TAU-04, NARA 1 First steps to radiative return studies at Belle B.A.Shwartz BINP, Novosibirsk
TAU-04, NARA 2 Plan 1.Basic things 2.A sample for first study 3.What’s seen for: , , K K and This is our first steps to see what can be done at Belle for radiative return physics. The events with 2 charged particles were studied
TAU-04, NARA 3 11 00 30 e+e e+e
TAU-04, NARA 4 KEKBVEPP Luminosity, см -2 s Integrated lum. (per 10 7 s) 100 fb -1 1 fb -1 Integrated in the range [1-2] GeV 0.1 fb -1 1 fb -1 Comparison to VEPP-2000 project, e e up to 2 GeV (under construction at BINP)
TAU-04, NARA 5 A sample to study The Tau-pair sample (skim) is used ( 2<Ntrk<8, Pch<9GeV, Eecl<9GeV) Then the following cuts were applied: 1.Ntrk=2 2.10<E rec <11 GeV 3.Ptot <0.5 GeV 4.N >0 5.E max>3 GeV 6.0.7< <2.6 7.Pmin >0.7 GeV (charged) 25.9 fb -1 is used study
TAU-04, NARA 6 E rec P tot M inv PP E 2 <0.2 (for 2 particles modes)
TAU-04, NARA 7 M inv (2tr), GeV All events , (p1 / , p2 / >0.5) Two particle events M inv (2tr), GeV
TAU-04, NARA 8 background calculation
TAU-04, NARA 9 N /N ratio By a simple separation procedure the number of and events are obtained and ratio is calculated (just demonstration, not for usage!) The difference 5% can be caused by the different trigger efficiency for pion and muon events. This is a measure of systematics.
TAU-04, NARA 10 How to compare with BaBar? N =1830 93 M =3106 1 MeV =16.3 0.9 MeV 71 J/ per 1 fb -1 From BaBar J/ paper – 7800 J/ event at 88.4 fb-1 88.2 J/ per 1 fb-1
TAU-04, NARA 11 KKKK 00 E CM – ( | p max | + | p + | +p | )>1 GeV
TAU-04, NARA 12 Conclusion 1.Events with radiative return can be seen at Belle with reasonable efficiency. 2.New Bhabha trigger implementation should improve the trigger efficiency at low invariant mass area