Hadronic B Decays
related to QCD
at Belle
2010.03.03
Jeri, M.C. Chang (張敏娟)
FU JEN CATHOLIC UNIVERSITY(輔仁大學)
2010/Mar./4 @ NTHU(清華大學)
1
Some names related to Belle Exp.
KEK: 高エネルギー加速器研究機
構 (High Energy Accelerator
Organization).
KEKB: The Accelerator at KEK
Belle: The Detector placed in the
electron and position interaction point
Located in Japan.
2010.02.09
The KEKB Collider (Tsukuba, Japan)
KEKB:
e-: 8.0 GeV
e+: 3.5 GeV
3km circumference
ECMS=M(U(4S))=10.58 GeV
2009
Ldt = 1000 fb-1
1999
3
Basic Knowledge
 ECMS=M(U(4S)) : U(4S) Resonance is
just above the threshold for BB-bar
production.
 Due to momentum conservation, the
B and B-bar has equal energy~5.29 GeV.
‘B Factory’
 Huge numbers of B meson decay
events are created. Therefore, Belle
experiment is also called a B Factory.
Analyzed Number of BB-bar
events = (771.581 +/- 10.566) x 106
Belle Detector
Aerogel Cherenkov counter
n=1.015~1.030
SC solenoid
1.5T
3.5GeV e+
CsI (Tl)
TOF counters
8GeV eTracking + dE/dx
small cell + He/C2H6
Si vertex Detector
m / KL detection
Belle detector can measure
 Position of the B Decay Vertex
 Tracks and Energy of flying particles
 Identify different Particles
ECL: absorbed particle energy
Taking shifts @ Belle control room
2009.12.18
Belle Collaboration
International cooperation (～300 scientists)
2009 Belle experiment run-end party
11
Some names related to BaBar Exp.
SLAC, SLAC National Accelerator
Laboratory : Stanford Linear Accelerator Center,
operated by Stanford University.
PEP-II: The Accelerator at SLAC
BaBar: The Detector placed in the
electron and position interaction point
Located in USA.
Old Situation
In 2001 there was a single dominant physics goal
B factories: extraordinary data samples
KEKB + PEP-II
and luminosities
~ 1.5 billion BB pairs
~946/fb (7/09)
KEKB/Belle
~100 fb-1 @U(5S)
PEP-II/BaBar
~553/fb
Recent progress at KEKB: L=2.1 x 1034/cm2/sec with crab cavities.
New Situation: Only One Major Player
In preparation, LHCb
(needs commissioning
time for the LHC) and
Belle-II (needs ~3 years
of construction).
Many physics goals: all motivated by the search for NP
Nobel Prizes from Surprising Discoveries about
Weak Interactions of Quarks
Maximal P
violation
1957
T.D. Lee
C.N. Yang
Small CP
violation
1980
J. Cronin
V. Fitch
O(1) CP
violation
and 3
generations
M. Kobayashi
T. Maskawa
2008
Everyone can take a picture with
Kobayashi-san
Particles in Physics (1)
 Elementary Particle:
Fermions
Quarks: u, d, c, s, t, b
Leptons: e-, e+, m-, m+, t-,
t+, ne, nm, nt , n e n m n t
Bosons
Gauge: g, g, W±, Z
Particles in Physics (2)
 Composite Particle:
Hadrons
Baryons/Hyperons:
N (p · n) · Δ · Λ · Σ · Ξ · Ω
Mesons/Quarkonia:
π · ρ · η · η′ · φ · ω · J/ψ · ϒ · θ · K · B · D ·
T
Selected topic (1):
Baryonic B Decays
Only Belle did the baryonic B decay measurements. No BaBar papers.
Introduction
 Profound baryonic decays: a unique feature of B
meson
 Well established after few years of B-factory running
 BF(2-body) < BF(3-body) < BF(4-body)
Baryonic B Decays
 Threshold enhancement in the baryon-antibaryon
system (No conclusive explanation yet)
 Searching ground for exotic states (eg. Pentaquark)
 There may be unexpected large CP violation in
charmless modes
+  New results from B  h and B  p 
21
B  h
22
23
The branching fraction indicate that there is
no one to one correspondence
24
25
26
27
28
+
+
B  p 
605fb-1
PRD 80: 111103(R) 2009
+0.88
BF( B +  p + - ) = (5.92 -0.84 ± 0.69)x10-6
Fit with threshold function
Significance = 9.1
+
0
BF( B  p
+0.67
) = (4.78 -0.64 ± 0.60)x10-6
Significance = 9.5
Hint:
+0.77
+
BF( B  pf 2 (1270) ) = (2.03 -0.72 ± 0.27)x10-6
Significance = 3
29
B  p 
+
B  p 
+
+
0
+
B  pf 2 (1270)
605fb-1
PRD 80: 111103(R) 2009
30
Summary (1)
 More baryonic modes have been found in B meson
decays
 Comparisons between pph and ΛΛh show that the
underlying dominant decay diagrams may be different
 First 4-body charmless baryonic decay has been
observed in B→pΛππ
 Threshold enhancement is the key to understand
baryonic B decays
31
Selected topic (2):
Selected topic (3): Belle-II
Belle and BaBar results lead to 2008
Nobel Prize for Kobayashi & Maskawa
KEKB→SuperKEKB
Belle →Belle-II
VERTEXING
PID
EM CALORIMETER
1999.May ~ 2009.Dec
2012 ~
40
Two super B-factory projects
KEKB/Belle
are prolongation of the successful B-factories
PEP-II/BaBar
8 × 1035
2.1 × 1034
10 ×
1035
1.2 × 1034
SuperKEKB/Belle2
SuperB
How to get high luminosity
 Target luminosity: 8×1035/cm2/s
 Continuous injection (succesful
experience of KEKB operation)
 Constraint: to save money use existing
KEKB components as much as possible
z
 x*
z
Two options:
High Current
Nano-Beam
Slightly smaller βy*
6.5(LER)/5.9(HER) → 3.0/6.0
Significantly increase beam currents
1.8A(LER)/1.45A(HER) → 9.4A/4.1A
Increase ξy
0.1(LER)/0.06(HER) → 0.3 or more
Developement of the LoI design
for SuperKEKB (2004)
 x*
L
2f
Half crossing angle: f~30mrad
Much smaller βy*
6.5(LER)/5.9(HER) → 0.21/0.37
Slightly increase beam currents
1.8A(LER)/1.45A(HER) → 3.6A/2.1A
Keep ξy
0.1(LER)/0.06(HER) → 0.09/0.09
Proposed by P. Raimondi et al. for use
at Italian Super B Factory; Now
considered also for SuperKEKB
Belle-II Organizational issues
Australia
Univ. of Sydney
Univ. of Melbourne
Austria
Austrian Academy of Sciences (HEPHY)
China
Institute of High Energy Physics, Chinese Academy of
Science
Univ. of Science and Technology of China
Czech
Charles University in Prague
Germany
Karlsruhe Institute of Technology
Max-Planck-Institut fur Physik - MPI Munich Univ. of Giessen
Bonn Univ.
India
Korea
Indian Institute of Technology Guwahati
Indian Institute of Technology Madras
Institute of Mathematical Sciences (Chennai)
Panjab Univ.
Tata Insitute of Fundamental Research
Gyeongsang National Univ.
Korea Institute of Science and Technology Information
Korea Univ.
Kyungpook National Univ.
Seoul National Univ.
Yonsei Univ.
Hanyang Univ.
Poland
The Henryk Niewodniczanski Institute of
Nuclear Physics - Polish Academy of Science
Russia
Budker Institute of Nuclear Physics
Institute for Theoretical Experimental Physics
Slovenia
Jozef Stefan Institute (Ljubljana)
Univ. of Nova Gorica
Taiwan
Fu Jen Catholic Univ.
National Central Univ.
National United Univ
National Taiwan Univ.
U.S.A.
Univ. of Cincinnati
Univ. of Hawaii
Virginia Polytechnic Institute and State Univ.
Wayne State Univ.
Japan
Nagoya Univ.
Nara Women's Univ.
Niigata Univ.
Osaka City Univ.
Toho Univ.
Tohoku Univ.
Tokyo Metroporitan Univ.
Univ. of Tokyo
KEK
Particle ID: TOP (Barrel) & RICH(Forward Endcap)
Cherenkov ring in quartz bar: difference of
propagation time for K/π is ~100ps
Photon detector
MCP-PMT
Radiator
aerogel tiles
Belle II
4σ K/π separation in 1-4GeV
Belle
Electromagnetic calorimeter and muon-KL detector
To keep Electromagnetic calorimeter
resolution with pile up:
 Barrel: Keep CsI(Tl) + improve read out
 Endcap: Replace with pure CsI (shorter
decay time) + photopentode + faster read out
To keep KLM efficiency:
 Barrel: Keep RPC
 Endcap: Replace with scintillator strips
+ WLS read out by SiPM
Organization
 Belle II is a new international collaboration (Spokesperson Peter Križan, Ljubljana) with
the most Belle members continuing with new project +
 Many new collaborators from new institutes joined last two years
 Open for new groups
 Current Status of the project:
 SuperKEKB is a lab priority
 The Japanese government has allocated in FY 2009 ~$32 M for R&D
 KEK has submitted a budget request for FY 2010 and beyond of $350 M for
construction; Funding in other countries on the way
 TDR to be submitted by March 2010
 Start data taking in 2013
Conclusion
 B factory -> Super B factory
 New B factories: Belle-II vs. LHCb
 New Physics found in 2020 and a new Nobel price
winner in this field?
Thank you!
Belle II
have to deal with:
• higher background
radiation damage,
higher occupancy
• higher event rates
DAQ
• improved performance
hermeticity
ECL:
wave form sampling
pure CsI endcaps
m, KL:
scintillator strips
endcaps
vertexing:
Central Drift Chamber: PID:
2 lyrs DEPFET pixel smaller cell size
TOP barrel
4 lyrs DSSD
improved read-out
ARICH forward
From Wikipedia
Resonance (particle physics)
 In particle physics, a
resonance is the peak located
around a certain energy found in differential cross
sections of scattering experiments. These peaks are
associated with subatomic particles (such as
Nucleons, Delta baryons, Upsilon mesons, ...) and
their excitations. The width of the resonance (Γ) is related
to the lifetime (τ) of the particle (or its excited state) by the
relation



t
 where ħ is the planck constant.