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-- Main.AlexanderFedotov - 24-Nov-2009

<center> 

              |  <h1> Average and Peak ET <br> of probe jet vs iEta </h1>  |

</center> 


%TOC{ title = "Sections:" }%

<!-- ########################  Section 1 #########################  -->

#SecN1

---++ 1. Intro



It was found in the [[CMS.HcalCalibrDiJetsLogbookEntry01][ Hcal !Dijet Logbook page 1  ]]
( [[CMS.HcalCalibrDiJetsLogbookEntry01#SecN4d2d1 ][ Sec.4.2.1  ]] )
from the ET_peak / Pthat_threshold for tag jets in 2009 sample (PThat > 30)
that the the uncorrected tag jet energy is __underestimated  by factor ~2.__ 
And the "unbiased" HF correction was found to be 0.50 (Sec.5.5).
 => It looks like the jet energy scale in HF is roughly correct.

*Puprose of this study:* try to see the jet scale recovery for probe jets as going from barrel region to HF,
by looking at the __evolution of the ET(probe jet) distribution.__

*Input sample*: [[https://twiki.cern.ch/twiki/bin/viewauth/CMS/HcalCalibrDiJetsLogbookEntry05#SeT11][ \
 2009 PThat>30, 10 !TeV Version 1 ]],  one root file =QCD_Pt30_10TeV.hi_100.root= with 70946 evs

Plots were made interactively with the  [[%ATTACHURL%/rd_tree2.C][ script ]] .






<!-- ########################  Section 2 #########################  -->

#SecN2

---++ 2. Probe jet only




The < ET > vs iEta plot:

#SecN2Fig1

<center>     
   <img src="%ATTACHURLPATH%/ProbeJet.Mean_ET_vs_iEta.gif"  width='400'  />
   <br>
   Original size:          [[%ATTACHURLPATH%/ProbeJet.Mean_ET_vs_iEta.gif ][ gif ]] , \
                                  [[%ATTACHURLPATH%/ProbeJet.Mean_ET_vs_iEta.eps ][ eps ]] 
</center> 

   * ET growth in HF as |iEta| increases, stops at |iEta| ~34, and changes to a fall off. 
    This must be a reflection of boudary condition  E(true probe jet) < E(beam), thus only the lowest
     values of ET(probe) get allowed in this region.
     For the same reason,  a third jet contribution may become more important near this boundary.

The ET distributions are shown below for 7 bins in |iEta|.
The peak positions as found by the standard root peak finder (function =ShowPeaks= )
are marked with red triangles.

#SecN2Fig2
<center>     
   <img src="%ATTACHURLPATH%/ProbeJet.ET_in_iEta_bins.gif"  width='600'  />
   <br>
   Original size:          [[%ATTACHURLPATH%/ProbeJet.ET_in_iEta_bins.gif ][ gif ]] , \
                                  [[%ATTACHURLPATH%/ProbeJet.ET_in_iEta_bins.eps ][ eps ]] 
</center> 

The ET peak values from the above plots are tabulated below: 

#SecN2Tab1
<center> 
%TABLE{ tablerules="all"  databg="#ffffff" }%
|  *iEta range*  |  *Peak ET / GeV*  | *peak(1-9) / <br> peak(iEta)* |
|   1-9   |  14.5  | 1.000 |
|  10-16  |  13.5  | 1.074 | 
|  17-19  |  12.4  | 1.169 |
|  20-25  |  16.4  | 0.884 |
|  26-29  |  19.2  | 0.755 |
|  30-35  |  23.1  | 0.628 |
|  36-40  |  24.1  | 0.602 |
</center> 


   * we do not get .50 , rather .60 only
   * are numerous cutoffs applied in the calibrtion, important? May well be...



<!-- ########################  Section 3 #########################  -->

#SecN3

---++ 3. Selecting &eta;(tag) < 1 . Zooming HF region. Use tag jet directly for a probe in HF.



Now we add cutoff &eta;(tag jet) < 1, used in calibration normally.

Probe jet ET :

#SecN3Fig1

<center>     
   <img src="%ATTACHURLPATH%/ProbeJet_ET_vs_iEta_at_etaTag_lt_1.gif"  width='400'  />
   <br>
   Original size:          [[%ATTACHURLPATH%/ProbeJet_ET_vs_iEta_at_etaTag_lt_1.gif ][ gif ]] , \
                                  [[%ATTACHURLPATH%/ProbeJet_ET_vs_iEta_at_etaTag_lt_1.eps ][ eps ]] 
</center> 

   * In HF region, the average ET is only few percent bigger than on the [[#SecN2Fig1 ][plot w/o &eta; ]] cutoff .
      This seems to be insignificant.

__Tag__ jet ET but still vs __probe__ jet iEta:

#SecN3Fig2

<center>     
   <img src="%ATTACHURLPATH%/TagJet_ET_vs_ProbeJet_iEta_at_etaTag_lt_1.gif"  width='400'  />
   <br>
   Original size:          [[%ATTACHURLPATH%/TagJet_ET_vs_ProbeJet_iEta_at_etaTag_lt_1.gif ][ gif ]] , \
                                  [[%ATTACHURLPATH%/TagJet_ET_vs_ProbeJet_iEta_at_etaTag_lt_1.eps ][ eps ]] 
</center> 

   *  The average ET( __tag__ jet) in HF region (~20 !GeV) is ~10% lower than ET( __probe__ )
       on the [[#SecN2Fig1 ][ very first plot ]] ( ~22 !GeV at |iEta| <=12 ) .
   *  What about the shape of the ET(tag) distribution relative to the ET(probe) one:
      * does it shrink?
      * does the peak value move?

Let us see:
#SecN3Fig3

<center>     
   <img src="%ATTACHURLPATH%/etaTag_lt_1.Tag_And_Probe_ET_in_HF_bins.gif"  width='600'  />
   <br>
   Original size:          [[%ATTACHURLPATH%/etaTag_lt_1.Tag_And_Probe_ET_in_HF_bins.gif ][ gif ]] , \
                                  [[%ATTACHURLPATH%/etaTag_lt_1.Tag_And_Probe_ET_in_HF_bins.eps ][ eps ]] 
</center> 

Peak values are collected in the table:

#SecN3Tab1
<center> 
%TABLE{ tablerules="all"  databg="#ffffff" }%
|  *iEta range*  |  *Peak ET(tag) / GeV*  |  *Peak ET(probe) / GeV*  | *peak_tag / <br> peak_probe* |
|  31-35  |  15.3  |  24.1  | 0.635 |
|  36-40  |  14.4  |  24.3  | 0.593 |
</center> 

   * Nothing good! We still get ~0.6 but not 0.5
   * Peak method seems to be quite imprecise.
   * Other cuts may be much more important than &eta; <  1 ( e.g. ET(third jet) < 5 is a very stong one!)

---------------------------------------------------------

Attachments

Topic attachments
I	Attachment	History	Action	Size	Date	Who
eps	ProbeJet.ET_in_iEta_bins.eps	r1	manage	52.6 K	2009-11-24 - 21:00	AlexanderFedotov
gif	ProbeJet.ET_in_iEta_bins.gif	r1	manage	40.5 K	2009-11-24 - 20:54	AlexanderFedotov
eps	ProbeJet.Mean_ET_vs_iEta.eps	r1	manage	19.0 K	2009-11-24 - 20:54	AlexanderFedotov
gif	ProbeJet.Mean_ET_vs_iEta.gif	r1	manage	13.3 K	2009-11-24 - 20:53	AlexanderFedotov
eps	ProbeJet_ET_vs_iEta_at_etaTag_lt_1.eps	r1	manage	19.3 K	2009-11-25 - 04:34	AlexanderFedotov
gif	ProbeJet_ET_vs_iEta_at_etaTag_lt_1.gif	r1	manage	15.4 K	2009-11-25 - 04:34	AlexanderFedotov
eps	TagJet_ET_vs_ProbeJet_iEta_at_etaTag_lt_1.eps	r1	manage	18.7 K	2009-11-25 - 04:37	AlexanderFedotov
gif	TagJet_ET_vs_ProbeJet_iEta_at_etaTag_lt_1.gif	r1	manage	15.3 K	2009-11-25 - 04:35	AlexanderFedotov
eps	etaTag_lt_1.Tag_And_Probe_ET_in_HF_bins.eps	r1	manage	32.3 K	2009-11-25 - 06:35	AlexanderFedotov
gif	etaTag_lt_1.Tag_And_Probe_ET_in_HF_bins.gif	r1	manage	37.4 K	2009-11-25 - 06:33	AlexanderFedotov
c	rd_tree2.C	r1	manage	7.8 K	2009-11-25 - 06:32	AlexanderFedotov

Topic revision: r6 - 2009-12-04 - AlexanderFedotov

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