Download - Highlights of the Belle Experiment
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
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
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()
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+)
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
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
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
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)
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…
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
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
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
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.
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
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
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
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
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
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 !
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#
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_
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
Andrzej Bożek nz11 Highlights of the Belle Experiment SAB Review 2007 23
K.UlmerUpdate after ICHEP2006 !
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
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
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