Problem with computing decay width of p > t z > w+ b l+ l-

Asked by Abdullah Bin Saqlain

Hi, I am trying to get the decays of the process to compute branching rations,
I am using the following commands

import model topFCNC_UFO
generate p > t z > l+ l- w+ b
output
launch -i
calculate_decay_width

I am faced with this error at the end of computation

INFO: Update the dependent parameter of the param_card.dat
WARNING: update the strong coupling value (alpha_s) to the value from the pdf selected: 0.13
WARNING: Failed to update dependent parameter. This might create trouble for external program (like MadSpin/shower/...)
INFO: compile directory
compile Source Directory
Calculating decay widths with run name run_01
survey run_01 --accuracy=0.01 --points=1000 --iterations=9
Using random number seed offset = 21
INFO: Running Survey
Creating Jobs
Working on SubProcesses
INFO: P1_u_tz_epemwpb
INFO: P1_u_tz_mupmumwpb
INFO: P1_c_tz_epemwpb
INFO: P1_c_tz_mupmumwpb
Zero result detected: No Phase Space. Please check particle masses.

ln: failed to create symbolic link 'ME5_debug': File exists

What seems to be the issue here, can you point it out? since i Think I do have correct masses in the param card
For context, here is the param card

######################################################################
## PARAM_CARD AUTOMATICALY GENERATED BY MG5 FOLLOWING UFO MODEL ####
######################################################################
## ##
## Width set on Auto will be computed following the information ##
## present in the decay.py files of the model. ##
## See arXiv:1402.1178 for more details. ##
## ##
######################################################################

###################################
## INFORMATION FOR CKMBLOCK
###################################
Block ckmblock
    1 2.277360e-01 # cabi

###################################
## INFORMATION FOR MASS
###################################
Block mass
    1 5.040000e-03 # MD
    2 2.550000e-03 # MU
    3 1.010000e-01 # MS
    4 1.270000e+00 # MC
    5 4.700000e+00 # MB
    6 1.720000e+02 # MT
   11 5.110000e-04 # Me
   13 1.056600e-01 # MMU
   15 1.777000e+00 # MTA
   23 9.118760e+01 # MZ
   25 1.250000e+02 # MH
## Dependent parameters, given by model restrictions.
## Those values should be edited following the
## analytical expression. MG5 ignores those values
## but they are important for interfacing the output of MG5
## to external program such as Pythia.
  12 0.000000e+00 # ve : 0.0
  14 0.000000e+00 # vm : 0.0
  16 0.000000e+00 # vt : 0.0
  21 0.000000e+00 # g : 0.0
  22 0.000000e+00 # a : 0.0
  24 7.982436e+01 # w+ : cmath.sqrt(MZ__exp__2/2. + cmath.sqrt(MZ__exp__4/4. - (aEW*cmath.pi*MZ__exp__2)/(Gf*sqrt__2)))

###################################
## INFORMATION FOR NEWCOUP
###################################
Block newcoup
    1 0.1000000e+00 # ReXLut
    2 0.000000e+00 # ImXLut
    3 0.000000e+00 # ReXRut
    4 0.000000e+00 # ImXRut
    5 0.1000000e+00 # ReXLct
    6 0.000000e+00 # ImXLct
    7 0.000000e+00 # ReXRct
    8 0.000000e+00 # ImXRct
    9 0.000000e+00 # ReKLut
   10 0.000000e+00 # ImKLut
   11 0.000000e+00 # ReKRut
   12 0.000000e+00 # ImKRut
   13 0.000000e+00 # ReKLct
   14 0.000000e+00 # ImKLct
   15 0.000000e+00 # ReKRct
   16 0.000000e+00 # ImKRct
   17 0.000000e+00 # ReZetaLut
   18 0.000000e+00 # ImZetaLut
   19 0.000000e+00 # ReZetaRut
   20 0.000000e+00 # ImZetaRut
   21 0.000000e+00 # ReZetaLct
   22 0.000000e+00 # ImZetaLct
   23 0.000000e+00 # ReZetaRct
   24 0.000000e+00 # ImZetaRct
   25 0.000000e+00 # ReEtaLut
   26 0.000000e+00 # ImEtaLut
   27 0.000000e+00 # ReEtaRut
   28 0.000000e+00 # ImEtaRut
   29 0.000000e+00 # ReEtaLct
   30 0.000000e+00 # ImEtaLct
   31 0.000000e+00 # ReEtaRct
   32 0.000000e+00 # ImEtaRct
   33 0.000000e+00 # ReLambdaLut
   34 0.000000e+00 # ImLambdaLut
   35 0.000000e+00 # ReLambdaRut
   36 0.000000e+00 # ImLambdaRut
   37 0.000000e+00 # ReLambdaLct
   38 0.000000e+00 # ImLambdaLct
   39 0.000000e+00 # ReLambdaRct
   40 0.000000e+00 # ImLambdaRct

###################################
## INFORMATION FOR SMINPUTS
###################################
Block sminputs
    1 1.279000e+02 # aEWM1
    2 1.166370e-05 # Gf
    3 1.184000e-01 # aS (Note that Parameter not used if you use a PDF set)

###################################
## INFORMATION FOR YUKAWA
###################################
Block yukawa
    1 5.040000e-03 # ymdo
    2 2.550000e-03 # ymup
    3 1.010000e-01 # yms
    4 1.270000e+00 # ymc
    5 4.700000e+00 # ymb
    6 1.720000e+02 # ymt
   11 5.110000e-04 # yme
   13 1.056600e-01 # ymm
   15 1.777000e+00 # ymtau

###################################
## INFORMATION FOR DECAY
###################################
DECAY 6 1.508336e+00 # WT
DECAY 23 2.495200e+00 # WZ
DECAY 24 2.085000e+00 # WW
DECAY 25 4.070000e-03 # WH
## Dependent parameters, given by model restrictions.
## Those values should be edited following the
## analytical expression. MG5 ignores those values
## but they are important for interfacing the output of MG5
## to external program such as Pythia.
DECAY 1 0.000000e+00 # d : 0.0
DECAY 2 0.000000e+00 # u : 0.0
DECAY 3 0.000000e+00 # s : 0.0
DECAY 4 0.000000e+00 # c : 0.0
DECAY 5 0.000000e+00 # b : 0.0
DECAY 11 0.000000e+00 # e- : 0.0
DECAY 12 0.000000e+00 # ve : 0.0
DECAY 13 0.000000e+00 # mu- : 0.0
DECAY 14 0.000000e+00 # vm : 0.0
DECAY 15 0.000000e+00 # ta- : 0.0
DECAY 16 0.000000e+00 # vt : 0.0
DECAY 21 0.000000e+00 # g : 0.0
DECAY 22 0.000000e+00 # a : 0.0

Question information

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Solved by:
Sihyun Jeon
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Revision history for this message
Best Sihyun Jeon (shjeon) said :
#1

This is a setup that is expected to not work

import model topFCNC_UFO
generate p > t z > l+ l- w+ b

Particles in "p" are light quarks and a gluon.
And among those, if you consider charge conservation, only u c are available.
And the mass of those are much smaller than w+ so a particle with mass much smaller than 1GeV cannot produce a particle with 80GeV.

Revision history for this message
Sihyun Jeon (shjeon) said :
#2

https://answers.launchpad.net/mg5amcnlo/+question/818635

it's same as your other question.

generate A > B C > D E

if particle D has larger mass than A, the process has no available phase space.

Revision history for this message
Abdullah Bin Saqlain (abdullah-saqlain) said :
#3

Thanks Sihyun Jeon, that solved my question.