We study the CMB observables in axion monodromy inflation. These well-motivated scenarios for inflation string theory have monomial potentials over super-Planckian field ranges, with superimposed sinusoidal modulations from instanton effects. Such periodic of potential can drive resonant enhancements correlation functions cosmological perturbations, characteristic amplitude as a function wavenumber. give an analytical result scalar power spectrum this class models, and we determine limits...

Models of inflation based on axions, which owe their popularity to the robustness against UV corrections, have also a very distinct class signatures. The relevant interactions axion are non-perturbative oscillating contribution potential and shift-symmetric coupling gauge fields. We review how these couplings affect cosmological perturbations via unified study in-in formalism. then note that, when inflaton fields is high enough lead interesting observational results, backreaction produced...

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...

The observation of primordial correlators by cosmological surveys is a very promising avenue to probe high energies and the perturbative regime quantum gravity. Hence, it imperative that we understand how these observables are shaped pillars fundamental physics, namely unitarity, locality symmetries. To this end, study three-point gravitons scalar curvature perturbations around quasi de Sitter spacetime. We identify set Bootstrap Rules fully fix form in asymptotic future, i.e. at boundary,...

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....

This white paper summarizes recent progress in the cosmologicalbootstrap, an approach to study of statistics primordialfluctuations from consistency with unitarity, locality and symmetryassumptions. We review key ideas bootstrap method, aneye towards future directions ambitions program. Focusing onrecent involving de Sitter quasi-de backgrounds, wehighlight role singularities unitarity constraining theform correlators. also discuss nonperturbative formulations ofthe bootstrap, connections...

A bstract Cosmological correlators, the natural observables of primordial universe, have been extensively studied in past two decades using in-in formalism pioneered by Schwinger and Keldysh for study dissipative open systems. Ironically, most applications cosmology focused on non-dissipative closed We show that, systems, correlators can be equivalently computed in-out with familiar Feynman rules. In particular, myriad propagators is reduced to a single (Feynman) time-ordered propagator no...

The field theoretic wavefunction in cosmological spacetimes has received much attention as a fundamental object underlying the generation of primordial perturbations our universe. Assuming an initial Bunch-Davies state, unitary time evolution implies infinite set cutting rules for to all orders perturbation theory, collectively known optical theorem. In this work, we generalise these results case Bogoliubov states, accounting both parity-even and parity-odd interactions. We confirm findings...

The squeezed limit of the three-point function cosmological perturbations is a powerful discriminant different models early Universe. We present conceptually simple and complete framework to relate any primordial bispectrum in this late time observables, such as cosmic microwave background (CMB) temperature scale-dependent halo bias. employ series convenient coordinate transformations capture leading nonlinear effects perturbation theory on these observables. This makes crucial use Fermi...

When inflation is driven by a pseudo-scalar field \chi coupled to vectors as \alpha/4 F \tilde F, this coupling may lead copious production of gauge quanta, which in turns induces non-Gaussian and non-scale invariant corrections curvature perturbations. We point out that mechanism generically at work broad class inflationary models supergravity hence providing them with rich set observational predictions. the fields are massless, significant effects on CMB scales emerge only for relatively...

We provide a derivation from first principles of the primordial bispectrum scalar perturbations produced during inflation driven by canonically normalized field whose potential exhibits small sinusoidal modulations. A this type has been derived in class string theory models based on axion monodromy. use model as concrete example, but we present our derivations and results for general slow-roll with superimposed show analytically that resonance between oscillations background fluctuations is...

We compute the renormalized two-point functions of density, divergence and vorticity velocity in Effective Field Theory Large Scale Structures. Because momentum mass conservation, corrections from short scales to large-scale power spectra must start at order k4. For this constitutes one two leading terms. Exact (approximated) self-similarity an Einstein-de Sitter (ΛCDM) background fixes time dependence so that spectrum is determined by symmetries problem around non-linear scale. show cancel...

We know very little about primordial curvature perturbations on scales smaller than a Mpc. Measurements of the $\ensuremath{\mu}$ distortion cosmic microwave background spectrum provide unique opportunity to probe these over unexplored range from 50 ${10}^{4}\text{ }\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$. This is clean probe, in that it relies only well understood linear evolution. Also, just information low multipoles ($l\ensuremath{\sim}100$) necessary. point out correlations between...

We study the bispectrum in Effective Field Theory of Large Scale Structure, consistently accounting for effects short-scale dynamics. begin by proving that, as long theory is perturbative, it can be formulated to arbitrary order using only operators that are local time. then derive all new required cancel UV-divergences and obtain a physically meaningful prediction one-loop bispectrum. In addition new, subleading stochastic noises viscosity term needed power spectrum, we find three effective...

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...

Poincar\'e invariance is a well-tested symmetry of nature and sits at the core our description relativistic particles gravity. At same time, in most systems not ground state hence broken spontaneously. This phenomenon ubiquitous cosmology where Lorentz boosts are spontaneously by existence preferred reference frame which universe homogeneous isotropic. motivates us to study scattering amplitudes without requiring interactions under boosts. In particular, using on-shell methods assuming...

A bstract Gravitational interferometers and cosmological observations of the cosmic microwave background offer us prospect to probe laws gravity in primordial universe. To study interpret these datasets we need know possible graviton non-Gaussianities. this end, derive most general tree-level three-point functions (bispectra) for a massless all orders derivatives , assuming scale invariance. Instead working with explicit Lagrangians, take bootstrap approach obtain our results using recently...

A bstract The wavefunction in quantum field theory is an invaluable tool for tackling a variety of problems, including probing the interior Minkowski spacetime and modelling boundary observables de Sitter spacetime. Here we study analytic structure coefficients as function their kinematics. We introduce off-shell terms amputated time-ordered correlation functions show that it complex energy plane except possible singularities on negative real axis. These are determined to all loop orders by...

We compute the tree-level late-time graviton four-point correlation function, and related quartic wavefunction coefficient, for Einstein gravity in de Sitter spacetime. derive this result several ways: by direct calculation, using in-in formalism of universe; a heuristic derivation leveraging flat space coefficient; boostless cosmological bootstrap, particular combination optical theorem, amplitude limit, manifestly local test. find agreement among different methods.

A bstract Cosmological correlators from inflation are often generated at tree level and hence loop contributions bounded to be small corrections by perturbativity. Here we discuss a scenario where this is not the case. Recently, it has been shown that for any number of scalar fields mass, parity-odd trispectrum massless must vanish in limit exact scale invariance due unitarity choice initial state. By carefully handling UV-divergences, show one-loop contribution non-vanishing leading....

A bstract Recent progress has revealed a number of constraints that cosmological correlators and the closely related field-theoretic wavefunction must obey as consequence unitarity, locality, causality choice initial state. When combined with symmetries, namely homogeneity, isotropy scale invariance, these enable one to compute large classes simple observables, an approach known (boostless) bootstrap. Here we show it is possible relax restriction if retains discrete scaling subgroup. We find...

A bstract The squeezed limit of the primordial curvature bispectrum is an extremely sensitive probe new physics and encodes information about additional fields active during inflation such as their masses spins. In conventional setup, are stable with a positive mass squared, hence induce decreasing signal in limit, making detection challenging. Here we consider scalar field that temporarily unstable by virtue transient tachyonic mass, construct models which it embedded consistently within...

The primordial non-Gaussian parameter fNL has been shown to be scale-dependent in several models of inflation with a variable speed sound, such as Dirac-Born-Infeld (DBI) models. We perform Fisher matrix analysis the bispectra temperature and polarization Cosmic Microwave Background (CMB) radiation derive expected constraints on nNG that quantifies running fNL(k) for current future CMB missions. find information alone, event significant detection component, corresponding = 50 local model 100...