Physics of Belle
today and tomorrowand the day after tomorrow
Masashi Hazumi (KEK)
February 16, 2004
KEKB Review

Outline•

Today (Feb. 2004)– Results with 140 fb-1•

Tomorrow ( Aug.2004 ~ Aug. 2007)– Prospects up to ~500 fb-1•

The day after tomorrow (2008 ~ )– SuperKEKB: 5~50 ab-1

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Todayresults with 140 fb-1

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Mission•

Test of Kobayashi-Maskawa model of CP violation––•

Time-dependent CP violation
Unitarity Triangle determination

Study rare B decays to find a hint of new physics–“Penguin” decays

Many other topics (new B decays, charm, tau etc.),
which I do not have time to show !
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Unitarity Triangle determination at Belle_BB mixing (Δmd)

b  ulν
with several
approaches

B DK

B0  π+π−B0  J/ψ KS(L), ψ(2S) KS,
χc1 KS, ηc KS? ( yes in SM)b  clνB0  φ KS, η’ KS, K+ K− KS
2008年 1月 25日

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Masashi Hazumi (KEK)5φ1: Time-dependent CP violation in B0  J/ψ Ks etc.
sin2φ1= 0.733±0.057(stat)±0.028(syst)
BelleAug. 2003

precision= 9% !

Poor tags|λccs| =1.007±0.041(stat)i.e., consistent with

Good tags

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no direct CPV.

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Masashi Hazumi (KEK)6sin2φ1 history

sin2φ1
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Unitarity triangle
as of August 2003

Beautifulagreement(triumph of
KM model)2008年 1月 25日

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Masashi Hazumi (KEK)8φ2: Paper submitted in Jan. 04

Belle
140fb−1

hep-ex/0401029,
submitted to PRL
on Jan. 18, 20042008年 1月 25日

CP violation at 5.2σ

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Masashi Hazumi (KEK)9Belle140fb−1

ResultsAππ = +0.58 ±0.15(stat) ±0.07(syst)
Sππ = −1.00 ±0.21(stat) ±0.07(syst)

1529 ev.
(all LR-r
regions)

0.86 < LR ≤ 1.0

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Masashi Hazumi (KEK)10φ2 “banana”

φ2

sinφ1 (WA) andBelle’s φ2
are consistent
with othermeasurements.

90° ≤ φ2 ≤ 146° (95.5% CL)
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History of Aππ and Sππ
BelleThis result
Belle 140fb−1

BaBar

Difference at ~2σ level
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Masashi Hazumi (KEK)12φ3 : the first constraint with a new method !

B±  D(Ksπ+π−)K±
φ3 (90% C.L.)

hep-ex/0308043

140fb-1
This is the result shown at
the Lepton Photon
Symposium in Aug. 2003
An improved results will
be shown at
Lake Louise this week !

CP violation not
yet significant
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Vub with B  Xu l ν
hep-ex/0311048 (accepted by PRL)

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Masashi Hazumi (KEK)14_
Hint of new physics ?: CPV in bsss

virtual particle (top quark, and more ?)CP violation “same” as J/ψKs
within the Standard Model
Penguin~O(λ2),

Penguin diagram

Tree~O(λ4)

deviation = O(1)%Breakthrough to New Physics
with loop (penguin) diagrams
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Motivation• One of the best places to discover physics
beyond the standard model (SM) in the loop
process
Motivated by large θ23 neutrino mixing in GUT context,
Atmospheric Neutrinos Can Make Beauty Strange !

• Toward understanding of the baryogenesis– More than one CP violating phase = breakthrough2008年 1月 25日

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Belle 2003: CP Asymmetry in Bφ KS
Belle

140 fb-1(A=-0.15±0.29±0.07)

3.5σ off+0.09
Belle: sin2φ1eff = -0.96 ±0.50 -0.11
Current WA: sin(2φ1)=0.736±0.049

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World average(Aug. 2003)

2.6σ

3.1σ
from “charmonium”
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A Bonus: Charm of Belle
140 fb-1

A new narrow resonancein B±  J/ψπ+π−K±

ψ’ππJ/ψ

X(3872)M(π+π− J/ψ ) –M(J/ψ )2008年 1月 25日

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MX = 3872 ± 0.6 ± 0.5 MeV
Γtot < 2.3 MeV (90%CL)
Masashi Hazumi (KEK)

19

What could X(3872) be ?
• Still no good charmonium candidate• X(3872) very near the D*D threshold. Does it
imply something ?
• Some more data analyses (e.g angularanalysis) is in progress. Stay tuned.

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Summary (2003. Feb – 2004. Feb)
• sin2φ1 now measured with 9% accuracy !
• CP violatioin in B0  π+π− observed !
• First constraint on φ3 !
• Improvement in Vub• Tantalizing hint of new physics in b  s CP asymmetries• New narrow resonance X(3872) !
… and many more new obesrvations for tomorrow !
(recall it is just a few years from the first obs. of B0  φ Ks !
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Masashi Hazumi (KEK)21b  sl+l−

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Tomorrowprospects up to ~500 fb-1

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Masashi Hazumi (KEK)23Main targets (2004. Feb – 2007. Aug)
• Global fit of the Unitarity Triangle (φ1,φ2,φ3,Vub)• Direct CP violatioin in B0  π+π− and other rare B decays• Rare B, tau, charm decays– Search for new physics– Understanding QCD effective theories• New particles• Observation of a new CP-violating phase in b  s !?

will have exciting (hectic) time each summer
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Expectation at 500 fb-1

From
Belle
alone

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B0  π+π− : Significance of CP violation
Feldman-Cousins Analysis

Belle
140fb−1

1) Observation of CP violation(5.2σ)
2) Evidence for direct CP violation

Aππ

≥3.2σ
for Aππ=0 and any Sπ
π

3.3σ
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Sππ

for “superweak” case
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The day after tomorrow
SuperKEKB: 5~50 ab-1

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B0  (cc)Ks vs. φ Ks
2716 signals

68±11 signals

L=5× 1035 (New)1999-2003 data set (158fb-1)
in 1 week
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One year operation (5 ab-1)
J/ψKs

φKs

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input:
presentb  s average
6.2σ with
φKs alone !

Masashi Hazumi (KEK)29

Distinguish different new physics models !
Different SUSY breaking scenarios can be distinguished !

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Doable with mass spectrum ?
Very hard to distinguish different SUSY breaking
scenarios from mass spectrum alone (at LHC)

quite similar
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Energy frontier vs. Luminosity frontier

Top-quark physics
Direct production, Mass, width etc.  CDF/D0
Off-diagonal couplings, phase BaBar/Belle
This will remain true when a new elementary particle is foundat a future energy frontier (e.g. LHC).
e.g. SUSY off-diagonal couplings, phase at a “super” B factory
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Masashi Hazumi (KEK)32τ  µ γ: another weapon

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Super-precise Unitarity Triangle

5ab-1

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Super-precise Unitarity Triangle

50ab-1

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If no New Physics in the mixing
SUSY SU(5) w/ νR(non-degenerate case)mSUGRA

consistent w/ SM even at 1% level: still very important information
Combining this with kaon CP violation and Δms  sensible test
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Present situation: lucky for SuperKEKB !
• We know that
– Standard Model (incl. Kobayashi-Maskawa mechanism) is the effective low
energy description of Nature.
– However most likely New Physics lies in O(1) TeV region.
• LHC will start within a few years and (hopefully) discover a new elementary
particle.

– Flavor-Changing-Neutral-Currents (FCNC) suppressed• New Physics w/o suppression mechanism excluded up to 103 TeV.  New Physics
Flavor Problem• Different mechanism  different flavor structure in B decays (tau, charm as well)

Luminosity upgrade will be quite effective and essential.
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Summary• Very fruitful and exciting time at Belle !
– sin2φ1 with 9% precision– Observation of CP violation in B0  π+π−
– First constraint on f3– Hint of new physics !? in b  s CP violation– Many rare decays, new resonances, etc. etc.

• Observed anomaly will continue to be the excitement.
• Physics case at SuperKEKB is compelling ! It will be thecentral place to elucidate the new physics flavor problem.
– LHC results will serve as important inputs to us (similar to Tevatron)

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Backup slides

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Rare B decays

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Jawahery (LP03)

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Vub measurement

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