---
# System prepended metadata

title: The annoying gap problem

---

# The annoying gap problem

### In the dropbox link: https://www.dropbox.com/sh/75arjmb0wu07db6/AAAvUjPOWP9PL4g7c93JeAMpa?dl=0
+ Correct ptl weight is original one: (eff/MR/sigMix: nTrk6)
    > having gap in onres thrust

    |  beam | thrust |
    | --- | --- |
    | ![](https://i.imgur.com/zOY8Sm6.png) | ![](https://i.imgur.com/J4zm9Tz.png) |    

+ FINALCHECK_full (eff/MR_ntrk6  sigMix_ntrk12)
+ FINALCHECK_full (MR_ntrk6 eff/sigMix_ntrk12)
    > having gap in long range onres beam

    |  beam | thrust |
    | --- | --- |
    | ![](https://i.imgur.com/YY70oq0.png) | ![](https://i.imgur.com/sRHkOHh.png) |

    (* ntrk12 onres are shown)
### The observation can be summarized in below
+ The main effect is on the efficiency correction actually. When using full ntrk12 to correct, beam's long range would start to have gap, but thrust would get closure.
+ NB: tgen in those plots are almost no change, this can be compared in 1st, 2nd folders. (sigMix is not the culprit)
    + Beam:
        ![](https://i.imgur.com/WM380ix.png)
    + Thrust:
        ![](https://i.imgur.com/FoZ4m9e.png)

And why the bizarre thing happens:
I think it is because the efficiency correction factor is working good on the signal function, but for the background function, it will tend to **over correct(?)** in some region. And most annoying, the over correct effect happen in different region in beam & thrust ana.

Below I show the ratio of reco/tgen:

|| sig | bkg |
|---|---|---|
| beam |![](https://i.imgur.com/j7fIqSG.png) | ![](https://i.imgur.com/ycEuIvb.png) |
| thrust | ![](https://i.imgur.com/XymBb7u.png) | ![](https://i.imgur.com/Tj7jCEw.png) |

```cpp
TFile *_file0 = TFile::Open("BELLE_reco_ntrk12_onres.root")
TFile *_file1 = TFile::Open("BELLE_tgen_ntrk12_onres.root")
_file0->cd()
TH2D* signal2PC_0_14_999_0_0_tgen = (TH2D*) _file1->Get("signal2PC_0_14_999_0_0")
TH2D* bkgrnd2PC_0_14_999_0_0_tgen = (TH2D*) _file1->Get("bkgrnd2PC_0_14_999_0_0")
signal2PC_0_14_999_0_0->Divide(signal2PC_0_14_999_0_0_tgen)
signal2PC_0_14_999_0_0->Draw()
signal2PC_0_14_999_0_0->Draw("LEGO")
bkgrnd2PC_0_14_999_0_0->Divide(bkgrnd2PC_0_14_999_0_0_tgen)
bkgrnd2PC_0_14_999_0_0->Draw("LEGO")
```
