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15.09.2004 TAU-04, NARA 1 First steps to radiative return studies at Belle B.A.Shwartz BINP, Novosibirsk.

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Presentation on theme: "15.09.2004 TAU-04, NARA 1 First steps to radiative return studies at Belle B.A.Shwartz BINP, Novosibirsk."— Presentation transcript:

1 15.09.2004 TAU-04, NARA 1 First steps to radiative return studies at Belle B.A.Shwartz BINP, Novosibirsk

2 15.09.2004 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

3 15.09.2004 TAU-04, NARA 3 11 00 30  e+e  e+e  

4 15.09.2004 TAU-04, NARA 4 KEKBVEPP- 2000 Luminosity, см -2 s -1 10 34 10 32 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)

5 15.09.2004 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

6 15.09.2004 TAU-04, NARA 6 E rec P tot M inv PP E  2 <0.2 (for 2 particles modes)

7 15.09.2004 TAU-04, NARA 7 M inv (2tr), GeV All events    , (p1  / , p2  /  >0.5) Two particle events M inv (2tr), GeV

8 15.09.2004 TAU-04, NARA 8      background   calculation

9 15.09.2004 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.

10 15.09.2004 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

11 15.09.2004 TAU-04, NARA 11 KKKK 00 E CM – ( | p  max | + | p + | +p  | )>1 GeV

12 15.09.2004 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


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