Bhabha veto                                                                        Kenji Hamano

Last modified : Sep 21, 2005                                              Back to Home Back to privious page

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Radiative Bhabha veto

1. Define the following variables
      nTrk = number of GoodTracksLoose
      nGam = number of CalorNeutral with E_gamma > 80 MeV
      nConv = number of identfied gamma->e+ e- pairs
         = number of gammaConversionDefault
      nTrk2 = nTrk - 2*nConv
      nGam2 = nGam + nConv
      mult2 = nTrk2 + nGam2/2
2. The Radiative Bhabha veto then requires
      nTrk >= 4 and mult2 >= 5
reference


R16b skims Run3 was used.
Data luminosities:

	luminosity	# events	# files
OnPeak	30.630 fb-1	17527801/438622047	351
OffPeak	2.394	659867/31451100	7

MC luminosity is adjusted to 30 fb-1

MC mode	cross section	selection rates	# events	# files
BpBm (1235)	0.525e6 fb	23854196/86492000	4343795	87
B0B0bar (1237)	0.525e6	17081965/61158000	4399112	88
ccbar (1005)	1.30e6	6127861/57700000	4141882	83
uds (998)	2.09e6	5639210/124040000	2850520	58
tautau (3429)	0.94e6	544465/69852000	219806	5

Example of calculatin of # events:
      BpBm: 0.525e6*30*23854196/86492000 = 4343795


D mass plots:
Without Bhabha veto
D0 mass plots
Dch mass plots
With Bhabha veto
D0 mass plots withBhabha veto
Dch mass plots withBhabha veto

After Bhabha veto, the agreement between OnPeak data and MC improved.
D0->Kpi mode agreeds quite well.
Dch->Kpipi mode does not agree well, but it looks like only combinatrial background disagree. So, there should be no problem after D mass sideband subtraction.

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