Introduction - Cut definitions - Common parameters - Wgamma (Total cuts) - Wgamma (Wide cuts) - Wgamma (Tight cuts) - Zgammma (Total cuts) - Zgamma (Wide cuts) - Zgamma (Tight cuts) - Zgamma (Tight cuts - Large sample) - template

Predicted cross sections for Z+photon and W+photon channels

Henry Frisch and Chadd Smith


These are the latest results from our lepton + photon event studies, which should be published shortly in CDF Note 6057. In the meantime, this page will serve to summarize the available CompHEP samples and the method of their generation.

For each process (Wgamma, Zgamma, etc.), we wished to create three sets of event cuts: TOTAL, WIDE, and TIGHT. The TOTAL cuts are defined to be extremely loose and allow for a rough calculation of the total cross section for the process while avoiding singularities near 0. The WIDE cuts are analogous to the selection criteria at the trigger level, while the TIGHT cuts are designed to represent a typical set of analysis cuts.

Note that in the WIDE and TOTAL cuts cases, the requirements placed on any second lepton or photon in the event are much looser than those on the primary lepton or photon. The cuts in CompHEP are applied to specific particles in the event, and there appears to be no functionality for cuts that take the form of MAX(Et3,Et4) > 25 or MIN(Et3,Et4) > 12.

Therefore, a two stage process is necessary. First, we generate events for using a modified set of cuts for each category. Then we apply the actual cuts by filtering the event sample, in our case using PAW routines.

The analysis-level and generator-level cuts are shown below. Note that there is no difference for the TOTAL cuts category. For the WIDE and TIGHT cases, if a process has >= 2 leptons and/or >= 2 photons, then all leptons and/or all photons are only required to pass the looser E_t and abs(eta) cuts. An event sample is generated, which is then passed through an external filter to apply the primary/secondary lepton (photon) cuts.

For processes where there is only one lepton, the tighter cuts will be applied to that single lepton. Similarly, for processes which produce only one photon, the tighter cuts would be placed on that photon.

Definitions of TOTAL, WIDE, and TIGHT cuts:



Analysis-level cuts Generator-level cuts
(value in parentheses used if >= 2 leptons or >= 2 photons)
TOTAL CUTS Et |eta| DeltaR Et |eta| DeltaR
First lepton 1 GeV 6.0 0.2 1 GeV 6.0 0.2
Addl. leptons 1 GeV 6.0 0.2 1 GeV 6.0 0.2
First photon 6 GeV 6.0 0.2 6 GeV 6.0 0.2
Addl. photons 6 GeV 6.0 0.2 6 GeV 6.0 0.2
Neutrino (MET) 1 GeV 6.0 -- 1 GeV 6.0 --


WIDE CUTS Et |eta| DeltaR Et |eta| DeltaR
First lepton 12 GeV 2.5 0.2 12 (6) GeV 2.5 0.2
Addl. leptons 6 GeV 2.5 0.2 6 GeV 2.5 0.2
First photon 6 GeV 2.5 0.2 6 GeV 2.5 0.2
Addl. photons 6 GeV 2.5 0.2 6 GeV 2.5 0.2
Neutrino (MET) 6 GeV 6.0 -- 6 GeV 6.0 --

TIGHT CUTS Et |eta| DeltaR Et |eta| DeltaR
First lepton 25 GeV 1.0 0.4 25 (12) GeV 1.0 (2.5) 0.4
Addl. leptons 12 GeV 2.5 0.4 12 GeV 2.5 0.4
First photon 25 GeV 1.0 0.4 25 (12) GeV 1.0 (2.5) 0.4
Addl. photons 12 GeV 2.5 0.4 12 GeV 2.5 0.4
Neutrino (MET) 25 GeV 6.0 -- 25 GeV 6.0 --


Definitions of analysis-level TOTAL, WIDE, and TIGHT cuts:

TOTAL CUTS Et |eta| DeltaR
First lepton 1 GeV 6.0 0.2
First photon 6 GeV 6.0 0.2
Neutrino (MET) 1 GeV 6.0 --


WIDE CUTS Et |eta| DeltaR
First lepton 12 GeV 2.5 0.2
First photon 6 GeV 2.5 0.2
Neutrino (MET) 6 GeV 6.0 --


TIGHT CUTS Et |eta| DeltaR
First lepton 25 GeV 1.0 0.4
First photon 25 GeV 1.0 0.4
Neutrino (MET) 25 GeV 6.0 --


Common parameters

We used the _SM_ud model (where the two lightest quark generations are treated as degenerate. When entering the process p P -> X, we had to manually define p and P as u#,U#,d#,D#,G.

All samples were generated with SQRT(s) = 1.96 TeV and used the CTEQ 5L parton distribution functions:

#Initial_state   SQRT(S) 1.960000E+03
  Rapidity(c.m.s) 0.000000E+00
  StrFun1: PDF:CTEQ5L(proton)
  StrFun2: PDF:CTEQ5L(anti-proton)

#Physical_Parameters
        EE = 3.122300000000000E-01
        SW = 4.730000000000000E-01
        MZ = 9.118840000000000E+01
        wZ = 2.494440000000000E+00


W+gamma: pP > e+ ve a (TOTAL cuts)

latest version: /cdf/data22d/chadd/comphep/samples/new-wgamma-total.pev (updated 09/06/2002)

#Subprocess 1 (U#, d# -> A, e1, N1)

#Kinematical_scheme
12 -> 3 , 45
45 -> 4 , 5

#Cuts
*** Table ***
 Cuts
  Parameter  |> Min bound <|> Max bound <|
T3           |6.0          |
T4           |1.0          |
T5           |1.0          |
N3           |-6.0         |6.0
N4           |-6.0         |6.0
N5           |-6.0         |6.0
J34          |0.2          |
==========================================

#Regularization
*** Table ***
 Regularization
 Momentum    |> Mass  <|> Width <| Power|
=========================================


#Subprocess 1 (U#, d# -> A, e1, N1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     1.6442E+00       7.37E-01   907200        1
#Subprocess 2 (d#, U# -> A, e1, N1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     1.2135E+01       4.70E-01   907200        2


Cross section for subprocess # 1 = 1.6442 pb
Cross section for subprocess # 2 = 12.135 pb

Total cross section is:   13.7792 pb

For 25000 mixed events:
 subprocess 1 should have 3100 events
 subprocess 2 should have 22100 events


results/events_5.txt:3085
results/events_6.txt:22030

MixPEV:  Mixed/randomized events (file events_6.txt exhausted): 25115





W+gamma: pP > e+ ve a (WIDE cuts)

latest version: /cdf/data22d/chadd/comphep/samples/new-wgamma-wide.pev (updated 09/06/2002)

#Subprocess 1 (U#, d# -> A, e1, N1)

#Kinematical_scheme
12 -> 3 , 45
45 -> 4 , 5

#Cuts
*** Table ***
 Cuts
  Parameter  |> Min bound <|> Max bound <|
T3           |6.0          |
T4           |12.0         |
T5           |6.0          |
N3           |-2.5         |2.5
N4           |-2.5         |2.5
N5           |-6.0         |6.0
J34          |0.2          |
==========================================

#Regularization
*** Table ***
 Regularization
 Momentum    |> Mass  <|> Width <| Power|
=========================================


#Subprocess 1 (U#, d# -> A, e1, N1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     1.0753E+00       4.79E-01   907200      0.6
#Subprocess 2 (d#, U# -> A, e1, N1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     7.4674E+00       4.59E-01   907200    1E+01


Cross section for subprocess # 1 = 1.0753 pb
Cross section for subprocess # 2 = 7.4674 pb

Total cross section is:   8.5427 pb

For 25000 mixed events:
 subprocess 1 should have 3200 events
 subprocess 2 should have 22000 events


results/events_5.txt:3177
results/events_6.txt:21850

MixPEV:  Mixed/randomized events (file events_6.txt exhausted): 25189



W+gamma: pP > e+ ve a (TIGHT cuts)

latest version: /cdf/data22d/chadd/comphep/samples/new-wgamma-tight.pev (updated 09/03/2002)

#Subprocess 1 (U#, d# -> A, e1, N1)

#Kinematical_scheme
12 -> 3 , 45
45 -> 4 , 5

#Cuts
*** Table ***
 Cuts
  Parameter  |> Min bound <|> Max bound <|
T3           |25.0         |
T4           |25.0         |
T5           |25.0         |
N3           |-1.0         |1.0
N4           |-1.0         |1.0
N5           |-6.0         |6.0
J34          |0.4          |
==========================================

#Regularization
*** Table ***
 Regularization
 Momentum    |> Mass  <|> Width <| Power|
=========================================


#Subprocess 1 (U#, d# -> A, e1, N1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     1.9882E-03       9.12E-01  2268000        1
#Subprocess 2 (d#, U# -> A, e1, N1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     2.0406E-02       1.02E+00  2268000        2


Cross section for subprocess # 1 = 0.0019882 pb
Cross section for subprocess # 2 = 0.020406 pb

Total cross section is:   0.0223942 pb

For 25000 mixed events:
 subprocess 1 should have 2300 events
 subprocess 2 should have 22900 events  (used 23000)


results/events_11.txt:2243
results/events_12.txt:20859

MixPEV:  Mixed/randomized events (file events_12.txt exhausted): 23356
PAW:     ==>  23355 events have been read    --> not sure why there is a discrepancy here <--

 Integrated cross section (pb) = 0.2236822E-01
                              +- 0.1463662E-03

This comes from createoutput.kumac (MYCUT=1) and printxintdata.kumac:

 XINTDATA(25) = 0.0223539    = 22.4
 XINTDATA(30) = 0.0160681    = 16.1
 XINTDATA(40) = 0.00826633   =  8.27
 XINTDATA(50) = 0.00503105   =  5.03
 XINTDATA(60) = 0.00339713   =  3.40
 XINTDATA(80) = 0.00168851   =  1.69
 XINTDATA(100) = 0.000967326 =  0.967
 XINTDATA(120) = 0.000560283 =  0.560
 XINTDATA(140) = 0.000343832 =  0.344
 XINTDATA(160) = 0.00022986  =  0.230
 XINTDATA(180) = 0.000126423 =  0.126
 XINTDATA(200) = 9.19439E-05 =  0.092

Zgamma: pP > e+ e- a (TOTAL cuts)

latest version: /cdf/data22d/chadd/comphep/samples/new-zgamma-total.pev (updated 09/03/2002)

#Subprocess 1 (u#, U# -> A, e1, E1)

#Kinematical_scheme
12 -> 3 , 45
45 -> 4 , 5

#Cuts
*** Table ***
 Cuts
  Parameter  |> Min bound <|> Max bound <|
T3           |6.0          |
T4           |1.0          |
T5           |1.0          |
N3           |-6.0         |6.0
N4           |-6.0         |6.0
N5           |-6.0         |6.0
J34          |0.2          |
J35          |0.2          |
J45          |0.2          |
==========================================

#Regularization
*** Table ***
 Regularization
 Momentum    |> Mass  <|> Width <| Power|
=========================================


#Subprocess 1 (u#, U# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     8.5553E+00       1.10E+00   192000        6
#Subprocess 2 (U#, u# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     1.0956E+00       9.92E-01   192000    1E+01
#Subprocess 3 (d#, D# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     2.2581E+00       1.22E+00   192000        9
#Subprocess 4 (D#, d# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     6.2228E-01       1.02E+00   192000        4


Cross section for subprocess # 1 = 8.5553 pb
Cross section for subprocess # 2 = 1.0956 pb
Cross section for subprocess # 3 = 2.2581 pb
Cross section for subprocess # 4 = 0.62228 pb

Total cross section is:   12.53128 pb

For 25000 mixed events:
 subprocess 1 should have 17200 events
 subprocess 2 should have 2300 events
 subprocess 3 should have 4600 events
 subprocess 4 should have 1300 events

Zgamma: pP > e+ e- a (WIDE cuts)

latest version: /cdf/data22d/chadd/comphep/samples/new-zgamma-wide.pev (updated 09/03/2002)

#Subprocess 1 (u#, U# -> A, e1, E1)

#Kinematical_scheme
12 -> 3 , 45
45 -> 4 , 5

#Cuts
*** Table ***
 Cuts
  Parameter  |> Min bound <|> Max bound <|
T3           |6.0          |
T4           |6.0          |
T5           |6.0          |
N3           |-2.5         |2.5
N4           |-2.5         |2.5
N5           |-2.5         |2.5
J34          |0.2          |
J35          |0.2          |
J45          |0.2          |
==========================================

#Regularization
*** Table ***
 Regularization
 Momentum    |> Mass  <|> Width <| Power|
=========================================


#Subprocess 1 (u#, U# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     3.1395E+00       1.21E+00   153600        2
#Subprocess 2 (U#, u# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     2.7621E-01       1.16E+00   153600        5
#Subprocess 3 (d#, D# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     1.5066E+00       8.49E-01   153600        3
#Subprocess 4 (D#, d# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     4.0551E-01       8.18E-01   153600        3


Cross section for subprocess # 1 = 3.1395 pb
Cross section for subprocess # 2 = 0.27621 pb
Cross section for subprocess # 3 = 1.5066 pb
Cross section for subprocess # 4 = 0.40551 pb

Total cross section is:   5.32782 pb

For 25000 mixed events:
 subprocess 1 should have 14800 events
 subprocess 2 should have 1400 events
 subprocess 3 should have 7200 events
 subprocess 4 should have 2000 events


results/events_17.txt:14675
results/events_18.txt:1384
results/events_19.txt:7151
results/events_20.txt:1994

MixPEV:  Mixed/randomized events (file events_17.txt exhausted): 24985

Zgamma: pP > e+ e- a (TIGHT cuts)

latest version: /cdf/data22d/chadd/comphep/samples/new-zgamma-tight.pev (updated 09/04/2002)

#Subprocess 1 (u#, U# -> A, e1, E1)

#Kinematical_scheme
12 -> 3 , 45
45 -> 4 , 5

#Cuts
*** Table ***
 Cuts
  Parameter  |> Min bound <|> Max bound <|
T3           |25.0         |             |
T4           |12.0         |             |
T5           |12.0         |             |
N3           |-1.0         |1.0          |
N4           |-2.5         |2.5          |
N5           |-2.5         |2.5          |
J34          |0.4          |             |
J35          |0.4          |             |
J45          |0.4          |             |
==========================================

#Regularization
*** Table ***
 Regularization
 Momentum    |> Mass  <|> Width <| Power|
=========================================


#Subprocess 1 (u#, U# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     1.5261E-01       6.10E-01   907200      0.8
#Subprocess 2 (U#, u# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     9.7307E-03       4.96E-01   907200      0.5
#Subprocess 3 (d#, D# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     5.8093E-02       6.24E-01   907200      0.3
#Subprocess 4 (D#, d# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     1.6035E-02       4.93E-01   907200      0.5


Cross section for subprocess # 1 = 0.15261 pb
Cross section for subprocess # 2 = 0.0097307 pb
Cross section for subprocess # 3 = 0.058093 pb
Cross section for subprocess # 4 = 0.016035 pb

Total cross section is:   0.2364687 pb

For 25000 mixed events:
 subprocess 1 should have 16200 events
 subprocess 2 should have 1100 events
 subprocess 3 should have 6200 events
 subprocess 4 should have 1800 events


results/events_5.txt:16112
results/events_6.txt:1099
results/events_7.txt:6169
results/events_8.txt:1784

MixPEV:  Mixed/randomized events (file events_7.txt exhausted): 24972
PAW:     ==>  24972 events have been read

 Integral first photon Et spectrum in 10.00 GeV bins (Et_gamma > 0, > 10, ... , > 200)
 0.179E+00 0.179E+00 0.179E+00 0.101E+00 0.389E-01 0.217E-01 0.141E-01 0.995E-02 0.727E-02 0.512E-02
 0.369E-02 0.280E-02 0.204E-02 0.163E-02 0.125E-02 0.973E-03 0.737E-03 0.614E-03 0.463E-03 0.416E-03
 0.284E-03 

 Integrated cross section (pb) = 0.2360070    
                              +- 0.1493459E-02

Zgamma: pP > e+ e- a (TIGHT cuts, large sample)

latest version: /cdf/data22d/chadd/comphep/samples/new-zgamma-tight-large.pev (updated 09/04/2002)

#Subprocess 1 (u#, U# -> A, e1, E1)

#Kinematical_scheme
12 -> 3 , 45
45 -> 4 , 5

#Cuts
*** Table ***
 Cuts
  Parameter  |> Min bound <|> Max bound <|
T3           |25.0         |             |
T4           |12.0         |             |
T5           |12.0         |             |
N3           |-1.0         |1.0          |
N4           |-2.5         |2.5          |
N5           |-2.5         |2.5          |
J34          |0.4          |             |
J35          |0.4          |             |
J45          |0.4          |             |
==========================================

#Regularization
*** Table ***
 Regularization
 Momentum    |> Mass  <|> Width <| Power|
=========================================


#Subprocess 1 (u#, U# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     1.5261E-01       6.10E-01   907200      0.8
#Subprocess 2 (U#, u# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     9.7307E-03       4.96E-01   907200      0.5
#Subprocess 3 (d#, D# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     5.8093E-02       6.24E-01   907200      0.3
#Subprocess 4 (D#, d# -> A, e1, E1)
 #IT   Cross section [pb]  Error %    nCall   chi**2
 < >     1.6035E-02       4.93E-01   907200      0.5


Cross section for subprocess # 1 = 0.15261 pb
Cross section for subprocess # 2 = 0.0097307 pb
Cross section for subprocess # 3 = 0.058093 pb
Cross section for subprocess # 4 = 0.016035 pb

Total cross section is:   0.2364687 pb

For 250000 mixed events:
 subprocess 1 should have 161400 events
 subprocess 2 should have 10400 events
 subprocess 3 should have 61500 events
 subprocess 4 should have 17100 events


results/events_5.txt:161232
results/events_6.txt:10339
results/events_7.txt:61384
results/events_8.txt:17007

MixPEV:  Mixed/randomized events (file events_7.txt exhausted): 249562
PAW:     ==> 249562 events have been read


Using Henry's integrate_Zg.for script (modified for CompHEP):

 Hit end of file- all done     249562 events
  SUMWIDE =  0.2370640      ERRORWIDE=  0.4728734E-03
  SUMTIGHT =  0.1808897      ERRORTIGHT=  0.4133695E-03
  SUMCC =  0.6248355E-01  ERRORCC=   0.000000    
 
 
 Integral Z pt spectrum in 10.00 GeV bins
 0.181E+00 0.181E+00 0.181E+00 0.102E+00 0.399E-01 0.229E-01 0.150E-01 0.102E-01 0.728E-02 0.527E-02
 0.381E-02 0.277E-02 0.205E-02 0.156E-02 0.118E-02 0.908E-03 0.692E-03 0.545E-03 0.411E-03 0.328E-03
 0.242E-03 
 
 
 Integral first photon Et spectrum in 10.00 GeV bins
 0.181E+00 0.181E+00 0.181E+00 0.102E+00 0.399E-01 0.229E-01 0.150E-01 0.102E-01 0.728E-02 0.527E-02
 0.381E-02 0.277E-02 0.205E-02 0.156E-02 0.118E-02 0.908E-03 0.692E-03 0.545E-03 0.411E-03 0.328E-03
 0.242E-03 

Comparing the integrated cross section above threshold, we get:

Et     small    large
gamma  sample   sample
 25     179     181
 30     101     102
 40     38.9    39.9
 50     21.7    22.9
 60     14.1    15.0
 80     7.27    7.28
100     3.69    3.81
120     2.04    2.05
140     1.25    1.18
160     0.737   0.692
180     0.463   0.411
200     0.284   0.242

Template

vi results/batch.dat                       -->   Get subprocess (for particle ordering), 
                                                 kinematics, cuts, regularization
grep -h -f ~/blah.txt results/prt_*        -->   Subprocess cross section summary
calcneededevents                           -->   Cross section summary (vegassummary.txt)
geteventcounts                             -->   Number of events in each subprocess file
mixPEV                                     -->   Mix events & get final sample
PAW                                        -->   Get cross section from PAW for analysis level cuts


Last updated September 10, 2002
by Chadd Smith