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Motivation and results


The frist plot shows the L/K ratio, the spectra without efficiency and G3/Fluka an FeedDown correction, we can found there is a bump at 4~8 GeV /c at 7 TeV

The second plot shows the raw lambda distribution, we can found there is a bump in 4~8 GeV /c at 7 TeV with leading cut, but no bump at 8 TeV.

This is the plot for of L/K ratio of 7TeV and 8TeV

Overlap Study of V0 daughters and jet track by DCA

From the former study, There is a bump in L/K ratio at 7 TeV, then maybe one reason is the Overlap of V0 daughters and jet track,

Select the hybrid track and V0 candidates

if(fTracks) { // fTracks is the list of Hybrid track.
const Int_t Ntracks = fTracks->GetEntries();
Int_t jetID=0;
for (Int_t iTracks = 0; iTracks < Ntracks; ++iTracks) {
AliAODTrack *t = static_cast<AliAODTrack*>(fTracks->At(iTracks));
if (t) continue;
if (t->IsGlobalConstrained()){ // constrained tracks have a changed ID
jetID = -1-jetID;
if(jetID!=pDauPos->GetID() && jetID!=pDauNeg->GetID()) continue; //pDauPos and pDauNeg( AliAODTrack) is the V0 daughters
Double_t d0z0[2],covd0z0[3];
}else{ cout<<"no hybird track founded"<<endl; return;}



The First plot show the overlap fraction dependent on hybrid track pt. and the second one show the overlap fraction dependent on V0 candidates.


This plot show the Overlap fraction of different kind of V0s , and the V0s are full selected. It means the V0s pass all the selection of cuts.











Efficiency comparison of 7 and 8 TeV

Jet pt>8 $GeV/c$


Spectra comparison

The following plots show the inclusive V0s production compared to matched to Jet V0s, and spectra normalized to MB event.


From these plot, we can found there is a gap between inclusive and matched V0s, and then, try to figure out the reason, why the high transverse momentum V0s not come from the jet.


The Eta acceptance

The V0 applied a eta cut with 0.75 =>Inclusive V0 acceptance

In this analysis the Jet apply a eta cut with TPC acceptance(0.9) - jet radius(0.4)= 0.5,

Matched V0s, the Jet applied another eta cut wiht V0 acceptance - jet radius =0.35,

the eta acceptance have a influnence on the matched V0s.

The Single V0s

suppose there is one V0s located at eta = 0.6,with a pT=10 GeV /c , and There is a jet reconstructed in 0.6, due to the eta acceptance on jet, we will lost this V0s,

Improved Spectra comparison

Due to the jet reconstructed only with the charged track, so when applied a jet pT cut will lost some V0s from jet.

1. After finding jets associate every V0 with the closest highest pT jet but still within R and sum the pT jet and pTV0 to use as the jet

2. applied the new jet pt cut

The following plots show the new and older matched V0s, and spectra normalized to MB0 event.


two hints : the 7TeV is higher than 8TeV, and there is a strange point in 7TeV near 6 GeV /c

From the plots, It shows this method contribute 10% to the matched V0 spectra

7GeV/c compare to 8GeV/c cut on Jet


Inclusive Compare to no pt cut on jet

Selected V0s in eta = 0.75 acceptance, and add the V0s pt to highest jet,

set the jet eta cut = 0.35,

selected V0s in 0.75 and In Jet range with Jet pt > 0.15 GeV /c.


The ratio is a little different between Kshort to Lambda about the matching

7GeV/c compare to no jet cut

Selected V0s in eta = 0.75 acceptance, and add the V0s pt to highest jet,

set the jet eta cut = 0.35,

selected V0s in 0.75 and In Jet range with Jet pt > 0.15 GeV /c and 7 GeV /c


In this plots , we can found the ratio between 7 GeV /c and 0.15 GeV /c cut is nearly 1 when pT high than 7GeV/c,

Compare the 0.15 GeV /c cut to Inclusive spectra, the spectra is little lower than the inclusive, since the

New Analysis without fiducial cut on jet

rerun the data sample without fiducial cut on jet,

1. Nearly 2.3\% $\Vzeros$ come from a event without jet,

2. Actrually, the jet clusters area in per event only take nearly 36.9% of the acceptance, since the multiplicity in pp collisions is small. After the jet with a minimum $\pT$ 0.15 $\GeVc$ to exclude the ghost jets. There are large fraction of vacant area (no jet), the $\Vzero$ located in this area will have a large possibility to be a Single $\Vzero$ -- no matched jet in acceptance <0.9

3. Applied fiducial and $\pT$ cuts to the combined clusters will introduce a acceptance cut on $\Vzeros$ ,the $\Vzeros$ located in the large $\eta$ will have a large possibiltiy to be a Single $\Vzeros$ -- have matched jet in acceptance <0.9 but no matched jet in acceptance <0.35

The frist case explained as small fraction of hard scattering processes in those events, The second case explained as small multiplicity in pp collisions. The third one explained as a fiducial cut

Discussion :


--lower $\pT$ $\Vzeros$, case one will hava a main effect on lower $\pT$ part, since soft process generated $\Vzeros$ will contribute a large fraction to lower $\pT$, the vacant area will have a uniform effect on lower part, the vacant area give a hint about the particles inside it are not generated by hard processes.

--high $\pT$ $\Vzeros$, case one should have a small effect on high $\pT$ part, the vacant area have a unknow effect on high $\pT$, but It should be less than the lower $\pT$, There are situations about the $\Vzeo$ with a $\pT$ higher than 7\~8 $GeVc$ should came from a jet, but 1.) the $\Vzero$ take a large fraction of the jet, and the residual particles only have a very small fraction of $\pT$, during the jet reconstrution step. this jet have been lost, 2.)the $\Vzero$ take a small fraction of jet, and the jet reconstucted with a long distance to $\Vzero$

\mrk{The third case will have the same effect on lower $\pT$ and higher $\pT$ if the $\Vzeros$ production have no dependence on $\eta$ acceptance}


This plot show the jet Area fraction in each event, and used to prove, There are some vacant area in each event, the average jet area in each event is nearly 0.369.


This three plots show the Single V0s and Matched V0s without any fiducial and pt cut distribution, It show that the Single V0s have a large possibility in low pT and nearly 50%, and become lower when v0 pt increase.



These plot shows the fiducial cut (eta cut ) on jet will cause nearly 50% of lost , and the fourth plot show the where is the 50%




At last is the Jet Pt cut, the red line, use the reconstruct jet pt as a threshold, the blue line use the jet and V0s pt as a threshold.



the eta dependence between inclusive and single V0s.

from the ratio between single V0s and inclusive V0s , there is a slope at the high eta range.


The counts for Lambda from 4-8 GeV /c(bump region) seems smooth,

The count at pt 10~12GeV/c of Lambda, It goes down to 20 counts, and its quite small ,and we already know due to the code bug, we overestimate the 22% of Good Event.

PS:Code Bug: if you found a "bad" event, copy the previous Good Event and overwritten it, and nearly 28% event. and 28% / (1+28%) =22%

After I fix the bug, It also show a abnormal bump in 4-8GeV/c, I think maybe I suppress the kshort production in jet.

Check the bump use LHC10d AND LHC10e bump exist

Change Jet R=0.4 and R=0.2, bump exist

Change V0 eta acceptance,bump exist

Leading Track Pt ,introduce bias. do not applied

Jet aea has a small effect on bump.

Select no pileup V0s, bum exist

Increase the Jet Pt , the bump exist and the statistics become lower. don't trust this results.

Maybe : 1. suppress the kshort production in jet.

2. V0s identification in 5-7GeV/c have mix, (exclude the miss V0s.) => Checked ,bump still exist

and I found the phi of V0s in jet is not uniform

After that I check the ratio about Single V0s and Matched V0s ,I fount the Matched Kshort and Lambda have slightly difference on high pT 85% and 94%, which will increase 10% of ratio.

and the eta cut nearly cut the same fraction of V0s,

the Jet PT ,will cut the different fraction of V0s, keep 50 % for kshort, and 70% for lambda. which will increase the 40% of the ratio

so How do I deal with it?

Jet Reconstruct with jet and V0 vectors

This two plot show the Inclusive and Single V0s ,and also include the matched V0s with eta 7GeV/c, and the new method with eta <0.35 and the pt of new jet(jet and V0s as input vectors) in 0/15GeV

The plot shows that the new method with pt>0 GeV. Its consistent with Inclusive V0s, and when you applied a pt>15GeV/c the results consistent with 7GeV/c


These two plots, asked by my supervisor, one is the Signal and background ratio for inclusive V0s ,Check the Note from LF, It's consistent

and the other one shows the result about the counts of InvMass in each Sigma bins, especially for the N sigma in 3-4 and 6-7.

-- YonghongZhang - 2015-06-29

Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng 7_8TeV.png r1 manage 54.4 K 2015-06-29 - 11:10 YonghongZhang  
PNGpng AntiLa.png r1 manage 28.9 K 2015-09-01 - 20:32 YonghongZhang  
PNGpng AntiLa07.png r2 r1 manage 31.3 K 2015-09-02 - 14:42 YonghongZhang  
PNGpng AntiLa0I.png r1 manage 30.3 K 2015-09-02 - 15:19 YonghongZhang  
PNGpng AntiLa78.png r1 manage 31.0 K 2015-09-01 - 21:20 YonghongZhang  
PNGpng Area_Fraction.png r1 manage 26.8 K 2015-09-03 - 23:07 YonghongZhang  
PNGpng Chi22_06_10.png r1 manage 82.3 K 2015-11-13 - 15:34 YonghongZhang  
PNGpng Chi22_0_1.png r1 manage 86.8 K 2015-11-13 - 15:34 YonghongZhang  
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PNGpng Chi22_3_6.png r1 manage 83.5 K 2015-11-13 - 15:34 YonghongZhang  
PNGpng Counts_Lambda_Kshort.png r1 manage 48.2 K 2015-09-08 - 01:12 YonghongZhang  
PNGpng Counts_Lambda_Kshort_Fixed.png r1 manage 47.6 K 2015-09-08 - 14:19 YonghongZhang  
PNGpng DCA2_0_1.png r1 manage 84.9 K 2015-11-13 - 15:34 YonghongZhang  
PNGpng DCA2_1_3.png r1 manage 78.5 K 2015-11-13 - 15:34 YonghongZhang  
PNGpng DCA2_3_6.png r1 manage 71.6 K 2015-11-13 - 15:34 YonghongZhang  
PNGpng DCA2_6_10.png r1 manage 71.8 K 2015-11-13 - 15:34 YonghongZhang  
PNGpng DCA_Overlap.png r1 manage 70.6 K 2015-11-11 - 18:33 YonghongZhang  
PNGpng DCA_hybrid_3Type_0_1.png r1 manage 102.1 K 2015-11-16 - 12:09 YonghongZhang  
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PNGpng DCA_hybrid_3Type_3_6.png r1 manage 86.3 K 2015-11-16 - 12:09 YonghongZhang  
PNGpng Efficincy78.png r1 manage 32.8 K 2015-09-16 - 14:53 YonghongZhang  
PNGpng Efficincy78_AntiLa.png r1 manage 33.0 K 2015-09-16 - 14:53 YonghongZhang  
PNGpng Efficincy78_Lambda.png r1 manage 34.4 K 2015-09-16 - 14:53 YonghongZhang  
PNGpng Eta_Cut_effect.png r2 r1 manage 28.5 K 2015-09-04 - 08:33 YonghongZhang  
PNGpng Eta_Cut_effect_7.png r1 manage 30.9 K 2015-09-04 - 08:33 YonghongZhang  
PNGpng Eta_Different_Pt.png r1 manage 49.0 K 2015-09-04 - 11:17 YonghongZhang  
PNGpng Eta_NoNorm_Kshort.png r1 manage 32.2 K 2015-09-04 - 11:17 YonghongZhang  
PNGpng Fiducial_Cut.png r1 manage 28.8 K 2015-09-03 - 23:07 YonghongZhang  
PNGpng Fiducial_Cut_AntiLambda.png r1 manage 28.8 K 2015-09-03 - 23:07 YonghongZhang  
PNGpng Fiducial_Cut_Lambda.png r1 manage 29.2 K 2015-09-03 - 23:07 YonghongZhang  
PNGpng Inclusive_AntiLambda.png r1 manage 33.6 K 2015-09-03 - 23:08 YonghongZhang  
PNGpng Inclusive_Kshort.png r1 manage 35.6 K 2015-09-03 - 23:08 YonghongZhang  
PNGpng Inclusive_Lambda.png r1 manage 33.8 K 2015-09-03 - 23:08 YonghongZhang  
PNGpng Jet_Inclusive_Comparision.png r1 manage 42.7 K 2015-09-01 - 20:34 YonghongZhang  
PNGpng Kshort.png r1 manage 26.9 K 2015-09-01 - 20:32 YonghongZhang  
PNGpng Kshort07.png r1 manage 30.4 K 2015-09-02 - 14:36 YonghongZhang  
PNGpng Kshort0I.png r1 manage 29.5 K 2015-09-02 - 15:19 YonghongZhang  
PNGpng Kshort78.png r1 manage 29.5 K 2015-09-01 - 21:20 YonghongZhang  
PNGpng Lambda.png r1 manage 26.5 K 2015-09-01 - 20:32 YonghongZhang  
PNGpng Lambda07.png r2 r1 manage 30.4 K 2015-09-02 - 14:40 YonghongZhang  
PNGpng Lambda0I.png r1 manage 28.7 K 2015-09-02 - 15:19 YonghongZhang  
PNGpng Lambda78.png r1 manage 29.5 K 2015-09-01 - 21:20 YonghongZhang  
PNGpng Last_AntiLambda.png r1 manage 38.2 K 2015-09-03 - 23:06 YonghongZhang  
PNGpng Last_Kshort.png r1 manage 38.3 K 2015-09-03 - 23:06 YonghongZhang  
PNGpng Last_Lambda.png r1 manage 37.9 K 2015-09-03 - 23:06 YonghongZhang  
PNGpng Leading_Track.png r2 r1 manage 36.5 K 2015-09-15 - 23:14 YonghongZhang  
PNGpng New_Comparison.png r1 manage 45.9 K 2015-09-01 - 20:32 YonghongZhang  
PNGpng New_Comparison07.png r1 manage 56.0 K 2015-09-02 - 14:36 YonghongZhang  
PNGpng New_Comparison0I.png r1 manage 51.2 K 2015-09-02 - 15:19 YonghongZhang  
PNGpng New_Comparison78.png r1 manage 55.8 K 2015-09-01 - 21:20 YonghongZhang  
PNGpng Nrows2_Hybrid_0_1.png r1 manage 103.0 K 2015-11-16 - 12:09 YonghongZhang  
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PNGpng Nsigma.png r1 manage 25.5 K 2015-09-10 - 16:36 YonghongZhang  
Unknown file formateps Overlap_Hybrid.eps r1 manage 9.9 K 2015-10-22 - 11:25 YonghongZhang  
Unknown file formateps Overlap_V0_daughters.eps r1 manage 10.3 K 2015-10-22 - 11:25 YonghongZhang  
PNGpng Overlap_V0daughters.png r1 manage 30.5 K 2015-10-22 - 11:31 YonghongZhang  
PNGpng Overlap_V0daughters1.png r1 manage 50.8 K 2015-10-22 - 12:38 YonghongZhang  
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PNGpng Ratio_AntiLa.png r1 manage 28.5 K 2015-09-01 - 20:34 YonghongZhang  
PNGpng Ratio_Kshort.png r1 manage 27.9 K 2015-09-01 - 20:34 YonghongZhang  
PNGpng Ratio_Lambda.png r1 manage 27.7 K 2015-09-01 - 20:34 YonghongZhang  
PNGpng SingalBackgroundRatio.png r1 manage 34.9 K 2015-09-10 - 16:11 YonghongZhang  
PNGpng Single_Kshort_eta.png r1 manage 29.6 K 2015-09-04 - 01:19 YonghongZhang  
PNGpng Single_Lambda_eta.png r1 manage 28.9 K 2015-09-04 - 01:19 YonghongZhang  
PNGpng Single_antiLambda_eta.png r1 manage 29.3 K 2015-09-04 - 01:19 YonghongZhang  
PNGpng TPCNRows2_0_1.png r1 manage 72.6 K 2015-11-13 - 15:35 YonghongZhang  
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PNGpng TPCRatio_0_1.png r1 manage 78.1 K 2015-11-13 - 15:35 YonghongZhang  
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PNGpng TPCRatio_3_6.png r1 manage 78.8 K 2015-11-13 - 15:35 YonghongZhang  
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PNGpng loose_cut_spectra.png r2 r1 manage 62.1 K 2015-11-16 - 14:44 YonghongZhang  
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