Cosmological Collider Signals From a Triangle Loop
Abstract
Triangular loop signals appear frequently in cosmological collider models but their analytical forms remain unknown due to multiple technical challenges. Here, we determine for the first time the leading analytical cosmological collider signals generated by a massive scalar triangle loop in inflationary bispectrum and trispectrum. Combining a directional cutting rule with partial Mellin-Barnes representations, we obtain both the local and nonlocal trispectrum signals in a soft limit and derive the leading signal in the squeezed bispectrum. Remarkably, all these signals are reproduced by the corresponding bubble diagram with a single effective pinched coupling. Signals beyond leading order and cases with arbitrary internal masses, spins, and interactions can be generated within the same framework. Our approach also provides a systematic route to extracting analytical loop signals from general cosmological correlators.
Related
- On the Numerical Integration of One-Loop Cosmological Collider Signals
- General Spin-1 Dynamics During Inflation: Microcausality Constraints and Cosmological Collider Signals
- Cosmological Collider Signals at Strong Mixing
- Analytical Cosmological Collider at Strong Mixing in Laplace Space
- Hubble Susceptibility: Beyond Effective-Mass Spectroscopy in the Cosmological Collider
BibTeX
@misc{qin2026cosmological,
title = {{Cosmological Collider Signals From a Triangle Loop}},
author = {Zhehan Qin and Zhong-Zhi Xianyu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.09288},
eprint = {2609.09288},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.09288},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Cosmological Collider Signals From a Triangle Loop
AU - Zhehan Qin
AU - Zhong-Zhi Xianyu
PY - 2026
DA - 2026/09/08
PB - arXiv
DO - 10.48550/arxiv.2609.09288
UR - https://arxiv.org/abs/2609.09288
AB - Triangular loop signals appear frequently in cosmological collider models but their analytical forms remain unknown due to multiple technical challenges. Here, we determine for the first time the leading analytical cosmological collider signals generated by a massive scalar triangle loop in inflationary bispectrum and trispectrum. Combining a directional cutting rule with partial Mellin-Barnes representations, we obtain both the local and nonlocal trispectrum signals in a soft limit and derive the leading signal in the squeezed bispectrum. Remarkably, all these signals are reproduced by the corresponding bubble diagram with a single effective pinched coupling. Signals beyond leading order and cases with arbitrary internal masses, spins, and interactions can be generated within the same framework. Our approach also provides a systematic route to extracting analytical loop signals from general cosmological correlators.
ER -