-1

B -> K*ll 8.8 +3.3/-2.9 1.0 113 fb-1

B -> K 7.0 10-5 (@90% C.L.) 51/80 fb-1


99% CL on MH+ from B → Xs as a function of the world

average of its error

Documents

Radiative and Rare B-Decays Fabrizio Salvatore IoP Meeting Manchester, 19 th November, 2003 Introduction Radiative Decays B->K * X s Limits