Phases of New Physics in the BAO Spectrum. Issue 11 (6th November 2017)

• Record Type: Journal Article
• Authors: Baumann, Daniel; Green, Daniel; Zaldarriaga, Matias
• Is Part Of: Journal of cosmology and astroparticle physics. Volume 2017:Issue 11(2017)
• Page Start: 007
• Page End: 007
• Publication Date: 2017-11-06
• Subjects: baryon acoustic oscillations -- cosmological neutrinos -- cosmological parameters from LSS; Cosmology -- Periodicals; Astrophysics -- Periodicals; 523.0105
• DOI: 10.1088/1475-7516/2017/11/007
• Languages: English
• ISSNs: 1475-7516

Abstract

Abstract: We show that the phase of the spectrum of baryon acoustic oscillations (BAO) is immune to the effects of nonlinear evolution. This suggests that any new physics that contributes to the initial phase of the BAO spectrum, such as extra light species in the early universe, can be extracted reliably at late times. We provide three arguments in support of our claim: first, we point out that a phase shift of the BAO spectrum maps to a characteristic sign change in the real space correlation function and that this feature cannot be generated or modified by nonlinear dynamics. Second, we confirm this intuition through an explicit computation, valid to all orders in cosmological perturbation theory. Finally, we provide a nonperturbative argument using general analytic properties of the linear response to the initial oscillations. Our result motivates measuring the phase of the BAO spectrum as a robust probe of new physics.