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# System prepended metadata

title: Primary Particle (**p.p.**) Selection For All Sample

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# Primary Particle (**p.p.**) Selection For All Sample
> Definition of primary particle 
> 
|  | Version 1 | Version 2 |
|---|---|----|
| Belle nominal p.p. sel | (gen) $V_{r} < 1 cm$, (reco) $V_{r} < 1 cm$ | (gen) $c_{\tau} < 1 cm$, (reco) $V_{r} < 1 cm$ |
| systematics (p.p. sel)| vary $V_{r}$ cut | (gen) $V_{r} < 1 cm$, (reco) $V_{r} < 1 cm$ |
| efficiency corr | $\frac{\text{reco: }V_{r} < 1 cm}{\text{gen: } c_{\tau} < 1 cm}$  | $\frac{\text{reco: }V_{r} < 1 cm}{\text{gen: } c_{\tau} < 1 cm}$ |
| systematics (eff corr) | still vary $V_{r}$ cut, or change to $\frac{\text{reco: }V_{r} < 1 cm}{\text{gen: } V_{r} < 1 cm}$ | (Same as nominal: $\frac{\text{reco: }V_{r} < 1 cm}{\text{gen: } c_{\tau} < 1 cm}$) |
| on generator sample | not sure | $c_{\tau} < 1 cm$ | 
| description (?) | We can only cut on Vr in reco level, therefore we do the same cut in reco and gen in order to eliminate the scaling problem. But we still have to use ctau definition to get the efficiency correction.| 1. Though in reco level we have limit and can only cut on Vr, (we want convince that) after efficinecy correction, it should be able to match back to the generator primary particle set ($c_{\tau}$ definition). <p> 2. Need to first check the **nominal** definition work (by Y(Δɸ) ratio plot)  |

