I tested KFparticle code on real data for V0's decay : K0s and lambda.

• correct mass of daughters were used :(pi,pi) for K0s ad (p,pi) for lambda
• the first track is assumed to be a proton(+)
• the second track loop is also requiring Q(track1)*Q(track2)<0
• There is a cut before filling the tree for the nSigmadEdx (cut |nSigma|<3) for both daughters to select good piD track

I tested on day 112,113 with the following cuts :

static const Double_t pTCut = 0.3; // transverse momentum cut
static const Double_t mKpiMin = 0.8; // min mass of (Kpi) association
static const Double_t mKpiMax = 1.5; // max mass of (Kpi) association
static const Double_t DcaCut = 3; // single track DCA to PV
static const Int_t TpcCut = 20; // TPC hits fitted
static const Double_t TrackLengthCut = 40; // min value for dEdxTrackLength
static const Int_t SiCut = 2; // (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 =-0.8; // min track pseudorapidity
static const Double_t EtaMax = 0.8; // 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 = 0.1; // lower limit for the probability of KF particle
static const Int_t writeHisto = 1; // flag to write histos

I also re-tested on day 114-119 with the following cuts :

static const Double_t pTCut = 0.2; // transverse momentum cut
static const Double_t mKpiMin = 0.8; // min mass of (Kpi) association
static const Double_t mKpiMax = 1.5; // max mass of (Kpi) association
static const Double_t DcaCut = 4; // single track DCA to PV
static const Int_t TpcCut = 20; // TPC hits fitted
static const Double_t TrackLengthCut = 40; // min value for dEdxTrackLength
static const Int_t SiCut = 2; // (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 = 0.1; // lower limit for the probability of KF particle
static const Int_t writeHisto = 1; // flag to write histos

The pT of dauhgters is relaxed from.3 to .2 and the max DCAXY of tracks increase to 4 cm.

The reason comes from the following cuts used by G. Vasconselo (Col. Meeting '10) :

Cuts set 1 :

Cuts set 2 :

We see that the release of the daughters pT increase the background

Now if I apply the cut pT>.3 for the set 2 :

The background to the left of the lambda inv. mass gets back to 'linear'