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13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 1
K. R. Schubert, TU DresdenColloquium U Edinburgh, 13 Feb 03
CP Violationin B-Meson Decays
CP Violation in the Standard ModelExpectations for B-Meson ExperimentsPEP-II and KEK-B, BABAR and BELLEResults and Interpretation
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 2
Particle physicists know three systems without particle-antiparticle symmetry:The UniverseMore matter than antimatter. n(N)/n(γ) ≈ 10-9 points toNN annihilation at the end of the „massive-quark gluon“ era;q/q ≈ 1+10-9 requires CP. Standard Model offers this at the end of the „massless“ era, but with q/q ≈ 1+10-20. Extra CP? The Neutral K MesonDiscovery of KL→π+π- by Cronin et al 1964 ⇒ Re(ε) ≈ 10-3,π0π0 ≠ π+π- by NA31/48, E731/KTeV 1988/99 ⇒ lε‘l ≈ 3.10-6.Only CP values till 2001.The Neutral B Meson2002: Measurements of BABAR (90 M BB) and BELLE (85 M BB) in e+e- annihilation at 10.6 GeV show sin2β = 0.73 ± 0.06in agreement with Standard Model CP for K0 and B0 mesons.
The Universe
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 3
Paul Adrien Maurice Dirac(1902 – 1984)
Standard Model ofElementary Particle Physics= Extension of Dirac equation by
gauge principle and „zoology“. Dirac 1928:Dirac 1928:
Dirac‘s eq.is C- and P-symmetric.),,,()( ++−−==
−∂=
RLRL eeeexee
eemeieL µµγ
µµµ
α
Aqiiexexe xi
−∂→∂⇒⋅→ )()()(
Weyl 1929:
PC
CPWith electricity,Dirac‘s eq.remains C- and P-symmetric.
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 4
Glashow 1961:Invariance of Dirac‘s eq. under local SU(2) + U(1) produces weak and electric interaction byW+, W-, Zo, γ exchange.
P- and C- symmetryare maximally broken;CP symmetry remains.
µµµµ
α
α
σ
νν
ν
BygWgii
exex
xUxex
eeeeofinsteadeande
aa
xi
L
L
L
L
xiRRR
L
L
'2
)()(
)()()(
,
)(
)(
−−∂→∂⇒
→
→
SU(2) invariance requires, because of mee = m(eLeR+eReL) → m ee :
.0)()()()()( ===== νγ memZmWmm
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 5
Introduction of a spin-0-doublet Φand spontanuous symmertry breaking
Higgs gives back Dirac‘s electron mass which was taken away by Glashow.
Glashow, Weinberg, Salam 1968:Same Higgs mechanism produces masses for µ andquarks udcs, and gives quark mixing in W exchange.
Higgs 1964:
( ) ( )
( )
( ) eemeeeecv
ehLeeeecvLLxhvx
x
eee
ecLL
RLLR
RLLR
RLLL
LR
=+
++−→⇒
+
→
ΦΦ
ΦΦ
+
ΦΦ−→
),()(
0)()(
int2
1
2
1*2
*1 ν
ν
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 6
Kobayashi, Maskawa 1973: Extension 2 → 3 families(discovery of τ-lepton 1975 , c-quark 1974, b 1977)
For gauge invariance, the complex matrices C arbitrary. C(u) can be diagonalized by rotations in family space:
.].
[
)3,3,3,3(
)(
)()(
321,
chdu
uC
du
dCl
lC
LLdulLL
L
LTR
u
L
LR
d
L
LR
l
bosonsSUSUUkinDirac
+
Φ+
Φ+
Φ−
++=
++
⊗⊗
β
βααβ
β
βααββ
βααβ
ε
ν
ν
→
→
→
'''
)(
3
2
1
;00
0000
;L
L
L
L
L
L
t
c
uu
bt
sc
duDubletts
mm
mCv
tcu
uuu
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 7
.,, '''LLLLLL bWtsWcdWu +++ ↔↔↔W exchange:
Dublet partners of uc t are not mass eigenstates.Since (uα dα) is one object to be rotated in family space,C(u) and C(d) cannot be diagonalysed simultanuously..
V was introduced into the Standard Model by Kobayashi and Maskawa 1973.Phenomenology for 2 families already by Cabibbo 1963.
Properties of the CKM matrix:
.1;'
'
'
==
=
+VVwithVV
bsd
Vbsd
CKM
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 8
bVsVdVb
bVsVdVs
bVsVdVd
tbtstd
cbcscd
ubusud
⋅+⋅+⋅=
⋅+⋅+⋅=
⋅+⋅+⋅=
'
'
'
The matrix Vik is complex. CPT symmetry requires:
Higgs mixes antiquarks in a different way than quarks. This is the origin of CP violation in the Standard Model.Vik
*≠ Vik is necessary, but not sufficient.Because of unobservable quark phases, we must have:
bVsVdVb
bVsVdVs
bVsVdVd
tbtstd
cbcscd
ubusud
⋅+⋅+⋅=
⋅+⋅+⋅=
⋅+⋅+⋅=
***'
***'
***'
.0)(Im ** ≠= jkjlilik VVVVJ
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 9
A, λ, ρ, η are 4 of 18 „free parameters“ of the St. Model.6 unitarity conditions of V can be drawnas triangles, e.g.:
.;1)1(
2/1
)(2/162
23
22
32
ηλληρλ
λλλ
ηρλλλ
AJAiA
A
iA
V ≈
−−−−−
−−
≈
Wolfenstein 1984:
.1//
,033*
*3*
≈+
=+−
λλ
λ
AVAV
VVAVV
tdub
tbtdubud
ρ
η
10
Vub*/Aλ3
Vtd/Aλ3
β
Area of this triangle is J/2.Measurements of λ, A, ρ2+η2
and (1−ρ)2+η2 giveλ = 0.223 ± 1% , A = 0.82 ± 4%,
lJl ≈ 3 • 10 –5 . Standard Modelviolates CP symmetry.
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 10
ckmLfit-0208-2
Max L, 1σ, 2σηLfitckm
B → ρlν, CLEO, BABAR
b → ulν, CLEO, LEP
∆m(Bs) limit, LEP with ξ from lattice
∆m (B0) value, LEP, BABAR...with fB√BB from lattice
J≠0 with >3σ
There is CP in the Standard Model, concluded from only CP-symmetric observations!1. Does this J explain ε(K0)? 2. What prediction for CP(B0)?
Informations on ρ and η
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 11
CPLEAR
( ) ( ) ( )SSLK KKmKmm Γ≈−=∆
Asymmetry betweenπ+π - decays of taggedK0 und K0 as fuction of time between production and decay:
Demonstration of CP(K) in a more recent experiment:CPLEAR 1999, pp → K+π -K0, K- π+ K0; K0,K0 → π+ π-
ttK
t
LS
LS
ee
tme
KNKN
KNKNta
Γ−−+
Γ−
−+Γ+Γ−
−+
−+−+
−+−+
+
−∆⋅∆−=
→+→
→−→=
2
2/)(
00
00
)( cos2
)()(
)()()(
η
ϕη
ππππ
ππππ
( ) ( ) oie 5.03.4331002.027.2 ±−−+ ⋅⋅±=η
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 12
ckmLfit-0208-3
η+-(Ko)
η
Lfitckm
Max L, 1σ, 2σ
1. Yes!
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 13
Prediction for CP(B0):2.
( ) ( )( ) ( ) ( )[ ]tBm
KJBNKJBNKJBNKJBNASS
SS ∆∆⋅=Ψ→+Ψ→Ψ→−Ψ→
= 00000
0000
sin2sin//// β
where ∆t is the time between B0(B0) production and decay.
η
Fit with lVubl, lVtdl, and η+-
β
Lfitckm
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 14
Short History:
1977 Discovery of b in Υ(9.46) = 13S1 bb at FNAL1978 Formation of Υ(9.46) and Υ(10.01) at DESY1980 First B mesons 11S0 bq at Cornell1986-89 „B-Meson Factory“ plans at PSI1987 ARGUS discovery of BoBo oscillations1988 Start of PEP-II studies at SLAC1993 Decisions for PEP-II and KEK-B1995 BABAR „TDR“ & approval7/98 First e+e- collisions in PEP-II5/99 First e+e- events in BABAR7/00 First BABAR & BELLE results at Osaka 10/00 PEP-II reaches design luminosity of 3
•1033/cm2/s3/01 BABAR and BELLE publish sin2β in PRL
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 15
SLAC photo← Fixed Target
Experiments
← BABAR
← SLD
← Linac
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 16
e-
e+
yes9.0 / 3.1E [GeV] e- / e+
308135Lint [pb-1/day]4.5 x 10 333 x 1033L [cm-2 s-1]980 / 1680610 / 2140I [mA] e- / e+
ReachedDesignyes9.0 / 3.1E [GeV] e- / e+
308135Lint [pb-1/day]4.5 x 10 333 x 1033L [cm-2 s-1]980 / 1680610 / 2140I [mA] e- / e+
ReachedDesign
e-
e+
The B-Meson Factory PEP-II:
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 17
KEKB
βγ = 0.43
achieved: 7.35 x 1033
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 18
Daily and Integrated Luminosity,October 1999 to February 2003
Design
BABAR
BELLERecorded 107.79/fb
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 19
(4) ElectromagneticCalorimeter (6) Instrumented
Iron Yoke(3) Cerenkov-Detector
(5) 1.5 T Solenoid
(2) Drift Chamber
(1) Silicon Vertex Detectore-
e+
The BABAR Detector:
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 21
BABAR Collaboration: 10 Countries, 74 Institutes USA Caltech PasadenaUC, IrvineUC, Los AngelesUC, San DiegoUC, Santa BarbaraUC, Santa CruzU of CincinnatiU of ColoradoColorado StateFlorida A&MU of IowaIowa State ULBNL BerkeleyLLNL LivermoreU of LouisvilleU of MarylandU of MassachusetsMITU of MississippiMount Holyoke CollegeNorthern Kentucky UU of Notre DameORNLU of OregonU of PennsylvaniaPrairie View A&MPrinceton USLACU of South CarolinaStanford UU of TennesseeU of Texas at DallasVanderbilt UU of WisconsinYale U
NetherlandsNIKHEF Amsterdam
Norway U of Bergen
Russia Budker Inst., Novosibirsk
Italy INFN BariINFN FerraraINFN Frascati INFN GenovaINFN MilanoINFN Napoli
CanadaU of British ColumbiaMcGill UU de MontréalU of Victoria
China Inst. of High Energy Physics, Beijing
GermanyRU BochumTU DresdenU Rostock
FranceLAPP AnnecyLAL OrsayU Paris 6 et 7Ecole PolytechniqueCEA Saclay
United Kingdom U of BirminghamU of BristolBrunel UniversityU of EdinburghU of LiverpoolImperial CollegeQueen Mary & Westfield CollegeRoyal Holloway, University of LondonU of ManchesterRutherford Appleton Laboratory
INFN PadovaINFN PaviaINFN PisaINFN Roma INFN TorinoINFN Trieste
≈500 physicists
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 22
Dresden Contributions to Calorimeter:
10 % of 6580 CsI(Tl) crystals, and all photodiodes
Optimisation of crystal light yield
Mechanics of readout electronics
Lightpulser system for monitoring
(with Edinburgh and Bochum)
Bhabha calibrationπo calibration
e identification
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 23
σz ≈ 70 µm for fully reconstructed B mesons
σz ≈ 180 µm forB0 meson tags
βγ = 0.55, βγ cτ(B) = 260 µm,π βγ c /∆m(B0) = 1 mm,
R=14cm
Silicon Vertex Tracker:
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 24
Belle Detector
≈ 300 physicists, 49 institutes, 14 countries: Australia, Austria, China, Germany, India, Korea, Japan, Philippines, Poland, Russia, Slovenia, Switzerland, Taiwan, USA
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 25
CP state
flavour state
A fully reconstructed event in BABAR:
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 26
CP asymmetries in B0 decays:
Decay of ϒ(4S) produces coherent 2-particle state(BoBo-BoBo)/√2 :
Integral of Α over all ∆t is zero ⇒ time dependent and boosted measurement necessary.
Tagging by partially reconstructed,but flavour-specific decays of the second B.
ttttt tagdecproddec ∆=−⇒− )()( ...
( ) ( )( ) ( ) ( )[ ].0000
0000
sin2sin////
proddecaySS
SS ttmKJBKJBKJBKJBA −∆⋅=
→Γ+→Γ→Γ−→Γ
= βψψψψ
Γ
B0B0
∆t/τ
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 27
Measurement of time-dependent CP asymmetry:
4: Flavour Determination of the other B Meson (“tag”)
1, 2, 3: B Reconstruction into CP Eigenstate
ϒ( )
( ) ( ) ( )( ) ( ) ( ) tt-t~t) msin(2sinD
/B/B
/B/Bt~A~
0000
0000
∆∆∆⋅∆∆⋅⋅=Ψ→Γ+Ψ→Γ
Ψ→Γ−Ψ→Γ=∆ ∫ dr
KJKJ
KJKJ
SS
SS β
e+
βγ = 0.55
6: Determination of ∆t = ∆z/βγc 7: Determination of the ∆z reso-lution function5: Determination of the fraction w of mistags
Dilution D = (1-2w) reduces observed Asymmetry.
8: sin2β Fit to both Time Distributions
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 28
Event Selection
N N
in B → J/ψKS
J/ψ → e+e- J/ψ → µ+µ-
π0π0
π+π-
2. K0 Reconstruktion
1. J/ψ Reconstruktion
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 29
3. B0 Reconstruction:
More CP Modesin addition toB0 → J/ψ KS :
B0 → ψ(2S) KSB0 → χc1 KSB0 → ηc KSall with CP = -1 and
B0 → J/ψ KL CP = +1
B0 → J/ψ K0*(KSπ0)CPeff = +0.65±0.07
mES
∆E∆E
MeV
mES GeV
J/ψ KS
∆E = E*(J/ψ)+E*(K0) – ECMS/2mES
2 = (ECMS/2)2 – [p(J/ψ)+p(K0)]2
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 30
Data 1999-2002: 81/fb on the ϒ(4S) , 90 M BB
CP = -1. N = 1506 after tagging. Purity = S/(S+B) = 94%
Ncand = 132Purity = 63 %
ηc(KKπ)KS
B0 → J/ψ K0L : Only K0
Ldirection measured. Energy from m(B0).
Ntot = 2641 (incl. J/ψK0*)78% purity.
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 31
Flavour-Tagging of the CP eigenstate by flavour-specific decays of the other B:Electrons, myons, charged Kaons, or Combi.
4.
4.+5.+6.
6. Determination of ∆t = ∆z/βγc :
5.
Fraction w of mistags determined from the „Flavour Sample“
B0 → J/ψK*0(K+π−),D(*)-π+,D(*)-ρ+...
∆z = zdecay – ztag, with ztag from vertex fit with two or moretracks with small χ2 contribution.
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 32
7.
perfect resolution real resolution
∆t/τ ∆t/τ
∆t/τ ∆t/τ
CP sampleswith1 ± sin2β sin∆mt
unmixed
mixed
B0
B0
7. R(∆z)
Flavour sampleswith1 ± cos ∆m t
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 33
8.
sin2β =0.741 ± 0.067 ± 0.033
8. sin2β fit to the ∆tdistributions
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 34
Belle results
July 2002Results with 78/fb,85 M ϒ(4S)
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 35
OPAL 3.2 ± 0.5
ALEPH 0.84 ± 0.16
CDF 0.79
BABAR 0.741 ± 0.067 ± 0.033
Belle 0.719 ± 0.074 ± 0.035
Mean 0.732 ± 0.055
+ 0.41- 0.44
+ 0.82- 1.04
+ 1.8- 2.0
All results for sin2β:
(13σ)
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 36
A new triumph for the Standard Model!
η Fit with lVubl, lVtdl, and η+-
Max L, 1σ, 2σ
sin2β
CP violation in K and Bdecays has its origin inquark mixing producedby Higgs coupling to 6q.
Lfitckm
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 37
Fit to all observations:
η Max L, ±1σ, ±2σ
ckmLfit-0212-5
Lfitckm
CKM quark mixing matrix parameters:A = 0.82 ± 0.03, λ = 0.223 ± 0.002, ρ = 0.20 ± 0.10, η = 0.36 ± 0.06, J = (2.9 ± 0.6)10-5.
13 Feb 2003 K. R. Schubert (TU Dresden), Colloquium U Edinburgh 38
Conclusions and Prospects:
BABAR from 90 M BB events: sin2β = 0.74 ± 0.07 ± 0.03.BELLE from 85 M BB events: sin2β = 0.72 ± 0.07 ± 0.04.World average sin2β=0.732±0.055 agrees with St.Model.
No hint for New Physics CP, which could help cosmology.
PEP-II & KEK-B work well, both plan to increase BB rates.Next years: Increase significance on sin2β
Precision measurements on ∆m(B0), lVubl, Vcb Search for rare decays like B → K l+l-, B → ρ γ Search for CP in other B decay modes ...
Check and overconstrain the description of theCharged Weak Interaction in the St. Model.
2003 CDF,D0; 2007 ATLAS,CMS,LHCb; BTeV.