prospects of super kekb and belle ii experiment
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Gagan Mohanty
Prospects of Super KEKB andBelle II Experiment
Tata Institute (TIFR), India
2
Talk outline
28-09-2009
• Physics case
• Accelerator Super KEKB in Japan
• Detector upgrade Belle → Belle II
• Current status of the project Timeline, collaboration, funding
• Closing remarks
3
Threefold Way
28-09-2009
Energy (Tevatron, LHC)
Today, breakthroughs in elementary particle physics are made possiblethrough the advances in three complementary directions
I shall concentrate on the right-most corner, i.e., luminosity frontier
Now: 10 years after the B factories
Discovery of CPV in B decaysDiscovery of CPV in B decays
Precision test of KM paradigmPrecision test of KM paradigm
Look for new physics (NP) signatureLook for new physics (NP) signature
Step1
Step2
Step3
2001 summer !
2008
28-09-2009 4
Kobayashi, Maskawa, PTP 49 (1973) 2
Need more than 50 times the data (50 ab−1) we have at present to decipherNP effects
What is so special about 50?
50 ab−1
Lu~
CKM UT triangleNow
New CP phaseNP effect
B K(*)l+l-: AFB
Theory error50 ab−1
50 ab−1
Flipped C7
28-09-2009 5
Xu et al., PRD 74 (2006) 114019
Is that all?
1, 2, 3s @ 50 ab−1
D0D0 mixingτ LFV decays X(3872)
Z+(4430)
Super B factories are really super flavor factories
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LFV in tau decays, CPV in D-mixing would be unambiguous signatures ofNP – beam polarization, operating @ threshold further benefit the cause
Good detector, huge data in a clean environment Rest assured
In fact a “treasure chest”
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Would be possible with a good amount data taken at ϒ(5S)
Complementary with the LHC
S.Stone
Bs
Com
mon
No IPg,n
50ab−1
NP flavor couplings
Diagonal: Energy frontier(LHC – ATLAS, CMS)
Off-diagonal: Lumi frontier(super flavor factory, LHCb)
• Settle NP models• Look for higher scale NP
Super flavor factory vs LHCb
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What about worst-case scenario?
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• Imagine the possibility, where NP follows the SM patternof flavor and CP violation (minimal flavor violation)
• Even in this most unfavorable scenario, super flavor factoriesare still sensitive up to NP mass range of 600-1000 GeV
D’Ambrosio et al., NPB 645 (2002) 155
• The model predicts all NP flavor couplings are zero – naturemay not be so much unkind to us!
• Going little up, in the next-to-minimal flavor violation, the to-beexploratory scale goes beyond 10 TeV LHC domain
• For generic flavor violation scenario, super flavor factoriesare sensitive up to ~1000 TeV
Explore luminosity frontier
2.1×1034
1.2×1034
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KEKB/Belle (Japan)
Super KEKB (Japan)
PEP II/BaBar (US)
SuperB (Italy)Peak luminosity ~1036 cm−2s−1
One eqn. – many ways to play around
L
2ere1
y*
x*
Iy
y*
RL
Ry
• Raise the beam current, I• Larger beam-beam par, xy
• Smaller b*y
× ~5~5
~1/2
~50
High current approach
< 1/20+ low emittance
Nano-beam approach
Brute forceRealizable
New schemeRisk?
Baseline:
(short bunch) (long bunch)
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Super KEKB (Japan) SuperB (Italy)
12
Crab cavities installed andundergoing testing in beam
Superconducting cavities willbe upgraded to absorb morehigher-order mode power upto 50 kW
The beam pipes and allvacuum components willbe replaced with higher-current design
Super KEKB
e− 4.1 A
e+ 9.4 A
High-current option (baseline)
L
2ere1
y*
x*
Iy
y*
RL
Ry
Damping ring
New IR: Belle II
Crab crossing
+ Linac upgrade
8 GeV
3.5 GeV
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Higher currentMore RFNew vacuum system
The state-of-art ARES coppercavities will be upgraded withhigher energy storage ratio tosupport higher current
Crab crossing and its impact
Crossing angle 22 mrad
Head-on (crab)
(Simulation: K. Ohmi)
2222 mradmradcrossingcrossing
crab crossingcrab crossing
28-09-2009 13
2007
2009Crab ON
2008
Crab OFF
Crabbing: successful!
L = 2.11×1034 (17 July)higher than without crab(new skew sextupoles)
Specific luminosityhas increased ~30%
Nano-beam scheme
Present KEKB
SuperB
L NN f
4 x* y
*RL
L
2ere
1 y
*
x*
I y
y*
R L
R y
5mm
1mm
100mm
(w/o crab)L
Hourglass condition:β*
y >~ L=sx/f
Half crossingangle: f
1mm
5mm100mm
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15
Replace long TRISTANdipoles with shorter ones
Tin coated beam pipeswith antechambers Nano-beam option
e− 2.1 A
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Low emittanceelectrons to inject
Low emittancepositrons to inject
New positron targetand capture section
Add/modify RF systems
New superconducting /permanent final focussing quads
New IR: Belle II
e+ 3.7 A
Super KEKB
Comparison of parameters
High-current option includes crab crossing and travelling focusNano-beam option does not include crab waist
KEKBdesign
KEKB achieved(with crab)
Super KEKBhigh-current
option
Super KEKBnano-beam
option
by* (mm)(LER/HER) 10/10
6.5/5.9(5.9/5.9)
3/6 0.24/0.37
ex (nm) 18/18 18(15)/24 24/18 2.8/2.0
sy (mm) 1.9 1.1 (0.84) 0.85/0.73 0.084/0.072
xy 0.0520.108/0.056
(0.101/0.096)0.30/0.51 0.09/0.09
sz (mm) 4 ~ 7 5(LER)/3(HER) 5
Ibeam (A) 2.6/1.11.80/1.45
(1.62/1.15)9.4/4.1 3.6/2.1
Nbunches 5000 1387 (1585) 5000 2119
Luminosity(1034 cm−2 s−1)
1 1.76 (2.11) 53 80
28-09-2009 16
Luminosity projection
3-year shutdownfor the upgrade
L~2×1035
L~8×1035
50ab−1 by ~2020
~10ab−1 by 2016
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Requirements for the detector
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• Will be built by upgrading the current Belle spectrometertaking the following points into account
1) Higher background
2) Higher event rates
3) New requirements
− Radiation damage, higher occupancy
− Higher DAQ rate
− Improved hermiticity for LFV searches and study of final states involving neutrinos
Super KEKB baseline detector
Belle
Belle II
SVD: 4 layers g 2 DEPFET + 4 DSSD layersCDC: small cell and long lever armPID: ACC+TOF g TOP+A-RICHECL: waveform sampling, pure CsI for endcapKLM: RPC g Scintillator+SiPM (endcap)
28-09-2009 19
Progress and planJun 2004: LoI for Super KEKBJan 2008: KEK Roadmap
Super KEKB is identified as high priorityDec 2008: New collaboration (Belle II) officially formed
13 countries, 43 institutesElection of the spokesperson
Mar 2009: BPAC (Chair: T.Nakada) endorsement
Mar 2009: FY2008/9 supplemental budget:~5M$ for the Belle upgrade
May 2009:~27M$ for KEKB upgrade R&DJuly 2009: 3rd Open Belle II collaboration meeting
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Current organizational setup
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22
Closing Remarks
• Super KEKB in Japan is one of the candidates Baseline design (high-current option) is finalized, work
in progress for the nano-beam option Belle II collaboration is formed Partial funding is already secured
28-09-2009
• Both the B factories – Belle and BaBar – have performedexceptionally well, beyond their original design
• CKM paradigm has been established as the only source ofCP violation in the SM
• Proposal for two super flavor factories with raison d’être toprobe NP effects (complementary to LHC)
Your active support and participation are most welcome
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