andrzej bożek nz11highlights of the belle experiment sab review 20071 selection of the most...
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 1
Selection of the most important Belle results since last SAB review (2005):
B0 'K0 : first observationof time dependent CPV
in rare B decays; B- - : evidence for purely leptonic decay (decay with missing energy); New particles with charm; First results from Bs ((5S) run).
B0 (db)
B- (ub)
Bs (sb)0
Highlights of the Belle Experiment
Precision tests of the Standard Model and New Physics searches at the B-Factory
e+e-(4S) B0 B0 / B- B+
Precision tests of the Standard Model and New Physics searches at the B-Factory
e+e-(4S) B0 B0 / B- B+
A.BożekNZ11
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 2
Rare B decays:
b s: B- f0(980)K- , B0 f0(980)K*0
B decays with missing energy: b c -: B0 D*- +
New particle searches :
-Dsj(2700) in B- D0D0K- analysis -Charmed baryons study
Physics analyses in Kraków
Krakow’s Belle group
•5 PhD physicists
•3 electronics eng.
•3 PhD students
•1 diploma student
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 3
B Factory Physics Program
W±qi
qjVij
Cabibbo-Kobayashi-Maskawa (CKM) matrix
1()
Unitarity Trianglebeing overconstrainedat B factories
d s b
u
c
t
CKMV ud us ub
cd cs cb
td ts tb
V V V
V V V
V V V
0*** tbtdcbcdubud VVVVVV
*ubudVV
*tbtdVV
*cbcdVV
• Studies of rare B, D and decays with potential sensitivity to new physics;
• Precise tests of the most stringent Standard Model (SM) predictions,
e.g. unitarity relations between elements of the quark mixing matrix.
2()
3()
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 4
~710x106 BB pairs
13 countries, 57 institutes, ~400 collaborators
More than milion BB pairs per day
Asymmetric ee collider
8GeV (e-) 3.5GeV (e+)
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 5
Time-dependent CP violation (tCPV)“double-slit experiment” with particles and antiparticles
a flagship measurement at B-factories
b c
d
csd
J/KS
b
d cJ/KS
B0
bcsddt
t
+
Quantum interference between two diagrams
tree diagram box diagram + tree diagram
You need to “wait” ( t0) to have the box diagram contribution.You need to “wait” ( t0) to have the box diagram contribution.
B0B0
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 6
B0 J/ K0
sin21= 0.642 ±0.031 (stat) ±0.017 (syst)sin21= 0.642 ±0.031 (stat) ±0.017 (syst)
B0 tag_B
0 tag
535 M BB pairs_
hep-ex/0608039hep-ex/0608039
1()
Obtained precision is 1.3oObtained precision is 1.3o
+sin21
tCPVtCPV
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 7
d
b_ _
sssd
_gtB0
K0
, ’...w
d
b_ _
sssd
_gB0
K0
, ’...g
b s
penguinb sqq
B decays with b s transition one of the best new physics probes
SUSY as an example
d
b_ c
c
sd
_wB0J/
K0
treeb ccs
Extra CPV phase from New Physics
=?)(2sin 1 cb )(2sin 1 sb SM
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 8
tCPV in B0 'K0
sin21(b→s) = 0.64 0.10(stat) 0.04(syst) sin21(b→s) = 0.64 0.10(stat) 0.04(syst)
_535M BB
First observation of tCPV (5.6in a single b s mode
First observation of tCPV (5.6in a single b s mode
t distribution and asymmetry
PRL 98, 031802 (2007)PRL 98, 031802 (2007)
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 9
Smaller than bccs in all of 9 modesSmaller than bccs in all of 9 modes
1 from b s transition
Theory tends to predict positive shifts
Naïve average of all modessin21(b→s) = 0.52 ± 0.05
2.6 deviation
Naïve average of all modessin21(b→s) = 0.52 ± 0.05
2.6 deviation
We need more statistics and more bs modesWe need more statistics and more bs modes
B0 J/ K0…
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 10
B0 f0(980)K*0
Motivation:
• Not observed yet, expected BF ~10-6
• Expected to be dominated by b s transitions -mode with simple final state
• In addition nature of f0(980) can be studied (candidate for four quark state or other exotic combinations).
Results should be published this year
Started as a diploma work; can lead to an important physics output in hot field.
Ver
y Pre
limin
ary
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 11
B decays with missing energy
• Fully reconstruct one of the B’s to :
- tag BB events– determine other B flavor/charge & momentum
Υ(4S)
e (8GeV)
e+(3.5GeV)
B
B
fully reconstructedsecond B i.e. BD
Decays of interests BXu l , BK BD,
Powerful tools to study B decays with neutrinos
Method
sensitive to new physics
sensitive to new physics
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 12
B++
BB++ D D0 0 ++
KK++ - - ++ --
BB-- --
ee--ee
BB++ D D0 0 ++
KK++ - - ++ --
BB-- --
ee--ee
Missing momentum
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 13
Observation based on the residual energy in the electromagnetic
calorimeter not used in both B reconstruction.
The First B Evidence
Signal +
background
BackgroundB
Signal
17.2 events in the signal region. 17.2 events in the signal region.
+5.3 - 4.7
+0.56 +0.46 -4-0.49 -0.51Br B 1.79 ×10
Measured branching fraction:
PRL 97,251802 (2006) PRL 97,251802 (2006)
Another „multi-neutrino” mode: B0 D*- + experimentally more difficultanalysis is carried on in Kraków, results are expected this year.
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 14
Dsb
c
c
cq
cs
q
b c
q
csq
e
e
e
e
BaBarat slac B-factory
Belle
2003 2004 2005
DsJ(2317)
DsJ(2458)
X(3872)Y(3940)
Y(4260)
Z(3930)
New charmed mesons : new unresolved questions about charm spectroscopy
Picture: R. Faccini, DOE review 2005
New particles, charm spectroscopy B factories are an abundant source of other particles:
charmed mesons and baryons : e+e- cc, B decays, …
lepton „factory” : e+e- +- ~700 M events
D,c , X
K
„cs” type
Charmonium type
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 15
efficiencysideband
New DsJ in B+→D0D0K+
N=399 40
DsJ(2700)new state
Dalitz plot M(D0D0) vs M(D0K) differs from 3-body phase space
Interpretation still open
hep-ex/0608031hep-ex/0608031
1J
)20115(
/)112715(
30182
P
3632
21114
MeV
cMeVM
N
KDDB 00 of Signal
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 16
We are in high statistics era at B factories ( 1ab-1 ~109 BB)
- many interesting & unexpected results
38 papers in Phys.Rev.Lett. (with discovery status) during 2005/2006
- powerful tool to study rare and experimentally difficult B decays
that are not accessible in other environments
Good prospects for next generation experiment at Super B-Factory
SuperKEKB (50 ab-1 ~5*1010 BB) New physics searches in rare B & decays, that are not accessible on hadron machines e.g: BK , BD,BD*, BXs/Xu
→→e…
solve the b s & other ~2.5 puzzles
Conclusions and prospects
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 17
Future plansFuture plans
~1010 BB/year !!& similar
number of +-
Lpeak = 1.71034cm-2s-1
Ltot = 710 fb-1 (Dec. 2006)
1.7x1034
700 fb-1
5x1034
~1 ab-1
8x1035
~10 ab-1
Lpeak (cm-2s-1)Lint
Major upgrade ofKEKB & Belle detector(>1yr shutdown)
world records !
We are here
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 18
e+ e- -> Y(5S) -> BB, B*B, B*B*, BB, BB, BsBs, Bs*Bs, Bs*Bs*
1985: CESR (CLEO,CUSB) ~116 pb-1 at Y(5S)
2003: CESR (CLEO III) ~0.42 fb-1 at Y(5S)
2005: Belle, KEKB ~ 1.86 fb-1 at Y(5S)
CLEO
PRL 54, 381 (1985)
(5S)
2006, June 9-31: Belle, KEKB ~21.7 fb-1 at Y(5S)
(5S) test runs
Bs -> Ds+ -
9 events in Bs* Bs*
5.408< MBC<5.429 GeV/c2
Bs* Bs*Nev=20.0 ± 4.8
6.7
BsBs , Bs*Bs , Bs*Bs*
MCsum of all Bs decay modes
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 19
Hunting Rare Decays
Observation of BK l+ l-
CPV in B decay
Beginning of B->K0 saga
Direct CPV in B0K+
FB asymmetry in BK* l+l-
Evidence of B
Observation of bd
• High luminosity • Good detector (PID, vertex…)• Analysis techniques
– qq background suppression– Fully reconstructed tag
Success of B factories brought rare B decays in leptonic and neutrino modes on the stage !
Success of B factories brought rare B decays in leptonic and neutrino modes on the stage !
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 20
Major Achievements Expected at SuperKEKB
Discovery of B K
Discovery of B DDiscovery of B
CKM Angle Measurements with 1 degree precision
Discovery of CP Violation in Charged B Decays
Discovery of Direct CP Violation in B0 K Decays (2005)
Discovery of CP Violation in Neutral B Meson System (2001)
|Vub| with 5% Precision
Search for New CP-Violating Phase in b s with 1 degree precision
“Discovery” withsignificance > 5
Discovery of New Subatomic Particles
sin2W with O(10-4) precision
Observations with (5S), (3S) etc.
Case 2: New Physics with Extended Flavor StructureCase 2: New Physics with Extended Flavor Structure
# SUSY GUT withgluino mass = 600GeV,tan = 30
Discovery of Lepton Flavor Violation in Decays#
Discovery of Lepton Flavor Violation in Decays#
Discovery of New Right-Handed Current in b s Transitions #
Discovery of New Right-Handed Current in b s Transitions #
Discovery of New CP Violation
in B K0 Decays#
Discovery of New CP Violation
in B K0 Decays#
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 21
= 0.425 (Belle) 0.56 (BaBar)
Principle of tCPV measurement
t z c
CP-side
Flavor tag and vertex reconstructi
on
Flavor tag and vertex reconstructi
on
1. Fully reconstruct one B-meson which decays to CP eigenstate2. Tag-side determines its flavor (effective efficiency = 30%)3. Proper time (t) is measured from decay-vertex difference (z)
electron
positron
(4S)resonance B1
B2
+-
K+
-0
D
+
-
KS/L
J/
z ~ 200m(Belle)
B0
B0_
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 22
tCPV in B0 decays
Mixing-induced CPVMixing-induced CPV Direct CPVDirect CPV
e.g. for J/ KsS = CPsin21 = +sin21 A = 0to a good approximation(CP : CP eigenvalue)
e.g. for J/ KsS = CPsin21 = +sin21 A = 0to a good approximation(CP : CP eigenvalue)
+
Vtd
Vtd
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 23
K.UlmerUpdate after ICHEP2006 !
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 24
Belle 2006: tCPV in B0 K0
“sin21” = 0.50 0.21(stat) 0.06(syst) A = 0.07 0.15(stat) 0.05(syst)
“sin21” = 0.50 0.21(stat) 0.06(syst) A = 0.07 0.15(stat) 0.05(syst)
KS and KL combined background subtracted good tags t –t for KL
t distribution and asymmetry
_535M BB
Consistent with the SM (~1lower) The most precise measurement
now
Consistent with the SM (~1lower) The most precise measurement
now
unbinned fitSM
hep-ex/0608039hep-ex/0608039
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 25
B0 D*- + search
Experimentally very difficult:•At least 2 in decay chain•Low effective Br: Effective Br for decay chain ~ 10-4 – 10-5
Motivations: • BD(*)not observed yet • Decays with heavy fermions enhancement of effects beyond SM• Many avaiable observables from decays transverse or longitudinal polarisation• Semileptonic heavy quark decay – clear theoretical situation: good description of b quark in HQET• BG for BDdecay
need for more effective reconstruction of Btag
or/and higher statistics
Results should be presented this year
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Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 26
New New DDsJsJ in B in B++→→DD00DD00KK++
N=399 40
hep-ex/0608031hep-ex/0608031
efficiency
sideband
Dalitz plot M(D0D0) vs M(D0K) differs from 3-body phase space
DsJ(2700)new state JP = 1-
ψ(4160) reflection