😀😄🧑‍💻😺

basf2 version: release-06-01-12

The distribution of different variables

• kaon selection
  • kaonID>0.2
• $\pi^0$ selection
  • gamma
    • clusterNHits > 1.5 and 0.2967 < clusterTheta < 2.6180
    • gamma in different range:
      • clusterReg=1: E>0.1 GeV
      • clusterReg=2: E>0.06 GeV
      • clusterReg=3: E>0.1 GeV
    • cluster shape: cluseterE9E21>0.9
  • $\pi^0$
    • the mass window used now: $0.111 \lt M_{\pi_{0}} \lt 0.153 \rm~GeV/c^2$, invariant mass between m_mean +- 3sigma.
    • $|\cos\theta_{helicity}|&lt;0.95$
• $B^0$
  • vertex fit
  • delta E
  • Mbc

We used two variables to select the best $B^0$ candidate:

• $\pi^0$ mass constrained chi2
• chiProb of $B^0$ vertex fit chi2

Selection strategy:

• Firstly, we select the $B^0$ candidate whose $\pi^0$ with lowest chi2.
• If there are still multi $B^0$ candidate, we select the $B^0$ candidate with higher chiProb.

MC sample: MC 15 run-indepent qqbar sample

We used FBDT to do continuum suppression, which is introduced in the basf2 website.

We used the MVA package in basf2 to mix signal and background sample, and evaluate the result of training.

The cut of continuum suppression output: $ContProb &lt; 0.4$.

To do fit process, transform this variable: $ContProb_{TRAN} = log(\frac{ContProb-0}{0.4-ContProb})$.

We also used the method indroduced in basf2 sofeware website

We add a cut on the output of flavor tag: $q \cdot r_{FBDT} &lt; 0.89$

Following the note from belle, we will remove the background from D meson decay, and do the fit.

But in the B2Kpipi0 analysis of BARBAR experiment, they do not remove the background from D, and considered this source of background in amplitude fit.