mass values in flavor combination do not coincide

Asked by Soyoung on 2020-03-13

Hello,

I am trying to test the Littlest Higgs model.

I generated some processes and WHIZARD keeps complaining like this:
******************************************************************************
******************************************************************************
*** FATAL ERROR: Process 'ththbar': mass values in flavor combination do not coincide.
******************************************************************************
******************************************************************************

What does this mean? What did I type wrong?

Thanks!

Sincerely yours,
So Young

Here is the log file, whizard.log:
|=============================================================================|
| |
| WW WW WW WW WW WWWWWW WW WWWWW WWWW |
| WW WW WW WW WW WW WW WWWW WW WW WW WW |
| WW WW WW WW WWWWWWW WW WW WW WW WWWWW WW WW |
| WWWW WWWW WW WW WW WW WWWWWWWW WW WW WW WW |
| WW WW WW WW WW WWWWWW WW WW WW WW WWWW |
| |
| |
| W |
| sW |
| WW |
| sWW |
| WWW |
| wWWW |
| wWWWW |
| WW WW |
| WW WW |
| wWW WW |
| wWW WW |
| WW WW |
| WW WW |
| WW WW |
| WW WW |
| WW WW |
| WW WW |
| wwwwww WW WW |
| WWWWWww WW WW |
| WWWWWwwwww WW WW |
| wWWWwwwwwWW WW |
| wWWWWWWWWWWwWWW WW |
| wWWWWW wW WWWWWWW |
| WWWW wW WW wWWWWWWWwww |
| WWWW wWWWWWWWwwww |
| WWWW WWWW WWw |
| WWWWww WWWW |
| WWWwwww WWWW |
| wWWWWwww wWWWWW |
| WwwwwwwwwWWW |
| |
| |
| |
| by: Wolfgang Kilian, Thorsten Ohl, Juergen Reuter |
| with contributions from Christian Speckner |
| Contact: <email address hidden> |
| |
| if you use WHIZARD please cite: |
| W. Kilian, T. Ohl, J. Reuter, Eur.Phys.J.C71 (2011) 1742 |
| [arXiv: 0708.4233 [hep-ph]] |
| M. Moretti, T. Ohl, J. Reuter, arXiv: hep-ph/0102195 |
| |
|=============================================================================|
| WHIZARD 2.8.2
|=============================================================================|
| Reading model file '/home/soyoung/programs/whizard/install/share/whizard/models/SM.mdl'
| Preloaded model: SM
| Process library 'default_lib': initialized
| Preloaded library: default_lib
| Reading model file '/home/soyoung/programs/whizard/install/share/whizard/models/SM_hadrons.mdl'
| Reading commands from file 'THTHbar.sin'
| Reading model file '/home/soyoung/programs/whizard/install/share/whizard/models/Littlest.mdl'
| Switching to model 'Littlest'
[user variable] jet = PDG(2, -2, 1, -1, 3, -3, 4, -4, 5, -5, 21)
[user variable] lepton = PDG(-11, -13, -15, 11, 13, 15)
[user variable] nutr = PDG(-12, -14, -16, 12, 14, 16)
[user variable] gaugeb = PDG(23, 24, -24, 25)
[user variable] quark = PDG(2, 1, 3, 4, 5)
[user variable] antiq = PDG(-2, -1, -3, -4, -5)
[user variable] pr = PDG(2, 1, 3, 4, 5, -2, -1, -3, -4, -5, 21)
| Process library 'default_lib': recorded process 'ththbar'
| Process library 'default_lib': compiling ...
| Process library 'default_lib': writing makefile
| Process library 'default_lib': removing old files
| Process library 'default_lib': writing driver
| Process library 'default_lib': creating source code
| Process library 'default_lib': compiling sources
| Process library 'default_lib': linking
| Process library 'default_lib': loading
| Process library 'default_lib': ... success.
sqrts = 1.300000000000E+04
luminosity = 3.610000000000E+01
Littlest.f_vev => 4.000000000000E+03
Littlest.st => 8.000000000000E-01
Littlest.stp => 8.000000000000E-01
Littlest.lam1 => 1.000000000000E+00
Littlest.mzh => 2.767983333333E+03
Littlest.mwh => 2.767983333333E+03
Littlest.mah => 6.624614511667E+02
Littlest.mpsi0 => 2.872152833322E+03
Littlest.mpsi1 => 2.872152833322E+03
Littlest.mpsip => 2.872152833322E+03
Littlest.mpsipp => 2.872152833322E+03
Littlest.mtoph => 3.979202772964E+03
| RNG: Initializing TAO random-number generator
| RNG: Setting seed for random-number generator to 25229
| Initializing integration for process ththbar:
| Beam structure: p, p => lhapdf
| Beam data (collision):
| p (mass = 0.0000000E+00 GeV)
| p (mass = 0.0000000E+00 GeV)
| sqrts = 1.300000000000E+04 GeV
| Phase space: generating configuration ...
| Phase space: ... success.
| Phase space: writing configuration file 'ththbar.i1.phs'
******************************************************************************
******************************************************************************
*** FATAL ERROR: Process 'ththbar': mass values in flavor combination do not coincide.
******************************************************************************
******************************************************************************
WHIZARD run aborted.
~

Question information

Language:
English Edit question
Status:
Solved
For:
WHIZARD Edit question
Assignee:
Juergen Reuter Edit question
Last query:
2020-03-13
Last reply:
2020-03-13
Pascal Stienemeier (pstienem) said : #1

Hi So Young,

the error message "Process 'ththbar': mass values in flavor combination do not coincide." usually means that you used an alias in the process definition of 'ththbar' that contains particles with different masses. WHIZARD complains because for all the particles in an alias, WHIZARD takes just one representative to sample the phase space. This will not work if the particles in an alias differ in their mass.
My guess is that the problem is either the bottom quark in your definition of 'quark' and 'pr' or the fact that you put W and Z bosons in the same alias.

Cheers,
Pascal

Juergen Reuter (j.r.reuter) said : #2

Juergen Reuter suggests this article as an answer to your question:

This always happens if final states contain aliases ("particle containers") with different masses. Note that most particles have different masses by their default setting, in jet definitions strange, charm (and bottom) have to be set as massless explicitly. The reason is that the kinematics of the phase-space configuration does depend on the masses. For high-energy scattering this is mostly irrelevant, but even there convolution with parton distribution functions can introduce a radiative return to low energies where mass effects are relevant, or at least lead to numerical instabilities.
FAQ #3216: “mass values in flavor combination do not coincide”.

Juergen Reuter (j.r.reuter) said : #3

One more note: this safeguard existed already in WHIZARD 1 but accidentally had been dropped in v2.1. It was reintroduced in v2.7.0. It can also be avoided by defining sums of final state processes, e.g.

alias jet = u:d:s:U:D:S
ms = 0
mc = 1.3 GeV

process dijet = e1, E1 => (jet, jet) + (c, cbar)

This will use two different phase-space setups for the massless jets and the charm jets.