˘ babar · 2001-02-14 · b a rt m & l.d e bru n hof babar ™ and © l. de brunhoff canada...

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Babar ™ and © L. de Brunhoff

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Canada [4/15]U of British ColumbiaMcGill UU de MontréalU of Victoria

China [1/5]Inst. of High Energy Physics, Beijing

France [5/51]LAPP, AnnecyLAL OrsayLPNHE des Universités Paris 6/7Ecole PolytechniqueCEA, DAPNIA, CE-Saclay

Germany [3/23]U RostockRuhr U BochumTechnische U Dresden

USA [36/253]California Institute of TechnologyUC, IrvineUC, Los AngelesUC, San DiegoUC, Santa BarbaraUC, Santa CruzU of CincinnatiU of ColoradoColorado StateElon CollegeFlorida A&MU of IowaIowa State ULBNLLLNLU of LouisvilleU of MarylandU of Massachusetts, AmherstMITU of MississippiMount Holyoke CollegeNorthern Kentucky UU of Notre DameORNL/Y-12U of OregonU of PennsylvaniaPrairie View A&MPrincetonSLACU of South CarolinaStanford UU of TennesseeU of Texas at DallasVanderbiltU of WisconsinYale

9 Countries73 Institutions516 Physicists

The BABAR Collaboration Italy [12/89]INFN, BariINFN, FerraraLab. Nazionali di Frascati dell' INFNINFN, GenovaINFN, MilanoINFN, NapoliINFN, PadovaINFN, PaviaINF, PisaINFNN, Roma and U "La Sapienza"INFN, TorinoINFN, Trieste

Norway [1/2]U of Bergen

Russia [1/7]Budker Institute, Novosibirsk

United Kingdom [10/71]U of BirminghamU of BristolBrunel UniversityU of EdinburghU of LiverpoolImperial CollegeQueen Mary & Westfield CollegeRoyal Holloway, University of LondonU of ManchesterRutherford Appleton Laboratory

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� Introduction

� PEP-II and BABAR

� Measurement of1) mixing and 2) CP-violating asymmetries in B0 decays to CP eigenstates

� Isolating and tagging the samples

� Determining the mistag fractions�Determining the �z resolution

�Measuring

�Determining the CP-violating asymmetries

� Conclusion and outlook

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PEP-II �� BABAR

❒ With the goal of measuring CP-violating asymmetries in B0 decay ❒ Construction of the PEP-II asymmetric storage ring commenced in 1993 ❒ Construction of the BABAR detector began in 1994

❒ PEP-II had first collisions in the Summer of 1998

❒ BABAR was rolled onto the beamline in Spring 1999 and saw its first events on May 26, 1999

❒ PEP-II performance has already exceeded design goals:

0.7 A

2.1 A

135 pb-1

3 x 1033 cm-2s-1

Design

0.92 Ae- current

2.14 Ae+ current

170 pb-1

3.1 x 1033 cm-2s-1Peak Luminosity

Performance

I n t e g r a t e d / d a yL

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The ϒ (4s) resonance

Mϒ(4s) = 10.5841 + 0.0007 GeV

Γϒ(4s) = 11.1 + 3.4 MeV

0 0(4 ) , in a coherent =1 state

s B B B BL

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PEP-II ��BABAR ��

PEP-II delivered: 25.3 fb-1

BABAR recorded: 23.6 fb-1

02000400060008000

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6/1/997/1/998/1/999/1/9910/1/9911/1/9912/1/991/1/002/1/003/1/004/1/005/1/006/1/007/1/008/1/009/1/0010/1/0011/1/00

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BABAR efficiency

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Babar Characters TM & © Laurent deBrunhoff

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��.�� '�� CP violation was found in decay 1964 by Christenson, Cronin, Fitch and Turlay� The fundamental role of CP Violation in producing the observed matter/antimatter

asymmetry of the universe was pointed out in the Nobel Prize Citation in 1980� "The new truth reached by the discovery of violations of the laws of symmetry in nature

recently also has been incorporated as an important ingredient in cosmological speculations. The aim has been to try to understand how a universe, originally very hot and symmetric, could avoid that matter and antimatter almost immediately annihilated each other. In other words, efforts have been made to describe how the matter we are made of was once created in a big bang and how it could survive the birth pains,"

� The new knowledge offered by the prizewinners "permits us to make a distinction between matter and antimatter in an absolute and not only relative way. The left and right dimensions could then also be given absolute meaning, thus losing the arbitrariness of definition.“

� It is difficult, however, to use CP-violating asymmetries seen in decay to determine the strength of the CP-violating phase in the Standard Model� Interpretation in terms of fundamental parameters is clouded by “hadronic engineering”

effects� The basic problem is that it is difficult to relate the observed decay of the meson to

the underlying process, the weak decay of the s quark

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LK

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LK

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/��+��!��.�� The interactions of the quarks are described by the

Cabibbo-Kobayashi-Maskawa (CKM) matrix of coupling constants

� The magnitudes of the CKM matrix elements are measured by determining the rates of various decay processes, primarily absolute branching ratios of inclusive and exclusive semileptonic decays, as well as the rates of neutral meson mixing

d s b

u

c

t

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V V V

V V V

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D K ��

d s b

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c

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Nuclear ��decay

K � ��

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B D

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� The most useful unitarity condition:

� The sides of the unitarity triangle are determined by measurements of the magnitudes of CKM matrix elements

� CP-violating asymmetries in B0 decays to CP eigenstates measure the anglesof the unitarity triangle, thereby providing an overconstrained situation and thereby a unique test of the Standard Model in the CKM sector

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� The angles of the unitarity triangle are the phases φM- φD :

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u d u b td tb c d c b

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February 12, 2001��

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*��1��!��#��2�� Any 3x3 unitary matrix can be completely described by 3 real numbers

and 1 complex phase

� There are a number of such descriptions in common use: θ12, θ13, θ23, δ� The Wolfenstein parametrization exhibits the relative size of the experimentally

measured magnitudes through an expansion:

� λ and A are well-determined

� The area of the unitarity triangle is proportional to the amount of CP violation in the Standard Model:the “Jarlskog Invariant”

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� CP-violating asymmetries in B0 meson decays directly measure the angles α, β, γ of the unitarity triangle, without hadronic engineering uncertainties

� Thus, by measuring these asymmetries, it is possible to provide an overconstrained set of measurements of the CKM matrix and test the consistency of the Standard Model of CP violation

� If inconsistencies are found, patterns of CP-violating asymmetries may be characteristic of particular extensions of the Standard Model

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��"��!�##��!��3.�.��(� The mass eigenstates of the neutral B meson system:

� Mixing is governed by a single phase:

� The amplitudes for decays into a CP eigenstate f are:

� When only a single amplitude with a given weak phase �D dominates the decay:

B p B q B

B p B q B

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Thus there is a asymmetry proportional to sin2( )

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M DCP

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'��& CP �� (4 )S�

The (4 ) resonance decays to pairs in a coherent =1 stateS BB L�

At PEP-II, with e- energy of 9 GeV and e+ energy of 3.1 GeV, the is produced with ��=0.56(4 )S�

The mean decay distance �z between the B decay vertices is ~250�m, making it possible to ascertain the time order of the decays

If we can measure the flavor (i.e. “tag”) of a decay (Btag) occurring at a time t, then at that time, the flavor of the other is known.

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We then reconstruct the decay of the second B0 at a time �t=tCP-ttag into a CP eigenstate:

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If all decay amplitudes have the same weak phase, as do the charmonium

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For these eigenstates: = , where is the eigenvalue of stai

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The sides of the unitarity triangle are determinedby the magnitudes of the CKM matrix elements.

Uncertainties in theoretical models for Vub, fB, BK, etc limit the determination of the triangle

The CP asymmetry in B0 decays to CP eigenstatesmeasures

allowing us to overdetermine the Unitarity Triangle

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The CP asymmetry is

There are four time distributions

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'��& ��,�&�� The probability of mixing is

� Thus there is an asymmetry due to mixing:

� Measuring mixing does not require the CP eigenstate sample BCP, but can use the much larger sample of decays to flavor eigenstates Bflav

� The CP asymmetry and mixing analyses are done with a combined PDF� They differ only in their use of the beam-spot constraint

(4 )S�0 0B B

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( ) 1 cos( )4

( ) 1 cos( )4

( ) 1 cos( )4

t

B B

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Both analyses can be done with a single optimum t binThis is used a a cross check (“One-bin method”)

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Reconstruct exclusive B decays to CP eigenstates and flavor eigenstates and tag the flavor of the other B decay

Measure �z between BCP and Btag to determine thesigned time difference �t between the decays

CPBtagB

e� e�

z

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flav

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Select candidates

( / , .)

and candidates

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S

B

B J K etc

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B D etc

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Select events using, primarily,

leptons and ’s from hadronic

decays & determine flavor

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mistag fractions ions

= 1- 2 w

wD

Determine the resolution function for �z

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*��+�� sin2� is measured with a 35 parameter fit using the likelihood function:

� Fit parameters� sin2�� 4 signal dilutions (D=1-2w)� 4 values of �D for the 4 signal categories� 9 parameters for the signal �t resolution function

� 8 background dilutions� 3 parameters describing the background resolution function� 1 parameter for the fraction of prompt CP background� 5 parameters for the fractions and lifetime of the prompt Bflav background

0 0flav,mix, tag

B BN

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0 0flav,mix, tag

B BN

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0 0flav,unmix, tag

B BN

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0 0flav,unmix, tag

B BN

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0 0

0

0

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and are fixed at the

PDG world average values:

= 0.472 ps

1.548 ps

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( ) 1 cos( )4 2

( ) 1 cos( )4 2

( )

t

B B

t

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t

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1 1( ) 1 cos( ) Im sin( )

2 2 22 (1 )

1 1( ) 1 cos( ) Im sin( )

2 2 22 (1 )

t

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t

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e Df t D m t m t

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These distributions are corrected for �t resolution as well as for backgrounds

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n2β P1 -0.4562E-02 0.6840E-02

P2 1.005 0.2093E-01

-1

0

1

-1 -0.5 0 0.5 1

Full Monte Carlo simulation of BCP, Bflav,background

No bias is observed

A systematic error of�0.014 is assigned

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5.2 5.22 5.24 5.26 5.28 5.3 B const vs deltaE ee

0

10

20

30

40

50

60

70

5.2 5.225 5.25 5.275 5.3

22.58 / 35NORM 686.8 299.6EFACT -10.57 74.56AREA 134.9 11.85MEAN 5.280 0.2518E-03SIGMA 0.2750E-02 0.

mES (GeV/c2)mES (GeV/c2)mES (GeV/c2)

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mES (GeV/c2)mES (GeV/c2)

Purity: 98.3%

S2/(S+B) = 127.2

delta E ee mB5.27

0

5

10

15

20

25

30

35

40

-0.1 -0.05 0 0.05 0.1

9.119 / 19P0 0.7025 0.1550P1 -6.350 1.828AREA 132.9 11.95MEAN 0.7975E-03 0.1044E-02SIGMA 0.1122E-01 0.8290E-03

Sig: 11.2 Y: 132.9

jpsiks_mm

-0.1

-0.075

-0.05

-0.025

0

0.025

0.05

0.075

0.1

5.2 5.22 5.24 5.26 5.28 5.3 B const vs deltaE mm

0

10

20

30

40

50

60

70

80

5.2 5.225 5.25 5.275 5.3



Com

bina

tions

/2.5

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Purity: 98.8%

S2/(S+B) = 150.2

delta E mm mB5.27

0

10

20

30

40

50

60

-0.1 -0.05 0 0.05 0.1

15.58 / 17P0 0.4653 0.1327P1 -0.8355E-03 70.96AREA 156.4 12.88MEAN 0.9925E-04 0.8207E-03SIGMA 0.9483E-02 0.7186E-03

Sig: 9.5 Y: 156.4

0, / ( )ES Sm E J K� � � �� !��

/J e e� � �� /J � � ��

� �2 2ES ( )cm cm

beam Bm E p� � �E = EBcm - Ebeam

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energy substituted mass (GeV)5.2 5.22 5.24 5.26 5.28 5.3

Eve

nts

/ 0.

0025

GeV

0

10

20

30

40

50

energy substituted mass dataset:xmb

Nent = 144

Mean = 5.273

RMS = 0.01901

28±shape = -16

0.015±purity = 0.971

0.00026 GeV±mass = 5.28017

11±nsig = 118


Nent = 144

Mean = 5.273

RMS = 0.01901


Eve

nts

/ 0.

0025

GeV

0

10

20

30

40

50


Nent = 150

Mean = 5.278

RMS = 0.01081

48±shape = -34

0.010±purity = 0.988

0.00023 GeV±mass = 5.28003

12±nsig = 140


Nent = 150

Mean = 5.278

RMS = 0.01081

0 / ( )ES Sm J K� � �� .�� ,��

/J e e� � �� /J � � ��

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0

2.5

5

7.5

10

12.5

15

17.5

20

5.2 5.225 5.25 5.275 5.3

24.22 / 35NORM 1914. 823.3EFACT -58.44 21.96AREA 32.01 6.548MEAN 5.281 0.6033E-03SIGMA 0.2750E-02 0.


Com

bina

tions

/2.5

MeV


Purity: 85.6%

S2/(S+B) = ’ 26.3’

delta E ee mB5.27

0

1

2

3

4

5

6

7

8

-0.1 -0.05 0 0.05 0.1

12.13 / 16P0 0.3273E-05 0.3827P1 -5.691 2.798AREA 40.44 7.965MEAN -0.1102E-02 0.8164E-02SIGMA 0.3516E-01 0.4377E-02

Sig: 35.2 Y: 40.4

jpsiks2pi0_mm

-0.1

-0.075

-0.05

-0.025

0

0.025

0.05

0.075

0.1


0

2

4

6

8

10

12

14

16

18

5.2 5.225 5.25 5.275 5.3



Com

bina

tions

/2.5

MeV


Purity: 93.4%

S2/(S+B) = ’ 31.3’

delta E mm mB5.27

0

1

2

3

4

5

6

7

8

-0.1 -0.05 0 0.05 0.1

15.38 / 19P0 0.5365 0.2970P1 -3.432 2.380AREA 22.62 12.10MEAN -0.5152E-02 0.1342E-01SIGMA 0.3157E-01 0.1532E-01

Sig: 31.6 Y: 22.6

0 0 0, / ( )ES Sm E J K� � � ��!��

/J e e� � �� /J � � ��

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Eve

nts

/ 0.

0025

GeV

0

2

4

6

8

10

12


Nent = 50

Mean = 5.267

RMS = 0.02299

28±shape = -77

0.094±purity = 0.771

0.00068 GeV±mass = 5.28164

5.7±nsig = 24.4


Nent = 50

Mean = 5.267

RMS = 0.02299


Eve

nts

/ 0.

0025

GeV

0

2

4

6

8

10


Nent = 43

Mean = 5.265

RMS = 0.0262

35±shape = -28

0.065±purity = 0.899

0.00063 GeV±mass = 5.28076

5.5±nsig = 25.2


Nent = 43

Mean = 5.265

RMS = 0.0262

0 0 0 / ( )ES Sm J K� � �.�� ,��

/J e e� � �� /J � � ��

BA BA

RTM

&L.d

eB runho

ff


��

��

psi2sks_mm

-0.1

-0.075

-0.05

-0.025

0

0.025

0.05

0.075

0.1


0

2.5

5

7.5

10

12.5

15

17.5

20

22.5

5.2 5.225 5.25 5.275 5.3


mES (GeV/c2)mES (GeV/c2)mES (GeV/c2)C

ombi

natio

ns/2

.5 M

eVmES (GeV/c2)mES (GeV/c2)

Purity: 96.1%

S2/(S+B) = ’ 29.9’

delta E mm mB5.27

0

2

4

6

8

10

12

14

16

-0.1 -0.05 0 0.05 0.1

13.24 / 9P0 0.2447 0.9207E-01P1 -0.8742 1.158AREA 32.21 5.990MEAN -0.3447E-02 0.1747E-02SIGMA 0.8765E-02 0.1698E-02

Sig: 8.8 Y: 32.2

psi2sks_ee

-0.1

-0.075

-0.05

-0.025

0

0.025

0.05

0.075

0.1


0

2

4

6

8

10

12

14

16

5.2 5.225 5.25 5.275 5.3



Com

bina

tions

/2.5

MeV


Purity: 94.0%

S2/(S+B) = ’ 25.8’

delta E ee mB5.27

0

2

4

6

8

10

12

-0.1 -0.05 0 0.05 0.1

6.051 / 10P0 0.3014 0.9609E-01P1 -2.559 1.661AREA 28.91 5.626MEAN 0.3562E-02 0.1560E-02SIGMA 0.7568E-02 0.1389E-02

Sig: 7.6 Y: 28.9

0, (2 )ES Sm E s K� ��!��

e e� �

� ��

BA BA

RTM

&L.d

eB runho

ff


��

�"


Eve

nts

/ 0.

0025

GeV

0

2

4

6

8

10


Nent = 31

Mean = 5.273

RMS = 0.01601

71±shape = -42

0.048±purity = 0.961

0.00059 GeV±mass = 5.27914

5.4±nsig = 25.6


Nent = 31

Mean = 5.273

RMS = 0.01601


Eve

nts

/ 0.

0025

GeV

0

2

4

6

8

10

12

14

16


Nent = 35

Mean = 5.274

RMS = 0.01852

56±shape = -23

0.027±purity = 0.973

0.00051 GeV±mass = 5.28031

5.5±nsig = 29.4


Nent = 35

Mean = 5.274

RMS = 0.01852

0 (2 )ES Sm s K�.�� ,��

e e� � � ��

BA BA

RTM

&L.d

eB runho

ff


��

��

mes ��!�� !��#��!��(��!0

SK

� ��

0

0 0 0

0

/ 259 events

/ 50 events

(2 ) 54 events

S

S

S

J K

J K

s K

� � �

� � �

�

� �

0

40

80

120

160

5.2 5.22 5.24 5.26 5.28 5.3

mES (GeV/c2)

Ent

ries

/ 2.5

MeV

/c2 a)

0

40

80

120

160

5.2 5.22 5.24 5.26 5.28 5.3

∆E (MeV)

Ent

ries

/ 6 M

eV

0

20

40

60

80

100

-120 -80 -40 0 40 80 120

ψ( 2S ) KS0(π+π−)

J/ψKS0(π0π0)

J/ψKS0(π+π−)

BA BA

RTM

&L.d

eB runho

ff


��

��

�� candidates are formed from clusters in the EMC(>200 MeV)

and in the IFR (at least 2 layers) not associated with charged tracks

� The energy is determined by combining its direction with thewith the reconstructed J/ momentum, assuming the decay

� This mode has by far the most background

� Detailed Monte Carlo studies have been done to understand the shape, normalization and CP content of the background

0/ LJ K�0

LK

0

LK

00 /L

B KJ ��

BA BA

RTM

&L.d

eB runho

ff


��

��

0/ LE J K� ��!��

Background

∆E (MeV)

Ent

ries

/ 2 M

eV

J/ψKL0 signal MC

Data

0

20

40

-20 0 20 40 60 80

Background

∆E (MeV)

Ent

ries

/ 2 M

eV

J/ψKL0 signal MC

Data

0

10

20

30

40

-20 0 20 40 60 80

Background

∆E (MeV)

Ent

ries

/ 2 M

eV

J/ψKL0 signal MC

Data

0

20

40

60

80

-20 0 20 40 60 80

EMC IFR

EMC+IFR

182 events above background

BA BA

RTM

&L.d

eB runho

ff


��

��

mes ��B0 ��!�( Bflav )

BABAR

Energy Substituted Mass (GeV/c2)

Eve

nts

/0.0

02 G

eV/c

2

0

500

1000

1500

2000

5.2 5.22 5.24 5.26 5.28 5.3

4637 events

� �* * * *0 *0

1, , and /D D D a J K K K� � � ��

BA BA

RTM

&L.d

eB runho

ff


��

��

�� #�!�� 4��

[deg]labθ0 20 40 60 80 100 120 140

electr

on id

entif

icatio

n eff

icien

cy

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0

0.05

0.1

0.15

0.2

0.25

-2x10

pion m

iside

ntific

ation

prob

abili

ty

BABARElectronsPions

[GeV/c]labp0 0.5 1 1.5 2 2.5

electr

on id

entif

icatio

n eff

icien

cy

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0

0.001

0.002

0.003

0.004

0.005

pion m

iside

ntific

ation

prob

abili

ty

BABARElectronsPions

E/p,EMC cluster shapeDCH de/dx,DIRC Cherenkov angle

Uses:

BA BA

RTM

&L.d

eB runho

ff


��

��

.�� #�!�� 4��

plab (GeV/c)

Muon

selec

tor pe

rform

ances BABAR

0

0.2

0.4

0.6

0.8

1

0 1 2 3 4 5

Polar angle (deg)

Muon

selec

tor pe

rform

ances BABAR

0

0.2

0.4

0.6

0.8

1

0 50 100 150

Penetration lengthSpread and number of IFR hits

Uses:

BA BA

RTM

&L.d

eB runho

ff


��

��

3�� #�!�� 4��

0

0.2

0.4

0.6

0.8

1

0 1 2 3 4

plab (GeV/c)

Pion m

isiden

tificati

on

y

plab (GeV/c)

K

aon e

fficien

cy

plab (GeV/c)

BABAR

Uses:SVT and DCH dE/dxDIRC Cherenkov angle

BA BA

RTM

&L.d

eB runho

ff


��

��

*�""�"��"��!� Tag candidates are assigned to one of four hierarchical, mutually exclusive

categories� Lepton

� An electron with pcm >1.0 GeV/c or a muon with pcm > 1.1 GeV/c

� Kaon

� No lepton tag and non-zero net kaon charge

� NT1

� NT2� primarily slow pions and recovered unidentified leptons

p(B0)

Num

ber

per

B p

er b

in

BABARMC

Data

NT1

NT2

0

0.05

0.1

0 0.25 0.5 0.75 10

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

-1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1

NetTagger Output

All

Two Kaons

Kaon and Lepton

Slow πStiff Track

low P Lepton

other

Q NT-2 Q NT-1

0.015

0.001

0.000

0.005

0.003

0.002

0.004

0.031

0.002

0.002

0.008

0.014

0.003

0.002

BA BA

RTM

&L.d

eB runho

ff


��

��

2

The effective tagging efficiency i

2 )

s

(1i i iQ w��

'��&� ��/��0� �� $�flav CPB B�

Tag Category "(%) w(%) Q(%)

Lepton 10:9� 0:4 11:6� 2:0 6:4� 0:7

Kaon 36:5� 0:7 17:1� 1:3 15:8� 1:3

NT1 7:7� 0:4 21:2� 2:9 2:6� 0:5

NT2 13:7� 0:5 31:7� 2:6 1:8� 0:5

Total 68:9� 1:0 26:7� 1:6

Efficiency (%)

Wro

ng ta

g fr

actio

n (%

)

BABAR

LeptonKaonNT1

NT2

0

20

40

60

0 10 20 30 40

BA BA

RTM

&L.d

eB runho

ff


��

�"

'��&� ��!��&�� $�flav CPB B�

flav

flav

flav

flav

flav

BA BA

RTM

&L.d

eB runho

ff


��

��

��!!��+!��#�!��"��!��!

Using 1) ~16,000 D*l decays 2) the “One-bin” method with Bflav sample

0.267 � 0.0170.264 � 0.0180.255 � 0.017Q

0.317 � 0.0260.323 � 0.027 � 0.0090.364 � 0.016 � 0.013w [NT2]

0.212 � 0.0290.197 � 0.030 � 0.0100.216 � 0.019 � 0.016w [NT1]

0.171 � 0.0130.176 � 0.014 � 0.0060.180 � 0.009 � 0.010w [Kaon]

0.116 � 0.020 0.116 � 0.021 � 0.0060.108 � 0.013 � 0.011w [Lepton]

Global likelihood fitOne bin hadronicone binParameter 0 *B D l��

BA BA

RTM

&L.d

eB runho

ff


��

��

� The time resolution is dominated by the z resolution of the tagging vertex

� The vertex resolution function is well-described by a sum of three gaussians

� We scale the core and tail widths to the event-by-event measurement error derived from the vertex fits.

�� t

t resolution is dominated by z resolution of tagging vertex: z = 180 �m for tagging vertex, z = 70 �m for fully reconstructed vertex

BA BA

RTM

&L.d

eB runho

ff


��

��

�� t

Parameter Value

SCore 1:1� 0:1

STail 3:8� 0:9

fTail (%) 11� 5

fOutlier (%) 0:8� 0:5

ÆCore;Lepton (ps) 0:08� 0:10

ÆCore;Kaon (ps) 0:21� 0:05

ÆCore;NT1 (ps) 0:01� 0:10

ÆCore;NT2 (ps) �0:18� 0:09

ÆTail (ps) �0:46� 0:38

BA BA

RTM

&L.d

eB runho

ff


��

��

��7.��#4��!�� z ��

B ��&��

B ��

BA BA

RTM

&L.d

eB runho

ff


��

��

1��

� The sin2� and mixing analyses are blinded to eliminate experimenter bias

� The amplitude in the asymmetry ACP(�t) is hidden by arbitrarily

flipping its sign and by adding an arbitrary offset� The CP asymmetry in the �t distribution is hidden by multiplying �t

by the sign of the tag and by adding an arbitrary offset � is hidden� The blinded aproach allows systematic studies of tagging, vertex

resolution and their correlations to be done while keeping the value of sin2� hidden

� The result was unblinded two weeks ago

0Bm�

BA BA

RTM

&L.d

eB runho

ff


��

��

�t ��!�� !��#�(��#�(��""��8��!�)��mes > 5.27 GeV/c2

BABARUnmixed Events

Eve

nts

/ 0.4

ps

∆t (ps)

Mixed Events0

100

200

300

400

0

100

200

300

400

-10 -5 0 5 10

Signal+background

Background

BA BA

RTM

&L.d

eB runho

ff


��

��

*�#��4��!�##�� )��#�(��#�(��!

|∆t| (ps)

Asy

mm

etry BABAR

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

0 2 4 6 8 10 12

( )mixA t�

0

-10.519 0.020(stat) 0.016 (syst) psB

m� � � � �

BA BA

RTM

&L.d

eB runho

ff


��

��

��#4��!�� #��!��#��!

0.4 0.45 0.5 0.55 0.6

∆mBo (ps-1)

LEP+SLD+CDFICHEP2000

0.486±0.015 ps-1

CDF * 0.495±0.026±0.025 ps-1

SLD * 0.526±0.043±0.031 ps-1

OPAL 0.479±0.018±0.015 ps-1

L3 0.444±0.028±0.028 ps-1

DELPHI 0.496±0.026±0.023 ps-1

ALEPH * 0.446±0.020±0.018 ps-1

Belle Dilepton 0.463±0.008±0.016 ps-1

BABAR Dilepton (Osaka) 0.507±0.015±0.022 ps-1

BABAR D*lnu (Osaka) 0.508±0.020±0.022 ps-1

BABAR Hadronic 0.519±0.020±0.016 ps-1

* working group average

0Bm�

BA BA

RTM

&L.d

eB runho

ff


��

��

�&&��!��&&�&��&��

BA BA

RTM

&L.d

eB runho

ff


��

�"

t ��!�� !��""��Ks ��!

0

10

20

30

40141 B0 tags

0

10

20

30

40

-10 -5 0 5 10

129 B− 0 tags

∆t in ps

BA BA

RTM

&L.d

eB runho

ff


��

��

-4

-3

-2

-1

0

-1 0 1 2

c)( )

sin 2�

ln(L

=L

max)

2,��&�sin2�

sin 2 0.34 0.20 (stat) 0.05 (syst)��

��$��!�!�� !��&��-��3��-��'��4��3��5

��$�

0/ LJ K�

0 modesSK

1��

BA BA

RTM

&L.d

eB runho

ff


��

��

2,��& sin2�

sin 2 0.34 0.20 (stat) 0.05 (syst)��

0 modesSK

0/ modeLJ K�

sin 2 0.25 0.22 (stat)��

sin 2 0.87 0.51 (stat)��

Binned asymmetry, plotted with asymmetric binomial errors

-1

-0.5

0

0.5

1 a)

-1

-0.5

0

0.5

1

-5 0 5

b)

Asy

mm

etry

�t (ps)

BA BA

RTM

&L.d

eB runho

ff


��

��

sin2� ��CP ��!�#4�!

Sample Ntag Purity (%) sin2�

J= K

0S, (2S)K

0S 273 96� 1 0:25 � 0:22

J= K

0L 256 39� 6 0:87 � 0:51

Full CP sample 529 69� 2 0:34 � 0:20

J= K

0S, (2S)K

0S only

J= K

0S (K0S ! �

+��) 188 98� 1 0:25 � 0:26

J= K

0S (K0S ! �

0�0) 41 85� 6 �0:05 � 0:66

(2S)K0S (K0S ! �

+��) 44 97� 3 0:40 � 0:50

Lepton tags 34 99� 2 0:07 � 0:43

Kaon tags 156 96� 2 0:40 � 0:29

NT1 tags 28 97� 3 �0:03 � 0:67

NT2 tags 55 96� 3 0:09 � 0:76

B0 tags 141 96� 2 0:24 � 0:31

B0 tags 132 97� 2 0:25 � 0:30

B av sample 4637 86� 1 0:03 � 0:05

Charged B sample 5165 90� 1 0:02 � 0:05

BA BA

RTM

&L.d

eB runho

ff


��

��

��!��#��!

Systematic J= K0S, (2S)K0S

J= K0L

Full sample

�t determination 0:04 0:04 0:04

J= K0S, (2S)K0S

back. 0:02 | 0:02

J= K0L

back. | 0:09 0:01

J= K0L

Sig. fraction | 0:10 0:01

�B0 0:01 0:01 < 0:01

�mB0 0:01 < 0:01 0:01

Other 0:01 0:01 0:01

Total 0:05 0:14 0:05

BA BA

RTM

&L.d

eB runho

ff


��

��

4��+�� &�The set of ellipses represents the allowed range of based on our knowledge of the magnitudes of CKM matrix elements, for a set of typical values of model-dependent theoretical parameters:

sin2� = 0.34 � 0.20 � 0.05is not included in the fits

( , ) �

0

0.2

0.4

0.6

0.8

1

-1 -0.5 0 0.5 1

sin 2βBaBar

εK

∆ms/∆md

∆md

|Vub/Vcb|

ρ

η

Parameter Value � Error(s)

jVud

j 0:97394� 0:00089

jVusj 0:2200� 0:0025

jVubj (3:49� 0:27� 0:55)� 10�3

CKM

jVcd

j 0:224� 0:014

Parameters

jVcsj 0:969� 0:058

jVcbj (40:75� 0:40� 2:0)� 10�3

j�K

j (2:271� 0:017)� 10�3

CP violating

�md

(0:487� 0:014) ps�1

and

�ms WA (Beauty2000) amplitude spectrum

Mixing Observables

sin2�BaBar 0:34� 0:21

sin2�WA

0:49� 0:16

mt (166� 5) GeV

mK

(493:677� 0:016) MeV

�mK

(3:4885� 0:0008)� 10�15 GeV

mB

d

(5:2794� 0:0005) GeV

Experimental

mBs

(5:3696� 0:0024) GeV

Parameters

mW

(80:419� 0:056) GeV

GF

(1:16639� 0:00001)� 10�5 GeV�2

fK

(159:8� 1:5) MeV

mc (1:3� 0:1) GeV

BK

0:87� 0:06� 0:13

�cc 1:38� 0:53

�ct 0:47� 0:04

Theoretical

�tt 0:574� 0:004

Parameters

�B

(MS) 0:55� 0:01

fB

d

pBd

(230� 28� 28) MeV

� 1:16� 0:03� 0:05

BA BA

RTM

&L.d

eB runho

ff


��

��

��#4��!��sin2� #��!��#��!

sin2β

Average 0.49±0.16

OPAL 3.20+1.8 ±0.53.20 -2.0

ALEPH 0.84+0.82 ±0.160.84 -1.04

CDF 0.79+0.410.79 -0.44

Belle 0.58+0.34 +0.100.58 -0.320.58+0.34 -0.09

BABAR 0.34±0.20±0.05

-0.5 0 0.5 1 1.5 2 2.5 3 3.5

+0.32 +0.09-0.34 -0.100.58

BA BA

RTM

&L.d

eB runho

ff


��

��

��

��

� �� ! �� "�� #�� $

�� %��& ��'!��

�� !'�� $�� $

�� (��

�� &��

BA BA

RTM

&L.d

eB runho

ff


��

��

� PEP-II and BABAR have had an exciting and productive start, producing 25.3 fb-1 in the region and recording 23.6 fb-1

� Using the total data sample of 23 x 106 pairs, we have reconstructed and tagged ~360 decays of B0 to CP eigenstates, and have measured:

� Many other analyses are nearing the publication phase as well

� The 2001 run is now underway� We expect to more than double the data sample by the end of

the run in August� Additional modes will be used for sin2�:

� Planned luminosity improvements to PEP-II should allow us to accumulate a sample of more than 0.5 ab-1 by 2005� This will allow us to measure sin2�, to compare values of sin2� in

individual CP eigenstate modes and to explore interesting rare decay modes

)��4��

(4 )S�

sin 2 0.34 0.20(stat) 0.05 (syst)��

BB

0

-10.519 0.020(stat) 0.016 (syst) psB

m� � � � �

1

*0 0/ , c SJ K K� �

BA BA

RTM

&L.d

eB runho

ff


��

��

��9�� "��#��!��

��

��

- 150

- 125

- 100

- 75

- 50

- 25

- 0

fb-1

BA BA

RTM

&L.d

eB runho

ff


��

�"

30 fb -1

sin2β

90 fb -1

sin2β, sin2α

180 fb -1

sin2β, sin2α

�

�

BABAR 0��*��"��!��

˘ babar · 2001-02-14 · b a rt m & l.d e bru n hof babar ™ and © l. de brunhoff canada...

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