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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
0Bm�
0 0B B
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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
100001200014000160001800020000220002400026000
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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��������.������ '������� 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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/���+����������!���������������.���� 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
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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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*���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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� 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:
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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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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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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
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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
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� 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
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0
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PDG world average values:
= 0.472 ps
1.548 ps
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( ) 1 cos( )4 2
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t
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t
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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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P2 1.005 0.2093E-01
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-1 -0.5 0 0.5 1
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No bias is observed
A systematic error of�0.014 is assigned
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jpsiks_ee
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-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 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)
Com
bina
tions
/2.5
MeV
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
15.73 / 35NORM 611.5 479.6EFACT -40.30 58.50AREA 158.3 15.42MEAN 5.280 0.2179E-03SIGMA 0.2750E-02 0.
mES (GeV/c2)mES (GeV/c2)mES (GeV/c2)
Com
bina
tions
/2.5
MeV
mES (GeV/c2)mES (GeV/c2)
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 � � �� ��
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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
energy substituted mass dataset:xmb
Nent = 144
Mean = 5.273
RMS = 0.01901
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 = 150
Mean = 5.278
RMS = 0.01081
48±shape = -34
0.010±purity = 0.988
0.00023 GeV±mass = 5.28003
12±nsig = 140
energy substituted mass dataset:xmb
Nent = 150
Mean = 5.278
RMS = 0.01081
0 / ( )ES Sm J K� � �� �.����� �� � ������,�����
/J e e� � �� /J � � �� ��
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Babar ™ and © L. de Brunhoff
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jpsiks2pi0_ee
-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 ee
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.
mES (GeV/c2)mES (GeV/c2)mES (GeV/c2)
Com
bina
tions
/2.5
MeV
mES (GeV/c2)mES (GeV/c2)
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
5.2 5.22 5.24 5.26 5.28 5.3 B const vs deltaE mm
0
2
4
6
8
10
12
14
16
18
5.2 5.225 5.25 5.275 5.3
14.17 / 35NORM 780.5 470.3EFACT -31.27 47.87AREA 34.94 6.435MEAN 5.281 0.5257E-03SIGMA 0.2750E-02 0.
mES (GeV/c2)mES (GeV/c2)mES (GeV/c2)
Com
bina
tions
/2.5
MeV
mES (GeV/c2)mES (GeV/c2)
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
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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
2
4
6
8
10
12
energy substituted mass dataset:xmb
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
energy substituted mass dataset:xmb
Nent = 50
Mean = 5.267
RMS = 0.02299
energy substituted mass (GeV)5.2 5.22 5.24 5.26 5.28 5.3
Eve
nts
/ 0.
0025
GeV
0
2
4
6
8
10
energy substituted mass dataset:xmb
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
energy substituted mass dataset:xmb
Nent = 43
Mean = 5.265
RMS = 0.0262
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psi2sks_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
2.5
5
7.5
10
12.5
15
17.5
20
22.5
5.2 5.225 5.25 5.275 5.3
6.859 / 35NORM 467.1 404.7EFACT -65.18 62.21AREA 32.44 5.981MEAN 5.280 0.5248E-03SIGMA 0.2750E-02 0.
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
5.2 5.22 5.24 5.26 5.28 5.3 B const vs deltaE ee
0
2
4
6
8
10
12
14
16
5.2 5.225 5.25 5.275 5.3
12.46 / 35NORM 652.0 560.1EFACT -68.88 46.05AREA 28.64 10.84MEAN 5.280 0.5576E-03SIGMA 0.2750E-02 0.
mES (GeV/c2)mES (GeV/c2)mES (GeV/c2)
Com
bina
tions
/2.5
MeV
mES (GeV/c2)mES (GeV/c2)
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
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energy substituted mass (GeV)5.2 5.22 5.24 5.26 5.28 5.3
Eve
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GeV
0
2
4
6
8
10
energy substituted mass dataset:xmb
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
energy substituted mass dataset:xmb
Nent = 31
Mean = 5.273
RMS = 0.01601
energy substituted mass (GeV)5.2 5.22 5.24 5.26 5.28 5.3
Eve
nts
/ 0.
0025
GeV
0
2
4
6
8
10
12
14
16
energy substituted mass dataset:xmb
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
energy substituted mass dataset:xmb
Nent = 35
Mean = 5.274
RMS = 0.01852
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mes ��!��� ����!�������������#���!������������(����!0
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S
S
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J K
J K
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40
80
120
160
5.2 5.22 5.24 5.26 5.28 5.3
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Ent
ries
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MeV
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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−)
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�������� 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 ��
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0/ LE J K� �������!������ ��
Background
∆E (MeV)
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J/ψKL0 signal MC
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40
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Background
∆E (MeV)
Ent
ries
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J/ψKL0 signal MC
Data
0
10
20
30
40
-20 0 20 40 60 80
Background
∆E (MeV)
Ent
ries
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J/ψKL0 signal MC
Data
0
20
40
60
80
-20 0 20 40 60 80
EMC IFR
EMC+IFR
182 events above background
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mes ��������������B0 ��������!�( Bflav )
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Eve
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02 G
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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� � � �� � � � � � � ��
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[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
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ntific
ation
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ty
BABARElectronsPions
E/p,EMC cluster shapeDCH de/dx,DIRC Cherenkov angle
Uses:
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0
0.2
0.4
0.6
0.8
1
0 1 2 3 4 5
Polar angle (deg)
Muon
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0
0.2
0.4
0.6
0.8
1
0 50 100 150
Penetration lengthSpread and number of IFR hits
Uses:
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plab (GeV/c)
K
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plab (GeV/c)
BABAR
Uses:SVT and DCH dE/dxDIRC Cherenkov angle
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*�""�"�����"����!� 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
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2
The effective tagging efficiency i
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s
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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
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)
BABAR
LeptonKaonNT1
NT2
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40
60
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flav
flav
flav
flav
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���!!�����+!����#�!��"�����������!��!
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���
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� 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.
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t resolution is dominated by z resolution of tagging vertex: z = 180 �m for tagging vertex, z = 70 �m for fully reconstructed vertex
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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
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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�
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ff
Babar ™ and © L. de Brunhoff
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��
�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
Babar ™ and © L. de Brunhoff
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*�#����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
Babar ™ and © L. de Brunhoff
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��#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
Babar ™ and © L. de Brunhoff
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�&&������!����������������&&�&����&���
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Babar ™ and © L. de Brunhoff
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�"
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
Babar ™ and © L. de Brunhoff
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��
-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)�� � �
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0/ LJ K�
0 modesSK
1��
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Babar ™ and © L. de Brunhoff
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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
Babar ™ and © L. de Brunhoff
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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
Babar ™ and © L. de Brunhoff
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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
Babar ™ and © L. de Brunhoff
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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
Babar ™ and © L. de Brunhoff
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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
Babar ™ and © L. de Brunhoff
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Babar ™ and © L. de Brunhoff
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� 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
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(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� �
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RTM
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Babar ™ and © L. de Brunhoff
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- 150
- 125
- 100
- 75
- 50
- 25
- 0
fb-1
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Babar ™ and © L. de Brunhoff
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30 fb -1
sin2β
90 fb -1
sin2β, sin2α
180 fb -1
sin2β, sin2α
�
�
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