Future flavour physics program at KEK

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Future flavour physics program at KEK
KEK, High Energy Accelerator Research
Organization
Seminar at BNL November 13, 2008 Masa
Yamauchi KEK
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Outline

• Introduction KEKB and Belle
• Physics case for KEKB/Belle upgrade
• KEKB upgrade plan
• Detector upgrade plan
• Schedule and funding status
• Summary

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KEKB and Belle
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KEKB
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Belle Detector
Cherenkov detector n1.0151.030
SC solenoid 1.5T
3.5GeV e
EM calorimeter (CsI(Tl))
TOF counter
8GeV e-
Central drift chamber He(50)C2H6(50)
m / KL detector
Si vertex detector
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Belle Collaboration
Krakow Inst. of Nucl. Phys. Kyoto U. Kyungpook
National U. U. of Lausanne Jozef Stefan
Inst. MPI, Munich U. of Melbourne Nagoya U. Nara
Womens U. National Central U. National United
U. National Taiwan U. Nihon Dental
College Niigata U. Nova Gorica U. Osaka U. Osaka
City U. Panjab U. Peking U. Princeton U.
Illinois U. - Riken Saga U. USTC Seoul National
U. Shinshu U. Sungkyunkwan U. U. of Sydney Tata
Institute Toho U. Tohoku U. Tohuku Gakuin U. U.
of Tokyo Tokyo Inst. of Tech. Tokyo Metropolitan
U. Tokyo U. of A and T. Toyama Natl College U.
of Tsukuba VPI Yonsei U.
BINP Chennai Chiba U. Hanyang U. U. of
Cincinnati Fu-Jen U. Giessen U. Gyeongsang Natl
U. U. of Hawaii Hiroshima Tech. HEPHY,
Vienna IHEP, Protvino IHEP, Beijing INFN,
Torino ITEP Kanagawa U. Karlsruhe KEK Korea U.
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Achievement of the B Factories
Quantitative confirmation of the KM model
PDG2008
Belle, July 05
B0?J/yKS
Discovery of CP violation in BB system
Af 0 Sf 0.6520.0390.020
Belle, July 05
Violation of CP symme
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Other highlights
Many new resonances
AFB in BgKll-
Evidence for Bgtn
Signal
X(3872)
Z(4430)
Belle, 2005
SM
D0-D0 mixing
bgdg transition
BgDtn
and more
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Another important achievement
Asymmetric ee- colliders with L gt 1034

• Success of KEKB and PEP-II enabled us to design a
  new ee- B factory with much higher Lpeak.

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What is next with flavour physics?

• LHC will start soon to explore the TeV region,
  which is the scale of the electroweak symmetry
  breaking, and most probably related to the New
  Physics scale.
• It is natural to assume that the NP
• effects are seen in B/D/t decays.
• Flavour structure of new physics?
• CP violation in new physics?
• These studies will be useful to
• identify mechanism of SUSY
• breaking, if NPSUSY.
• Otherwise
• Search for deviations from SM in
• flavor physics will be one of the
• best ways to find new physics.

Search for New Physics in precision meas.
In order for the flavor physics to be useful in
the coming LHC era, the precision of
various flavor measurements must be significantly
improved, both in terms of experimental
reach and understanding of theoretical
uncertainty.
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From KEKB to SuperKEKB
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Belle upgrade
Faster calorimeter with Wave sampling and pure
CsI crystal
Super particle identifier with precise Cherenkov
device
KL/m detection with scintillator and new
generation photon sensors
Background tolerant super small cell tracking
detector
New Dead time free readout and high speed
computing systems
Si vertex detector with high background tolerance
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KEK Roadmap
2006
2008
2010
2012
2014
2016
2018

• J-PARC

construction experiment upgrade

• KEKB

• LHC

• PF/PF-AR

• RD for Advanced Accelerator and Detector
  Technology

ERL
construction test experiment
C-ERL RD
PF-ERL
RD construction experiment
ILC
ILC RD
construction
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Physics at upgraded KEKB
New source of CP violation
New source of flavor mixing

Precision test of KM scheme
LFV t decays
SUSY breaking mechanism
Charm physics New resonances, D0D0 mixing
Super-high statistics measurements
aS, sin2qW, etc.
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Search for new CP phases
In general, new physics contains new sources of
flavor mixing and CP violation.
4In SUSY models, for example, SUSY particles
contribute to the b?s transition, and their
CP phases change CPV observed in B?fK, hK etc.
SuperKEKB
SM
SUSY contribution
In general, if SUSY is present, the
s-quark mixing matrix contains complex phases
just as in the Kobayashi-Maskawa matrix.
T.Goto et al., 2007
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Direct CP Violation in B?Kp Decays
P.Chang, ICHEP2008
New Update
Belle Results Nature 452, 332 (2008)

- 0.004
-0.094 0.018 0.008 Belle
Acp(Kp-)
-0.086 0.023 0.009 CDF
-0.04 0.16 0.02 CLEO
0.012
? -0.098 _at_ 8.1s AVG
- 0.011

0.030 0.039 0.010 BaBar
Acp(Kp0)
0.07 0.03 0.01 Belle
-0.29 0.23 0.02 CLEO
? 0.050 0.025 _at_2.0s AVG
DAKp Acp(Kp-) - Acp(Kp0)
-0.147 0.028 _at_ 5.3s
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DAKp Puzzle
P.Chang, ICHEP2008
/T
Expectation from current theory T P are
dominant ? DAKp 0
T
P
C
PEW
T
P

• Enhancement of large C with large strong
  phase to T ? strong inter. !?

• Enhancement of large PEW
  ? New physics

Yoshikawa 2003 Mishima Yoshikawa 2004 Buras
et. al. 2004, 2006 Baek London 2007 Hou et.
al. 2007 Feldmann, Jung Mannel 2008
Chiang et. al. 2004 Li, Mishima Sanda 2005
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Model independent checks for NP
P.Chang, ICHEP2008
M. Gronau, PLB 627, 82 (2005) D. Atwood A.
Soni, Phys. Rev. D 58, 036005(1998).

New
B? K0 p
B0? K0 p0
Sum rule
A -0.13 0.13 0.03
A 0.14 0.13 0.06
HFAG AVG -0.01 0.10
P dominants. ?Acp(K0p) 0
World Average
Important topic for Super B factory
Acp(K0p) 0.0090.025
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Searches for new sources of quark mixing and CP
violation
CP asymmetries of penguin dominated B decays
Deviation from SM
Present upper limits
New source of CP violation
Deviation from SM
Measurements at upgraded KEKB
Relevant to baryogenesis?
( ab-1 )
Reach of present B factories
Reach of upgraded KEKB
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Probing b? s transition with l l -
l
Probe the flavor changing process with the
EW probe.
l -
g, Z0
This measurement is especially sensitive to new
physics such as SUSY, heavy Higgs and extra dim.
b quark
s quark
?
Possible observables
4Ratio of branching fractions 4Branching
fraction 4CP asymmetry 4q 2 distribution
4Isospin asymmetry 4Triple product correlation
4Forward backward asymmetry 4Forward backward CP
asymmetry
B?Kll
B?Kll
-?- Belle, ICHEP 08 -?- BABAR, FPCP 08
-?- Belle, ICHEP 08 -?- BABAR, FPCP 08
The F/B asymmetry is a consequence of g-Z0
interference.
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Probing b? s transition with l l -
A
657 M BB
384 M BB
Isospin symmetry AI?0??
Forward-backward charge asymmetry as a
consequence of g-Z0 interference
Data show positive AFB at low q2, while the SM
predicts negative AFB.
At high q2, data above the SM expectation.
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B to t decays
B
B (B?tn) (1.51 0.33 )x10-4
e-
e
?
B
2.1s deviation
p
D
full reconstruction
0.20.3 for B
Belle, 2008
10ab-1
Provides a unique method to measure b-H-u
and b-H-c coupling strengths.
657M BB
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B to t decays
Two-fold ambiguity is resolved by the two
measurements.
B?Dtn has been measured.
Itoh, Komine, Okada 2005
WA
A.Bozek at Tau08
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Comparison with H production at LHC

• The parameter region covered
• by B decays and the charged Higgs
• production overlaps.
• If both experiments find positive effects, we can
  perform Universality Test of the charged Higgs
  couplings.

B-gttn H-b-u coupling B-gtDtn H-b-c
coupling gb-gttH H-b-t coupling
n
B?tn
t
n
H
b
c
B?Dtn
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Precise measurements of t decays
LFV violating t decay?
Upper limits
t-gtmg
m-gteg
t-gteg
Integ. Lum.( ab-1 )
T.Goto et al., 2007
Reach of B factories
SuperKEKB
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From KEKB to SuperKEKB
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Machine Parameters of SuperKEKB
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Detector Study Report
Detector Study Report as Year 2008 supplemental
update to the LoI detector part Quick studies in
one year including software development To be
replaced with full simulation studies in TDR
http//belle.kek.jp/ushiroda/private/cgi-bin/sBN/
dl.cgi?id0001
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Baseline Design LoI (2004)
sBelle
Belle
SVD 4 lyr g 6 lyr DSSD (option pixel,
striplet) CDC small cell, long lever arm ACCTOF
g TOPA-RICH ECL waveform sampling, pure CsI for
end-caps KLM RPC g Scintillator SiPM (end-caps)
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Beam Background
Rad-Bhabha mask around QCS magnet IR chamber
design
Results based on GEANT sims validated by
Belle/KEKB experience.
1st layer
Conservative, robust detector should be handle up
to 20 times more background
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Keys of PID upgrade
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Barrel PID (TOP)

• Quartz 255cmL x 40cmW x 2cmT
• Focus mirror at 47.8deg.
• angle(l) g y(l) correct chromatic dispersion
  t(l)
• Multi-anode (GaAsP) MCP-PMT
• Linear array (5mm pitch), Good time resolution
  (lt40ps)

re-polishing going on
lifetime to be checked
MCP-PMT
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Possible options for B-PID w/ TOP
K. Inami
3 readout type
Focusing type
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GaAsP MCP-PMT QE distribution

• Better QE
• gt35 at 500nm
• Less chromatic error
• Lifetime test has started.
• Need to check the QE degradation

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Endcap PID (A-RICH)
S. Korpars talk for details
Focusing Aerogel radiator
Npe 9.1, s(track) 4.2 mrad achieved 5.5??sepa
ration for 4 GeV/c K/p
1.045
1.055
1.050
1.062

• Photon Sensors
• Sensitive to single photon
• High QE gt 20
• High gain
• Position detection accuracy 5x5 mm2
• Large effective area gt 70
• Operational with 1.5 Tesla magnetic field

• Hybrid (Avalanche) Photon Detector
• MCP (Micro Channel Plate) PMT
• Si-PM/MPPC

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Photon Detectors

• Basic requirements
• Sensitive to single photon
• High QE gt 20
• High gain
• Position detection accuracy 5x5 mm2
• Large effective area gt 70
• Operational with 1.5 Tesla magnetic field

• Hybrid (Avalanche) Photon Detector
• dedicated detector for A-RICH
• 2. MCP (Micro Channel Plate) PMT
• good timing resolution
• 3. Si-PM/MPPC ?
• high QE

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Luminosity prospect
Goal
50ab-1 by 2020
L 81035
Initial target
L21035
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Strong competitors
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Comparison with LHCb
ee- is advantageous in
LHCb is advantageous in
CPV in B?fKS, hKS,
CPV in B?J/yKS
CPV in B?KSp0g
Most of B decays not including n or g
B?Knn, tn, D()tn
Time dependent measurements of BS
Inclusive b?smm, see
t?mg
and other LFV
B(s,d)?mm
D0D0 mixing
Bc and bottomed baryons
These are complementary to each other !!
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Summary

• KEKB/Belle and PEP-II/BaBar have been running
  successfully, and brought important scientific
  and technical achievements.
• Next generation ee- B factory with L1036 will
  be very useful to study the new sources of flavor
  mixing and CP violation.
• Search for new CPV in bgs transition
• Very precise test of CKM scheme
• Search for lepton flavor violating t decays
• Studies of H interactions with fermions
• Very precise measurements of aS(_at_10GeV),
  sin2qW(_at_10GeV)
• KEKB machine upgrade plan
• Detector upgrade necessary to improve BKG/rate
  immunity.
• New collaboration to be formed soon. Third open
  meeting is scheduled on December 10-12 at KEK.

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BACK UP SLIDES
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Search for right handed interaction
Left-right summetry in new physics?
CP violation in B ? KSp 0g
Sizable CP asymmetry is expected in B0?Xg decay,
if right-handed interaction exists in new
physics.
Present exp. precision
Precision of the measurement
U-KEKB
Reach of upgradedKEKB
SM
T.Goto et al., 2007
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B decays into invisible particles?
Light dark matter?
_
B ? K()nn or cc
Heavy darm matter is being searched for in direct
detection experiments.
Model prediction
Light dark matter can be Searched for in the
upgraded KEKB.
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New resonances
New resonances found at Belle
More than 10 new resonances have been found at
Belle
Y(4660) Y(4008)
Z(4430)
DsJ(2860)
DsJ(2700) Xcx(3090)
Among them X(3872) and Z(4430) are considered to
be exotic states.
Y(4320)
cc2
X(3940), Y(3940)
Y(4260)
Sc baryon triplet
X(3872)
More and more exotic states will be Observed by
the upgraded KEKB.
D00 D10
DsJ(2317/2460)
hc ee-?cccc
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Keys of SVD upgrade
Chip-on-sensor
Material effect is an issue
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Baseline option

• Inner layers
• Pixel detector
• MAPS,DEPFET,SOI
• Or striplet?
• Outer layers
• DSSD
• APV25
• tp 50ns, pipelined, weak at Cd
• VA1TA (currently used)
• tp 800ns, hold readout

• Open questions
• Inner radius
• Outer radius
• Material budget
• Readout pitch of outer layers
• Slant angle

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Conventional ladders do not help
Belle
VA1 _at_ Tp1ms enc e- 180 7.5/CdpF
3DSSD60pF 630e-
sBelle
APV25 _at_ Tp50ns enc e- 246 36/CdpF
2500e-
4 times larger Noise
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sKEKB Chip on sensor !?
The only possibility, so far, to use APV25 chips
for the outer layers

• Worries to be cleared away
• Material inside det. acceptance
• Heat cycle
• Coolant leak, clog

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Vertex Detector (inner layers)

• Start with DSSD at t0
• Upgrade with Monolithic pixel later (hybrid pixel
  too thick for us)
• CAPS in Hawaii (since 2002)
• SOI in KEK (since 2005)
• will take 23 years

DEPFET is now a promising option.
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Slant angle
Total sensor area can be half of LoI design in a
spherical design Lose KS g should go even outer
if we take this option
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Keys of CDC upgrade
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Tracks under x20 background
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Background effect on tracking
Checked with the old Gold-plated mode (J/yKS) and
the severest mode (DD) for tracking that
contains many slow tracks in the final state
Efficiency drops drastically with increasing the
background, but will be better than Belle thanks
to the software efforts SVD track finder. DE
resolution will be worse relatively mildly.
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Key points of ECL upgrade
End caps
Barrel
Bonus Material inside ECL changes (reduces)
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Pure CsI counter performance
5krad
E, t resolution test beam at BINP
radiation hardness
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Photon Detector
2 UV sensitive photo pentodes (PP) by Hamamatsu
C 10pF
Gain Factor k 120-240 for 21 samples k 46-92
gt 30 _at_ B1.5T, endcap Q 14
MPPC, APD will also be tested
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Keys of KLM upgrade
End caps
Barrel
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Scintillator SiPM
17k scintillator strips with WLS fiber
readout.
h?
SiPM main features Sensitive size 1x1mm2 on
chip 1.5x1.5 mm2 Gain 2106 Ubias50V
Recovery time 100 ns/pixel Number of pixels
576-1024 Insensitive to magnetic field
Dynamic range 103/mm2
pixels
R 50O
20µm
Depletion Region 2µm
substrate
Resistor Rn400 kO
Al
Ubias 50V
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ITEP scintillator 1m1m test module (96 readout
ch.)
These modules will be installed in Oho side
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sKEKB Beam Energy Asymmetry

• Toy MC results considering Dt resolution and
  geometrical acceptance.
• Geometrical acceptance is assumed to be same as
  the current Belle detector.

KEKB
worse

• - J/yK0 tCPV
• - fK0 tCPV
• - B?tn BF

ELER 3.5 GeV looks good
better
January 25, 2008
BNM2008_at_Atami
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Possible Hints for New Physics in Flavor Decays
Anomalous CPV in b?s transition?
Opposite CP asymmetry between B0 and B
Small inconsistency in the unitarity triangle?
Theoretical calculations using Vub, Dmd,eK
Direct measurement
x(0.970.29), y(0.780.19)
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