Automatic model builder


The Automatic Model builder can be used as an educational toy. The scientific data, which the program uses, is from late 1990's and therefore the results may not correspond to the current scientific knowledge of neutrinos.


The Automatic Model Builder is a computer program (Java servlet) that builds a particle physics model that solves the problems you choose. For most cases, the solution is incomplete, though, but with realistic choices you may get a reasonable result.

The Automatic Model Builder is controlled by filling the following www-form. After making your choices, submit your order by pressing the submit button, and hope for the best.

What do you want to buy?

Place a click on the observations you want to solve by neutrinos:

Solar neutrino problem

  • Cl-Ar experiments
  • Gallium experiments
  • Water Cerenkov experiments
  • Time variations and correlations with other solar phenomena (sunspots, solar magnetic phenomena)
Atmospheric neutrino problem
Dark matter
Generation of baryon or lepton asymmetry
LSND events
Karmen time anomalies
Anomalous ionization of interstellar matter
Supernova nucleosynthesis of heavy elements
Supernova explosions
Big bang nucleosynthesis "crisis"
Other anomalies:

What do you want to pay?

What kind of neutrinos do you want to have?
Majorana neutrinos. The most general case.
Dirac neutrinos. Special case of Majorana neutrinos with the right-handed states.
Weyl neutrinos. Completely massless!
What kind of mechanisms do you want to use for generating neutrino masses? Select at least one. Check all to let the program to make the choice (recommended).
See-saw mechanism. Assumes the existence of right-handed neutrino states.
Radiative mechanisms. Assumes the existence of new (possibly ad hoc) scalar bosons.
Directly by a coupling to a higgs that acquires a non-zero vacuum expectation value.
Quantum gravity. Always speculative.
What other properties do you want to generate for neutrinos.
Magnetic moments. Assumed implicitly in radiative models and some other cases.
Conventional mass hierarchy. Preferred by some for aesthetic reasons.
Other features you may include:
New gauge interactions
New global symmetries - if broken leads to the existence of Goldstone bosons, like majorons.
Existence of light singlet (sterile, right-handed) neutrinos. You need a new symmetry protecting the right-handed neutrinos from having bare masses, unless you want to tune them by hand.
What is your tolerance for fine tuning?
Definitely no finetuning
Moderate tuning can do
Anything that fits is OK
How much weight you put for the constraints from the primordial universe?
Ignore completely
some weight (=allow four equivalent neutrino species but no more)
Take at face value (= a fourth light neutrino species not allowed)
And what about the constraints from the supernova dynamics?
Use conservative limits
My model should not affect the dynamics.
If you want to restrict your query to a specific model, choose it from below. You are strongly recommended to be satisfied with the pre-selected model, since the others probably do not work.
no specific model
minimally extended standard model
Superstring inspired
Model with quantum gravity

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Last update 9 January 1998 by Juha Peltoniemi (

Last modified 17.1.2003 (webmaster)