With the new notions of flat holography introduced in recent years, there has been increased interest in relating the new formalisms to the flat space limit of AdS/CFT. We study Carrollian amplitudes of massless scalars in (1+2) Minkowski space. Using the prescription recently shown by Alday et al. originally designed for the AdS4 Witten diagrams, we show that AdS3 Witten diagrams in position space in the flat space limit reduce to Carrollian amplitudes. The flat space limit in the bulk is implemented by the Carrollian limit at the boundary. Focusing on four-point correlators with contact and exchange diagrams, we show that the Carrollian limit makes the universality of the bulk point singularity manifest upon performing analytic continuation to the Lorentzian signature of the boundary correlators. Unlike four-point Carrollian amplitudes in (1+3) dimensions, the (1+2) dimensional ones are non-distributional, having analytic properties simpler than the AdS correlators. We also report the first observation of a double copy structure of Carrollian amplitudes. 

Generalizing the result to higher spacetime dimensions, we use the scattering equations and ambitwistor strings to prove the correspondence between an appropriate flat limit of boundary correlators in AdS and Carrollian scattering amplitudes – massless amplitudes written in position space on the null conformal boundary – for any number of external states and spacetime dimensions in tree-level, cubic scalar theories. We first derive the Carrollian version of the scattering equations in Minkowski space and their associated Carrollian amplitude formulae, by direct Fourier transform from momentum space and from ambitwistor strings with a Carrollian basis of vertex operators. We then take the flat limit of known formulae for all tree-level boundary correlators of cubic scalar theories in AdS, recovering the Carrollian amplitudes in flat space. In the special case of AdS3, we also make some comments on the flat space limit of spinning boundary correlators.

[1] I. Surubaru, B. Zhu, Carrollian Amplitudes and Holographic Correlators in AdS3/CFT2, Phys. Rev. D 112 (2025) 2, 026023 [2504.07650]

[2] T. Adamo, I. Surubaru and B. Zhu, From AdS correlators to Carrollian amplitudes with the scattering equation, JHEP 02, 198 (2026) [2512.03677]

Biography

朱彬，南开大学物理科学学院副教授。2022年博士毕业于美国东北大学，导师为Tomasz Taylor。2022年至2025年先后在加拿大圆周理论物理研究所和英国爱丁堡大学做博士后。于25年底加入南开大学物理科学学院，研究方向为散射振幅、共形场论和平直时空的全息理论，在PRL, JHEP, PRD, PLB, NPB等期刊发表19篇SCI论文。

Inviter: Song He