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

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

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

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.

All these are great benefit 4p general purpose spectrometer with High momentum resolution, sp/p = 0.3%@1GeV/c. 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.

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− −.

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)

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=3914.6+3.8-3.4(stat)±2.0(syst) MeV =34+12-8(stat)±5(syst) MeV PRL101,082001(2008)

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).

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)

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, 142001 (2005)

Synergy among measurements. (IV) arXiv:1312.1026, 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.

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.

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

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

LHCb gave a confirmation Fit with Z(4430)+ Fit without Z(4430)+ Statistical significance : 13.9s arXiv:1404.1903, submitted to PRL

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

LHCb gave another result Taken from Polyakov Ivan’s slides in Moriond QCD, arXiv:1404.0275 submitted to NPB.

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

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.

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, 232002(2012) MM(p+p- g)

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

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

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, 212001 (2011)

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!

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

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

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”.

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

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!

VXD=PXD+SVD SVD Belle PXD+SVD Belle II z impact parameter resolution r [cm] DSSD’s pixels sBelle Design Group, KEK Report 2008-7 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.

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

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

TOP test beam result

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.

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

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

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