Abstract The unitarity of time evolution, or colloquially the conservation probability, sits at heart our descriptions fundamental interactions via quantum field theory. implications for scattering amplitudes are well understood, example through optical theorem and cutting rules. In contrast, in-in correlators in curved spacetime associated wavefunction universe, which measured by cosmological surveys, much less transparent. For fields any mass de Sitter with a Bunch-Davies vacuum general...

A bstract We derive a set of no-go theorems and yes-go examples for the parity-odd primordial trispectrum curvature perturbations. work at tree-level in decoupling limit Effective Field Theory Inflation assume scale invariance Bunch-Davies vacuum. show that scalar vanishes presence any number fields with arbitrary mass correlator spinning massless de Sitter mode functions, agreement findings Liu, Tong, Wang Xianyu [1]. The same is true correlators an odd conformally-coupled external fields....

In the standard approach to deriving inflationary predictions, we evolve a vacuum state in time according rules of given model. Since only observables are future values correlators and not their evolution, this brings about large degeneracy: vast number different models mapped same minute observables. Furthermore, due lack time-translation invariance, even tree-level calculations require an increasing nested integrals that quickly become intractable. Here ask how much final can be...

A bstract Speed matters. How the masses and spins of new particles active during inflation can be read off from statistical properties primordial density fluctuations is well understood. However, not when propagation speeds degrees freedom curvature perturbation differ, which generic situation in effective field theory inflationary fluctuations. Here we use bootstrap techniques to find exact analytical solutions for 2-,3- 4-point correlators this context. We focus on imprints a heavy...

Abstract Massive particles produced during inflation leave specific signatures in soft limits of correlation functions primordial fluctuations. When the Goldstone boson broken time translations acquires a reduced speed sound, implying that de Sitter boosts are strongly broken, we introduce novel discovery channel to detect new physics inflation, called cosmological low-speed collider signal. This signal is characterised by distinctive resonance lying mildly-soft kinematic configurations...

Parity violation in the early Universe holds great promise for uncovering new physics. In particular, primordial scalar four-point correlation function is allowed to develop a parity-violating component when massive spinning particles coupled helical chemical potential are present during inflation. this paper, we explore rich physics of such trispectrum presence reduced speed sound Goldstone boson broken time translations. We show that signal can be significantly large while remaining under...

Identifying useful flat-space limits for cosmological correlators, where they can be expressed in terms of observables Minkowski space is nontrivial due to their scale-invariant nature. In recent years, it has been shown that momentum-space correlators encode amplitudes at specific singularities emerge the complex plane kinematics after analytical continuation. This limit massless sense amplitude corresponds ultraviolet regime associated process, masses internal propagators are effectively...

We study the asymmetric primordial fluctuations in a model of inflation which translational invariance is broken by domain wall. calculate corrections to power spectrum curvature perturbations; they are anisotropic and contain dipole, quadrupole, higher multipoles with non-trivial scale-dependent amplitudes. Inspired observations these multipole asymmetries terms two-point correlations variance real space, we demonstrate that this can explain observed anomalous asymmetry cosmic microwave...

We present the model-independent studies of non attractor inflation in context effective field theory (EFT) inflation. Within EFT approach two independent branches non-attractor solutions are discovered which a near scale-invariant curvature perturbation power spectrum is generated from interplay between variation sound speed and second slow roll parameter η. The first branch captures extends previously studied models not frozen on super-horizon scales single non-Gaussianity consistency...

We derive cosmological soft theorems for solids coupled to gravity. To this end, we first all adiabatic modes solids, which display the interesting novelty of non-vanishing anisotropic stresses on large scales. Then, from corresponding symmetries action perturbations compute leading order related using operator product expansion. For scalar bispectrum, re-derive result that Maldacena's consistency relation is recovered only upon angular averaging over long mode direction. In addition, find...

Adiabatic modes are cosmological perturbations that locally indistinguishable from a (large) change of coordinates. At the classical level, they provide model independent solutions. quantum lead to soft theorems for correlators. We present systematic derivation adiabatic in spatially-flat backgrounds with asymptotically-perfect fluids. find several new including vector, time-dependent tensor and scalar modes. The vector decay time standard cosmologies but leading contracting universes....

The celebrated Weinberg theorem in cosmological perturbation theory states that there always exist two adiabatic scalar modes which the comoving curvature is conserved on super-horizon scales. In particular, when perturbations are generated from a single source, such as field models of inflation, both allowed independent solutions and There few known examples literature violate this theorem. We revisit specify loopholes some technical assumptions non-attractor fluid solid inflation model...

The effect of spatial curvature on primordial perturbations is controlled by $ \Omega_{K,0}/c_{s}^{2} $, where \Omega_{K,0} today's fractional density and c_{s} the speed sound during inflation. Here we study these effects in limit c_{s}\ll 1 $. First, show that standard cosmological soft theorems flat universes are violated curved limits correlators can have non-universal contributions even single-clock This a consequence fact that, presence curvature, there gap between spectrum residual...

The initial conditions of our universe appear to us in the form a classical probability distribution that we probe with cosmological observations. In current leading paradigm, this arises from quantum mechanical wavefunction universe. Here ask what imprint mechanics is on late time observables. We show requirement unitary evolution, colloquially conservation probabilities, fixes analytic structure and all correlators it encodes. particular, derive perturbation theory an infinite set...

We provide a complete classification of Poincar\'e-invariant scalar field theories with an enlarged set classical symmetries to leading order in derivatives, namely for the so-called $P(X,\phi)$ theories, two or more spacetime dimensions. find only three possibilities: Dirac-Born-Infeld, Cuscuton and Scaling theories. The latter classes actions involve arbitrary function field. As application, we use scaling symmetry derive infinite constraints on Wilsonian coefficients low-energy Effective...

In this work, we study the imprint of an individual primordial cosmic string within a Hubble patch on inflationary power spectrum. A straight induces two distinct contributions to curvature perturbations The first type correction respects translation invariance while violating isotropy. This generates quadrupolar statistical anisotropy in microwave background maps, which is constrained by Planck data. second contribution breaks both homogeneity and isotropy, generating dipolar asymmetry...

In the setup of ghost condensation model generalized second law black hole thermodynamics can be respected under a radiatively stable assumption that couplings between field responsible for condensate and matter fields such as those in Standard Model are suppressed by Planck scale. Since not only holes but also cosmology expected to play important roles towards our better understanding gravity, we consider cosmological test theory condensation. particular shall show de Sitter entropy bound...

A bstract In contrast to massless spinning particles, scalars are not heavily constrained by unitarity and locality. Off-shell, no gauge symmetries required write down manifestly local theories, while on-shell consistent factorisation is trivial. Instead a useful classification scheme for based on the they can non-linearly realise. Motivated breaking of Lorentz boosts in cosmology, this paper we classify possible shift-symmetric scalar that assumed realise as, example, EFT inflation. Our...

In this work we study the imprints of bubble nucleation on primordial inflationary perturbations. We assume that is formed via tunneling a spectator field from false vacuum its potential to true vacuum. consider configuration in which observable CMB sphere initially outside bubble. As expands, more and regions exterior vacuum, including our sphere, fall into interior The modes leave horizon during inflation at time when wall collides with are affected most. induces non-trivial anisotropic...

We consider production of additional relativistic particles coupled to the inflaton. show that imprints these on spectrum primordial perturbations can be used for direct measurement speed sound scalar perturbations, regardless mechanism this species. study a model where localized sources are decay products heavier generated via resonance mechanism. These emit in-phase inflaton which interfere constructively so-called boom, leading an ``inflationary Cherenkov effect.'' The resulting shock...

Speed matters. How the masses and spins of new particles active during inflation can be read off from statistical properties primordial density fluctuations is well understood. However, not when propagation speeds degrees freedom curvature perturbation differ, which generic situation in effective field theory inflationary fluctuations. Here we use bootstrap techniques to find exact analytical solutions for 2-,3- 4-point correlators this context. We focus on imprints a heavy relativistic...

Massive particles produced during inflation leave specific signatures in soft limits of correlation functions primordial fluctuations. When the Goldstone boson broken time translations acquires a reduced speed sound, implying that de Sitter boosts are strongly broken, we introduce novel discovery channel to detect new physics inflation, called cosmological low-speed collider signal. This signal is characterised by distinctive resonance lying mildly-soft kinematic configurations correlators,...

Parity violation in the early universe holds great promise for uncovering new physics. In particular, primordial scalar four-point correlation function is allowed to develop a parity-violating component when massive spinning particles coupled helical chemical potential are present during inflation. this paper, we explore rich physics of such trispectrum presence reduced speed sound Goldstone boson broken time translations. We show that signal can be significantly large while remaining under...

We derive a set of no-go theorems and yes-go examples for the parity-odd primordial trispectrum curvature perturbations. work at tree-level in decoupling limit Effective Field Theory Inflation assume scale invariance Bunch-Davies vacuum. show that scalar vanishes presence any number fields with arbitrary mass correlator spinning massless de Sitter mode functions, agreement findings Liu, Tong, Wang Xianyu [1]. The same is true correlators an odd conformally-coupled external fields. these...