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-- AlexanderFedotov - 18-Apr-2010

1. Sample and cuts

• generator: calchep 2.5.4

• process:       
  at = 7 TeV, with
  • both and jet consisting of quarks, their antiquarks, and gluons
  • proton PDF CTEQ6M in use

• cuts:
  • > 15 GeV
  • < 2.5

The cutoffs are taken as those in the JETPHOX NLO pQCD calculation http://cms.cern.ch/iCMS/jsp/openfile.jsp?tp=draft&files=AN2010_026_v1.pdf (CMS AN-2010/026 -- "Prospects for Measuring The Isolated Photon Cross Section at CMS" ). With the additional photon isolation selection of < 2 GeV in the cone < .4 around the photon, they come to the cross-section of

• The cutoff < 2.5 is equivalent to iEta <= 26 :

• Statistics: about evs ( = 999836, 999195 entries, = 991388)

• Calculated cross section: σ = 104 nb

• List of 30 subprocesses with partial cross sections:
  Show... Hide

  The output of the command `subproc_cycle 0.00957048  1000000' :
  
  #Subprocess 1 ( G, u -> A, u ) Cross section = 1.6164E+04 , 154697 events
  #Subprocess 2 ( G, U -> A, U ) Cross section = 8.8370E+03 , 84574 events
  #Subprocess 3 ( G, d -> A, d ) Cross section = 3.3202E+03 , 31775 events
  #Subprocess 4 ( G, D -> A, D ) Cross section = 2.3449E+03 , 22441 events
  #Subprocess 5 ( G, s -> A, s ) Cross section = 1.8035E+03 , 17260 events
  #Subprocess 6 ( G, S -> A, S ) Cross section = 1.8044E+03 , 17268 events
  #Subprocess 7 ( G, c -> A, c ) Cross section = 5.9559E+03 , 57000 events
  #Subprocess 8 ( G, C -> A, C ) Cross section = 5.9390E+03 , 56839 events
  #Subprocess 9 ( G, b -> A, b ) Cross section = 8.5514E+02 , 8184 events
  #Subprocess 10 ( G, B -> A, B ) Cross section = 8.5451E+02 , 8178 events
  #Subprocess 11 ( u, G -> A, u ) Cross section = 1.6132E+04 , 154390 events
  #Subprocess 12 ( u, U -> G, A ) Cross section = 2.8143E+03 , 26934 events
  #Subprocess 13 ( U, G -> A, U ) Cross section = 8.8458E+03 , 84658 events
  #Subprocess 14 ( U, u -> G, A ) Cross section = 2.8137E+03 , 26928 events
  #Subprocess 15 ( d, G -> A, d ) Cross section = 3.3113E+03 , 31690 events
  #Subprocess 16 ( d, D -> G, A ) Cross section = 5.8948E+02 , 5641 events
  #Subprocess 17 ( D, G -> A, D ) Cross section = 2.3436E+03 , 22429 events
  #Subprocess 18 ( D, d -> G, A ) Cross section = 5.8778E+02 , 5625 events
  #Subprocess 19 ( s, G -> A, s ) Cross section = 1.8062E+03 , 17286 events
  #Subprocess 20 ( s, S -> G, A ) Cross section = 2.4564E+02 , 2350 events
  #Subprocess 21 ( S, G -> A, S ) Cross section = 1.8033E+03 , 17258 events
  #Subprocess 22 ( S, s -> G, A ) Cross section = 2.4496E+02 , 2344 events
  #Subprocess 23 ( c, G -> A, c ) Cross section = 5.9447E+03 , 56893 events
  #Subprocess 24 ( c, C -> G, A ) Cross section = 6.6036E+02 , 6319 events
  #Subprocess 25 ( C, G -> A, C ) Cross section = 5.9553E+03 , 56995 events
  #Subprocess 26 ( C, c -> G, A ) Cross section = 6.6027E+02 , 6319 events
  #Subprocess 27 ( b, G -> A, b ) Cross section = 8.5641E+02 , 8196 events
  #Subprocess 28 ( b, B -> G, A ) Cross section = 6.1392E+01 , 587 events
  #Subprocess 29 ( B, G -> A, B ) Cross section = 8.5578E+02 , 8190 events
  #Subprocess 30 ( B, b -> G, A ) Cross section = 6.1469E+01 , 588 events
  Sum of distributions is stored in file distr_200_229
  Total Cross Section 104472.291 [pb]
  see details in prt_200 - prt_229 files
       

  Ev. statistics broken into subprocesses:
  Show... Hide

                  Event statistics 
                  ~~~~~~~~~~~~~~~~ 
     file    Nev        Nev        sum of        Neff 
        #  (header)   (lines)     weights 
  
        1    154697    154668    154697.0    154613.0 
        2     84574     84567     84574.0     84558.0 
        3     31775     31731     31775.0     31509.2 
        4     22441     22424     22441.0     22393.1 
        5     17260     17241     17260.0     17206.2 
        6     17268     17255     17268.0     17234.1 
        7     57000     56994     57000.0     56988.0 
        8     56839     56742     56839.0     53305.3 
        9      8184      8168      8184.0      8114.6 
       10      8178      8169      8178.0      8152.1 
       11    154390    154168    154390.0    151427.9 
       12     26934     26932     26934.0     26930.0 
       13     84658     84651     84658.0     84640.0 
       14     26928     26912     26928.0     26852.2 
       15     31690     31673     31690.0     31646.1 
       16      5641      5638      5641.0      5635.0 
       17     22429     22426     22429.0     22423.0 
       18      5625      5610      5625.0      5561.7 
       19     17286     17283     17286.0     17280.0 
       20      2350      2346      2350.0      2336.1 
       21     17258     17258     17258.0     17258.0 
       22      2344      2342      2344.0      2340.0 
       23     56893     56860     56893.0     56527.4 
       24      6319      6317      6319.0      6315.0 
       25     56995     56975     56995.0     56925.1 
       26      6319      6315      6319.0      6309.0 
       27      8196      8194      8196.0      8190.0 
       28       587       586       587.0       585.0 
       29      8190      8188      8190.0      8186.0 
       30       588       562       588.0       345.1 
  
  all  30    999836    999195    999836.0    991388.0 
       

• text files of the calchep output were converted to a root file with the calchepAjjToRoot program : cxx , mk , run

• Analysis program an : an , h1fInteg , hcalEta2iEta

• Root file with the analysis output: root file

2. QCDscale distribution

3. Jet Flavours

• quarks codes : d=1, u=2, s=3, c=4, b=5, gluon: 21,
  antiquarks have negative sign
• gluons are born only in a annihilation
  => the annihilation amounts to ~9% only
• the rest belongs to the QCD Compton process . here quarks u,c of charge 2/3 are enhanced over d,s,b due to the factor

• More detail break up:
  Show... Hide

   Subprocess          Cross section 
                          / pb       %
  
    1 ( G, u -> A, u )  1.6172E+04  47.8
   11 ( u, G -> A, u )  1.6129E+04
    2 ( G, U -> A, U )  8.8299E+03
   13 ( U, G -> A, U )  8.8276E+03
  
   23 ( c, G -> A, c )  5.9634E+03  22.8
    8 ( G, C -> A, C )  5.9587E+03
    7 ( G, c -> A, c )  5.9512E+03
   25 ( C, G -> A, C )  5.9438E+03
  
   15 ( d, G -> A, d )  3.3164E+03   6.3
    3 ( G, d -> A, d )  3.3153E+03
  
   12 ( u, U -> G, A )  2.8199E+03   5.4
   14 ( U, u -> G, A )  2.8080E+03
  
    4 ( G, D -> A, D )  2.3427E+03   4.5
   17 ( D, G -> A, D )  2.3365E+03
  
    5 ( G, s -> A, s )  1.8149E+03   6.9
    6 ( G, S -> A, S )  1.8111E+03
   19 ( s, G -> A, s )  1.8075E+03
   21 ( S, G -> A, S )  1.8012E+03
  
    9 ( G, b -> A, b )  8.5975E+02   3.3
   29 ( B, G -> A, B )  8.5740E+02
   27 ( b, G -> A, b )  8.5653E+02
   10 ( G, B -> A, B )  8.5522E+02
  
   24 ( c, C -> G, A )  6.6018E+02   3.0
   26 ( C, c -> G, A )  6.5924E+02
   18 ( D, d -> G, A )  5.8970E+02
   16 ( d, D -> G, A )  5.8850E+02
   20 ( s, S -> G, A )  2.4489E+02
   22 ( S, s -> G, A )  2.4471E+02
   28 ( b, B -> G, A )  6.1616E+01
   30 ( B, b -> G, A )  6.1333E+01
       

4. σ()

5. η distributions

• the variation is not very large

• a negligible part of jets lie outside the HCAL
• the variation is very large: σ(HF) << σ(HB)
• σ(HF) drops faster as cutoff increases than σ(HB) does

• η(jet) and η() are positively correlated

6. <> vs η for and jet

• Jet is smaller in the HF region
  => cross section should drop faster there with the increase of the cutoff

7. E vs η for and jet