Searching for inflationary physics with the CMB trispectrum. II. Code and validation
Phys. Rev. D 111, 123533 – Published 17 June, 2025
DOI: https://doi.org/10.1103/bprw-3zj1
Abstract
To unlock the vast potential of the cosmic microwave background (CMB) trispectrum, we require both robust estimators and efficient computational tools. In this work, we introduce the public code polyspec: a suite of quartic estimators designed to measure the amplitudes of a wide variety of inflationary templates, including local non-Gaussianity, effective field theory models, direction-dependent trispectra, spinning massive particle exchange, and weak gravitational lensing. polyspec includes a python/cython implementation of each estimator derived by Philcox [O. H. E. Philcox, companion paper, Phys. Rev. D 111, 123532 (2025).] and has been carefully optimized to ensure efficient use of computational resources. We perform a broad range of validation tests, which demonstrate that the estimator is unbiased and minimum variance, both in Gaussian and non-Gaussian regimes. In addition, we forecast constraints on various types of trispectra; this highlights the utility of CMB polarization and demonstrates that many models of primordial physics are poorly correlated with the simple templates considered in previous studies. This work lays the foundation for the Planck trispectrum analyses performed by Philcox [O. H. E. Philcox, companion paper, Phys. Rev. D 111, 123534 (2025).].
