Protos Configurations for VLQ Production

In this page, necessary Protos (PROgram for TOp Simulations) configurations for VLQ production, especially for Tbj channel, are summarized. For introduction and setup, please look at the page https://twiki.cern.ch/twiki/bin/view/Sandbox/ProtosGenerator.

LHAPDF installation

After following the necessary steps described here for lxplus machines, one can install the missing pdf sets by using the command, lhapdf install <name-of-the-pdf-set>.

lhapdf install NNPDF23_lo_as_0130_qed

for instance, and it can be verified with

lhapdf list --installed

Configurations for Tbj

Rose directory contains necessary files for VLQ physics. Protos22/Rose/Tbj/input/run.dat is supposed to be like

Tbj                          ! PROCNAME
1                            ! IMOD
13000d0                      ! CM energy
0                            ! IPPBAR
1                            ! NRUNS
1 0                          ! ILOADGRID, ISAVEGRID
100000  10                   ! NCALL1, ITMX1
100000  10                   ! NCALL2, ITMX2
2017                            ! idum0
1 1 1                        ! IDW1, IDZ1, IDH1
0                            ! ICUT
1 1 1                        ! IEVTOUT, IPLOT, ILOG
0 0 1                        ! IVERB, IPRSUB, IPRAS
700d0 0.1d0                  ! mT, Vmix
-1  1d0                      ! ISCAN, SCANSTEP
247000                        ! IPDSET
1d0 1d0                      ! QFAC1, QFAC2
0                            ! IMATCH: 0 = none; 1 = subtraction; 2 = PT cut
20d0                         ! PTbmin

IEVTOUT has to be 1 in order to obtain the ASCII file with the events (with IPLOT and ILOG you get the plots and the logs respectively, but not the events themselves). Here, Vmix is the coupling of Top partner. IPDSET=247000 is the id of NNPDF23_lo_as_0130_qed.

SM model parameters should be configured by changing smpar.dat file to

91.1876d0               ! MZ
80.399d0                ! MW
125d0                   ! MH
172.5d0                 ! mt
4.95d0                  ! mb
1.55d0                  ! mc
1.777d0                 ! mtau
127.934d0               ! alpha^-1 (MZ)
0.23113d0               ! sW2 (MZ)

Then run it with the command ./Protos-tbj in an upper directory. Necessary outputs, tbj.wgt and tbj.par will be created in Protos22/events directory.

Unweighted events are created by writing Tbj for PROCNAME in Protos22/unw/input/run.dat and running Protos-unw similarly. This time tbj.unw and tbj_unw.par will be created inside the events directory.

Possible Problems at High Mass and Coupling Scenarios

Input mT and GT values are defined as F6.2 in Fortran language by default in Protos. So, Protos can't calculate with masses above 999 GeV (i.e. 4 digits) due to the constraint on mT, and with higher couplings due to the constraint on GT. The recipe is explained below.

Inside /Protos22/Rose/Tbj/evtout.f, change the line

4006 FORMAT (F6.2,' ',F6.3,' ',F6.4,

   & ' ! mT, GT, Vmix')

to

4006  FORMAT (F7.1,'  ',F8.3,'  ',F6.4,
     &  '           ! mT, GT, Vmix')

and similarly inside /Protos22/unw/formats.f make the same changes for unweighting. Then make Protos again! (You may need to say make clean before make command if you make it before.)

-- MesutUnal - 2017-06-06