05/17 :
I run 2k events from Yifei's thick production :
/star/u/yfzhang/lbl/hft/upgr15/cd1/production/thick/events/StEvent/pileup0/
/star/u/yfzhang/lbl/hft/upgr15/cd1/production/thick/events/StEvent/pileup1/

I run Mukpi using KFParticle for the D0.

The list of cuts are below :
static const Double_t pTCut = .5; // transverse momentum cut
static const Double_t mKpipiMin = 1.2; // min mass of (Kpi) association
static const Double_t mKpipiMax = 2.2; // max mass of (Kpi) association
static const Double_t DcaCut = .5; // single track DCA to PV
static const Int_t TpcCut = 15; // TPC hits fitted
static const Double_t TrackLengthCut = 40; // min value for dEdxTrackLength
static const Int_t SiCut = 4; // (SVT+SSD) hits fitted
static const Float_t SigmaPionCut = 2.5; // ndEdx for pion
static const Float_t SigmaKaonCut = 2.5; // ndEdx for kaon
static const Double_t EtaMin =-1.0; // min track pseudorapidity
static const Double_t EtaMax = 1.0; // max track pseudorapidity
static const Double_t zcut = 10; // zvertex cut
static const Double_t PrimZResCut = 0.02; // zvertex cut
static const Double_t sigmaTCut = 2.0; // ratio single track dca/sigmaDca
static const Double_t ProbKFCut = 0.01;
static const Int_t writeHisto = 0; // flag to write histos

The main changes are the silicon hits number cuts (3-->4) and the cuts used for the PID (3-->2.5)

 

The plots above show the decay length significance ; we see the positive contribution is over the negative contribution for Sl > 7

Applying this cut, I get the following invariant mass :

invariant mass D0 (left : before cut ; right : after Sl>7 cut)

From this plot I obtain :

significance calculated as in HFT proposal : signi = sig / sqrt(sig+background) taken in 1.84 < Minv < 1.92

The background is estimated with a pol1 function in the inv. mass range [1.7;2.0]

 signal = 1156 back = 744.049 s/b =1.55366 significance = 12.1162

 

• cuts study (1) : function of dca pair tracks

The following plot show the inv. mass for

1.  first row : dca pair tracks < 200 microns ;from left to right : Sl >5 : Sl> 10 ; Sl >15
2.  first row : dca pair tracks < 100 microns ;from left to right : Sl >5 : Sl> 10 ; Sl >15

and the respected signal, noise values :

 signal = 1158 back = 734.007 s/b =1.57764 significance = 12.4596

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 signal = 169 back = 30.3403 s/b =5.57015 significance = 10.6661

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 signal = 69 back = 12.2763 s/b =5.6206 significance = 6.82874

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 signal = 1127 back = 705.268 s/b =1.59797 significance = 12.5624

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 signal = 165 back = 29.4309 s/b =5.60635 significance = 10.554

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 signal = 68 back = 12.1133 s/b =5.61366 significance = 6.77726

 

•  cuts study (2) : function of cos(Theta_{opening})

Theta_{opening} is the angle formed by the vector that joined the primary vertex and the secondary vertex WITH the D0 momentum vector

 

 signal = 391 back = 113.471 s/b =3.44581 significance = 14.0352

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 signal = 370 back = 99.0022 s/b =3.73729 significance = 14.0885

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 signal = 305 back = 69.807 s/b =4.36919 significance = 13.4671

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 signal = 380 back = 110.17 s/b =3.44922 significance = 13.842

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 signal = 360 back = 96.1179 s/b =3.7454 significance = 13.9078

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 signal = 300 back = 68.2389 s/b =4.39632 significance = 13.3807

 

• cuts study (3) : function of pT (DO)

the plots correspond to (from left to right, top to bottom)

1. pT  < 1
2. 1    < pT < 1.5
3. 1.5 < pT < 2.0
4. 2.0 < pT < 2.5
5. 2.5 < pT < 3.0
6. pT>3

 signal = 94 back = 24.423 s/b =3.84883 significance = 7.17632

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 signal = 80 back = 15.3594 s/b =5.20855 significance = 7.22704

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 signal = 67 back = 11.4739 s/b =5.83936 significance = 6.7836

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 signal = 46 back = 12.1538 s/b =3.78482 significance = 4.99035

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 signal = 36 back = 10.4986 s/b =3.42902 significance = 4.25023

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 signal = 85 back = 52.0421 s/b =1.63329 significance = 3.57478

 

• single DCA characteristics

I've looked at the Kaon track candidates for 2 samples :

1. no cut
2. DCAT<0.01 && (Sl>7)

The later condition is supposed (from the previous plot) to select good D0 candidates.

The idea is to see if they are difference between tracks from the background and tracks from signal

Each of the following plots are : left = no cut ; right = cut

 

1. DCAXY distribution

 

     2. DCAXY vs 1/(beta*momentum)

For the calculation of the beta factor, I've assumed the kaon mass (= .493MeV/c)

 

     3. FitSlicesY() of the previous panel = DCAXY resolution

    4. DcaXY / sigmaDCAXY distribution

note : the error on DCAXY - sigmaDCAXY - is coming fro the covariance matrix.