Strongly Coupled Sectors in Inflation: Gapless Theories and Unparticles
arXiv:2503.17840 · doi:10.1007/JHEP04(2026)146
Abstract
We compute correlation functions of the primordial density perturbations when they couple to a gapless, strongly coupled sector of spectator fields -- ``unparticles" -- during inflation. We first derive a four-point function of conformally coupled scalars for all kinematic configurations in de Sitter, which exchanges an unparticle at tree-level, by performing direct integration using the Mellin-Barnes method. To obtain inflationary bispectra and trispectra, we apply weight-shifting operators to the conformally coupled scalar correlator. We show that the correlators solve differential equations determined by the additional symmetries enjoyed by the unparticle propagator. Based on these differential equations, we are able to discuss the spinning-unparticle exchanges, focusing on two possible cases where the currents or the stress tensor of unparticles are coupled to inflatons, with the help of spin-raising operators. Finally, we study the phenomenology of the resulting shape functions. Depending on the value of the unparticle scaling dimension, we classify three characteristic shapes for the inflationary bispectra, including near-equilateral, near-orthogonal, and a novel shape which appears when the scaling dimensions are close to half-integers. More generally, we find that the leading order squeezed limits are insufficient to conclusively determine the detection of a light particle or unparticle. Only the full shapes of bispectra and trispectra can break this degeneracy.
arXiv comment41 pages, 10 figures; v2: references added, typo fixed; v3: typo fixed; v4: typo fixed
References in corpus (74)
- A Large Mass Hierarchy from a Small Extra Dimension
- An Alternative to Compactification
- Non-Gaussian features of primordial fluctuations in single field inflationary models
- The Effective Field Theory of Inflation
- DBI in the Sky
- Observational Signatures and Non-Gaussianities of General Single Field Inflation
- Echoes of a Hidden Valley at Hadron Colliders
- Unparticle Physics
- Primordial Non-Gaussianities from Inflation Models
- Quasi-Single Field Inflation and Non-Gaussianities
- The shape of non-Gaussianities
- Missing Energy Signatures of Dark Matter at the LHC
- Non-Gaussianities in Single Field Inflation and their Optimal Limits from the WMAP 5-year Data
- The Composite Nambu-Goldstone Higgs
- Another Odd Thing About Unparticle Physics
- Composite Higgses
- Signatures of Supersymmetry from the Early Universe
- EPFL Lectures on Conformal Field Theory in D>= 3 Dimensions
- On Soft Limits of Inflationary Correlation Functions
- Large non-Gaussianities with Intermediate Shapes from Quasi-Single Field Inflation
- On non-gaussianities in single-field inflation
- Effective field theory approach to quasi-single field inflation and effects of heavy fields
- Non-Gaussianity as a Particle Detector
- The Higgs boson from an extended symmetry
- Collider signals in unparticle physics
- Equilateral Non-Gaussianity and New Physics on the Horizon
- Comments on Unparticles
- Entanglement entropy in de Sitter space
- The Cosmological Bootstrap: Weight-Shifting Operators and Scalar Seeds
- Primordial fluctuations and non-Gaussianities in multi-field DBI inflation
- The dS/dS Correspondence
- Towards a Big Crunch Dual
- Holographic Description of AdS Cosmologies
- Collider Phenomenology of Unparticle Physics
- Deconstruction of Unparticles
- Productive Interactions: heavy particles and non-Gaussianity
- Constant Curvature Black Holes
- Clean Time-Dependent String Backgrounds from Bubble Baths
- Anti-de Sitter space and black holes
- The dual of nothing
- Boostless Cosmological Collider Bootstrap
- Tilted Ghost Inflation
- Holographic models of de Sitter QFTs
- The Scalar Chemical Potential in Cosmological Collider Physics
- Seeing Higher-Dimensional Grand Unification In Primordial Non-Gaussianities
- Lorentzian CFT 3-point functions in momentum space
- The AdS/CFT/Unparticle Correspondence
- The conformal window in QCD and supersymmetric QCD
- Unparticle & Higgs as Composites
- Colored Unparticles
- Gauge/gravity correspondence in accelerating universe
- Unparticle Dark Matter
- On Time-dependent Backgrounds in Supergravity and String Theory
- Constant Curvature Black Hole and Dual Field Theory
- Anomalous Dimensions and Non-Gaussianity
- Much Ado About Nothing
- A Holographic Dual of CFT with Flavor on de Sitter Space
- An Unparticle Example in 2D
- Real time response on dS_3: the Topological AdS Black Hole and the Bubble
- Continuum Naturalness
- On Bubbles of Nothing in AdS/CFT
- Continuous Spectrum on Cosmological Collider
- Gapped Continuum Kaluza-Klein spectrum
- Time-dependent spacetimes in AdS/CFT: Bubble and black hole
- Composite Higgs theory
- CFTs Blueshift Tensor Fluctuations Universally
- The Thermal Bath of de Sitter from Holography
- Unparticle self-interactions
- Cosmohedra
- Confinement in de Sitter Space and the Swampland
- A Note on Kinematic Flow and Differential Equations for Two-Site One-Loop Graph in FRW Spacetime
- Bananas are Unparticles: Differential Equations and Cosmological Bootstrap
- Unparticles and inflation
- Expansion of hypergeometric functions in terms of polylogarithms with nontrivial variable change