Recent results from Belle and Status of SuperKEKB/Belle II Chengping ShenUniv. of Hawaii, Belle collaboration
OutlineDavid Atwood, Isard Dunietz, and Amarjit Soni [PRL 78, 3257 (1997), PRD 63, 036005 (2001)]
First evidence of ADS B DK
3/ is the least well measured of the unitarity angles.One of methods uses DK+-, ADS(David Atwood, Isard Dunietz, and Amarjit Soni ) mode [PRL 78, 3257 (1997), PRD 63, 036005 (2001)], for which the effect of CP violation can be enhanced by the comparable magnitudes of interfering amplitudes. CKM and color suppressed
RDK measurement is an importantInput value for the 3 angle determination
Bs J/(, ', f0), Ds(*)+Ds(*)-(CP-eigenstates)
Difference in widths between two Bs-Bs mass eigenstates (time-independent)
(indirect measurement)direct measurements CDF and D0 measured Delta Gamma using the time distributions of Bs decays. This has no model dependence.
X(3915)&& X(4350)in ggwJ/y and J/ (first observed at Belle)XX: JPC=0++,0-+,2++,2-+,
New peak in ggwJ/yX M: 3914 3 2 MeV, G: 23 10 +2 MeV, Nres = 55 14 +2 MeV Signif. = 7.7s, Background only fit e+e- undetected pt balance requiredX(3915)J/ in fusion?PRL 104, 092001 (2010) -8-14
Could it be the Z(3930) ( ) ?M: 3914 3 2 MeV, G: 23 10 +2 MeV, Nres = 55 14 +2 evtsM = 392952 MeV Gtot = 29102 MeV Nsig = 64 18 evtsgg DDgg J/PRL 96, 082003 (2006) cc2 -8 -14
X(3915) Ggg partial widthGggB(wJ/y) = 69 16 +7 eV (JP=0+)GggB(wJ/y) = 21 4 +2 eV (JP=2+)For comparison:Z(3930): GggB(DD) = 180 5030 eVIf X(3915) = Z(3930) = cc2 0.08B(cc2wJ/y)B(cc2DD)Huge for above-open-charm-threshold charmonium -18 -5
Could it be the Y(3930)?BK wJ/yPRL94, 182002M3943 17 MeVG 87 34 MeVB+B0M3915 5 MeVG 33 13 MeVGood overlap withBaBar Y(3930) values X(3915):M: 3914 3 2 MeV, G: MeV, PRL101, 082001PRD82, 011101B+B0M3919 5 MeVG 31 12 MeV
K. Yi ICHEP 2010m = MeV/c2 a 2nd one atm=4275 MeV? B(Y4140fJ/y) 10% G(Y4140fJ/y) 1.2 MeVIf B(B+K+ Y4140) B(B+K+J/y)B+ K+ f J/yThe CDF Y(4140)J/D*sD*s molecule? [cscs] tetraquark?
Searched for Y(4140) in J/No Y(4140) (efficiency is very low ~0.3%)White histograms are data, the shaded are normalized and J/ sidebands eventsA few events accumulate at 4.35 GeV in both J/ee & modes Our upper limits disfavor the scenario Y(4140) being a Ds*+ Ds*-molecule with JPC=0++ or 2++ [PRD80, 054019,2009]JP=0+: Br(Y(4140)) J/) < 39 eV @ 90% C.L.JP=2+: Br(Y(4140)) J/) < 5.7 eV @ 90% C.L.825 fb-1
Fit to J/ invariant massJP=0+: Br(X(4350)) J/) = eV
JP=2+: Br(X(4350)) J/) = eVS.S.=3.9, const. bkgS.S.=3.2, linear bkg825 fb-1PRL 104, 112004 (2010)M= MeV/c2 = MeV/c2 N (X(4350))=Excited P-wave charmonium? Tetraquark? Fl. Stancu, arXiv: 0906.2485D*sD*s0 molecule at 4.340.09 GeV? J.R.Zhang et al., arXiv:0905.4672
e+e to charm cross sections via ISR
Use ISR to measure open charm exclusive final states s=(Ecm-E)2-p2ISR at B factoriesQuantum numbers of final states are fixed JPC = 1 Continuous ISR spectrum: access to the whole s intervalem suppression compensated by huge luminosity comparable sensitivity to energy scan (CLEOc, BES)
Sum of all exclusive contributionsHere D=D0 or D+ . The same for D*Only small room for unaccounted contributions Charm strange final states Limited inclusive data above 4.5 GeV Charm baryons final states
Full reconstruction of hadronic part ISR photon detection is not required but used if it is in the detector acceptanceTranslate measured Ds(*)+Ds(*)- mass spectrum to cross section Ds+ are reconstructed using six decay modes: KsK+,K-K++, KsK- + +, + and +
e+e Ds(*)+Ds(*)- via ISR with full reconstruction
A clear peak is seen at threshold near (4040) mass in Ds+Ds- Two clear peaks are seen at the (4160) and the (4415) masses in Ds+Ds*- With limited statistics no structure are evident in Ds*+Ds*- Both the e+e- Ds+Ds*- cross section and R ratio exhibit an obvious dip near the Y(4260) mass, similar to what is seen in e+e-D*D* and in the total cross section for charm production.Exclusive e+eDs(*)+Ds(*)- cross-sectionsarXiv:1011.4397 (accepted by PRD)
Status of SuperKEKB/Belle II
What is the next experimental step? Precision measurementsMuch larger sample needed for this purpose Super B factoryHopefully new phenomena might be seen: CPV in B and D decays from the physics outside the CKM scheme.Lepton flavour violations in decays.Physics models can be identified (if new effects are observed) or new ones can be constrained (if nothing is seen). Physics motivation is independent of LHC. If LHC finds NP, precision flavour physics is compulsory. If LHC finds no NP, high statistics B/ decays would be a unique way to search for the physics far beyond the TeV scale.Further Continuation of Flavour Physics possible at a Super B Factory
How to do it? => Upgrade KEKB & Belle
SuperKEKB colliderThe improvement in luminosity is due to the dramatic reduction of beam size (y ~1 micron -->50 nanometer)
21-24 Oct 2010 Charm2010Plan and Expectation with SuperKEKBMilestone of SuperKEKBWe will reach 50 ab-1in 2020~2021.9 month/year20 days/monthIntegrated Luminosity(ab-1)Peak Luminosity(cm-2s-1)Commissioning starts In later half of 2014Shutdownfor upgrade
Status: Termination of KEKB on June 30, 2010 marked the start of SuperKEKB/BelleIIFirst physics run on June 2, 1999Last physics run on June 30, 2010Lpeak = 2.1x1034/cm2/sL > 1ab-1
*5.8 oku yen (M$) for Damping Ring (FY2010)100 oku yen (M$) for machine: Very Advanced Research Support Program approved for FY2010-20122010-2013: construction, installation2014(later half): commissioningFunding and Construction
New Collaboration (Belle II)Belle II is a new international collaboration360 members - 57 institutions Regular collaboration meetings TDR (Technical Design Report) has been published (arXiv:1011.0352)
All possible two-body decays of (3770), (4040), (4160), (4415) are included Significant effect of interference : model dependent!To reduce model dependence we need to measure exclusive cross sections to open charm final statesBES fit to the inclusive R spectrum Parameters of the JPC = 1 conventional charmonia (3770), (4040), (4160), (4415) M, tot, ee remain quite uncertain and model dependent
How to improve luminosity?
Zhen-An Liu 21-24 Oct 2010 Charm2010*Belle II:Belle Upgrade for the Super KEKBSC solenoid1.5TNew readout and computing systemsCsI(Tl) 16X0pure CsI (endcap)new electronics (waveform sampling) Aerogel Cherenkov counter + TOF counter TOP + Aerogel RICHTDR: KEK Report 2010-1
*******This figure shows a possible near term plan.We run KEKB in 2009 for 6 months, and then shutdown for 3 years as already mentioned.At Belle side, as I told, we just had the kick-off meeting of the new collaboration this week.We still invite detector proposals. This continues until summer 2009, then the design should be finalized by December 2009.
BaBar y(3770)DDRearrange slide*For the silicon vertex detector, we replace the 4-layer DSSD with the 6-layer configuration; the two innermost layers will be pixels to cope with the increasing occupancy. The outer radius will be enlargedTo do the tracking, the central drift chamber will be replaced with smaller cell size.The end-cap part of the electromagnetic calorimeter will be replaced with pure CsI to reduce the pile-up noise.The RPC chambers for the K-long and muon detectors will bereplaced with a system based on scintillator + new solid-state photon sensors, SiPM.We also introduce new dead-time free readout and high speedcomputing system.
Finally, in order to improve the particle id performance, weplan to replace the system based on threshold aerogel Cherenkov detector and Time-Of-Flight with ring imagingtype detectors called Time-Of-Propagation counter (forthe barrel) and RICH with aerogel as a radiator (for the end-cap).