Physics at BelleY.Sakai (KEK)

21-Mar-2006

KEKB Accelerator Review 2006 1

Goal of B-factory
Step1

Discovery
Discovery ofof CPV
CPV inin BB decay
decay
Step2

2001 summer !

PrecisePrecise test
test ofof KM(CPV)
KM(CPV) andand SMSM

Step3

Now
Search/Evidence
Search/Evidence forfor New
New Physics
Physics

B decays → QCD/Lattice, New Resonances
Also, excellent τ/charm factory
KEKB Accelerator Review 2006 2

Integrated Luminosity
KEKB

Data used in analyses_275M → 386M BBsteady2005 Summer
increase !
2004 Summer

PEP-II_232M BBKEKB Accelerator Review 2006 3

Physics Results in past year
71+2 abstracts submitted to LP05/EPS05
43 papers submitted to journals

b → d Penguin
CP Violation (φ1,2,3 , NP)
New Resonances
Y(5S), Y(3S) runs
KEKB Accelerator Review 2006 4

b → d Penguins
Loops → Sensitive to New Physics(b → s ) x |Vtd/Vts|2b

ρ/ωVtb

Wt∗

Vts/dgs

Κ0s Κ0,+d,ud,ub → dγ penguin

db → dg penguin
KEKB Accelerator Review 2006 5

b → dγ[hepex/0506079]
submitted to PRL

386M BB37.2 signals

First observation (5.5σ) !
Simultaneous fit to 3 modes:
Γ(B→(ρ,ω)γ) = Γ(B+→ρ+γ) = 2Γ(B0→ρ0γ) = 2Γ(B0→ωγ)+0.14-6
B(B→(ρ,ω)γ) = 1.34 +0.34(stat)−0.31−0.10 (sys) x 10

Consistent with SM (1~2 x 10-6 )Constraint to |Vtd|
KEKB Accelerator Review 2006 6

Constraint on |Vtd/ Vts |= 0.032 ± 0.008 ± 0.003
0.002
Belle combined

0.143 < |Vtd/Vts| < 0.260(95%CL)KEKB Accelerator Review 2006 7

B → ΚΚ275M BB+5.4

2.5 −4.113.3 ± 5.6

15.6 ± 5.8[PRL 95, 231801(05)]
KEKB Accelerator Review 2006 8

CPV Measurements*Vud Vubφ (α)

2Vtd Vtb*

φ3(γ)

φ1(β)

*Vcd Vcb

made by H. Miyake

A CP = S sin(ΔmΔt) + A cos (ΔmΔt)

B0mixing
q/p

A

B0Mixing induced CPVｆ− ̲̲A

Direct CPVｆ= B0B0̲̲
KEKB Accelerator Review 2006 9

sin2φ1 : B0  J/ψ K0S,L10056
signals_B0 tag
B0 tagsin2φ1= 0.652 ±0.039 ±0.020
A = 0.010 ±0.026 ±0.036(stat) (sys)386M BB

BG subtracted asymmetry

Belle preliminary

BaBar measurement
sin2φ1= 0.722 ± 0.040_ ± 0.023(227 M BB pairs)

WA: sin2φ1= 0.69 ±0.03
Good tags< 5% accuracy !

consistent w/ SM expectation
KEKB Accelerator Review 2006 10

φ2 : B0→ ρ+ρ− CPV
Similar to π+π−, but more complicated …
B → VV: not CP eigenstate in general
ρ+ → π+π0: wide resonanceTwo lucky cards !
fL ~ 100% → CP ≈ +1

B(ρ0ρ0) << B(ρ+ρ−), B(ρ+ρ0)< 1.1

26 ± 4(HFAG 2005 End)
26 ± 6 x10-6small Penguin effect (θ )2Sππ = 1 − Aππsin( 2φ2 + 2θ )M. Gronau and D. London, PRL 65, 3381 (1990)

Isospin relation2θ

A+-/ 2A00

A+0
KEKB Accelerator Review 2006 11

B0→ ρ+ρ− Result
275M BBbackground

232M BBsignalfL= 0.978 ±0.014± 0.020
0.028Good tagΔt (ps)S = +0.09 ±0.42±0.08
A = 0.00 ±0.30 ± 0.10
0.09
[hep-ex/0507039, submitted to PRL]S = -0.33 ±0.24± 0.08
0.14
A = 0.03 ±0.18±0.09[PRL 95,041805(05)]0.029
fL= 0.951 ± 0.033±0.0390.031
KEKB Accelerator Review 2006 12ρ+ρ− Isospin analysis

ρ+ρ−: most precise φ2 determination to date !
add new Belleρ+ρ−: B, S, A
B0 → ρ+ρ− (Belle)
Note:Isospin triangle
does not close• experimental error ?

φφ22 ==96
96 ±± 13
13 deg.
deg.

76 < φ2 <116 deg.
@90% CLKEKB Accelerator Review 2006 13

φ3 : B→ D[Ksπ+π−]K Dalitz∗Vus

B+dbVcbuWs Κ+u+π−Kπ_ sc0Du

B+:+dBW ∗Vcusu D0cKsπ+π−s Κ+urm−2

B-:bVubD2−m0m+2Drobtain
fromtagged D0(D*+→ D0π+)
sample0m+2|A2|
r = |A |1

CPV: Asymmetry in Dalitz dist.: m+=m(Ksπ+), m−=m(Ksπ−)
KEKB Accelerator Review 2006 14

B→ D(*)[Ksπ+π−]K(*) Signals
386M BBNew at Winter Conf.
B±DK±
B→

331±17 events
B-

B+K±± →D*

81±8 events
B-arynilimerP
B ±→DK* ±54±8 events
B+B-

B+KEKB Accelerator Review 2006 15φ3 : Fit Results
BB ±→±K± →D386M BB
DK* ±K±± →D*B

φ3=66 +19-20 °(stat)

φ3=86 +37-93 °(stat)

φ3=11+23-57 °(stat)+15

3 modes combined: φ3=53 ° − 18(stat) ±3 (syst) ±9 (model)

arynilimerP

8°<φ3<111° (2σ interval)
rDK =0.159+0.054±0.012(syst)±0.049(model)-0.050

CPV significance: 78% rD*K=0.175+0.108±0.013(syst)±0.049(model)-0.099rDK*=0.564+0.216±0.041(syst)±0.084(model)-0.155KEKB Accelerator Review 2006 16

CKM UT summaryb→ulν
*
Vud Vubφ (α)Δmdb→dγ2Vtd Vtb*

φ3(γ)

φ1(β)

*Vcd Vcbb→clν

KEKB Accelerator Review 2006 17

New physics Search : b → sqq_B0bdts φs+sKd SbdXs φss Kd S

SM: b→s Penguin- K0phase = (cc)+ New Physics
with New PhaseSbs ≠ Sbc , A can ≠ 0- sin2φ ” (SM reference)“b → ccs:
deviation
1
KEKB Accelerator Review 2006 18

B0 → φ K0386M BBEvent ShaperyanimPreliφKS
Nsig=180 ±16
purity 0.57

φKL
Nsig= 78 ±13purity 0.12

KEKB Accelerator Review 2006 19

B0 → φ K0 : result
BG subtracted asymmetry

φK0386M BB“sin2φ“sin2φ11”=+0.44”=+0.44 ±0.27±0.27 ±0.05±0.05
AA =+0.14=+0.14 ±0.17±0.17 ±0.07±0.07
ryanimPreliGood tags
S J/ψK0fit
KEKB Accelerator Review 2006 20

B0 → η’ K0386M BB highest statistics mode

Event Shape

η’KL

η’KS
Nsig=830 ±35purity 0.61
Nsig= 187 ±18purity0.66
ryanimPreliKEKB Accelerator Review 2006 21

B0 → η’ K0 : result
BG subtracted asymmetry

η’K0386M BB“sin2φ“sin2φ11”=+0.62”=+0.62 ±0.12±0.12 ±0.04±0.04
AA =+0.04=+0.04 ±0.08±0.08 ±0.06±0.06First CPV established ! (~5σ)- Penguin modefor b → sqq

Good tags
S J/ψK0fit

ryanimPreli
KEKB Accelerator Review 2006 22

Summary: b → sqq CPV(Cf= −Af)Naïve average
sin2φ1eff = 0.5 ± 0.09
(2.6σ from sin2φ1)
KEKB Accelerator Review 2006 23

New ResonancesBelleψ(2S)

X(3872)[PRL 91, 262001(2003)]

BaBar : DsJ(2317/2457) [PRL 90, 242001(2003)]

New resonances “X,Y, Z(3940)”
KEKB Accelerator Review 2006 24

Y(3940)
275M BB

B → J/ψ (π+π−π0)Κ

M2(J/ψ ω)

cut here ( >1.62 GeV2)[PRL 94,182002(2005)]

M≈3943±11±13 MeV
Γ ≈ 87±22±26 MeVY(3940)Significance
8.1 σ

BK** J/ψKω
M2(Kω)- stateunlikely normal (cc)cc-gluon
hybrid ? [D.Horn, PRD17,898(78)]KEKB Accelerator Review 2006 25

X3940e+e− → J/ψ (cc)res

357 fb-1-1[hepex/0507019]
submitted to PRLX(3940)• Significant peak at
N=266±63 (5.0σ)• X(3940) → DD* seenin e+e− → J/ψD(D*)
M=3.943±0.006 ±0.006

GeV/c2n =24.5±6.9 (5.0σ)
Γ < 52 MeV/c2 @90%CL

ηcX(3940)→ DD*

χco η’ce+e− → J/ψD(D*)• X(3940) → J/ψω: not seenin e+e− → J/ψω(J/ψ)
KEKB Accelerator Review 2006 26

−Z(3940): γγ → DD
N = 41 ± 11(5.5σ)
spin=2χ2/dof=7/9

spin=0χ2/dof=35/9

Γ = 20 ± 8 ± 3 MeV
M = 3.931 ± 0.004 ± 0.002 GeV/c2
Heliciy dist. → χ’c2 (23P2 )[PRL 98,082003(06)]

KEKB Accelerator Review 2006 27

Two New Charmed Baryons
462 fb-1

ΛΛcc++KK--ππ++
New atWinter Conf.
arynimiPrelwrong-sign Λc+ K+ π-

KEKB Accelerator Review 2006 28

Y(5S) Run
Y(5S) → BsBs, Bs*Bs, Bs*Bs*
BB, B*B, B*B*, BBπ(π)

10.865• Engineer run: 21-Jun-2005, 3 days
Integ. Lum: 1.86 /fb (World largest)[cf. CLEO: 0.42/fb ]Acc./Detector: ~same as Y(4S)ryanimPrelifs = N(Bs(*)Bs(*))/Nbb = (16.4 ± 1.4 ± 4.1)%(inclusive Ds yield)[CLEO: (16.0 ± 2.6 ± 5.8)% ]KEKB Accelerator Review 2006 29

Exclusive Bs Decays
Bs → Ds+ π-

Bs → Ds*+ π-

9 events in Bs* Bs*

4 events in Bs* Bs*

BsBs , Bs*Bs , Bs*Bs*

Ds+ → φ π+ , Ds+ → K*0 K+, Ds+ → Ks K+
ryanimPreli• Bs → Ds(*)+ ρ- , Bs → J/ψ φ/η signals also seen
KEKB Accelerator Review 2006 30

Sum of all exclusive decays- 0.08<ΔE<- 0.02 MeV

Bs* Bs*Mbc =E*B2 – P*B2

Bs*Bs* fraction =(94 ± 69)%

arynimPreliM (Bs*) = 5418 ± 1 ± (acc. err) MeV/c2
Photon momentum is neglected => does
not change Bs* mass position, only smearing.

KEKB Accelerator Review 2006 31

Search for Bs → γγunique modeat B-factoryryanimPreliMore analyses on going
KEKB Accelerator Review 2006 32

Y(3S) RunDark Matter search:[B.McElrath, PRD72, 103508 (05)]

B( Y(1S) → DM(invisible) ) ~ 0.0041 (mDM<4.73GeV/c2)
Y(3S) → π+π−Y(1S)
No sensitivity

DAMANaI 3σRegion

CSDM
C

WIMPs: good candidate

04SDM05

o% antimatter
KEKB Accelerator Review 2006 33

Search Sensitivity
Y(4S): σ(e+e-  Y(3S)γISR ) ~ 0.02 nb
Y(3S): σ(e+e-  Y(3S)) ~ 3 nb S/N ratio x150
Y(3S) Trigger
runLooserw/o
TRG modificationx 4 trigger
efficiency

Y(4S) run
460 /fb

90 %C.L
Theory prediction*) Syst. error isnot considered

KEKB Accelerator Review 2006 34

Engineering run(25-Feb-2006, 4.5 days)
CLEO

3 times hadrons~0.47 on Y(4S)~0.33 off-resonance

Energy scan ~ 4hours
We set E(4S)-223.6 MeV~ 3 /fb on 3S resonance~0.25 /fb on 30MeV below 3SAnalysis on going…
KEKB Accelerator Review 2006 35

Summary_
2004 summer → 2005 summer: 275M → 386M _BB
Excellent KEKB performance: now ~550M BB!
Significant New/improved results !
• New b → d penguin established ! B→ ρ/ωγ, KK_• CKM UT/SM test & NP search: progresses• More New resonances observed !
• Y(5S), Y(3S) engineering runs: successfully done
: (lot more… not shown here)
We (Belle) are looking forward to having
higher/more luminosity and New excitements !
KEKB Accelerator Review 2006 36

CPV in Dalitz plane
MC simulation
φ3 = 70 deg.
δ = 0, r = 0.125

B−
B+

Sensitivity to φ312

3
4

KEKB Accelerator Review 2006 37

Exclusive Bs Decays (2)Bs → Ds(*)+ ρ-

7 events in Bs* Bs*Ds+->φ π+ ,Ds+->K*0 K+,Ds+->KsK+

Bs → J/ψ φ/η

3 events in Bs* Bs*Bs -> J/ψ φ, Bs -> J/ψ η(γγ)

KEKB Accelerator Review 2006 38

Trigger Efficiency
Control sample dataΥ(3S)  Υ(1S)π+π−Υ(1S)  µ+µ−
Eff. depends on opening angle

opening angle (degree)

π+
π−yx

4 times efficiency gain is expected- loose opening angle cut
135  45 degree- loose pt cut
pt>350 MeV for both tracks
 for one (or both) track
KEKB Accelerator Review 2006 39