April 11, 2006 V. Erkcan Özcan, UCL 1

Radiative Penguins@ B Factories

V. Erkcan ÖzcanUniversity College

London

April 11, 2006 V. Erkcan Özcan, UCL 2

Radiative Penguin FamilyFlavor Changing Neutral Currents

t,c,u

W+

b s

t,c,u

W+

b d

EW~

2/ tstd VV

bs penguin

BF, CPV, E-spectrum

bd penguin

BF, CPV, E-spectrum

Z

t,c,u

W+

b d

l+

l-

+ BOX

bsll penguin

BF, CPV, AFB, FL, / e, q2-spectrum

*KB pB

KB …

SXB

/B

llKB *KllB

llXB S

63749 10361

BFRARE!

For Bs penguins, see talk by R. V. Kooten.

April 11, 2006 V. Erkcan Özcan, UCL 3

Experimental Challenge

Signal and Backgrounds vs. photon energy for inclusive

BXs.

Analyses of all radiative penguins impeded by huge BGs.

• Continuum Backgrounds

e+e-qq() or ll().• BB Backgrounds Mostly decays of light mesons (π0/η)Problem for inclusive measurements.

• Penguins as signal & BG One signal mode is the BG of another.

April 11, 2006 V. Erkcan Özcan, UCL 4

A Signal Event

B-tagging: High-P* lepton from other B

meson.

Isotropic BB event topology.

Isolated high-E* EM deposition in the calorimeter. /s vetoed.

γ0 SKB

BG suppression not enough:

Psedo-reconstruction, event weighting, BG subtraction,

peaking BG fits etc. needed!

April 11, 2006 V. Erkcan Özcan, UCL 5

B Factories

KEKB (KEK)

PEP-II (SLAC)

Asymmetric-energy beams

Hermetic detectors

High-granularity EM CAL

Excellent vertex resolution

Data @ Y(4S) resonance and off-resonance (~10%)Analyses based on

111-386 M BBAnalyses based on

88-232 M BB

Total ~560fb-1

Total ~330fb-1

April 11, 2006 V. Erkcan Özcan, UCL 6

Exclusive bsas of Summer 05

Reconstructing particular exclusive decay. Experimentally cleaner.

BF calculations depend on form factors, so theoretically less precise.

Other observables, like CP violation parameters, to be compared to those from tree-level B decays.

Some surprises of 2005: K1(1270) / K0 as large as K*(892), p observed.

~40% of total rate.

First baryonic channel

Comparable

to K*(892)

Resonance structure in

K could tell about

polarization

Branching Ratio × 106

April 11, 2006 V. Erkcan Özcan, UCL 7

BK(’)First studied by Belle (275 M BB).

New BaBar results consistent (232 M BB).

6102.4γKB B

600 106.6γKB B

TD CP violation can be studied like BK00.

hep-ex/0603054, submitted to PRL

γK

γK0s

68.26.2 106.0 3.11

BF

γKB 00 69.1

6.11.37.2 10 7.8

BF

6105.03.10.10 BF

005.0120.0075.0 CPA

γKB 62.1

9.0 10 5.14.8 BF

First measurement

5.3 observation

γ'K

γ'K0s

First upper limits

Expected to be suppressed due to destructive interference

April 11, 2006 V. Erkcan Özcan, UCL 8

Inclusive bsConstraints on NPTotal branching fraction very sensitive decay to NP.

Two techniques: Sum-of-exclusive (K(n)), fully inclusive (reconst. only).

World average in good agreement with SM theory. => Strong constraints on NP.

Hurth et. al., Nucl. Phys. B, 704, 56 (2005)

BaBar sum-of-exclusive value statistically & systematically independent of BaBar fully inclusive value (not in HFAG).

BaBar fully inclusive value to be updated very soon.

Exp. world average (HFAG):

430.027.0S 10 39.3γXB

B

437.049.0s 10 61.3γXB

SMB

SM prediction (NLO): Experimental errors already smaller than theory.

NNLO calculation expected to significantly reduce error.

bsconstraint

bconstraint (pre-

FPCP)

Combined constraint

BaBar Physics Reach Study

Constraints to H

+ mass in 2hdm

. (follow

ing Hou, P

RD

48 2

342, 1993; and G

ambino

-Misiak hep-p

h/0104034)

2HDMin minimum Hm

E

> 1

.6 G

eV

April 11, 2006 V. Erkcan Özcan, UCL 9

bsPhoton Spectrum

2bB m

E

1st Moment:

2nd Moment:

(Momentum of b)2

Motion of b inside B, “Fermi motion”, is “universal” so information from B→XB→Xs can be used in studying other B decays (ex. extracting Vub).

s

b

Xs

BFermi motion

b

GluonRadiation

222)( BB EE

preliminary

CLEO

sum-of-exclusive fully inclusive

April 11, 2006 V. Erkcan Özcan, UCL 10

Moments of the Photon Spectrum

Moments as a function of minimum E.

Good agreement among experiments and with theory predictions.

Minimum Photon Energy (GeV)

Theory is Bigi,Benson and Uraltsev (Nucl Phys B 710 371 2005) using BaBar measured B->XclmomentsPRL 93 011803 (2004).

2 24.6 , 0.45Bm GeV GeV (Moments at higher E from Belle – not shown – also consistent.)

April 11, 2006 V. Erkcan Özcan, UCL 11

Fits to HQE Parameters

• Fits performed to obtain b quark mass and Fermi momentum in kinetic scheme (Benson, Bigi, Uraltsev) and SF scheme (Lange, Neubert, Paz).

• Fits to bcl moments, bs moments or bs spectra are consistent.

Fit to bs moments

Fit to bcl moments

Combined fit to moments

Fit to bs spectrum (BaBar)

mb (GeV) 2 (GeV2)

Kin. 4.590±0.039

0.401±0.040

SF 4.604±0.038

0.189±0.038

Fits from O. Buchmüller, H. Flächer, hep-ph/0507253. Thanks to H. Flächer for plot.

mb error less than 1%!

April 11, 2006 V. Erkcan Özcan, UCL 12

Direct CP AsymmetryInclusive BX

310)42(~γb sASMCP

CP Asymmetry measured in many exclusive modes.

Even time-dependent asymmetry studied in channels like Ks

00 (see talk by H. Kakuno).

For inclusive bs :

Belle psedo-reco. technique (152 M BB)

310)30502(~γb sABelleCP

BaBar sum-of-exclusive modes (89 M BB)

310)155025(~γb sABaBarCP

0.017 0.115 0.110– )( dsbABaBarCP

910~γ)(b dsASMCPFor inclusive “untagged” b(s+d) :

BaBar lepton-tagged fully-inclusive (89 M BB)

April 11, 2006 V. Erkcan Özcan, UCL 13

bdFirst Observation

1.6 10 55.0γB 609.008.0

42.036.0

B

5.2 10 25.1γB 607.006.0

37.033.0

00

B

2.3 10 56.0γB 605.010.0

34.027.0

0

B

• Requires strong BG suppression: • Flavor-tagging, vertex displacement from

other B, K* veto, / helicity cuts…• Fit for signal, continuum, K*, other B BGs.

• Central values show big isospin violation!

Combined fit, assuming isospin.

000

00

22)),(( BBBBBBBBB

B

B

B

5.1 10 32.1γ),(B 610.009.0

34.031.0

B

hep-ex/0506079

386 M BB

April 11, 2006 V. Erkcan Özcan, UCL 14

bdComparison with BaBar

Combined fit, assuming isospin:

2.1

100.10.30.6

γ),(B6

B

PRL 94 011801 2005

211 M BB

0.0 101.02.00.0 6

γB 00 γB γB0

1.9 101.0 9.0 66.05.0

1.5 101.03.05.0 6

April 11, 2006 V. Erkcan Özcan, UCL 15

bd: |Vtd/Vts|

R

mm

mm

V

V

KBB

BB

BK

B

ts

td

1/1

/1),( 2322

*

322,

2

*

Ratio of form factors

2 = 0.85 ± 0.10

SU(3) breaking

R = 0.1 ± 0.1

theo.

018.0015.0

exp.

026.0025.0 199.0/

tstd VV

Recent Belle result:

19.0/ tstd VV

Earlier BaBar result:

Independent constraint on CKM – “ms of B Factories”

UTfit to all modes UTfit to 0 data only

02.016.0/ tstd VV 04.016.0/ tstd VV

April 11, 2006 V. Erkcan Özcan, UCL 16

bsllC7, C9 & C10

Inclusive(Sum-of-exclusive)

q2 range:

1-6 GeV2

>4m2

2004 1.8±0.9 5.6±2.0

2005 1.5±0.6 4.1±1.1

exp. avg.

1.6±0.5 4.5±1.0

SM 1.6±0.2 4.4±0.7

C7=-C7

SM

3.3±0.3 8.8±1.0

Gambino et.al., PRL 94 061803 (2005)

ExclusiveKll and K*ll

• Established in all individual modes except K*+ modes & K0ee mode.• Kll smallest B decay measured at 5.

BF

(10

-6)

3 away from exp.

Kll

preliminary

April 11, 2006 V. Erkcan Özcan, UCL 17

BK*ll @ Bellehep-ex/0603018

386 M BB

• 113.6 ± 13.0 K*ll events (44% purity).

• Fix A7=-0.33 (SM) and fit for A9/A7 and A10/A7.

• Repeat for A7=+0.33.

• Use Kll for null test.

1.1 3.15/ 4.38.479

AA

8.1 3.10/ 2.55.3710

AA

A9/A7 = -12.33 A10/A7 = 12.82

SM

April 11, 2006 V. Erkcan Özcan, UCL 18

BKll @ BaBar229 M BB

preliminary

• BaBar follows broader approach.

• C1-C10 would not account for pseudoscalar/scalar particles that can replace /Z.

• In presence of such scalar contribution, FS, AFB can be non-zero even for BKll.

**2*

cos2

1cos11

4

3

cos

1 FBSS AFF

d

d

Fits are performed to obtain both AFB & FS.

46.0 81.0 61.0

0.58SF

08.0 15.0 2123.0

0.

FBA

Consistent with zero

(SM).

08.048.0 06.1

KeeB

KBRK

April 11, 2006 V. Erkcan Özcan, UCL 19

BK*ll @ BaBar

229 M BB

preliminary

• For K*ll decay, in addition to AFB, another quantity of interest : longitudinal polarization FL of K*.

• FL sensitive to left-handed currents with complex phases or right-handed currents in penguin amplitude.

**2*2*

coscos118

3cos1

4

3

cos

1 FBLL AFF

d

d

KLKLK

FFd

d

22 cos114

3cos

2

3

cos

1

FL fit consistent with SM. With 1 ab-1 could

exclude wrong-sign C7.

SM inconsistent with AFB fit at low-q2 !!!

(98% CL)

Wrong sign C9C10

excluded! (consistent with Belle)

April 11, 2006 V. Erkcan Özcan, UCL 20

Summary

Extracted BFs / CPV / AFB almost all in agreement with SM.

BaBar AFB (BK*ll) measurement at low q2 away from SM; would

be useful to average BaBar and Belle measurements. Developed techniques highly scaleable, experimental errors to

be reduced significantly as B factories collect more data.

Inclusive modes : NNLO theoretical calculation to reduce theory errors (as much

as a factor of two) in two years. Measured HQE parameters quantify “universal” motion of b

quark in B meson. Useful in extracting Vub and Vcb from

semileptonic decays.

Exclusive modes : bd penguin observed. CKM fits with rare radiative decays… Wilson coefficients are now experimental observables. With

even 1ab-1 data important discoveries are at hand.

Backup Slides

April 11, 2006 V. Erkcan Özcan, UCL 22

PEP-II @ SLAC KEKB @ KEK

Off-resonance data @ 10.54/10.52 GeV CM; no BB

pairs, only continuum BGBB threshold

~90% data on-resonance @ 10.58 GeV CM

BB pairs almost at rest in e+e– CM frame.

Enough energy to create b quark pairs, but not enough

for B-meson pairs.

Detector

Cavity

e+ source

KEKB HER[8 GeV]

KEKB LER[3.5 GeV]

1033cm-2s-1 ≈ 1 BB pair / sec

Design Peak

3 10.0

10 16.3

April 11, 2006 V. Erkcan Özcan, UCL 23

/ KL detection 14/15 lyr. RPC+Fe

Central Drift Chamber small cell +He/C2H6

CsI(Tl) 16X0

Aerogel Cherenkov cntr. n=1.015~1.030

Si vertex det.3/4 layer DSSD

ToF cntr.

SC solenoid 1.5T

8 GeV e

3.5 GeV e

Belle DetectorThanks to I. Bizjak.

April 11, 2006 V. Erkcan Özcan, UCL 24

BABAR Detector

EMC6580 CsI(Tl) crystals

2.39,8.15 21 Cherenkov Detector

(DIRC)144 fused-silica bars

11000 PMTs

1.5 T Solenoid

Electromagnetic Calorimeter 6580 CsI(Tl) crystals

Drift Chamber40 radial layers

Instrumented Flux Returnsteel / RPCs (muon / neutral hadrons)

Silicon Vertex Tracker5 layers, double sided strips

e+ (3.1 GeV)

e- (9 GeV)

SVT: 15 m z hit resolution (inner layers, perp. tracks)SVT+DCH: 98% efficiency, (pT)/pT = 0.13 % pT + 0.45 %

DIRC: K- separation 4.2 @ 3.0 GeV/c >3.0 @ 4.0 GeV/c EMC: E/E = (2.3 E-1/4 1.9)%, (3.9 E-1/2) mrad

April 11, 2006 V. Erkcan Özcan, UCL 25

Box Diagrams & Z-Mediated Penguins

April 11, 2006 V. Erkcan Özcan, UCL 26

• Continuum BGs still dominate over signal after previous cuts!

• Requiring a lepton tag strongly suppresses what remains (signal efficiency 5%, but continuum suppressed by 1300!).Tag: High-momentum lepton, not back to back with photon, missing energy due to neutrino

MC tagging rate corrected from independent measurements of inclusive lepton spectra.

• What remains is subtracted with off-resonance data.

Continuum Backgroundsvs. Lepton Tag

Xs

B

XcB

lepton

νl

Xs

B

Xs

B

XcB

lepton

νlXcB

lepton

νl

γ

~20% of all B

decays are Xlν.

(4S)

April 11, 2006 V. Erkcan Özcan, UCL 27

BXsSum-of-Exclusive

Reconstruct B candidate in one of 38 modes. Use event shape to reduce continuum BG. Fit mES (for each mXS bin) to extract signal yield. Use observed yields in different modes to correct MC fragmentation.

Single-bin fit to all events

Continuum BG (fixed from MC)

BB BG and cross-feed

Peaking BG (fixed from MC)

Signal

April 11, 2006 V. Erkcan Özcan, UCL 28

Wilson CoefficientsOperator Product Expansion

Wilson coefficients encode hard-gluon exchange info

Ci() Ôi

10

1

*/

,,,,

2

4

itbtdts

FbcsduQEDQCDeff VV

GLL

Fermi

Ô7 : dipole (EM)

Ô1-6 : 4-quark

Ô8 : dipole (gluonic)

Ô9 : vector electroweak

Ô10 : axial-vector EW

Common framework – Effective theory.

New physics expected to change Ci().

scorrection

1

32

2

7

2*4

5em

2

b

efftbts

bF

mCVV

mGsb

2

227

192

102

/

Re*

dqd

q

FCFCqC

qA

effeffeff

llKbFB