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Method to Check Number of D S Tags

Method to Check Number of D S Tags. All modes combined. M(Ds). MM* 2. Number of Tags (2D Fit). # in signal windows: D S invariant mass  17.5 MeV MM* 2 [3.872, 4.0] GeV 2. M bc Distribution. D S. [2.015, 2.067] GeV window used to select Tags

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Method to Check Number of D S Tags

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  1. Method to Check Number of DS Tags

  2. All modes combined M(Ds) MM*2 Number of Tags (2D Fit) # in signal windows: DS invariant mass 17.5 MeV MM*2 [3.872, 4.0] GeV2

  3. Mbc Distribution DS • [2.015, 2.067] GeV window used to select Tags • In a wider window [2.0, 2.08], the amounts of DS (peaking curve) and DS*(flat curve) are the same, and the efficiency ratio is 1 (test by MC 1.007  0.009). • i.e. N(DS) = N(DS*) 2.067 2.015 DS*

  4. C1 A1 B A2 C2 Idea • We look at DmS = m(DSg) - m(DS) • DS* (flat) peaks in DmS, DS (peaking in mbc) is flat • Divide in three regions • N(DS*) = A + B + C • Total number of tags we used is N(DS) + N(DS*) – C = 2 N(DS*) – C = 2(A+B) + C A=A1+A2 C=C1+C2 A, B, C are the # in the flat curve

  5. DS* signal DS signal Fake gamma BG Fake DS BG DmSDistributions from MC DS mass and MM*2 signal windows applied to get DmS distribution • Fitted by CB function, a and n obtained from double tag • Sideband subtraction to remove this background

  6. Double Tagging Signal DmS distribution (DS subtracted), to obtain a and n DS subtraction: Events in A - 0.12  B; 0.12 is ratio of # in A to B for DS signal (peak in mbc) MC DATA Single Tag in red Events / 2 MeV DmS (GeV) DmS (GeV)

  7. DATA Fit (I) • Fit to mass sideband subtracted distribution of all modes • Two backgrounds: DS signal (in blue) and fake g (in green) • Their shapes are fixed to MC, normalizations allowed to float A = 9446  476 B = 1760  164 C = 1202  102 Ntag = 2(A+B) + C = 23613  1012 Ntag = 23270  606 from the MM*2 fit

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