nLab bottom-up and top-down model building



Quantum Field Theory

algebraic quantum field theory (perturbative, on curved spacetimes, homotopical)



field theory:

Lagrangian field theory


quantum mechanical system, quantum probability

free field quantization

gauge theories

interacting field quantization



States and observables

Operator algebra

Local QFT

Perturbative QFT

String theory



In particle physics phenomenology one distinguishes two strategies for constructing models of a theory with desired properties:

  • in a “top-down approach” one considers the full theory right away and tries to narrow in, in its space of models, to a subspace of models with the desired properties;

  • in a “bottom-up approach” one first specifies exactly which properties a model is supposed to have, and then incrementally uses the remaining wiggle room to see if this specification may be completed to an actual model of the full theory.

This distinction was highlighted, and the terminology established, in (Aldazabal-Ibáñez-Quevedo-Uranga 00); there in the context of discussion of string phenomenology and specifically of intersecting D-brane models in type II string theory. In fact the article proposes and advertizes the bottom-up-strategy, felt to be in contrast with the, at that time, dominant top-down-strategy going back to (Candelas-Horowitz-Strominger-Witten 85).

snippet grabbed from Aldazabal-Ibáñez-Quevedo-Uranga 00

For more on this see at string phenomenology the section Top-down models and Bottom-up models.


In string phenomenology the terminology as such was introduced and specifically the “bottom-up approach” was advertized in

while the “top-down approach” in string phenomenology originates with

Last revised on October 27, 2021 at 05:02:10. See the history of this page for a list of all contributions to it.