Rare and Semileptonic Decays of B and K Mesons

Jeffrey D. RichmanJeffrey D. RichmanUniversity of California, Santa BarbaraUniversity of California, Santa Barbara

BBAABBAR CollaborationAR Collaboration

Particles and Nuclei International ConferenceSanta Fe, Oct. 27, 2005

Goals and challenges

KL0

The “kaon revolution”: KL e- , |Vus|, and the recalibration of kaon branching fractions

Electroweak penguin/box diagram processes: BK*, B, BXs and BK l+l-, BK* l+l-

Semileptonic B decays and the measurement of |Vcb |, |Vub |, mb, mc

[Leptonic B decays: Bs+B+ ] Perspective and conclusions

Outline Outline

Far too many topics to cover... my apologies! Parallel session talks contain manymore details (Bizjak, Godang, Koeneke, Mohapatra,…)

Rare decay: loop/box process test SM at 1-loop level new (heavy) particles can be produced in virtual intermediate states; can compete with SM amps search for effects of new physics

Semileptonic decay: tree diagram measure |Vij| determine quark masses, QCD parameters

W

, b s,c u

d d

Rare and Semileptonic Decays: GoalsRare and Semileptonic Decays: Goals

ijV

b , ,u c t

W

,s d

d d

Common theme: understanding dynamicsCommon theme: understanding dynamics

• Amplitude factorizes single hadronic current• Form factors/QCD parameterscan sometimes be extracted from data or be calculated• Precise rate predictions possible

for some processes• Methods: HQET, heavy-quark expansions, lattice QCD,…

b , c u

B

Z0K

ub BV f

W

B

b

u

0s

Wd

dd

W

t

Understanding dynamics is an important goal in itself!

212

2 412

2

2

3

3

1 ( )

1 ( )

(1 ) 1

0.97 0.23 0.004

0.23 0.97 0.04 (leaving out phases)

0.008 0.04 1

ud us ub

cd cs cb

td ts tb

V V V A i

V V V A O

V V V A i A

CKM matrix: CKM matrix: bb and and ss decays are both suppressed! decays are both suppressed!(Wolfenstein parametrization)

5 highlighted Vij: discuss in this talk!

*

*ud ub

cd cb

V V

V V

*

*td tb

cd cb

V V

V V

2 ( )

1 ( ) 3 ( )

( , )

(0,0) (1,0)

*Col(1) Col(3) 0

unitarity:6 triangles, allwith same area

0 0 0 0S S SB K K K BABAR

Buras, Schwab, & Uhlig, hep-ph/0405132; very small theory errors achievable.

KKLL00

d

d

Z

s

d

W

t

0K tsV *tdV

• KL decay directly measures height of unitarity triangle)!

• SM prediction: • Use K+0 e+ measurement to compute hadronic current.

tsV *tdV

sd d

d

0 0 * * 2 5( ) ( )L ts td ts tdAmp K V V V V A

* 2 3( ) ( ) (1 )ts tdV V A A i

0K

t

W W

0 0 11( ) (3.0 0.6) 10L SMB K

11( ) (7.8 1.2) 10SMB K 1.30 10

787 / 949 0.89( ) (1.47 ) 10E EB K E949, PRL 93, 031801 (2004)

0

• Prelim. result uses 1.14 x 109 KL decays; =0.73x10-2 • So far, only very small fraction of data used. • No events observed in signal box

• E391a goal

• Proposal in preparation for follow-on experiment at

J-PARC

Preliminary results on Preliminary results on KKLL00 from KEK E391a from KEK E391a

(90% C.L.)

2. Reconstruct decay vertex assuming

M=M(0).

3. Signature: z(vertex) and pt

0 0 7( ) 2.86 10LB K

0 0 9( ) 1.4 10LB K

0 0 0

0

LK

n X Y

Major backgrounds

1. Measure position and energy in CsI

KKee , | , |VVusus|, and the “kaon revolution”|, and the “kaon revolution”

2 52 2 2 2

3 23(1 ) ( 0)

192F K

K us EW K SU K

G MV S C f q I

W

s u

d d

usV

long distance rad. corrections

I-spin corr.for K+ decay

KLe: 1K+e:1/2

form factortheory: q2=0exp’t: shape

2 2 21 0.0043 0.0019ud us ubV V V

0.0104 0.002

0.019 0.003

0.0006 0.002

L

L

eK

K

e

K

Review of Particle Properties, 2002

Cirigliano et al.,Eur.Phys. J C35, 53 (2004)Andre, hep-ph/0406006

Leutwyler & Roos, Z.Phys.25, 91 (1984)

short distanceradiative corr.

1.022EWS

Sirlin, Nucl. Phys. B196, 83 (1982)

0.9734 0.0008udV

0.2196 0.0023usV

+other work in progress

experiment: BR,

Recalibration of Recalibration of KKLL branching fractions branching fractionsKTeV measured 6 largest KL modes [PRL 93, 181802-1 (2004)]

• Account for 99.93% of decays; 5 ratios of branching fractions • 105-106 events/mode; careful treatment of radiation from electrons.• Measurement of KL semilep form factors (1.7%-4.2% shifts) [hep-ex/0406003, 0406006]

LK e

0 0 0LK

LK

LK

0LK

0 0LK

E. Blucher, Lepton-Photon 2005fit to all new meas.

Extraction of |Extraction of |VVusus||

Average of recent results: • KLOE, KTeV, NA48, ISTRA+• correlations taken into account

E. Blucher, Lepton-Photon 2005

(0) 0.2173 0.0008usV f (0) 0.961 0.008f

0.2261 0.0021usV

Competing method: (K++ [KLOE, hep-ex/0509045] + lattice [MILC,

PRD70, 114501 (2004); Marciano, PRL93, 231803 (2004)]

0.2223 0.0026usV

2 2 21 0.0004 0.0011ud us ubV V V (0)usV f

b , ,u c t

W

,s d

d d

Radiative penguin decays of Radiative penguin decays of BB mesons mesons

Observation of BK* CLEO II (1993): Loops in B decays!

6(10 )B

*( )M K

*

5

( )

4 10

B B K

PRL 71, 674 (1993)cited >500 times!

Now it’s a physics program!

Observation of theObservation of the b bdd decaysdecays B B

0.026 0.0380.025 0.0290.200td

ts

V

V

*

*

32 2(

2

, ) 232 2

( ( , ) )

( )

1 / 1

1 /

td

t

B

BsK

B B

B B K

m mR

m

V

V m

Ali, Lunghi, Parkhomenko, PLB 595, 323 (2004)

0.85 0.10

0.1 0.1

Belle

8.2 evts

20.8 evts

5.9 evts

Belle, 386 M BB hep-ex/0506079

BABAR, 211M BB PRL 94, 011801 (2005)

good agreementw/global CKM fit

ModeMode BABAR BABAR (10(10-6-6) ) (2.1(2.1 signif.) signif.)

Belle (10Belle (10-6-6) ) (5.5(5.5 signif.) signif.)

0 0B

B

0B

0.35 0.090.31 0.081.17

0.43 0.120.37 0.110.55

0.4

1.8

1.0 0.34 0.140.31 0.100.58

Belle

BABAR PRD 72, 052004 (2005)

• Canonical process for testing the SM at 1 loop level• Provides powerful constraints on new physics models• Major effort by theory community to compute QCD and EW corrections; NLL calculation complete; NNLL calculation forseen

Belle, PRL93, 061803 (2004)

fully incl.

sum of 38 excl.modes

Hurth, Lunghi, Porod, Nucl. Phys. B 704, 56 (2005); see also Neubert, Eur.Phys. J C40, 165 (2005); Buras et al., Nucl.Phys. B631, 219 (2002)

Inclusive Inclusive BBXXs s Decay Decay

E E

4/( ) (3.70 0.35 | 0.02 | 0.25 | 0.15 | ) 10

c bs m m CKM param scaleB B X

0.30 40.27( ) (3.39 ) 10sB B X HFAG July 2005

*K

Moments of Moments of BBXXss Photon Energy Spectrum Photon Energy Spectrum

Minimum Eγ (GeV)

hep-ex/0507001

1st Moment (GeV) 2nd Moment (GeV2)

Minimum Eγ (GeV)

D. Benson, I.I. Bigi and N. Ultrasev Nucl. Phys. B 710, 371-401 (2005)

(see talk by Karsten Koeneke, Section VI.4)

Used in determination of mb, |Vcb |, and | Vub |

b s

d d

, Z

b, ,u c t

s

d d

Electroweak penguinsElectroweak penguins B BKlKl++ll-- and and BBKK**ll++ll--

BABAR hep-ex/0507005 (229M BB) Belle prelim. hep-ex/0410006, 0508009

B K *B K

• With l+l- pair, can produce both pseudoscalar and vector mesons• New physics can affect both rate and kinematic distributions.

W W

W

, ,u c t

BBKlKl++ll-- and and BBKK**ll++ll- - : branching fractions : branching fractions

Theory errorsmainly due to form factors.

(rarest observed B decay) 6 (10 )

6( ) (0.45 0.05) 10WAB B K

* 6( ) (1.18 0.17) 10WAB B K

2q2q

pole at low q2

BBKK**ll++ll--: : Lepton F-B AsymmetryLepton F-B Asymmetry

Bl

l

s

q*K

l

Lepton angular distribution in ll rest frame

hep-ex/0508009Belle: lepton A(FB) [raw]

2q

386 M BB

SM

NP scenarios

constraints on Wilson coeffs describing short-distance physics

FBA

Precision measurement of |Precision measurement of |VVcbcb|| and the atomic and the atomic physics of physics of BB mesons mesons

s

s

3exp HQE th

exp HQE

exp HQE

exp HQE

(41.4 0.4 0.4 0.6 ) 10

(10.61 0.16 0.06 )%

(4.61 0.05 0.04 0.02 )GeV

(1.18 0.07 0.06 0.02 )GeV

cb

c

b

c

V

m

m

Bs

s

s

s

2 2exp HQE

2 2exp HQE

3 3exp HQE

3 3exp HQE

(0.45 0.04 0.04 0.01 )GeV

(0.27 0.06 0.03 0.02 )GeV

(0.20 0.02 0.02 0.00 )GeV

( 0.09 0.04 0.07 0.01 )GeV

G

D

LS

BABAR, PRL 93, 011803 (2004)

22

3

5

23 3 3 3

34

2 2

42 30 2

( ) (1 ) ( , )192

( ) 1 2(1 ) ( ) (1/ )2

b

b bb

b b b

FSL c cb ew pert

D LS DG

S

DG

L

m

m mm

m

GB X l V

m m

A A r

z r r d r O

Observables• inclusive semileptonic rate• inclusive lepton-energy spectrum (moments)• inclusive recoil hadron mass spectrum (moments)

Heavy-quark expansion theory params: |Vcb|, mb, mc, , G , D , LS

Benson, Bigi, Mannel & Uraltsev, hep-ph/0410080Gambino & Uraltsev, Eur.Phys.J. C34, 181 (2004)

chromomagnetic expec. value

kinetic expec.value

Darwin term

spin-orbit

2( / )c br m mkinetic scheme

||VVcbcb| and inclusive parameters from | and inclusive parameters from BBXXccll and and BBXXss

Buchmuller and Flacher; hep-ph/0507253• Fit to moments of inclusive distributions in BXc l and BXs • Experiments: BABAR, Belle, CDF, CLEO, DELPHI

3(41.58 0.45 0.58) 10cbV

4.591 0.040 GeVbm

(GeV)bm bm

2

2(GeV )

3(10 )

cbV

<2%errors

1.5 31.7(41.2 1.0 ) 10cbV D*l

zero rec.kinetic mass scheme

b s

b c

b c

all moments

all moments

Measuring |Measuring |VVub ub | is hard, but the error is shrinking| is hard, but the error is shrinking

BABAR hep-ex/0509040

bu

continuum data (off res)

bc subtraction

BBrecoreco

BBrecoilrecoilXXuu ll

ee--

DD**

ee++

( )0.1 2%

( )ub u

cb c

V B X

V B X

Lepton spectrum endpoint analysis Fully reconstructed B recoil analysis

Large bc background; suppression cuts introduce dependence on theory predictions for kinematic distributions.

Belle hep-ex/0505088

( )uM X 2q

||VVub ub | inclusive measurements| inclusive measurements

• Key CKM constraint

• Use mb and QCD parameters extracted from inclusive BXc l and BXs spectra.• Many methods with uncertainties around 10%. • Uncertainty from mb has been reduced to 4.5%.• With more data, the |Vub| uncertainties could be pushed down to 5%-6.5%.

2 2ub

cb

V

V

mX vs. q2

Eℓ endpoint

mX

Eℓ vs. q2

3

WAvg(4.38 0.19 0.27) 10ubV

expt mb, theory

u

q

2 2maxq q

uq

2 2minq q

HPQCD: hep-lat/0408019

Fermilab/MILC: hep-lat/0409116

f+(q2) is relevantform factor forB l l=e

HPQCD

Fermilab/MILC

restricted q2 range

At fixed q2, lepton momentum spectrum is exactly known in this mode, since only one form factor.

2q

BB00 l l-- form-factor predictions form-factor predictions

Measuring |Measuring |VVubub| using | using BB ll and lattice QCDand lattice QCD

B l branching fraction and q2 distributionBecher and Hill, hep-ph/0509090

Relatively flatdistribution in spite of rapidly changing form factor.

Consequence of p3 factor in decay rate.

HFAG averages

0 4( ) (1.35 0.08 0.08) 10B B 0 4( | 16) (0.40 0.04 0.04) 10B B q

2 0.67 30.46(HPQCD; 16) (4.47 0.30 ) 10ubV q

2 0.65 30.43(FNAL; 16) (3.78 0.25 ) 10ubV q

Search forSearch for B Bss++-- and and BB00ll++ll--

Highly suppressed in the SM• • Bd suppressed by |Vtd/Vts|2

• No SM signals expected at Tevatron or at B factories, but can have large enhancements from new physics.

9( ) (3.5 0.9) 10sB B

SM predict.SM predict. CDFCDF D0D0 BABARBABAR BelleBelle

-- --sB

dB

dB e e

71.6 10 73.0 10 93.5 1088.3 10 86.1 10

11(10 )O

15(10 )O

83.9 10 71.9 10

71.6 10

WWZ

b W

W s

t

b

bt

0 0H A

6

4

tan( )s

A

B Bm

W W Z

Strong correlation withneutralino-proton crosssection in mSUGRA!Beck,Kim,Ko hep-ph/0406033

K Physics• Early results from 1st dedicated KL experiment• KL branching fractions re-measured: 5% to 8% shifts• |Vus| shift: +3% • Unitarity of 1st row of CKM matrix looks better; work in progress

on |Vud|

B Physics• B observed; provides interesting constraint on |Vtd|/|Vts|• Many bs and bsl+l- modes observed; studies of kinematic distributions are especially interesting• |Vcb| measured to 2% via inclusive method; mb well determined• |Vub| precision now below 10%. • Keep pushing inclusive vs. exclusive crosscheck!• Leptonic B decays providing interesting sensitivity to new physics • B factories will push to 1 ab-1. Many more results to come!

Perspective/ConclusionsPerspective/Conclusions

Backup slidesBackup slides

Huge program on B decays to charmless hadronic final states...

(10-6)

see H. Jawahery talk for hadronic bs decays

6/10B

Observation of theObservation of the b bdd decaysdecays B B

Note: naïve expectation is (B++(B00(B0BABAR/Belle discrepancy on B00; to be resolved with more data.

BABAR Belle

0 0 0 0S S SB K K K BABAR

BBXXss New Physics Sensitivity New Physics Sensitivity• Constraints on Two Higgs doublet models (Type II)• mH = charged Higgs mass• tan = ratio of vacuum expectation values of the two doublets• Hou [PRD48, 2342 (1993)], Gambino & Misiak [Nucl. Phys

B611, 338 (2001)], Neubert [Eur. Phys. J C40, 165 (2005)].

(GeV)Hm

tan tan

90% C.L. allowedregions (above lines)

current BABAR data future projections

B

sB X

combined

sB X B

2 ab-1

0.5 ab-11 ab-1

Search for leptonic Search for leptonic BB-- decaysdecays

Non-relativistic mesons (2 heavy quarks): 22 12 (0)Mf M

ubV W

B

b

u

• helicity suppressed• CKM suppressed (Vub) • annihilation diagram• tree-level sensitivity to H-

22 22 2 2

2( ) 1

8F

Qq qQ M

G mM V f M m

M

meson B (e) B () B ()

KK++

BB++

41.2 10 99.99%51.2 10 63.5%111.1 10 74.8 10 41.1 10

Predicted leptonic branching fractions: (|Vub| = 0.0039, fB = 200 MeV)

Search for Search for BB--

SMSM BABARBABAR (232 M BB) (232 M BB) Belle (275 M BB)Belle (275 M BB)

B(B+

42.6 10 (90% C.L.)

Belle, hep-ex/0507034

BABAR, hep-ex 0507069 reconstruction: a major challenge• fully reconstruct other B in event• require lepton (or pion) and no additional observed energy (2-3)

ee--

ee++

recB

B

eee-

Eextra

ee

Backgrnd Backgrnd

Expected signal x10

41.8 10 (90% C.L.) 41.1 10

Search forSearch for B Bss++-- and and BB00ll++ll--

Highly suppressed in the SM• • Bd suppressed by |Vtd/Vts|2

• No SM signals expected at Tevatron or at B factories, but can have large enhancements from new physics.

9( ) (3.5 0.9) 10sB B

SM predict.SM predict. CDFCDF D0D0 BABARBABAR BelleBelle

-- --sB

dB

dB e e

71.6 10 73.0 10 93.5 1088.3 10 86.1 10

11(10 )O

15(10 )O

83.9 10 71.9 10

71.6 10

WWZ

b W

W s

t

W W Z

90% C.L.

BBss++--and SUSYand SUSY

b

bt

0 0H A6

4

tan( )s

A

B Bm

Dark matter cross section (p) vs. B(Bs+-).

Dermisek, Raby, Roszkowski, Ruiz de Austri, hep-ph/0507233

Baek, Kim, Ko, hep-ph/0406033

Experiment vs. Lattice: Experiment vs. Lattice: DDKK ll form factorform factor

Measuring |Measuring |VVubub| using | using BB ll

BABARProjection to 1 ab-1 (data taken to be on BK fit curve from present measurement).PRD 72, 051102 (2005)

In the high q2 region alone, we will measure the branching fraction with an uncertainty of (6-7)% , or (3-3.5)% uncertainty on |Vub |. Lattice theorists expect to reach 6%, so exclusive/inclusive will be similar.

Precision measurement of |Precision measurement of |VVcbcb|: fits to moments of |: fits to moments of lepton spectrum and hadron recoil spectrum lepton spectrum and hadron recoil spectrum

mX moments

Eℓ moments

● = used, ○ = unusedin the nominal fit

Red line: OPE fitYellow band: theory errors

BABAR

2/ndf = 20/15

BABAR PRL 93:011803 (2004)