Line: 1 to 1  

PDF Systematics Study at HU Berlin  
Line: 15 to 15  
Partonic distribution functions (PDFs) along with partonparton interaction cross sections determine hadronic cross sections of processes in protonproton collisions according to the formula,
%\[  
Changed:  
< <  \sigma^{pp\rightarrow X,Y,...}(...)=\sum_{i_A,j_B=q(g),\bar{q}(g)} \int dx_1dx_2 f^A_i(x_1,Q^2) f^B_j(x_2,Q^2)\sigma^{i_A j_B \rightarrow X,Y,...}(x_1,x_2,\alpha_s,...).  
> >  \sigma^{pp\rightarrow X,Y,...}(...)=\sum_{i_A,j_B=q(g),\bar{q}(g)} \int dx_1dx_2 f^A_i(fl_1,x_1,Q^2) f^B_j(fl_2,x_2,Q^2)\sigma^{i_A j_B \rightarrow X,Y,...}(x_1,x_2,\alpha_s,...).  
\]%  
Changed:  
< <  where is a partonparton cross section induced by th and th partons interaction in incoming protons A and B, respectively, and are th and th parton distribution functions (PDF) in the Ath and Bth protons, correspondingly, and and momentum fraction of each interacting parton in incoming nucleons.  
> >  where is a partonparton cross section induced by th and th partons interaction in incoming protons A and B, respectively, and are th and th parton distribution functions (PDF) in the Ath and Bth protons, correspondingly, with and to be the flavor of the interacting partons, and momentum fraction of each interacting parton in incoming nucleons.  
Since the PDFs are not calculable from the first principles but are determined experimentally with some errors (which come from experimental measurements, theoretical models used to extract PDFs etc.), inclusion of any PDF into the cross section calculation introduces an additional systematic error. Thus, in this study we want to estimate the effect of a PDF change in the Pythia6 generator (used to produce signal samples) on a signal event selection efficiency.  
Line: 35 to 35  
\epsilon^1 = \frac{N^1_{cuts}}{N^1_{gen}}, \]%  
Changed:  
< <  where is the total number of events generated be the generator before applying any cut and is the number of selected signal events after applying all selection criteria. If the event filter of an efficiency is applied on the generator, then the event selection efficiency will look like  
> >  where is the total number of events generated by the generator before applying any cut and is the number of selected signal events after applying all selection criteria. If an event filter of an efficiency is applied on the generator, then the event selection efficiency will look like  
%\[ \epsilon^1 = \epsilon^1_{gen} \frac{N^1_{cuts}}{N^1_{gen}}.  
Line: 44 to 44  
Now, had these events been generated with the same generator but using another PDF (call it PDF2) then the relative probability of producing a particular event as a result of an interaction of two partons with the same flavor, momentum fraction and energy scale, as in the case of using the PDF1, will be defined, as it is obvious from the formula above, by the relative PDFs weight, , defined as
%\[  
Changed:  
< <  w^i=\frac{f_{PDF2}(f_1,x_1,Q^2)}{f_{PDF1}(f_1,x_1,Q^2)} \times \frac{f_{PDF2}(f_2,x_2,Q^2)}{f_{PDF1}(f_2,x_2,Q^2)}.  
> >  w^i=\frac{f_{PDF2}(fl_1,x_1,Q^2)}{f_{PDF1}(fl_1,x_1,Q^2)} \times \frac{f_{PDF2}(fl_2,x_2,Q^2)}{f_{PDF1}(fl_2,x_2,Q^2)}.  
\]%
Now the and for the PDF2 will be defined as and and the event selection efficiency would look like  
Line: 55 to 55  
The generator filter efficiencies and have to be determined by separate runs of the generator with the both PDFs, PDF1 and PDF2.  
Changed:  
< <  So, the role of the PDF reweighting tool is to extract the PDF info, and , from the available sample(s), extract the new PDF info, and , from a new PDF set (one can go here for that http://lhapdf.hepforge.org/pdfsets ), calculate the relative event weight, and apply this weight to every single event in the sample to be reweighted. For this purpose one can use the tools mentioned below.  
> >  So, the role of the PDF reweighting tool is to:
Applying of the weights to the events in the sample(s) to be reweighted is usually not done withing the PDFreweighting tool, it is a business of the person who does the reweighting. From the technical point of view there are three (ATLAS??) tools available to implement PDFreweighting method, which can be found following the links:
Some additional relevant info on the reweighing method you can get from In our analysis for PDF reweighting we use TopPdfUncertainty tool from the Top group.  
Direct method 
Line: 1 to 1  

PDF Systematics Study at HU Berlin  
Line: 7 to 7  
This page is under construction  
Changed:  
< <  This Twikipage is to give some more or less detailed infotmation about the analysis to estimate systematics uncerntainties coming from a choice of parton distribution functions (PDF) in the Pythia6 generator to produce signal samples in an analysis to search for 4th generation SMlike heavy quarks, b' and t'.  
> >  This Twikipage is to give some more or less detailed information about the analysis to estimate systematic uncertainties coming from a choice of parton distribution functions (PDF) in the Pythia6 generator to produce signal samples in an analysis to search for 4th generation SMlike heavy quarks, b' and t'.  
Introduction  
Line: 18 to 18  
\sigma^{pp\rightarrow X,Y,...}(...)=\sum_{i_A,j_B=q(g),\bar{q}(g)} \int dx_1dx_2 f^A_i(x_1,Q^2) f^B_j(x_2,Q^2)\sigma^{i_A j_B \rightarrow X,Y,...}(x_1,x_2,\alpha_s,...). \]%  
Changed:  
< <  where is a partonparton cross section induced by th and th partons interaction in incoming protos A and B, respectively, and are th and th parton distribution functions (PDF) in the Ath and Bth protons, correspondingly, and and momentum fraction of each interacting parton in incoming nucleons.  
> >  where is a partonparton cross section induced by th and th partons interaction in incoming protons A and B, respectively, and are th and th parton distribution functions (PDF) in the Ath and Bth protons, correspondingly, and and momentum fraction of each interacting parton in incoming nucleons.  
Since the PDFs are not calculable from the first principles but are determined experimentally with some errors (which come from experimental measurements, theoretical models used to extract PDFs etc.), inclusion of any PDF into the cross section calculation introduces an additional systematic error. Thus, in this study we want to estimate the effect of a PDF change in the Pythia6 generator (used to produce signal samples) on a signal event selection efficiency.
Analysis methods  
Changed:  
< <  Our analysis to estimate PDF uncerntainties is done using two different methods, reweighting method and a direct method. In the following shortly the idea of both methods is outlined.  
> >  Our analysis to estimate PDF uncertainties is done using two different methods, reweighting method and a direct method. In the following shortly the idea of both methods is outlined.  
Reweighting method  
Line: 35 to 35  
\epsilon^1 = \frac{N^1_{cuts}}{N^1_{gen}}, \]%  
Changed:  
< <  where is the total number of events generated be the generator before applying any cut and is the number of selected signal events after applying all selection criteria. If the event filter of an efficiency is applied on the generator, then the event selection efficienly will look like  
> >  where is the total number of events generated be the generator before applying any cut and is the number of selected signal events after applying all selection criteria. If the event filter of an efficiency is applied on the generator, then the event selection efficiency will look like  
%\[  
Changed:  
< <  \epsilon^1 = \epsilon^1_{gen} \frac{N^1_{cuts}}{N^1_{gen}},  
> >  \epsilon^1 = \epsilon^1_{gen} \frac{N^1_{cuts}}{N^1_{gen}}.  
\]%  
Changed:  
< <  Now, had these events been generated with the same generator but using another PDF (call it PDF2) then the relativer probabality of producing a particular event as a result of an interaction of two partons with the same flavor, momentum fraction and energy scale, as in the case of using the PDF1, will be defined, as it is obvious from the formula above, by the relative PDFs weight, , defined as  
> >  Now, had these events been generated with the same generator but using another PDF (call it PDF2) then the relative probability of producing a particular event as a result of an interaction of two partons with the same flavor, momentum fraction and energy scale, as in the case of using the PDF1, will be defined, as it is obvious from the formula above, by the relative PDFs weight, , defined as  
%\[ w^i=\frac{f_{PDF2}(f_1,x_1,Q^2)}{f_{PDF1}(f_1,x_1,Q^2)} \times \frac{f_{PDF2}(f_2,x_2,Q^2)}{f_{PDF1}(f_2,x_2,Q^2)}.  
Line: 50 to 50  
Now the and for the PDF2 will be defined as and and the event selection efficiency would look like
%\[  
Changed:  
< <  \epsilon^2 = \epsilon^2_{gen} \frac{ \sum^{N^1_{cuts}}_{i=1}w^i }{ \sum^{N^1_{gen}}_{i=1}w^i}.  
> >  \epsilon^2 = \epsilon^2_{gen} \frac{N^2_{cuts}}{N^2_{gen}} = \epsilon^2_{gen} \frac{ \sum^{N^1_{cuts}}_{i=1}w^i }{ \sum^{N^1_{gen}}_{i=1}w^i}.  
\]%  
Changed:  
< <  The generator filter efficiences and have to be determined by separate runs of the generator with the both PDFs, PDF1 and PDF2.  
> >  The generator filter efficiencies and have to be determined by separate runs of the generator with the both PDFs, PDF1 and PDF2.  
So, the role of the PDF reweighting tool is to extract the PDF info, and , from the available sample(s), extract the new PDF info, and , from a new PDF set (one can go here for that http://lhapdf.hepforge.org/pdfsets ), calculate the relative event weight, and apply this weight to every single event in the sample to be reweighted. For this purpose one can use the tools mentioned below.
Direct methodIn the Direct method one has to generate new signal event samples including into a generator not only other PDF(s) (different from the default one) but also tunes corresponding to these new PDF(s) to account for Underlying Event(UE), which in generator in general depends on the PDF used to run the generator and after to go through the whole chain of the sample production, i.e. simulation, digitization, reconstruction and production of D3PDs for the final analysis.  
Changed:  
< <  The advantige of this method over reweighting is that in this case one counts for the possible effects coming from UE, in contrast to the previous method. On the other hand, the main disadvantige of this method is, it's time and cpu consuming.  
> >  The advantage of this method over reweighting is that in this case one counts for the possible effects coming from UE, in contrast to the previous method. On the other hand, the main disadvantage of this method is, it's time and cpu consuming.  
PDFs and tunes  
Changed:  
< <  This PDF systematic uncerntainty study is done using MC samples produced within MC11b ATLAS production setup. In this production MC samples generated with Pythia6 generator have been obtained using MRST LO** (20651) as the default PDF along with its recent "ATLAS Underlying Event Tune 2B" (AUET2B) tune.  
> >  This PDF systematic uncertainty study is done using MC samples produced within MC11b ATLAS production setup. In this production MC samples generated with Pythia6 generator have been obtained using MRST LO** (20651) as the default PDF along with its recent "ATLAS Underlying Event Tune 2B" (AUET2B) tune.  
In the both methods outlined above we have used the following PDFs to estimate the uncerntainty:
 
Line: 79 to 79  
Pythia6 parameters tuned in the the AUET2B tuning campain are as follows:  
Changed:  
< <  Paremeters PARP(62), PARP(64) and PARP(72) are responsible for shower parameterization, namely,  
> >  Paremeters PARP(62), PARP(64) and PARP(72) are responsible for shower parametrization, namely,  
 
Line: 109 to 109  
Samples:  
Changed:  
< <  The following samples have been used to get default efficiences (i.e. with default MRST LO** PDF) for both direct and reweighting methods as well as used in the reweighting method to get shifted efficiences:  
> >  The following samples have been used to get default efficiencies (i.e. with default MRST LO** PDF) for both direct and reweighting methods as well as used in the reweighting method to get shifted efficiencies:  
Mass point of 400 GeV:
 
Line: 129 to 129  
To implement this method we use default signal heavy b' ?? samples to reweight them.  
Changed:  
< <  From the technical point of view there are three ATLAS? tools available to implement PDFreweighting methog, which can be found following the links:  
> >  From the technical point of view there are three ATLAS? tools available to implement PDFreweighting method, which can be found following the links:  
Line: 1 to 1  

PDF Systematics Study at HU Berlin
<!optional>  
Changed:  
< <  This page is under construction and contains no useful information yet  
> >  This page is under construction  
This Twikipage is to give some more or less detailed infotmation about the analysis to estimate systematics uncerntainties coming from a choice of parton distribution functions (PDF) in the Pythia6 generator to produce signal samples in an analysis to search for 4th generation SMlike heavy quarks, b' and t'.
Introduction  
Changed:  
< <  Partonic distribution functions (PDFs) along with partonparton interaction cross sections determine cross sections of processes in protonproton collisions. Since the PDFs are not calculable from the first principles but are determined experimentally with some errors (which come from experimental measurements, theoretical models used to extract PDFs etc.), inclusion of any PDF into the cross section calculation introduces an additional systematic error. Thus, in this study we want to estimate the effect of a PDF change in the Pythia6 generator to produce signal samples on a signal event selection efficiency.  
> >  Partonic distribution functions (PDFs) along with partonparton interaction cross sections determine hadronic cross sections of processes in protonproton collisions according to the formula,
where is a partonparton cross section induced by th and th partons interaction in incoming protos A and B, respectively, and are th and th parton distribution functions (PDF) in the Ath and Bth protons, correspondingly, and and momentum fraction of each interacting parton in incoming nucleons. Since the PDFs are not calculable from the first principles but are determined experimentally with some errors (which come from experimental measurements, theoretical models used to extract PDFs etc.), inclusion of any PDF into the cross section calculation introduces an additional systematic error. Thus, in this study we want to estimate the effect of a PDF change in the Pythia6 generator (used to produce signal samples) on a signal event selection efficiency.  
Analysis methods  
Line: 21 to 29  
Reweighting method  
Changed:  
< <  Suppose, we have MC signal events generated using PDF1. Interacting partons in incoming protons (antiprotons) are characterized by flavours, flav1, flav2, momentum fractions, , , and an energy scale . The PDF reweighting technique consists of evaluating, on the eventbyevent basis, the probability of picking up the same flavoured partons with the same momentum fractions, , , according to a second PDF set, PDF2, at the same energy scale , then evaluating the following ratio  
> >  Suppose, we have MC signal events generated using PDF1 in a generator. If we apply selection cuts to these events, then the signal event selection efficiency, , by definition is,
where is the total number of events generated be the generator before applying any cut and is the number of selected signal events after applying all selection criteria. If the event filter of an efficiency is applied on the generator, then the event selection efficienly will look like  
%\[  
Changed:  
< <  EW=\frac{f_{PDF2}(f_1,x_1,Q^2)}{f_{PDF1}(f_1,x_1,Q^2)} \times \frac{f_{PDF2}(f_2,x_2,Q^2)}{f_{PDF1}(f_2,x_2,Q^2)}  
> >  \epsilon^1 = \epsilon^1_{gen} \frac{N^1_{cuts}}{N^1_{gen}},  
\]%  
Changed:  
< <  After the EventWeight, , is applied on MC events generated with PDF1 and then they will effectively be distributed according to PDF2.  
> >  Now, had these events been generated with the same generator but using another PDF (call it PDF2) then the relativer probabality of producing a particular event as a result of an interaction of two partons with the same flavor, momentum fraction and energy scale, as in the case of using the PDF1, will be defined, as it is obvious from the formula above, by the relative PDFs weight, , defined as  
Added:  
> >  
Added:  
> >  Now the and for the PDF2 will be defined as and and the event selection efficiency would look like
 
Added:  
> >  The generator filter efficiences and have to be determined by separate runs of the generator with the both PDFs, PDF1 and PDF2.  
Added:  
> >  So, the role of the PDF reweighting tool is to extract the PDF info, and , from the available sample(s), extract the new PDF info, and , from a new PDF set (one can go here for that http://lhapdf.hepforge.org/pdfsets ), calculate the relative event weight, and apply this weight to every single event in the sample to be reweighted. For this purpose one can use the tools mentioned below.  
Direct method 
Line: 1 to 1  

PDF Systematics Study at HU Berlin 
Line: 1 to 1  

PDF Systematics Study at HU Berlin  
Line: 72 to 72  
Added:  
> >  Sample Production  
Changed:  
< <  Sample Production
MC11bWithin the official production campain the 4th generation quark samples (b' and t') are produced using the tags combination  e972_s1310_s1300_r3043_r2993_p834. Thus, to perform this study samples have been produced privately and following official production setup as closely as possible.  
> >  MC signal samples (4th generation b' quark pair production) used in this study have been produced with ATLAS MC production setup MC11c using the tags combination  e972_s1310_s1300_r3043_r2993_p834. The samples have been produced privately and following official production instructions.  
Athena releases used for different production steps are the following:  
Changed:  
< < 
 
> >  
 
Changed:  
< <  For more information on the MC11b production setup have a look at the following links:  
> >  For more information on the MC11 production setup have a look at the link.  
Changed:  
< <  MC11c  
> >  Samples:  
Changed:  
< <  The difference in MC11b and MC11c productions mainly comes from the usage of Pythia6 pileup setup in MC11c instead of Pythia8 in MC11b. In terms of production setup details the difference comes in Digitization and Reconst steps. The Athena release used for this step is:
 
> >  The following samples have been used to get default efficiences (i.e. with default MRST LO** PDF) for both direct and reweighting methods as well as used in the reweighting method to get shifted efficiences:  
Changed:  
< <  For details on the MC11c production, go to  
> >  Mass point of 400 GeV:
 
Changed:  
< <  Inclusion of the PDFs into a JO file  
> >  Next samples have been produced with nondefault PDFs listed above and used to extract efficiency shifts for the corresponding PDFs for the mass point of b' of 500 GeV:
 
Added:  
> >  Extraction of efficiencies  
Changed:  
< <  Reweighting method  
> >  Reweighting method  
To implement this method we use default signal heavy b' ?? samples to reweight them.  
Line: 118 to 118  
In our analysis for PDF reweighting we use TopPdfUncertainty tool from the Top group.  
Changed:  
< <  Samples used for the reweighting are:
MC11b: mc11_7TeV.119314.Pythia_d4PairToWtWtbar_400_1LepIncl.merge.NTUP_TOP.e972_s1310_s1300_r3043_r2993_p834
MC11c:
Direct method
Validation of samples
Extracting efficiencies
Reweighting method
Direct method
Discussion of the results
HowtosTo read more on the subject, go to References. Example:You may also directly contact P.Uwer to get the package.
b'b'bar>ttbar+WW (Panda link) t't'bar > WW+qqbar (q=b',d,s,b) (Panda link) t't'bar > WW+qqbar (q=d,s,b) (Panda link)
 
> >  Direct method  
Deleted:  
< <  Below Top quark pair production cross sections in protonproton (pp) and protonantiproton (ppb) collisions calculated by this tool (in red) are compared with ones obtained from arXiv/hepph/0804.2800 (in blue). PDF errors are calculated in the asymmetric way. Cross sections are given in picobarns (pb).  
Changed:  
< < 
 
> >  Discussion of the results 
Line: 1 to 1  

PDF Systematics Study at HU Berlin  
Line: 144 to 144  
To read more on the subject, go to References.  
Changed:  
< <  Example:You may also directly contact P.Uwer or S.Moch to get the package.  
> >  Example:You may also directly contact P.Uwer to get the package.
b'b'bar>ttbar+WW (Panda link) t't'bar > WW+qqbar (q=b',d,s,b) (Panda link) t't'bar > WW+qqbar (q=d,s,b) (Panda link)
 
Line: 1 to 1  

PDF Systematics Study at HU Berlin  
Line: 112 to 112  
Changed:  
< <  Additional info on the reweighing method you can get from  
> >  Some additional relevant info on the reweighing method you can get from  
In our analysis for PDF reweighting we use TopPdfUncertainty tool from the Top group.  
Added:  
> >  Samples used for the reweighting are:
MC11b: mc11_7TeV.119314.Pythia_d4PairToWtWtbar_400_1LepIncl.merge.NTUP_TOP.e972_s1310_s1300_r3043_r2993_p834
MC11b:  
Direct method 
Line: 1 to 1  

PDF Systematics Study at HU Berlin  
Line: 75 to 75  
Sample Production  
Added:  
> >  MC11b  
Within the official production campain the 4th generation quark samples (b' and t') are produced using the tags combination  e972_s1310_s1300_r3043_r2993_p834. Thus, to perform this study samples have been produced privately and following official production setup as closely as possible.
Athena releases used for different production steps are the following:  
Line: 88 to 90  
Added:  
> >  MC11cThe difference in MC11b and MC11c productions mainly comes from the usage of Pythia6 pileup setup in MC11c instead of Pythia8 in MC11b. In term of production setup details the difference comes in Digitization and Reconst steps like:
 
Added:  
> >  For the details on the MC11c production, go to  
Inclusion of the PDFs into a JO file 
Line: 1 to 1  

PDF Systematics Study at HU Berlin  
Line: 46 to 46  
This PDF systematic uncerntainty study is done using MC samples produced within MC11b ATLAS production setup. In this production MC samples generated with Pythia6 generator have been obtained using MRST LO** (20651) as the default PDF along with its recent "ATLAS Underlying Event Tune 2B" (AUET2B) tune.
In the both methods outlined above we have used the following PDFs to estimate the uncerntainty:  
Changed:  
< < 
 
> > 
 
 
Changed:  
< < 
 
> > 
 
For more details on the PDFs go to LHAPDF.
Reason for choosing the above PDFs: MRST LO** is a LO PDF, so the above PDFs, chosen for the PDF systematics study, should also be of LO. 
Line: 1 to 1  

PDF Systematics Study at HU Berlin  
Line: 22 to 22  
Reweighting method  
Changed:  
< <  Suppose, we have MC signal events generated using PDF1. Interacting partons in incoming protons (antiprotons) are characterized by flavours, flav1, flav2, momentum fractions, , , and an energy scale . The PDF reweighting technique consists of evaluating, on the eventbyevent basis, the probability of picking up the same flavoured partons with the same momentum fractions, x_flav1, x_flav2, according to a second PDF set, PDF2, at the same energy scale Q, then evaluating the following ratio  
> >  Suppose, we have MC signal events generated using PDF1. Interacting partons in incoming protons (antiprotons) are characterized by flavours, flav1, flav2, momentum fractions, , , and an energy scale . The PDF reweighting technique consists of evaluating, on the eventbyevent basis, the probability of picking up the same flavoured partons with the same momentum fractions, , , according to a second PDF set, PDF2, at the same energy scale , then evaluating the following ratio  
%\[ EW=\frac{f_{PDF2}(f_1,x_1,Q^2)}{f_{PDF1}(f_1,x_1,Q^2)} \times \frac{f_{PDF2}(f_2,x_2,Q^2)}{f_{PDF1}(f_2,x_2,Q^2)}  
Line: 98 to 98  
To implement this method we use default signal heavy b' ?? samples to reweight them.  
Added:  
> >  From the technical point of view there are three ATLAS? tools available to implement PDFreweighting methog, which can be found following the links:
Additional info on the reweighing method you can get from In our analysis for PDF reweighting we use TopPdfUncertainty tool from the Top group.  
Direct method
Validation of samples 
Line: 1 to 1  

PDF Systematics Study at HU Berlin 
Line: 1 to 1  

PDF Systematics Study at HU Berlin  
Line: 7 to 7  
This page is under construction and contains no useful information yet  
Changed:  
< <  This Twikipage is to give some more or less detailed infotmation about the analysis to estimate systematics uncerntainties coming from a choice of parton distribution functions (PDF) in the generator to produce signal samples in an analysis to search for 4th generation SMlike heavy quarks.  
> >  This Twikipage is to give some more or less detailed infotmation about the analysis to estimate systematics uncerntainties coming from a choice of parton distribution functions (PDF) in the Pythia6 generator to produce signal samples in an analysis to search for 4th generation SMlike heavy quarks, b' and t'.  
Introduction  
Changed:  
< <  Partonic distribution functions (PDFs) along with partonparton interaction cross sections determine cross sections of processes in protonproton collisions. Since the PDFs are not calculable from the first principles but are determined experimentally with some errors (which come from experimental measurements, theoretical models used to extract PDFs etc.), inclusion of any PDF into the cross section calculation introduces an additional systematic error. Thus, in this study we have tried to estimate the effect of a PDF change in a generator to produce signal samples on a signal event selection efficiency.  
> >  Partonic distribution functions (PDFs) along with partonparton interaction cross sections determine cross sections of processes in protonproton collisions. Since the PDFs are not calculable from the first principles but are determined experimentally with some errors (which come from experimental measurements, theoretical models used to extract PDFs etc.), inclusion of any PDF into the cross section calculation introduces an additional systematic error. Thus, in this study we want to estimate the effect of a PDF change in the Pythia6 generator to produce signal samples on a signal event selection efficiency.  
Deleted:  
< <  Our analysis to estimate PDF uncerntainties is done using two different methods, reweighting method and a direct method. In the following shortly the idea of both methods is outlined as well as described how the analysis is done.  
Analysis methods  
Added:  
> >  Our analysis to estimate PDF uncerntainties is done using two different methods, reweighting method and a direct method. In the following shortly the idea of both methods is outlined.  
Reweighting methodSuppose, we have MC signal events generated using PDF1. Interacting partons in incoming protons (antiprotons) are characterized by flavours, flav1, flav2, momentum fractions, , , and an energy scale . The PDF reweighting technique consists of evaluating, on the eventbyevent basis, the probability of picking up the same flavoured partons with the same momentum fractions, x_flav1, x_flav2, according to a second PDF set, PDF2, at the same energy scale Q, then evaluating the following ratio  
Line: 39 to 40  
Changed:  
< <  Realizations of the analysis methods
For MC11, the default tune for Pythia samples is the "ATLAS Underlying Event Tune 2B" (AUET2BLO** ) ATLPHYSPUB2011009, with the * MRST LO** (20651) as a default PDF. This study is done in release 17 using MC11blike production setup.  
> >  PDFs and tunes  
Added:  
> >  This PDF systematic uncerntainty study is done using MC samples produced within MC11b ATLAS production setup. In this production MC samples generated with Pythia6 generator have been obtained using MRST LO** (20651) as the default PDF along with its recent "ATLAS Underlying Event Tune 2B" (AUET2B) tune.  
In the both methods outlined above we have used the following PDFs to estimate the uncerntainty:  
Deleted:  
< <  

Line: 1 to 1  

PDF Systematics Study at HU Berlin  
Line: 37 to 37  
In the Direct method one has to generate new signal event samples including into a generator not only other PDF(s) (different from the default one) but also tunes corresponding to these new PDF(s) to account for Underlying Event(UE), which in generator in general depends on the PDF used to run the generator and after to go through the whole chain of the sample production, i.e. simulation, digitization, reconstruction and production of D3PDs for the final analysis. The advantige of this method over reweighting is that in this case one counts for the possible effects coming from UE, in contrast to the previous method. On the other hand, the main disadvantige of this method is, it's time and cpu consuming.  
Added:  
> >  
Realizations of the analysis methods  
Changed:  
< <  For MC11, the default tune for Pythia samples is the "ATLAS Underlying Event Tune 2B" (AUET2BLO** ) ATLPHYSPUB2011009, with the * MRST LO** (20651) as a default PDF.  
> > 
For MC11, the default tune for Pythia samples is the "ATLAS Underlying Event Tune 2B" (AUET2BLO** ) ATLPHYSPUB2011009, with the * MRST LO** (20651) as a default PDF.  
This study is done in release 17 using MC11blike production setup.  
Line: 51 to 55  
 
Changed:  
< <  Reason for choosing the above PDFs: MRST LO** is a LO PDF, so the above PDFs, chosen for the PDF systematics study, should also be of LO  
> >  For more details on the PDFs go to LHAPDF.
Reason for choosing the above PDFs: MRST LO** is a LO PDF, so the above PDFs, chosen for the PDF systematics study, should also be of LO. Pythia6 parameters tuned in the the AUET2B tuning campain are as follows: Paremeters PARP(62), PARP(64) and PARP(72) are responsible for shower parameterization, namely,
Paremeters PARP(77), PARP(78), PARP(82), PARP(84) and PARP(90) difene MPI model parameters with
For more info the AUET2B tune have a look at the ATLAS note ATLPHYSPUB2011009.  
Deleted:  
< <  For more details on the PDFs see LHAPDF.  
Sample Production  
Changed:  
< <  MC11b  
> >  Within the official production campain the 4th generation quark samples (b' and t') are produced using the tags combination  e972_s1310_s1300_r3043_r2993_p834. Thus, to perform this study samples have been produced privately and following official production setup as closely as possible.
Athena releases used for different production steps are the following:
For more information on the MC11b production setup have a look at the following links:  
Deleted:  
< <  Event generation – AtlasProduction 16.6.6.3  16.6.7.X(16.6.8.2), using
Generators/MC11JobOptions
Generate_trf.py
G4 simulation – AtlasProduction 15.6.6.3  16.6.7.X(16.6.7.13), AtlasG4_trf.py uses two beam spot settings: wide beam spot (90mm in z); narrow(er) beam spot (75 mm in z); Digitization and Reconst. – AtlasProduction 17.0.5.1(17.0.5.1) and newer DigiMReco_trf.py (new) transform which enables one to mix the v2 and v3 triggers according to the data periods ( run numbers ) in the run dependent conditions  
Inclusion of the PDFs into a JO file  
Changed:  
< <  The roles of the PARP(n) parameters are as follows for the various n: 77  suppression of colour reconnection for highp_T strings, 78  strength of colour reconnection, 82  MPI p_T cutoff at the nominal reference energy of 1800 GeV, 84  fractional radius of core part of doubleGaussian transverse proton matter distribution, 90  exponent governing the rate of increase of the p0_T MPI cutoff as a function of . The fraction of the proton matter distribution contained in the core Gaussian is given by PARP(83) and was, as for the A*T2 tunes, fixed to the AMBT1 value of 0.356.  
> >  
Reweighting method 
Line: 1 to 1  

PDF Systematics Study at HU Berlin  
Line: 16 to 16  
Our analysis to estimate PDF uncerntainties is done using two different methods, reweighting method and a direct method. In the following shortly the idea of both methods is outlined as well as described how the analysis is done.  
Added:  
> >  Analysis methods  
Changed:  
< <  Reweighting method  
> >  Reweighting method  
Suppose, we have MC signal events generated using PDF1. Interacting partons in incoming protons (antiprotons) are characterized by flavours, flav1, flav2, momentum fractions, , , and an energy scale . The PDF reweighting technique consists of evaluating, on the eventbyevent basis, the probability of picking up the same flavoured partons with the same momentum fractions, x_flav1, x_flav2, according to a second PDF set, PDF2, at the same energy scale Q, then evaluating the following ratio  
Line: 31 to 32  
Changed:  
< <  Direct methodIn Direct method one has to generate signal events using in the generator PDF different from the default one and going through the whole chain of sample production, generation, simulation, digitization, reconstruction and production of D3PDs for the final analysis.  
> >  Direct method  
Added:  
> >  In the Direct method one has to generate new signal event samples including into a generator not only other PDF(s) (different from the default one) but also tunes corresponding to these new PDF(s) to account for Underlying Event(UE), which in generator in general depends on the PDF used to run the generator and after to go through the whole chain of the sample production, i.e. simulation, digitization, reconstruction and production of D3PDs for the final analysis. The advantige of this method over reweighting is that in this case one counts for the possible effects coming from UE, in contrast to the previous method. On the other hand, the main disadvantige of this method is, it's time and cpu consuming.  
Realizations of the analysis methods  
Changed:  
< <  For MC11, the default tune for Pythia samples is the "ATLAS Underlying Event Tune 2B" (AUET2BLO**) ATLPHYSPUB2011009, with the * MRST LO** (20651) as a default PDF.  
> >  For MC11, the default tune for Pythia samples is the "ATLAS Underlying Event Tune 2B" (AUET2BLO** ) ATLPHYSPUB2011009, with the * MRST LO** (20651) as a default PDF.  
This study is done in release 17 using MC11blike production setup. 
Line: 1 to 1  

PDF Systematics Study at HU Berlin  
Line: 38 to 38  
Realizations of the analysis methods  
Changed:  
< <  For MC11, the default tune for Pythia samples is the "ATLAS Underlying Event Tune 2B" (AUET2BLO**) ATLPHYSPUB2011009, with the * MRST LO** as a default PDF.  
> >  For MC11, the default tune for Pythia samples is the "ATLAS Underlying Event Tune 2B" (AUET2BLO**) ATLPHYSPUB2011009, with the * MRST LO** (20651) as a default PDF.  
This study is done in release 17 using MC11blike production setup.
In the both methods outlined above we have used the following PDFs to estimate the uncerntainty:  
Changed:  
< < 
 
> > 
 
Added:  
> >  Reason for choosing the above PDFs: MRST LO** is a LO PDF, so the above PDFs, chosen for the PDF systematics study, should also be of LO  
Added:  
> >  For more details on the PDFs see LHAPDF.  
Changed:  
< <  Reweighting method  
> >  Sample Production  
Changed:  
< <  To implement this method we use default signal heavy b' ?? samples to reweight them.  
> >  MC11b
Event generation – AtlasProduction 16.6.6.3  16.6.7.X(16.6.8.2), using Generators/MC11JobOptions Generate_trf.py G4 simulation – AtlasProduction 15.6.6.3  16.6.7.X(16.6.7.13), AtlasG4_trf.py uses two beam spot settings: wide beam spot (90mm in z); narrow(er) beam spot (75 mm in z); Digitization and Reconst. – AtlasProduction 17.0.5.1(17.0.5.1) and newer DigiMReco_trf.py (new) transform which enables one to mix the v2 and v3 triggers according to the data periods ( run numbers ) in the run dependent conditions  
Deleted:  
< <  Direct method  
Inclusion of the PDFs into a JO file  
Line: 64 to 80  
energy of 1800 GeV, 84  fractional radius of core part of doubleGaussian transverse proton matter distribution, 90  exponent governing the rate of increase of the p0_T MPI cutoff as a function of . The fraction of the proton matter distribution contained in the core Gaussian is given by PARP(83) and was, as for the A*T2 tunes, fixed to the AMBT1 value of 0.356.  
Added:  
> >  Reweighting methodTo implement this method we use default signal heavy b' ?? samples to reweight them.
Direct method
Validation of samples
Extracting efficiencies
Reweighting method
Direct method
Discussion of the results  
HowtosTo read more on the subject, go to References. 
Line: 1 to 1  

 
Changed:  
< <  PDFS ystematics Study of HU Berlin  
> >  PDF Systematics Study at HU Berlin  
<!optional>  
Changed:  
< <  This Twikipage is to give some more or less detailed infotmation about the analysis to estimate systematics uncerntainties coming parton distribution functions (PDF) choice in the generator to produce signal samples in an analysis to search for 4th generation heavy quarks done at HU Berlin.  
> >  This page is under construction and contains no useful information yet  
Added:  
> >  This Twikipage is to give some more or less detailed infotmation about the analysis to estimate systematics uncerntainties coming from a choice of parton distribution functions (PDF) in the generator to produce signal samples in an analysis to search for 4th generation SMlike heavy quarks.  
Deleted:  
< <  Introduction  
Changed:  
< <  Partonic distribution functions (PDFs) along with partonparton interaction cross sections determine cross sections of processes in protonproton collisions. Since the PDFs are not calculable from the first principles but are determined experimentally with some errors (which come from experimental measurements, theoretical models used to extract PDFs etc.), inclusion of any PDF into the cross section calculation introduces an additional systematic error.  
> >  Introduction  
Changed:  
< <  Thus, in this study we have tried to estimate the effect of a PDF change in a generator producing signal samples on a signal event selection efficiency.  
> >  Partonic distribution functions (PDFs) along with partonparton interaction cross sections determine cross sections of processes in protonproton collisions. Since the PDFs are not calculable from the first principles but are determined experimentally with some errors (which come from experimental measurements, theoretical models used to extract PDFs etc.), inclusion of any PDF into the cross section calculation introduces an additional systematic error. Thus, in this study we have tried to estimate the effect of a PDF change in a generator to produce signal samples on a signal event selection efficiency.  
Changed:  
< < 
To read more on the subject, go to References.
Example:You may also directly contact P.Uwer or S.Moch to get the package.  
> >  Our analysis to estimate PDF uncerntainties is done using two different methods, reweighting method and a direct method. In the following shortly the idea of both methods is outlined as well as described how the analysis is done.  
Reweighting method  
Changed:  
< <  Suppose, we have MC events generated using PDF1. Interacting partons in incoming protons (antiprotons) are characterized by flavours, flav1, flav2, momentum fractions, x_flav1, x_flav2, and an energy scale Q. The PDF reweighting technique consists of evaluating, on the eventbyevent basis, the probability of picking up the same flavoured partons with the same momentum fractions, x_flav1, x_flav2, according to a second PDF set, PDF2, at the same energy scale Q, then evaluating the following ratio  
> >  Suppose, we have MC signal events generated using PDF1. Interacting partons in incoming protons (antiprotons) are characterized by flavours, flav1, flav2, momentum fractions, , , and an energy scale . The PDF reweighting technique consists of evaluating, on the eventbyevent basis, the probability of picking up the same flavoured partons with the same momentum fractions, x_flav1, x_flav2, according to a second PDF set, PDF2, at the same energy scale Q, then evaluating the following ratio  
Changed:  
< <  After the EventWeight is applied on MC events generated with PDF1, they will effectively be distributed according to PDF2.  
> >  After the EventWeight, , is applied on MC events generated with PDF1 and then they will effectively be distributed according to PDF2.
Direct methodIn Direct method one has to generate signal events using in the generator PDF different from the default one and going through the whole chain of sample production, generation, simulation, digitization, reconstruction and production of D3PDs for the final analysis.
Realizations of the analysis methodsFor MC11, the default tune for Pythia samples is the "ATLAS Underlying Event Tune 2B" (AUET2BLO**) ATLPHYSPUB2011009, with the * MRST LO** as a default PDF. This study is done in release 17 using MC11blike production setup.  
Added:  
> >  In the both methods outlined above we have used the following PDFs to estimate the uncerntainty:
Reweighting methodTo implement this method we use default signal heavy b' ?? samples to reweight them.
Direct method
Inclusion of the PDFs into a JO fileThe roles of the PARP(n) parameters are as follows for the various n: 77  suppression of colour reconnection for highp_T strings, 78  strength of colour reconnection, 82  MPI p_T cutoff at the nominal reference energy of 1800 GeV, 84  fractional radius of core part of doubleGaussian transverse proton matter distribution, 90  exponent governing the rate of increase of the p0_T MPI cutoff as a function of . The fraction of the proton matter distribution contained in the core Gaussian is given by PARP(83) and was, as for the A*T2 tunes, fixed to the AMBT1 value of 0.356.
HowtosTo read more on the subject, go to References. Example:You may also directly contact P.Uwer or S.Moch to get the package.  
Line: 38 to 76  
 
Deleted:  
< < 
Direct method 
Line: 1 to 1  

PDFS ystematics Study of HU Berlin
<!optional>  
Deleted:  
< <  A few words  
Changed:  
< <  Example:You may also directly contact P.Uwer or S.Moch to get the package.  
> >  This Twikipage is to give some more or less detailed infotmation about the analysis to estimate systematics uncerntainties coming parton distribution functions (PDF) choice in the generator to produce signal samples in an analysis to search for 4th generation heavy quarks done at HU Berlin.  
Introduction  
Changed:  
< <  Functionality of HATHOR is based on the use of the expression:  
> >  Partonic distribution functions (PDFs) along with partonparton interaction cross sections determine cross sections of processes in protonproton collisions. Since the PDFs are not calculable from the first principles but are determined experimentally with some errors (which come from experimental measurements, theoretical models used to extract PDFs etc.), inclusion of any PDF into the cross section calculation introduces an additional systematic error.  
Changed:  
< <  
> >  Thus, in this study we have tried to estimate the effect of a PDF change in a generator producing signal samples on a signal event selection efficiency.  
Deleted:  
< <  where is a quarkantiquark pair production cross sections induced by ith and jth partons interaction, and are th and th partons distribution functions (PDF) in the Ath and Bth incoming nucleons correspondingly, and are factorization and renormalization scales, and and momentum fraction of each interacting parton in incoming nucleons.  
Changed:  
< < 
 
> >  To read more on the subject, go to References.  
Changed:  
< <  In order to calculate the central value factorization and renormalization scale parameters are set to a heavy quark mass, i.e. . Along with central value the tool calculates also errors. There are two kind of errors: 1) errors coming from factorization and renormalization scales and 2) PDFs errors.  
> >  Example:You may also directly contact P.Uwer or S.Moch to get the package.  
Deleted:  
< <  1) Scale errors are calculated by setting and in order to get upper and lower deviations from the central value respectively.  
Changed:  
< <  2) PDF errors can be calculated in two ways: a) in a simplified way, where upper and lower deviations from the central value are calculated as averaged, according to the formula and thus errors are symmetric; b) in a more general way, where deviations from the central value are calculated according to the formula , for the upper deviation, and formula , for the lower deviation, so that the errors are asymmetric.  
> >  Reweighting method  
Added:  
> >  Suppose, we have MC events generated using PDF1. Interacting partons in incoming protons (antiprotons) are characterized by flavours, flav1, flav2, momentum fractions, x_flav1, x_flav2, and an energy scale Q. The PDF reweighting technique consists of evaluating, on the eventbyevent basis, the probability of picking up the same flavoured partons with the same momentum fractions, x_flav1, x_flav2, according to a second PDF set, PDF2, at the same energy scale Q, then evaluating the following ratio
After the EventWeight is applied on MC events generated with PDF1, they will effectively be distributed according to PDF2.  
Deleted:  
< <  To read more on the subject, go to References.  
Deleted:  
< <  Validation  
Deleted:  
< <  Validation of the tool is done comparing heavy quarks pair production cross sections calculated using this tool with ones obtained from other open official sources, first of all from different articles.  
Below Top quark pair production cross sections in protonproton (pp) and protonantiproton (ppb) collisions calculated by this tool (in red) are compared with ones obtained from arXiv/hepph/0804.2800 (in blue). PDF errors are calculated in the asymmetric way. Cross sections are given in picobarns (pb).
 
Added:  
> > 
Direct method 
Line: 1 to 1  

Added:  
> > 
PDFS ystematics Study of HU Berlin
<!optional> A few words
Example:You may also directly contact P.Uwer or S.Moch to get the package.
IntroductionFunctionality of HATHOR is based on the use of the expression:
where is a quarkantiquark pair production cross sections induced by ith and jth partons interaction, and are th and th partons distribution functions (PDF) in the Ath and Bth incoming nucleons correspondingly, and are factorization and renormalization scales, and and momentum fraction of each interacting parton in incoming nucleons.
In order to calculate the central value factorization and renormalization scale parameters are set to a heavy quark mass, i.e. . Along with central value the tool calculates also errors. There are two kind of errors: 1) errors coming from factorization and renormalization scales and 2) PDFs errors. 1) Scale errors are calculated by setting and in order to get upper and lower deviations from the central value respectively. 2) PDF errors can be calculated in two ways: a) in a simplified way, where upper and lower deviations from the central value are calculated as averaged, according to the formula and thus errors are symmetric; b) in a more general way, where deviations from the central value are calculated according to the formula , for the upper deviation, and formula , for the lower deviation, so that the errors are asymmetric.
To read more on the subject, go to References.
ValidationValidation of the tool is done comparing heavy quarks pair production cross sections calculated using this tool with ones obtained from other open official sources, first of all from different articles. Below Top quark pair production cross sections in protonproton (pp) and protonantiproton (ppb) collisions calculated by this tool (in red) are compared with ones obtained from arXiv/hepph/0804.2800 (in blue). PDF errors are calculated in the asymmetric way. Cross sections are given in picobarns (pb).
