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Introduction. At the 4170, the g * was proven to decay mostly into D * D * , DD * , and D s D s * Directly produced D s Narrow M BC , the indirect D s Wide M BC ( g smearing). Then plot. D S Selection Loose cut on D s Mbc,. Tag Selection. direct Ds. D S + D S - Events peak
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Introduction • At the 4170, the g* was proven to decay mostly into D*D*, DD*, and DsDs* • Directly produced Ds Narrow MBC , theindirect Ds Wide MBC (gsmearing) Then plot • DSSelection • Loose cut on Ds Mbc,
Tag Selection direct Ds DS+DS- Events peak at the right Ds mass Indirect Ds Indirect Ds
DS+ fp, from DS+DS- yield = 40.3 ± 7.6 e = (41.0 ± 0.5)% # of Events / 2MeV Mbc (GeV) |DE| < 18.2 MeV (98.8% of the area under the DE distribution, i.e. 2.5s)
Thee+e- Ds+Ds- Cross Section DS+ fp, from DS+DS- DS+ fp, from DS+DS-* # of Events / 2MeV Mbc (GeV) Invariant Mass (GeV) yield = 40.3 ± 7.6 e = (41.0 ± 0.5)% yield = 1038.3 ± 34.6 e = (41.6 ± 0.5)% s(e+e- Ds+Ds-)/s(e+e- Ds+Ds-*) = ( 3.93 ± 0.76 )%
Ds+Ds- fp KKp # of Events / 2MeV Invariant Mass (GeV) |DE| < 18.2 MeV (98.8% of the area under the DE distribution, i.e. 2.5s)
Invariant Mass of Ds Tags from DATA K-p+p0 Total Number of Tags = (5067 ± 112) The signal region is defined ascontaining 98.8% (2.5 r.m.s widths) of the signal events with invariant mass below and above the Dspeak.
DsDs phipi dele 6mev Kkpi dele 6mev phipi dele 18.2mev Kkpi dele 18.2mev