Prospects for cosmological collider physics

Abstract

It is generally expected that heavy fields are present during inflation, which can leave their imprint in late-time cosmological observables. The main signature of these fields is a small amount of distinctly shaped non-Gaussianity, which if detected, would provide a wealth of information about the particle spectrum of the inflationary Universe. Here we investigate to what extent these signatures can be detected or constrained using futuristic 21-cm surveys. We construct model-independent templates that extract the squeezed-limit behavior of the bispectrum, and examine their overlap with standard inflationary shapes and secondary non-Gaussianities. We then use these templates to forecast detection thresholds for different masses and couplings using a 3D reconstruction of modes during the dark ages (z ∼ 30 − 100). We consider interactions of several broad classes of models and quantify their detectability as a function of the baseline of a dark ages interferometer. Our analysis shows that there exists the tantalizing possibility of discovering new particles with different masses and interactions with future 21-cm surveys. Contents

Probing P and CP violations on the cosmological collider

“…Indeed, the large-mass fall-off behavior of the P-and CP-violating signal obtained in our model is faster than the naive power laws in (54). This suggests that this signal is suppressed by exponential factors like e −πµ h or e −πµ Z , which decrease faster than any powers of…”

Standard Model Background of the Cosmological Collider

“…Given current experimental constraints, these bispetra are likely unobservable in CMB, but future experiments in large scale structure surveys [14] and the 21cm tomography [15] are expected to significantly improve the constraints on primordial non-Gaussianities. For the type of signals we are interested in, it has been forecasted that future 21cm experiments can in principle be sensitive to f N L O(0.01) [16]. Assuming C α , C H ∼ O(1), we see that the SM background would be detectable if f Finally, we note an interesting window of parameter space where the SM background becomes both predictable and observable.…”

Cosmological collider physics and the curvaton

“…Upcoming LSS experiments will improve this by having a precision σ f NL ∼ O(1) [30] which will be useful to probe heavy particle-induced NG [31,32]. The ultimate sensitivity in this regard will be provided by an only cosmic-variance-limited 21-cm experiment which can roughly achieve σ f NL ∼ 10 −4 − 10 −3 [33]. Thus we will consider f NL ∼ 10 −4 as the ultimate limiting strength of NG for observability.…”