The transport method is a technique for computing the correlation functions of fluctuations generated in an inflationary epoch during the early universe.

This site collects a number of tools that enable computations to be made in generic inflationary models up to the three-point function. Our numerical methods capture all relevant quantum and classical effects at tree-level, including quantum interference between growing and decaying modes near horizon exit, classical correlation between species near horizon exit and on superhorizon scales, effects from mass hierarchies, and coupling to gravity.

We currently provide three tools with differing capabilities and use cases. PyTransport and CppTransport are two- and three-point function solvers (for multiple-field models with an arbitrary potential and an optional non-Euclidean field-space metric. They use Python and C++, respectively. mTransport is a Mathematica code that solves only for the two-point function, also in multiple-field models with arbitrary potential and a non-Euclidean field-space metric. It is easier to get started with mTransport than PyTransport or CppTransport, but PyTransport and CppTransport have more features.

3-point functions in curved field-space

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PyTransport and CppTransport are automated tools that compute the two- and three-point correlation functions for field-space, tensor and curvature perturbations produced by arbitrary multiple-field inflationary models with optional non-Euclidean field space metric.

PyTransport is a Python platform developed by a team at Queen Mary, University of London. CppTransport is a C++ platform developed by a team at the University of Sussex.

Both tools can compute the statistical properties of the inflationary perturbations directly from the inflationary potential. They both accurately compute the amplitude, shape and scale dependence of the power spectrum and bispectrum. Each package has different strengths and is suitable for different use cases. PyTransport is lightweight and easily scriptable. CppTransport provides a more managed environment, including automated parallelization of large calculations.

Explore CppTransport (New! 2018.1) Explore PyTransport

2-point functions in curved field-space

3Dfeature PyTransport and CppTransport currently do not support inflation models with a non-trivial field-space metric.

mTransport is implemented in Mathematica and computes the two-point correlation function of the curvature and tensor perturbations with an arbitrary field-space metric and scalar potential. It retains all the other benefits of the transport framework including accommodation of arbitrary mass hierarchies.

The code is designed to be simple and easy to follow, and should be useful for anyone interested in computing observables related to the power spectrum of curvature and tensor perturbations in non-canonical multiple-field models.

Explore mTransport

transportmethod.com

tools for automatic computation of inflationary perturbations

3-point functions in curved field-space

2-point functions in curved field-space