experimental aspects of cp violation in b decays : lecture iii vivek sharma university of...

Experimental Aspects of CP Violation in B Decays : Lecture

III

Experimental Aspects of CP Violation in B Decays : Lecture

III

Vivek Sharma University of California, San Diego

http://vsharma.ucsd.edu/prague/cpv.pdf

2

Outline of Lecture II: Yesterday• PEP-II and KEK-B Colliders : Notable features

• Detectors at the Asymmetric energy collider

– General requirements for CPV measurements• Implementation in BaBar & Belle (similar but different)

• General Data analysis methods

– B Meson Reconstruction & Continuum background rejection

– B meson flavor determination : B or a B ??– Blind analysis !

3

Outline of Lectures 3 & 4 • Lecture 3

• Three types of CP violation & SM expectations in B Decays

– Decay amplitude Weak phase structure

– Decay asymmetry prediction in SM

• General strategy for time-dependent CP asymmetry measurement

– Observables that probe angle • Time dependent CP asymmetry in B -> Charmonium KS modes Step-by-Step

• Other modes with subdominant or dominant Penguin

• Lecture 4

– Observables that probe angle– Observables that probe angle – Summary of current measurements

– Future prospects

CP Violation In B Decays: SM Expectations

5

Decay Amplitude Weak Phase Structure in CPV

• Most B decay final states have contributions from both “Tree” and 3 “Penguin” (Pt,Pc,Pu) diagrams.

– All Tree diagrams (Spectator, W-exchange, W-Annihilation, rescattering) have same weak phase

– The three Pi can have different Weak and Strong phases

– EW penguins “suppressed” due to EW coupling

Decaysb q qq

6

B Decay Amplitude Weak Phase Structure

* *

* *

* *

( )

( )

( )

c t u tcb cs s s ub us s sccs

c t u tcb cs s s ub us s suus

c t u tcb cs s s ub us s s

A ccs V V T P P V V P P

A uus V V P P V V T P P

A sss V V P P V V P P

Classification of Decaysb q qq

* *

* *

* *

( )

( )

( )

t u c utb td d d cb cd d dccd

t c u ctb td d d ub ud d duud

t u c utb td d d cb cd d d

A ccd V V P P V V T P P

A uud V V P P V V T P P

A ssd V V P P V V P P

7


8


Decay Modesb qqd

9

Five “Classes” of B Decays For CPV

+

0

1. Decays dominated by single term: b ccs & b

SM Small Direct CPV since second term is CKM sup

Any large Direct CPV New Physics ( e.g. B

B modes have cleanly predicted r

pre

elat

sse

o

,

d

)

i

s

K

ss

K

nship between CKM angle

and measured asymmetry from CPV due to interference between

decays with/Without Mixing

0

2. Decays with small second term: ;

Expectation that P/T << 1 small Direct CPV possible

Approximate predictions in B decay for relation between

measured CPV and CKM phase

b ccd b uud

10

Five “Classes” of B Decays For CPV

*ub us3. Decays with suppressed (V V )Tree as in

Large interference effects. Example: B K

b uus

4. Decays with no Tree contrib: .

Interference comes from Penguin diagrams

with different Q=2/3 quarks in loop. e.g. B KK

b ssd

*

5. Radiative Penguin Decays: b s .

Situation same as in (4) but leading contribution

from EM penguin. e.g: B K

11

Some Examples of Class I (b c c s): B0 KS

*2

*Kics cd

cs cdK

V Vpe

q V V

* *2

* *S B

S

S

K icb cs cs cdK

K cb cs cs cd

V V V VAe

A V V V V

* * *

* * *sin(2 )

S

tb td cb cs cs cbS K

tb td cb cs cs cb

V V V V V VB K

V V V V V V

Im

CP

CP CP

CP

f

f ff

q A

p A 1

SK

12

Another Example of Class I (b u u d): B0 +-

*2

*Biub ud

ub ud

V VAe

A V V

* *

* *sin(2 2 2 ) sin(2 )tb td ud ub

tb td ud ub

V V V VB

V V V V

Im

Neglecting Penguin diagram

1

*

and depending on its relative strength w.r.t Tree. (Penguins are large!)

Weak Phase in Penguin term is arg( ) different from Tree so it will modifytd tbV V

Im

13

An Example of Class II (b c c d): B0 D+ D-

Ignoring Penguin Diagram (?)

* *

* *sin(2 )tb td cd cb

DDD Dtb td cd cb

V V V VB D D

V V V V

Im

14

CPV in Decay aka Direct CP Violation

( )A B f

2 2

B

f fB

( )A B f

2

wk sti iA e e

1AB f

1Ast

B f2A

wkB fwk

2

1

2

1 22( ) , ( ) wk s w stt ki ii i B fB f A A A e ee e A

2 2

2 20 Direct

ff

CP

ff

A ABr B f Br B fA CPV

Br B f Br B f A A

15

Observation of Direct CPV in B0K- +

2 iSM amplitude e T P sinKA

• Loop diagrams from New Physics (e.g. SUSY) can modify SM asymmetry

• Clean mode with “large” rate :• Measure charge asymmetry, reject B background with Particle ID

0 618.2 0.8 10 BF B K

B background

signal

E (G

eV

)

K separation

K

sep

ara

tion()

16

B0K+

B0K+

BABAR

BaBar: First Observation of Direct CPV in B decay !BaBar: First Observation of Direct CPV in B decay !

4.2, syst. included

BABAR

1606 51

0.133 0.030 0.009K

K

n

A

0

0

9

696

10

n B K

n B K

signal enhanced

background

subtracted

17

Confirmation of Direct CPV by Belle at ICHEP04

ACP = -0.101 0.025 0.005

274M BB

3.9 significance

B0 K _B0 K

Signal=2139 53

Combined BaBar & Belle significance = 5.7Establishes CPV not just due to phase of B Mixing (M12)Theoretical (npQCD) uncertainties insufficient to prove or rule out NP

18

Direct CPV in B- K- 0

Belle

ACP(K) = 0.04 0.05 0.02

Belle

ACP(K) = 0.06 0.06 0.01

BaBar

0 ,

Expect bot

( ) 0.049 0.040 ( ) 0.10 0.02Average

h to be same, difference is 3.6 ...(EW Penguin ?

Average

?)CP

CP

CPA K K

A

A

Not in BK- +

20

CPV in B0 Mixing

Occurs when Mass eigenstates CP eigenstates

(|q/p|1 and<BH|BL> 0)

The Box diagrams provide the required 2 phases

Strong phases depend on quark masses and

non-perturbative physics.

Asymmetries are small and hard to calculate precisely

0 0 4

440 0

( ) ( ) 1 /(10 )

1 /( ) ( )

phys phys

sl

phys phys

B t X B t X q pa O

q pB t X B t X

0 0( )A B B

2

2

B0 B0

ffB0

0 0( )A B B

B0

21

CPV in B0 Mixing

122i

12M0B 0B

off-shell states f

on-shell

states f

0 0( )A B B

2

2

B0 B0

ffB0

0 0( )A B B

B0

0 0

,

in the mixing matrix

results from:Mass eigenstates | eigenstates | L H

CPV B B

B CP B

0 0

, 2

1| | | (| | )

1 | | d

d

L H B

B

B p B q B B B

0 0 0 01

1 Prob( ) Prob( )1

d

d

B

B

qB B B B

p

22

CPV in B0 Mixing

3 2SM: 2 10 ; hence 10 New Physics T TA A

0 0

0 0 2

4Re( )( ( ) ) ( ( ) )( )

( ( ) ) ( ( ) ) 1 | |

d

d

Bphys physT

phys phys B

B t X B t XA t

B t X B t X

Time-dependent CP Asymmetry:

In the System, ~ purely imaginary H Ld B B d dB m m m ε

Babar Search for asymmetry in same-sign dilepton sample containing 20381 events

( , ) ( , ) ( )( )

( , ) ( , ) ( ) ( )T

obsT

N t N t S tA t A

N t N t S t B t

( )

( ) f rom B decay and continuum

S t signal

B t background

23

CPV in B0 Mixing

BBAABBARAR20.7 fb20.7 fbBBAABBARAR20.7 fb20.7 fb

Sample backgrounds B(t):

4.3% continuum24% direct+cascade

12% direct+fake0 0 0 0, signal ( )B B B B S t

Measurement region > 200m

24

CPV in B0 Mixing


2

( ) ( )

( ) ( )

Conclude: Re( )/ (1 | | )

0.0012 0.0029 0.0036

/ 0.998 0.006 0.007

d dB B

stat syst

stat systq p

( ) ( )Find: 0.005 0.012 0.014stat syst

BABAR PRL 88, 231801 (2002)

To a good approximation:

212 12/ 1 and / | | /Miq p q p e M M

So far, no experimental evidence of large CP violation in B0 mixing

25

CPV In Interference Between Mixing and Decay

0 0

0

Neutral B Decays into CP final state accesible by both & decays

This is CPV when 1 and 1 and the Quantity of interest is

CPV is defined as

( )

C CP

CP C

CP

P

CP

P

CP

f

f

phy

ff

CP

f

s

f

CPf

f B B

q A

p A

B t

A

f B

q A

p

a

20

20 0

When B decay is dominated by a

2 sin 1 c

single diagram, 1 si

os( )

( )

n

( ) 1

CP CP

C

CP CP P

P

C

f B f Bphys CP

phys CP phys CP

f f f B

f

m t m tt f

B t f B t

a m t

f

Im

Im

+

2

+

2

B0

B0

B0

fcpB0

fcpB0

B0

fcpfcp

CP asymm. can be very large and can be cleanly related to CKM angles

0B

fiCPA e

CPf

0B

12

2 Mi

M

ie

fiCPA e

26

CPV In Interference Between Mixing and Decay

2

f f2 2

f f

1 λ 2Im(λ )( ) exp( ) 1 cos( ) sin( )

1 λ 1 λ

t t mt mtF

0 0B denoted by and a B denoted by is(t) (t) CP CPf fF F+ -

Requires measurement of proper time difference t=t between thedecay of Btag and BCP. Time dependent rates for a

S C

27

Time-Dependent CP Asymmetry with a Perfect Detector

sin2( ) sin(ΔmΔβ )CPA t t sin2( ) sin(ΔmΔβ )CPA t t

• Perfect measurement of time interval t=t• Perfect tagging of B0 and B0 meson flavors•For a B decay mode such as B0Ks with |f|=1

sin 2

B0B0

Asy

mm

etry

AC

P

Time Dependent CPV Measurement Technique

Since the techniques of time-dependent analysis is common to many modes, I will now describe this in detail using the “golden” mode B0 (cc) K0 from which CP violation in B0

decays was first established.

The analysis (from 2002) based on 88 fb-1 is “old” but forms basis for all other new (2004) analysis results that I

will present later

Vivek Sharma , UCSD 29

+e-e

B0 J/ KsB0 J/ Ks

CP Violation in Picture

z

Δ zΔ tβγ c

Brec

Btag 4s

(4S) = 0.55

z-π

0sK

+π

+μ-μ

Coherent BB pair

B0

B0

Separate

B0 and B0

Separate

B0 and B0


Sin2 Analysis Strategy

Measurements B±/B0 Lifetimes

B0 B0-Mixing

CP-Asymmetries

Analysis Ingredient Reconstruction of B mesons

in flavor eigenstates B vertex reconstruction

Flavor Tagging + a + b

Reconstruction of neutralB mesons in CP eigenstates + a + b + c

Hig

her p

recisio

n

Incre

asin

g co

mple

xity

Factorize the Time Dependent analysis into building blocks

Obtain All analysis ingredients from DATA

Calibrating The BaBar Clock With B Meson Lifetime Measurement


Measurement of the B0 and B+ Lifetime

3. Reconstruct Inclusively the vertex of the “other” B meson (BTAG)

4. compute the proper time difference t5. Fit the t spectra

(4s)

= 0.55

Tag B

z ~ 110 m Reco Bz ~ 65 m

+z

t z/c

K0

D-

--

K+

1. Fully reconstruct one B mesonin flavor eigenstate (BREC)

2. Reconstruct the decay vertex


( )b c c s

Cabibbo-favored hadronic decays

“Open Charm” decays

Fully-Reconstructed B sample

Neutral B Mesons

ducb

Flavor eigenstates Bflav : for lifetime and mixing measurements

0 *0/ ( )B J K K / , (2 )B J K S K

0( )B D π 0

1( )B D π /ρ /a

Hadronic decays into final stateswith Charmonium

Charged B Mesons

cm 2 cm 2ES beam Bm = (E ) - (p ) [GeV]

~21000 signalPurity: 85%

~20000 signalPurity: 85%


Vertex and t Reconstruction

Reconstruct Brec vertex from charged Brec daughters

Determine BTag vertex from charged tracks not

belonging to Brec

Brec vertex and momentum

beam spot and (4S) momentum

High efficiency (97%)

Average z resolution is 180 m (<|z|> ~ c = 260 m)

t resolution function measured from data

Beam spot

Interaction Point

BREC Vertex

BREC daughters

BREC direction

BTAG direction

TAG Vertex

TAG tracks, V0s

z


e-|t|/

Either Brec or Btag can decay first (this analysis)

BaBar

t resolution

e-t/

true t

B production point known eg. from beam spot

LEP/SLD

B Measurement in BaBar

Need to disentangle resolution function from physics !

measured t

Resolutionfunction lifetime

Resolution Function + Lifetime =

=


event-by-event (t) from vertex errors

Lifetime-like bias to Small correlation between

lifetimeand Resolution Function parameters

t Resolution Function

(1 ) ( , 0)

( , 0) exp( / )

( , )

tail outlier t core

tail t bias t

outlier outlier outlier

R f f G S

f G S t

f G

z

Signal MC (B0)

t (meas-true)/t

tracks from long-lived D’s in tag vertex

asymmetric Resolution Function

~0.6 ps


Lifetime Likelihood Fit

Simultaneous unbinned maximum likelihood fit to B0/B+ samples

Use data to extract the properties ofbackground events Mass distribution provides the

signal probability Use the events in the sideband

(mES < 5.27) to determine thet structure of the backgroundevents under the signal peak

19 free parameters (B+) and (B0) 2 t signal resolution 5 empirical background 12

description

)2

Beam-Energy Substituted Mass (MeV/c5200 5210 5220 5230 5240 5250 5260 5270 5280 5290 5300

2E

ve

nts

/ 1

Me

V/c

0

200

400

600

800

1000

1200

1400 BAB

B0 mES

B0 Bkg t


B Lifetime Fit Results

World’s best measurement 2 % statistical error 1.5% systematic error

Main source of systematic error Parameterization of the t

resolution function Description of events with large

measured t (outliers)

B0/ B0

B

t (ps)

0 = 1.546 0.032 0.022 ps

PDG: 1.548 0.032 ps

= 1.673 0.032 0.022 ps

PDG: 1.653 0.028 ps

/0 = 1.082 0.026 0.011

PDG: 1.062 0.029

20 fb-1

background

signal + bkg

PRL 87, 201803 (2001)

B Flavor Mistag Knowledge From Data

40

sin2 results from charmonium modes

0 0( ) 1 cos( )tBP mB e t

Start with a B0 beam, slowly (compared to the lifetime) a B0 component builds upBut no “Mixed” events at t=0. If the detector measures some “mixed” events, it must be because it has measured the flavor of the B incorrectly ( mistag)

B0

B0 B0

B Lifetime


Analysis Strategy (II)

Measurements

B±/B0 Lifetimes

B0 B0-Mixing

CP-Asymmetries

Analysis Ingredient

Reconstruction of B mesons in flavor eigenstates

B vertex reconstruction


Reconstruction of neutral B mesons in CP eigenstates + a + b + c


Measurement of B0B0 Mixing rate Vs t

3. Reconstruct Inclusively the vertex of the “other” B meson (BTAG) 4. Determine flavor of BTAG to separate Mixed and Unmixed events

5. compute the proper time difference t 6. Fit the t spectra of mixed and unmixed events

(4s)

= 0.55

Tag B

z ~ 110 m Reco Bz ~ 65 m

+z

t z/c

K0

D-

--

K+

1. Fully reconstruct one B meson in flavor eigenstate (BREC) 2. Reconstruct the decay vertex


t Spectrum of Mixed and Unmixed Events

0 0

0 0

0 0

0 0Mixed:

Unmixed: tagflav

tagflav

tag flav

tagflav

or

or

B B

B B

B B

B B

perfect flavor tagging & time

resolution

Decay time diff (t) in ps

MiU

xnmix 1 cos( )

4f (Δ t)

Bd

d

| Δ t |/τ

Bd

eΔm Δt

τ

Unmix

xMi

f (Δ t) 1 1 2 cos( ) ResolutionFunction4

Bd

d

d

| Δt |/τ

B

e tτ

mw Δ Δ

_+

w: the fraction of wrongly tagged eventsmd: oscillation frequency

realistic mis-tagging & finite time

resolution

Decay time diff (t) in ps


NN output

Not U

sed

B Flavor Tagging Methods

For electrons, muons and Kaons use the charge correlation

b c

d d

l-

B0 D, D*

W-

0

0

l

l

B

B

Lepton Tag

b

d

B0

W- W+c s

K*0

d

0

0

0

0

kaons

kaons

Q

Q

B

B

Kaon Tag

Each category is characterized by the probability of giving the wrong answer (mistag fraction w)

Multivariate analysis exploiting the other kinematic information of the event, e.g., Momentum spectrum of the charged particles Information from non-identified leptons and kaons Soft from D* decay Neural Network

Hierarchical Tagging CategoriesHierarchical Tagging Categories


Flavor Tagging Performance in Data

Tagging category

Fraction of tagged

events(%)

Wrong tag fraction w (%)

Mistag fraction difference w

(%)

Q =

(1-2w)2 (%)

Lepton 10.9 0.3 9.0 1.4 0.9 2.2 7.4 0.5

Kaon 35.8 1.0 17.6 1.0 -1.9 1.5 15.0 0.9

NT1 7.7 0.2 22.0 2.1 5.6 3.2 2.5 0.4

NT2 13.8 0.3 35.1 1.9 -5.9 2.7 1.2 0.3

ALL 68.4 0.7 26.1 1.2

The large sample of fully reconstructed events provides the precise determination of the tagging parameters required in the CP fit

Highest “efficiency” Smallest mistag fraction


Error on sin2 and md depend on the “quality factor” Q approx. as:

1sin 2

Q


Flavor Tagged B Meson Sample For Mixing Studies

1097 34(96.0 0.7)%

signalNPurity

798 31(88.9 1.2)%

signalNPurity

3156 63(84.6 0.7)%

signalNPurity

1293 43(79.4 1.3)%

signalNPurity

Gaussian

ARGUS function

psig,i ~ 0 psig,i ~ 0.96

Background properties from

sideband events

Lepton KaonLepton

NT2NT1


,1

, 0

,

, 8

,

, ,

tail

tail tai

outl

outl outl outl o

l tai

core core c

utl

or

l

e i

tail

f

f G t p

G

s

R t

p

f

f G t

t

S

S

s

t Resolution Function

t

ttail tail

core coevt

evt

reS

S

Tail

Core

OutlierUse the event-by-eventuncertainty on t

t Residual (ps)

R(t)

Different bias scale factor

For each tagging category

B0 flavoursample

CP sample

t (ps)


UnmixMix

f (Δ t) 1 1 2 cos( )4

Bd

d

| Δ t |/τ

Bd

e ΔtΔmw Rτ

Fit Parametersmd 1Mistag fractions for B0 and B0 tags 8Signal resolution function 2 x 8Empirical description of background t 16+3B lifetime fixed to the PDG value B = 1.548 ps

Mixing Likelihood Fit on Reconstructed B0 Sample

Unbinned maximum likelihood fit to flavor-tagged neutral B sample

44 total free parameters

All t parameters extracted from data


1(0 516 0 016 0 010 ) ps d (stat) (syst)Δm . . . BABAR PRL 88, 221802 (2002)

Mixing with Hadronic Sample


Precision measurement consistent with world average

Signal: mES>5.27

Bgnd: mES<5.27


md Measurement in Comparison With World

Precision md measurement

3% statistical error

2% systematic error dominated by MC correction

BaBar Measurements

World Average: 0.496 ± 0.007 ps-1


dm/π~

21~

Folded raw asymmetry

|t| [ps]

Flavor mistag ratewell calibrated frommixing measurement

)

1 2 cosd

mixing

B

A ( tω Δm Δt

B0 B0 Mixing Asymmetry with Hadronic Sample

Unfolded raw asymmetry

t [ps]



Mixing Measurement at Belle (Hadronic Modes)

1(0 528 0 017 0 011 ) ps d (stat) (syst)Δm . . .

BELLEBELLE29.1 fb29.1 fb

BELLEBELLE29.1 fb29.1 fb

Mistag rate


CP Analysis Analysis Strategy (Step III)

Measurements

B±/B0 Lifetimes

B0 B0-Mixing

CP-Asymmetries

Analysis Ingredient

Reconstruction of B mesons in flavor eigenstates

B vertex reconstruction


Reconstruction of neutral B mesons in CP eigenstates + a + b + c


Measurement of CP Asymmetry

3. Reconstruct Inclusively the vertex of the “other” B meson (BTAG) 4. Determine the flavor of BTAG to separate Mixed and

Unmixed events

5. compute the proper time difference t 6. Fit the t spectra of B0 and B0 tagged events

1. Fully reconstruct one B meson in CP eigenstate (BCP)2. Reconstruct the decay vertex

(4s)

= 0.55

Tag B

z ~ 110 m CP Bz ~ 65 m

+z

t z/c

K0

+

-

Ks0

-


Charmonium+K0 CP Sample for BABAR (’02)

1 modesf

0 0

0 0 0 0

0

0

0 01

0 0

2

CP S

CP S

CP

S

CP c S

CP c S

B J/ψK { π π }B J/ψK { π π }B ψ S { or

J/ψπ π }KB χ { J/ψγ}KB { KK }K

(after tagging & vertexing)

988 signal candidates,purity 55%

1506 signal

candidates,purity 94%

modes 1f

1 modef 0 0CP LB J/ψK



00tag BB 00

tag BB

perfect flavor tagging & time

resolution

t Spectrum of CP Events

Mistag fractions wAnd resolution function R

1 (1 2 )sin4

sin2 ( )d

d

B

B|Δt|/τ

f def (Δt) η Δm

τw Δβ t

R1 (1 2 )sin

4sin2 ( )

d

d

B

B|Δt|/τ

f def (Δt) η Δm

τw Δβ t

R

CP PDF

00tag BB 00

tag BB

realistic mis-tagging & finite time

resolution

1 (1 2 )cos( )4

dB

Bd|Δt|/τ

mixing, dwef (Δt) Δm Δt

τ

R1 (1 2 )cos( )

4dB

Bd|Δt|/τ

mixing, dwef (Δt) Δm Δt

τ

R

Mixing PDFdetermined byflavor sample

0

0

( ) 1 sin(sin 2 )4

Bd

d

| Δ t |/τ

f dBBB

ef t η Δm Δt

τβ

57

Sin2 Likelihood Fit

Combined unbinned maximum likelihood fit to t spectraof flavor and CP sample

35 total free parameters

All t parameters extracted from data Correct estimate of the error and correlations

Fit Parameterssin2 1Mistag fractions for B0 and B0 tags 8Signal resolution function 8Empirical description of background t 17

B lifetime fixed (PDG value) B = 1.548 psMixing Frequency fixed (PDG value) md = 0.472 ps-

1

tagged flavor sample

tagged CP samples

58

sin2 Likelihood Fit Description

Combined unbinned maximum likelihood fit to t spectra of Bflav and CP samples

All t parameters extracted from data Correct estimate of the error and correlations

Fit Parameters # Main Sample

Sin2 1 Tagged CP sample

Mistag fractions for B0 and B0 tags 8 Tagged flavor sample

Signal resolution function 8 Tagged flavor sample

Empirical description of background t 17 Sidebands

B lifetime from PDG 2002 0 B = 1.542 ps

Mixing frequency from PDG 2002 0 md = 0.489 ps-1

Total parameters 34

Global correlation coefficient for sin2: 13%

59

Check “null” Control Sample at BABAR

Input Bflav sample to CP fitNo asymmetry expected

Sample “sin2”

Bflav 0.021±0.022

B+ 0.017±0.025

60

BABAR Result for sin2 (July 2002)

sin2 = 0.755 0.074

CP = -1 CP = +1

sin2 0 741 0 067 0 033(stat) (syst). . .

61

Pure Gold : Lepton Tags Alone


sin2 0 79 0 11β . .

98% purity3.3% mistag rate

20% better t resolution

220 lepton-tagged

f = -1 events

CP asymmetryis obvious !

62

Systematic Errors on sin2 from BABAR

[sin2]

Description of background events 0.017

CP content of background components

Background shape uncertainties, peaking component

Composition and CP content of J/KL background 0.015

t resolution and detector effects 0.017

Silicon detector residual misalignment

t resolution model (Gexp vs 3G, Bflav vs BCP)

Mistag differences between BCP and Bflav samples (MC) 0.012

Fit bias correction and MC statistics 0.010

Fixed lifetime and oscillation frequency 0.005

Total 0.033

63

Updated (ICHEP04) sin2 results from Charmonium Modes

sin2 0 722 0.040 0.023/ 0.950 0.031 0.013

.A A

0( ) ( odd) modesScc K CP

1205 on peak or 227 pairs7730 CP events (tagged signal)

f b M BB

Limit on direct CPV

BBAABBARARBBAABBARAR

0

0

( ) +

( )

S

L

cc K

cc K

0( ) ( even) modesLcc K CP

BBAABBARARBBAABBARAR

64

Belle Results on sin2 from Charmonium Modes

1140 on peak or 152 pairs4347 CP events (tagged signal)

fb M BB

sin 2 0 728 0.056 0.023/ 1.007 0.041 0.033

.A A

BBelleelle20032003BBelleelle20032003

65

Lessons From sin2 Measurement With B0K0

• In 2001, CP Violation in B system was discovered in this mode by BaBar and Belle. It was the first instance of CPV outside the Kaon system.

• It was also the first instance of a CPV effect which was O(1) in contrast with the Kaon system and confirms the conjecture of Kobayashi & Maskawa made in 1972 for CPV phenomenon. It excludes models with approximate CP symmetry (small CPV).

• In 2004 sin2 is a precision measurement (5%) and agrees well with the constraints in the - plane from measurements of the CKM magnitudes.

• Now it appears unlikely that one will find another O(1) source of CPV and the enterprise now moves towards looking for corrections rather than alternatives to the SM/CKM picture

• Focus now shifts to measurements of time-dependent asymmetries in rare B decays which are dominated by Penguin diagrams in the SM and where New Physics could contribute to the asymmetries

66

sin2 From Penguin Modes: B0K0

4~ iV V R eub us u

2~tb tsV V

0 0

T

f K K

No tree level SM diagram, P Penguin dominates

Expect little direct CPV and - S S in SM

NP can change this picture in unpredictable way

+1.3 -6-1.2Exptal challenge is the small rate BF= 7.6 ±0.5 ×10

67

CP Asymmetry In Penguin Modes: B0K0

0 0 ( )SB K K K 0 0

LB K

full background

continuum bkg

0 0L SK K

114 12 signal events 98 18 signal events

Analysis based on 227 Million BB pairs

Sample orthogonal to the non-resonant BKKK0 data

68


B0KSB0KS

B0KLB0KL 0 1.05 0.51

LKS

0 0.29 0.31SK

S

0tagB

0tagB

0tagB

0tagB0 1

LK

0 1SK

0

0

0.070 50 0.25 0.040 00 0.23 0 05

CP K

K

S .

C . .

0

98 18 events1.05 0.51

LKS

0 0LB K

0

114 12 events0.29 0.31

SKS

0 0SB K

-

- -

K

Also, Direct CP Asymm in complementary mode

B K : C 0.054 0.056 0.012

69


KS

Nsig=139 14purity 0.63

pB*

Nsig= 36 15

KL

purity 0.17

Belle 274M BB

70


K0

KS + KL

: S (K0) = +0.06 ±0.33 ±0.09

C (K0) = -0.08 ±0.22 ±0.09 ~2.2 away from SM

KS + KL

: S (K0) = +0.06 ±0.33 ±0.09

C (K0) = -0.08 ±0.22 ±0.09 ~2.2 away from SM

Good tags

Poor tags

S = 0.736fit Good tags

Belle 274 M BB

71

CP Asymmetry In Penguin Modes: B0/ K0

b

dg

t0B

d

ss

s

W

2~tb tsV V

0', f

0K

4~ iub us uV V R e

W b

d

0B

d

uu

0', f

s 0K

Nsig=512 27

Belle 274M BB0 0

SB K

819 38 signal

BaBar 227 M BB

72

CP Asymmetry In Penguin Modes: B0/ K0

0tagB

0tagB

Asymmetry

Raw

Asy

mm

etry

Good tags

S = 0.736fit

Belle 274M BB

0

0

0.10.27 0.034

0.100.21 0.03S

S

K

K

S

C

sin

2

[cc]

@ 3

.0

S = +0.65 0.18 0.04 C = +0.19 0.11 0.05

73

Results on sin2 from s-penguin modes

All new!All new!

2.7 from s-penguin to sin2(cc)


74

Summary of sin2eff

75

World Averages for sin2 and s-penguin modes


No sign of Direct CP in averages

Beginning to look suspicious but must wait for 5/expt to get exciting

76

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40Ja

n-03

Jul-

03

Jan-

04

Jul-

04

Jan-

05

Jul-

05

Jan-

06

Jul-

06

Jan-

07

Jul-

07

Jan-

08

Jul-

08

Jan-

09

Jul-

09

Err

or

on

sin

e am

pli

tud

eProjections for Penguin Modes

K*

5 discovery region if non-SM physics is 30% effect

2004=240 fb-1

2009=1.5 ab-1

Similar projections for Belle as

well

Projections are statistical errors only; but systematic errors at few percent

level

Luminosity expectation

s:

20092004

( ) 0.30S f0KS

KS0

KS

’KS

KKKS

77

PEP II Luminosity Projections

2006 1.6 x 10342004

0

200

400

600

800

1000

1200

Year

Inte

gra

ted

Lu

min

os

ity

( fb

-1)

0

5

10

15

20

25

30

Pe

ak

Lu

min

os

ity

[10

**3

3]

Yearly Integrated Luminosity [fb-1]

Cumulative Integrated Luminosity [fb-1]

Peak Luminosity [10**33]

Yearly Integrated Luminosity [fb-1] 3 23 41 39 62.6 66.1 120.1 151 160.1 217 216

Cumulative Integrated Luminosity [fb-1] 3 26 67 106 168.6 234.7 354.8 505.8 665.9 882.9 1098.9

Peak Luminosity [10**33] 1 2 4.4 5 7.5 10 13 16 20 22 25

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

0.5 ab-1

78

CP Asymmetries in bc cd Modes

Statistics limited, may get interesting in about 2 years !

experimental aspects of cp violation in b decays : lecture iii vivek sharma university of...

Documents

b f f b slide

cpv slide

significance b

phase of b mixing

classes of b decays

separation slide

s slide

np slide