Lecture III - Forside€¦ · Lecture III Measurement of sin 2 in B K0 S Measurement of sin 2 in B K0 S Measurement of sin 2 in B + -, B + - Measurement of in B DK Direct CP Violation

ITRG lecture week Oslo 06-03-2006ITRG lecture week Oslo 06-03-2006 G. Eigen, IFT BergenG. Eigen, IFT Bergen

Lecture IIILecture III Measurement of sin 2 in B K0

S

Measurement of sin 2 in B K0S

Measurement of sin 2 in B + -, B + -

Measurement of in B DK

Direct CP Violation

Model-independent Test for New Physics

Prospects


Strategy for Strategy for CPCP Asymmetry Measurements Asymmetry Measurements

0tagB

+ee

( )S4

0recB

2. B-Flavor Tagging

1.Exclusive B Meson Reconstruction

3. Measure t t t z/z/< >< > c c

=0.55=0.55

J /

K

S

0

z K


Charmonium Charmonium & Tag Samples& Tag Samples

E [MeV]

J/ KL signal

J/ X background

Non-J/ background

BABAR4370 tagged events 2877 tagged events

mES (GeV/c)

CP sample

control sample >64000 tags

mES (GeV/c)

Control sample has sControl sample has same ame mistag mistag rate, rate, t resolution as t resolution as CPCP sample sample

(( tt error dominated by recoil side) error dominated by recoil side) use in fit as well use in fit as well

J/J/ KK00SS & related modes & related modes


Tagging the 2Tagging the 2ndnd B B00 and and t Reconstructiont Reconstruction

(sin2 )1

Q Error on Error on sin2sin2 depends on tagging quality depends on tagging quality

Parameters extracted from B-flavor sample using a neural net Parameters extracted from B-flavor sample using a neural net AchieveAchieve Q=30.5±0.4%Q=30.5±0.4%

( )221=Q

Tagging 2nd B0

Tagging quality

t reconstruction

Get Get BBrecrec vertex fromvertex from charged daughter trackscharged daughter tracks zz((BBrecrec )=65 )=65 μμmm BBrecrec momentummomentum

DetermineDetermine BBtagtag vertex from remainingvertex from remaining

charged tracks charged tracks BBtagtag vertex &vertex & BBtagtag momentummomentum

Average Average z resolution: 180 z resolution: 180 μμm (m ( t resolution: 0.6ps)t resolution: 0.6ps)


BB00 J/ J/ K K00SS

/J

0

SK

Flavor tag:b ce

e ee--

ee++


sin 2sin 2 Results from B Results from B00 (cc)K(cc)K00S(L)S(L) Modes Modes

sin 2 =0.722±0.04±0.023

=0.95±0.031±0.013

7730 tagged events (227 M BB)7730 tagged events (227 M BB) 5261 tagged events (368 M BB)5261 tagged events (368 M BB)

sin 2 1=0.652±0.039±0.020

=1.005±0.013±0.018

ccKccK00SS

BelleBelle B0

B0


sin 2sin 2 Results from b Results from b (cc)s Modes(cc)s Modes

0.69±0.030.69±0.03

sin 2sin 2 World averageWorld average is is 0.69±0.030.69±0.03

BABAR/Belle average BABAR/Belle average is is 0.685±0.0320.685±0.032

(ambiguity lifted)(ambiguity lifted)

cosine term cosine term is consistent with zerois consistent with zero

C=0.027±0.028C=0.027±0.028

0.027±0.0280.027±0.028

= 21.7

1.2

1.3( )°


CPCP Violation in Violation in bb ssssss PenguinsPenguins

In the Standard ModelStandard Model, CPCP asymmetries from BB J/J/ KK00SS & &

BB KK00SS modes yield the same value of “sin 2sin 2 ”

But contributions from new physics processes, e.g. SupersymmetrySupersymmetry may modify these asymmetries in different ways

Since BB KK00SS and related modes are

suppressed by penguin loops, they are sensitive to new physics contributions in loops, which may carry new phases deviation from nominal sin 2sin 2

Standard Model

e.g. from SUSY:

B0

K0


““sin 2sin 2 ”” from B from B KK00

S

K0= +0.50 ± 0.25

0.04

+0.07

C

K0= +0.00 ± 0.23 ± 0.05

B0

B0

BABAR has measured the CP asymmetries in BB KK00SS

& & BB KK00LL modesmodes

In 227 106 BB events BABAR observed 114±12114±12 KK00

SS

&& 98±1898±18 KK00LL eventsevents

The CPCP asymmetry measurements yield:

B0 KS

A

fCP

( t) = S sin m t C cos m t


Comparison of sin 2Comparison of sin 2 Results Results

For For BB J/J/ KK00SS

modesmodes BABARBABAR & Belle& Belle resultsresults deviatedeviate byby >1>1standard deviationstandard deviation

ForFor BB KK00S S &&

related modesrelated modes BABARBABAR & Belle & Belle resultsresults are are consistentconsistent

See See discrepancy ofdiscrepancy of

2.6 standard dev.2.6 standard dev.

betweenbetween B B KK00SS

&& BB J/J/ KK00SS modesmodes

0.69±0.030.69±0.03

0.50±0.060.50±0.06


Measurements of sin2Measurements of sin2

A ( t) = C cos m

dt + S sin m

dt

Thus Thus we need to measure we need to measure t-dependentt-dependent CPCP asymmetries asymmetries of of bb uud uud processes,processes, such assuch as BB ,, ,, ,, ……

However, penguin pollution complicates However, penguin pollution complicates extraction ofextraction of measure measure sin 2sin 2 effeff

Since |Since | || 11,, CPCP asymmetry has formasymmetry has form

Interference of bInterference of b uud uud decay decay ww&&w/ow/o BB00BB00 mixing yields anglemixing yields angle

tree B0 B0 mixingpenguin

)2

(GeV/cESm5.24 5.26 5.28

)2E

vent

s / (

4 M

eV/c

0

20

40

60(a)

617 ± 52 events

BB00 ++ --


Complication from PenguinsComplication from Penguins

SS measuresmeasures 22 effeff = 2= 2 ++ , where, where can becan be determined using thedetermined using the Gronau-LondonGronau-London methodmethod

The decaysThe decays BB + + --, , + + 00, , 0 0 00 are related by SU(2)are related by SU(2)

Have isospin relations between amplitudes AA+-+-, A, A+0+0, A, A0000

Central observation is that Central observation is that states can have I=2 or 0, whilestates can have I=2 or 0, while gluonic gluonic penguins only contribute to I = 0 (penguins only contribute to I = 0 ( II = rule) = rule)

+ + 00 is pure I = 2, so only tree amplitude is pure I = 2, so only tree amplitude |A|A+0+0| = |A| = |A-0-0||

Need to measure:Need to measure: CC+-+-, C, C0000 (amplitudes in (amplitudes in CosCos terms for terms for ++ - - & & 00 00),), && AA0000, A, A+0+0

Effective Effective isospinisospin

analysis requiresanalysis requires AA0000 && AA0000

very large, or very small!very large, or very small!

BB isospin isospin analysisanalysis

Phys. Rev. Lett. 65, 3381 (1990)


CP CP Asymmetry in BAsymmetry in B ++ --

S = 0.30 ± 0.17 ± 0.03

C = 0.09 ± 0.15 ± 0.04

S = 0.67 ± 0.16 ± 0.06

C = 0.56 ± 0.12 ± 0.06

B

tag

0

hep-ex/0501071 227227 101066 BB events BB events

666±43 666±43 ++ -- eventsevents

275275 101066 BB events BB events

B

tag

0


Results for BResults for B±± ±± 00 and and BB00 00 00

B+ K+ 0

B+ + 0

hep-ex/0412037

B0 0 0

bkg

Weak constraintWeak constraint

60 10)4.06.08.5()( +±±=B

02.010.001.0)( 0±±=

+

CPA

61±18 events61±18 events379±41 events379±41 events

600 10)10.032.017.1()( ±±=B

06.056.012.000

±±=C

67° < < 131°


BABARBABAR’’s s Measurement from B Measurement from B00 ++ --

(deg)α0 60 120 180

1 -

CL

0

0.2

0.4

0.6

0.8

1

BB00

BB00

S( + ) = 0.33 ± 0.24 0.14

+0.08

C( + ) = 0.03 ± 0.18 ± 0.09 = [100 ± 7

exp± 11

peng]o

From study ofFrom study of BB 00 00 penguinpenguin amplitude can beamplitude can be constrained constrained

We donWe don’’t seet see BB 00 00

yieldingyielding model model uncertaintyuncertainty ofof || effeff-- |< 11|< 1100 onon extractionextraction

B(B0 0 0 ) < 1.1 10 6 @ 90% C.L.

B(B0 + ) = (33 ± 4 ± 5) 10 6


Summary on Summary on

= [99

-9

+12]o

Mirror solutionsMirror solutions are disfavoredare disfavored

CKM indirectCKM indirect constraint yields:constraint yields:

= [98

-19

+13]o

From combined From combined ,, , , results results constrain constrain to: to:

Very good agreementVery good agreement

Best constraintsBest constraints

from from B B


Measuring Measuring in in BB DKDK(*)(*) Modes Modes

Color

suppressed*

cb usA V V

*

ub csA V V

cbV

*

usV

ubV

*

csV

3

3 2 2

ie+

The angle The angle is measurable via interference between is measurable via interference between BB-- DD00KK-- && BB-- DD00KK-- decays, where thedecays, where the DD0 0 /D/D00 decay to decay to common final statecommon final state

Different methods:Different methods: most promising is a most promising is a DD0 0 KK00

SS++ --

DalitzDalitz plotplot analysis in analysis in

Error on Error on becomes smaller becomes smaller for larger values of for larger values of rr(*)(*)

BB

(( )~38)~3800 for for rrBB~0.1~0.1 & & (( )~20)~2000 for for rrBB~0.2~0.2

B- D0(K

S

0 + -)K-

rB

(*)=|A(B- D

(*)0

K-)|

|A(B- D(*)0K-)|

~ 0.1-0.3

m

KS

0 +

2

m

KS

0

2


Results for Results for Combining all Combining all 33 methods for methods for BB-- D D(*)0(*)0KK(*)-(*)- yields first yields first

measurement of measurement of

A few years ago thisA few years ago this was thought to bewas thought to be impossibleimpossible

From combined analysisFrom combined analysis

From indirect constraintsFrom indirect constraints

= [51 -18

+23]o

measurements obtainedmeasurements obtained from 2 independent methodsfrom 2 independent methods are in are in excellent agreementexcellent agreement

= [57

-13

+7 ]o

rB= 0.106

0.042

+0.036

rB

*= 0.102

0.057

+0.034

Results forResults for

rr(*)(*)BB::


StatusStatus of of Unitarity Unitarity TriangleTriangle

Allowed region isAllowed region is determined fromdetermined from UT sides & UT sides & sin 2sin 2

Both angles Both angles , , , , & UT sides are in& UT sides are in good agreementgood agreement

Allowed UT regionAllowed UT region agrees withagrees with Standard ModelStandard Model prediction prediction

Look for New PhysicsLook for New Physics as correction toas correction to Standard ModelStandard Model


Observation of Direct CP in BObservation of Direct CP in B00 KK±± --

B0 K+ -

B0 K- +

We observe decay asymmetry between We observe decay asymmetry between BB00 KK++ -- & B & B00 KK-- ++

++

~5-0.113 ± 0.022stat ±0.008syst

# AK

4.2-0.133 ± 0.030stat ±0.009syst

This effect is not seen in This effect is not seen in BB++ KK++ 00 & B & B-- KK-- 00

A

CP= 0.049 ± 0.04 (BABAR & Belle average)(BABAR & Belle average)

227227 10106 6 BB eventsBB events 386386 10106 6 BB eventsBB events


New Physics may affect both BdBd mixing, changing size of mBd and introducing new CP-violating phase in aCP( Ks)=S Ks

This is based on the scenario discussed by Y. Nir in the BABAR physics book (Y. Okada has discussed similar ideas)

Yossi considered measurements of Vub/Vcb, mBd, a Ks, a

In the presence of new physics: i)

remain primarily tree level

ii) There would be a new contribution to KK mixing constraint: small (ignore new parameters)

iii) Unitarity of the 3 family CKM matrix is maintained if there are no new quark generations

b ccs : a

Ks=a

CP( K

s

0 )

b uud : a =a

CP( + )

K

Model-independent Analysis of BB MixingModel-independent Analysis of BB Mixing


Under these circumstances new physics effects can be described by 2 parameters: rd, d

Thus, New Physics parameters modify the parameterization of following observables

Extend 2 function to include new parameters rd, d

A

Ks

0= sin (2 +2

d)

A

+= sin (2 -2

d)

m

Bd

= CtR

t

2rd

2

Bd

0 Heff

full Bd

0

Bd

0 Heff

SM Bd

0= (r

de

id )2

Model-independent Analysis of BB MixingModel-independent Analysis of BB Mixing


New Physics in BNew Physics in B00BB00 Mixing Mixing

NirAgashe, et al.


ProspectsProspects Due to recent decision by DOE PEP II will run till end of 2008

expected integrated luminosity will be Ldt~1ab-1, (500 fb-1 by summer 2006)

KEKB has a short term program till 2008 with similar integrated luminosity, and a long term plan that gets Ldt~10ab-1 by 2014 (not approved), based on peak luminosity of 2.5 1035 cm-2 s-1

To be competitive with LHCb one needs a peak luminosity of

1 1036 cm-2 s-1

LHCb is expected to come on 2008 with 50% efficiency main emphasis will be on Bs physics

B-physics capabilities in ATLAS & CMS are rather limited

SLAC will focus on ILC, but within BABAR efforts remain for 1036 cm-2 s-1 super B-factory joint experiment with super KEKB? new project (study at Frascati based on linear collider)?


Global CKM fit: 2008Global CKM fit: 2008

(V

ub) = 6.5%

( m

s) = 5% ( ) = 8

o

( ) = 10o

(sin2 ) = 0.019


The World is not CP SymmetricThe World is not CP Symmetric

Documents

Lecture III - Forside€¦ · Lecture III Measurement of sin 2 in B K0 S Measurement of sin 2 in B K0 S Measurement of sin 2 in B + -, B + - Measurement of in B DK Direct CP Violation