1. Prospect of hadron spectroscopy in higher intensity e+e- collider
Kenkichi Miyabayashi
(Nara Women’s University, Japan)
Hadron Symposium, Nagoya
2014 Apr. 17th

2. Outline Key features of B-factory experiments
What we learned and experienced
LHCb as competitor
What shall we aim with SuperKEKB/Belle II
Summary

3. 772M BB
470M BB
In total, more than 1.5 ab-1 including 1G BB pairs are recorded at B-factories

4. Detector capable to measure time-dependent CPV
CP side
(B to fCP)
Dz=bgcDt,
bg=0.425(KEKB),
0.56(PEP-II)
Tag side
(the other B)
Dz measurement
This is very demanding measurement, requires sophisticated detector and analysis methodology.

5. All these are great benefit
4p general purpose spectrometer with
High momentum resolution, sp/p =
Ability to detect g down to 30 MeV.
Good g energy resolution, sM =5MeV for p0→gg.
Lepton identification capability, e>0.9, fake<0.01.
K/p/p separation capability, e~0.9, fake<0.1.
Excellent B decay vertex reconstruction, sDz =80mm.

6. Variety of recorded reactions
Υ decay
B decay
JPC=0-+, 1− −, 1++ in factorization limit.
Double chamonia production
C=+1.
gg collision
Continuum
Initial state radiation
JPC=0-+, 2++.
JPC=1− −.

7. A lot of discoveries have been made
Zb(10610) ±→Υ(3S)p±
Zb(10650) ±→Υ(3S)p±
X(3872)→J/yp+p-
PRL108,122001(2012)
PRL91,261801(2003)
M(Υ(3S)p±) (GeV)
Ml+l-p+p- - Ml+l- (GeV)

8. Synergy among measurements (I)
Belle; B±→J/K±
275M BB
BaBar; B±→J/K±
383M BB
Y(3940)
B signal yield
BaBar; B0→J/KS
M=3943±11(stat)±13(syst) MeV
=87±22(stat)±36(syst) MeV
PRL94,182002(2005)
M= (stat)±2.0(syst) MeV
= (stat)±5(syst) MeV
PRL101,082001(2008)

9. M(J/y w) in gg (Pt < 0.1 GeV)
PRL104,092001(2010)
Resonance contribution
Estimated background
Without resonance
Clear enhancement seen just above J/y w threshold!
Statistical significance=7.7s, Signal=49±14(stat)±4 events.
M=3915±3(stat)±2(syst) MeV
G=17±10(stat)±3(syst) MeV
→ Now PDG argues that this is cc0(2P).

10. Synergy among measurements (II)
PRD82,091106(2010)
Υ(2S)
Anomalous Υ(nS)p+p- production at Υ(5S)
→ Zb+ in Υ(nS)p+
Υ(3S)
PRL108,
122001(2012)

11. Synergy among measurements (III)
PRL110,252001(2013)
Y(4260)→J/yp+p- ↓
Z(3895)+ in J/yp+
BaBar discovered
Y(4260)→J/yp+p- in Initial State Radiation
PRL110,252002(2013)
PRL95, (2005)

12. Synergy among measurements. (IV)
arXiv: , accepted by PRD
J-PARC P50 proposal
pN→D* Yc
(Yc: charmed baryon)
MC: assuming 1nb for Lc.
Exclusive reconstruction ⇄ missing mass technique complementary each other.

13. Now LHC experiments are in the town
ATLAS cb(3P) observation
PRL108,152001(2012)
LHCb exited Lb observation
PRL109,172003(2012)
We should think about how to compete.

14. LHCb, a strong rival B→K+p- example
Very large cross section in forward region in pp collision.
~×2000 B mesons /fb-1 w.r.t. e+e- B-factories
Flight length of bottom and charm hadrons ~5-10×svtx
Bs→Ds example

15. Limitation at existent B-factories (I)
Belle : 660M BB
Z(4430)±→y(2S)p±
Significant signal at Belle
v.s.
Only hint with 1.9 at BaBar
Statistically, both are not contradicting with each other, but clear answer is to be given by higher statistics data.
PRL100,142001
BaBar : 455M BB
PRD79,112001

16. LHCb gave a confirmation
Fit with Z(4430)+
Fit without Z(4430)+
Statistical significance : 13.9s
arXiv: , submitted to PRL

17. Limitation at existent B-factories (II)
X(3872)→J/y g : established
X(3872)→y(2S) g : contradicting
PRL107,091803(2011)
Not seen
This puzzle was thought to be solved only by a higher statistics e+e- machine, but,
PRL102,132001(2009)
seen

18. LHCb gave another result
Taken from Polyakov Ivan’s slides in Moriond QCD, arXiv: submitted to NPB.

19. Now situation becomes …
LHCb gives the most precise measurement.
Hypothesis of admixture for charmonium and molecule looks to get more likely.
Taken from Polyakov Ivan’s slides in Moriond QCD

20. What shall we aim at SuperKEKB/Belle II
For B decays, quickly do new extraordinary idea oriented analysis before LHCb notices it.
Analysis software tools preparation is especially important.
ISR, gg collision are still unique at e+e- machine.
Clever logic to identify Bhabha is important to avoid being prescaled together with.
We can utilize missing mass technique.
In bottomonium and some other cases.
Try to find new synergy effects.

21. Υ(5S)→hb(mP)p+p- (m=1,2) hb(mP)→hb(nS) g (n=1,2)
Since hb(mP) do not have prominent decay mode, can only be recognized by missing mass recoiled against p+p-.
Selecting candidate events, visit missing mass against p+p- g.
→hb peak seen.
PRL 109, (2012)
MM(p+p- g)

22. X-, W-, Wc0 X- [dds] → Lp- W- [sss] → LK-
Wc0 [ssc] →W-p+
In Belle, long-lived baryons are properly reconstructed.
Points :
X- /W- is produced at Interaction point(IP)
X- , W- and L are long life,
decay points are not always at IP.
Precise vertex reconstruction is required. p p- L
ct = 7.89cm p-
Same topology for W-
ct=2.46cm X-
ct = 4.91cm IP
p+ for Wc0
Taken from M.Sumihama’s slides at Hadron2013

23. Mass spectrum of X- and W-
X W-
After usage of kinematical constraint fit to get the most probable decay vertices positions, otherwise very much mass spectrum smeared.
Taken from M.Sumihama’s slides at Hadron2013

24. In heavy ion collision Compact multiquark Molecule q q q q p q q q q
Larger size object may have larger production rate in coalescence in RHIC/LHC.
→another synergy, e+e- good at JPC determination.
Sungtae Cho et al. (ExHIC collaboration)
PRL 106, (2011)

25. Summary
Because of superb detector performance with excellent accelerator luminosity, B-factory experiments have been serving as the “Hub” to give a comprehensive understanding in hadron spectroscopy.
Let’s pursue this direction by SuperKEKB/Belle II with new synergy among experiments/measurements
Be clever and innovative to compete LHC experiments. Importance of missing mass technique and long-lived baryons reconstruction have been identified. Let’s try to find more!

26. B-factories
PEP II&BaBar 9GeV×3.1GeV
KEKB&Belle 8GeV×3.5GeV

27. SuperKEKB e+ e- To aim ×40 luminosity
Belle II e+
New IR
New superconducting /permanent final focusing quads near the IP
New beam pipe
& bellows
Replace short dipoles with longer ones (LER) e-
Add / modify RF systems for higher beam current
Low emittance positrons to inject
Redesign the lattices of HER & LER to squeeze the emittance
Positron source
Damping ring
Low emittance gun
Low emittance electrons to inject
New positron target / capture section
TiN-coated beam pipe with antechambers
To aim ×40 luminosity

28. Nano-beam collision KEKB SuperKEKB
To increase luminosity, small b function is used.
To handle hourglass effect, b>size of collision spot.
→Large crossing angle, one bunch behaves as “super bunch”.

29. Magnets have been installed
March 2013
D2(Oho-side)
D1(Nikko-side)

30. Belle II Detector KL and muon detector: EM Calorimeter:
electron (7GeV)
positron (4GeV)
KL and muon detector:
Resistive Plate Counter (barrel outer layers)
Scintillator + WLSF + MPPC (end-caps, inner 2 barrel layers)
Particle Identification
Time-of-Propagation counter (barrel)
Prox. focusing Aerogel RICH (fwd)
Central Drift Chamber
He(50%):C2H6(50%), Small cells, long lever arm, fast electronics
EM Calorimeter:
CsI(Tl), waveform sampling (baseline)
(opt.) Pure CsI for end-caps
Vertex Detector
2 layers DEPFET + 4 layers DSSD
Beryllium beam pipe
2cm diameter
Better or same performance under ×20 beam background!

31. VXD=PXD+SVD SVD Belle PXD+SVD Belle II z impact parameter resolution
r [cm]
DSSD’s
pixels
sBelle Design Group, KEK Report
z [cm]
z [cm]
DCDB
R/O chip
DEPFET matrix
z impact parameter
resolution
DEPFET mockup
Belle
Switcher control chip
20 mm
10 mm
prototype DEPFET
sensor
pb*sin5/2(q) [GeV/c]
Belle II
Si Vertex Det.

32. CDC Larger diameter than Belle. Wire stringing is on going.
Innermost part has been completed
Electronics is tested by cosmic.

33. Particle identification
Time Of Propagation counter (barrel) y x
prototype quartz bar
Hamamatsu
16ch MCP-PMT
partial Cerenkov ring reconstruction
from x, y and t of propagation
Proximity focusing Aerogel RICH
(endcap)
Aerogel
Aerogel radiator
Hamamatsu HAPD
Cherenkov photon
200mm
n~1.05
Hamamatsu
HAPD

34. TOP test beam result

35. Electromagnetic calorimeter
amplitude
time sampling
New electronics with
2MHz wave form sampling
ECL (endcap):
pure CsI crystals;(not day-1)
faster performance and better
rad. hardness than CsI(Tl).
off-time
bkg.
signal t t
trigger
trigger
2x improved
s at 20x bkg.

36. KLM status In this FY, installation is going on.
RPC → Scintillator+MPPC readout.

37. SuperKEKB/Belle II schedule
Calendar
2010
2011
2012
2013
2014
2015
2016
2017
・・・
Japan FY
2010
2011
2012
2013
2014
2015
2016
2017 ・・
Nov. 2013
Jan. 2015
SuperKEKB construction
Detector upgrade to Belle II
SuperKEKB operation
Belle II roll in
QCS install
VXD install
Belle roll out
KEKB
operation
Dismantling KEKB
Accelerator tuning
BEAST
Fabrication and tests of ring components
Physics run
Install and set up
Electricity and cooling facility
MR & DR buildings
DR tunnel
Upgraded Linac operation
for SuperKEKB, PF, PF-AR
Linac
Linac upgrade / operation for PF&PF-AR

38. Expected luminosity
50 ab-1 will be accumulated by 2022.