The ΛCDM model provides a thoroughly tested account of the cosmic microwave background, yet persistent large-angle anomalies remain unexplained. Among these is the hemispherical power asymmetry (HPA), an L=1 dipolar modulation reported in Planck at the 2–3σ level. The participatory horizon programme proposes that large-scale CMB anomalies occur because the observer's causal diamond acts as a recording aperture on the realised sky, otherwise retaining ΛCDM. Previous papers derived a three-level scalar recording architecture addressing the geometry of the low-power, cosmic dipole, alignment, and parity anomaly sectors. The current paper extends this work to address the HPA.
\nWe show that every sign-erasing scalar channel constructed in the programme's architecture produces an antipodally even evidence rate whose odd spherical harmonic content vanishes identically, structurally blocking the scalar sector from L=1. The lowest-rank extension of the local stress-energy measurement class that evades this obstruction is a tangent vector evidence current built from the modularly weighted momentum-density component T\u2080\u1d62. Its curl component on the sky sphere produces a pure L=1 pseudoscalar, χ_H(n\u0302) = n\u0302·(v\u0302 × Qv\u0302). If the classical evidence register processes the scalar and curl readouts jointly, this pseudoscalar can enter recording completeness at first order while leaving the diagonal C_\u2113 unchanged.
\nAs an exploratory full-sky diagnostic, we estimate joint L=1 and L=2 covariance-generator components from the Planck SMICA temperature map. For \u2113=2–64, the recovered L=1 generator  lies 10.0° from the covariance-curl direction d\u0302\u207b_cov = (v\u0302 × Q_cov v\u0302) (p=0.014±0.004, exact null, headless-axis test), while the raw temperature quadrupole gives only 36.2° (p=0.188). The relation introduces no additional fitted direction once Q_cov has been estimated.
\nThe curl channel extends the programme's recording hierarchy to the vector sector. In this interpretation, the hemispheric asymmetry is not attributed to a primordial modulation of the sky, but to an observer-linked recording effect — the observer's motion through the universe skewed by the quadrupolar covariance shear of the recorded field. The vector channel's activation is deferred to future work, while the amplitude solution is developed in a forthcoming paper.
", "languages": [ { "id": "eng", "title": { "en": "English" } } ], "publication_date": "2026-05-06", "publisher": "Zenodo", "related_identifiers": [ { "identifier": "10.5281/zenodo.17956983", "relation_type": { "id": "issupplementedby", "title": { "de": "Wird erg\u00e4nzt durch", "en": "Is supplemented by" } }, "resource_type": { "id": "publication-preprint", "title": { "de": "Preprint", "en": "Preprint" } }, "scheme": "doi" }, { "identifier": "10.5281/zenodo.17946020", "relation_type": { "id": "issupplementedby", "title": { "de": "Wird erg\u00e4nzt durch", "en": "Is supplemented by" } }, "resource_type": { "id": "publication-preprint", "title": { "de": "Preprint", "en": "Preprint" } }, "scheme": "doi" }, { "identifier": "10.5281/zenodo.17922164", "relation_type": { "id": "issupplementedby", "title": { "de": "Wird erg\u00e4nzt durch", "en": "Is supplemented by" } }, "resource_type": { "id": "publication-preprint", "title": { "de": "Preprint", "en": "Preprint" } }, "scheme": "doi" }, { "identifier": "10.5281/zenodo.19528259", "relation_type": { "id": "issupplementedby", "title": { "de": "Wird erg\u00e4nzt durch", "en": "Is supplemented by" } }, "resource_type": { "id": "publication-preprint", "title": { "de": "Preprint", "en": "Preprint" } }, "scheme": "doi" }, { "identifier": "10.5281/zenodo.19639604", "relation_type": { "id": "issupplementedby", "title": { "de": "Wird erg\u00e4nzt durch", "en": "Is supplemented by" } }, "resource_type": { "id": "publication-preprint", "title": { "de": "Preprint", "en": "Preprint" } }, "scheme": "doi" }, { "identifier": "10.5281/zenodo.19647157", "relation_type": { "id": "issupplementedby", "title": { "de": "Wird erg\u00e4nzt durch", "en": "Is supplemented by" } }, "resource_type": { "id": "publication-preprint", "title": { "de": "Preprint", "en": "Preprint" } }, "scheme": "doi" }, { "identifier": "10.5281/zenodo.19658674", "relation_type": { "id": "issupplementedby", "title": { "de": "Wird erg\u00e4nzt durch", "en": "Is supplemented by" } }, "resource_type": { "id": "publication-preprint", "title": { "de": "Preprint", "en": "Preprint" } }, "scheme": "doi" }, { "identifier": "10.5281/zenodo.19713513", "relation_type": { "id": "issupplementedby", "title": { "de": "Wird erg\u00e4nzt durch", "en": "Is supplemented by" } }, "resource_type": { "id": "publication-preprint", "title": { "de": "Preprint", "en": "Preprint" } }, "scheme": "doi" }, { "identifier": "10.5281/zenodo.19722842", "relation_type": { "id": "issupplementedby", "title": { "de": "Wird erg\u00e4nzt durch", "en": "Is supplemented by" } }, "resource_type": { "id": "publication-preprint", "title": { "de": "Preprint", "en": "Preprint" } }, "scheme": "doi" }, { "identifier": "10.5281/zenodo.19722950", "relation_type": { "id": "issupplementedby", "title": { "de": "Wird erg\u00e4nzt durch", "en": "Is supplemented by" } }, "resource_type": { "id": "publication-preprint", "title": { "de": "Preprint", "en": "Preprint" } }, "scheme": "doi" }, { "identifier": "10.5281/zenodo.19840795", "relation_type": { "id": "issupplementedby", "title": { "de": "Wird erg\u00e4nzt durch", "en": "Is supplemented by" } }, "resource_type": { "id": "publication-preprint", "title": { "de": "Preprint", "en": "Preprint" } }, "scheme": "doi" } ], "resource_type": { "id": "publication-preprint", "title": { "de": "Preprint", "en": "Preprint" } }, "rights": [ { "description": { "en": "The Creative Commons Attribution license allows re-distribution and re-use of a licensed work on the condition that the creator is appropriately credited." }, "icon": "cc-by-icon", "id": "cc-by-4.0", "props": { "scheme": "spdx", "url": "https://creativecommons.org/licenses/by/4.0/legalcode" }, "title": { "en": "Creative Commons Attribution 4.0 International" } } ], "subjects": [ { "subject": "cosmic microwave background" }, { "subject": "CMB" }, { "subject": "large-angle anomalies" }, { "subject": "hemispheric power anomaly" }, { "subject": "HPA" }, { "subject": "participatory horizon" }, { "subject": "causal diamond" }, { "subject": "modular Hamiltonian" }, { "subject": "covariance generator" }, { "subject": "curl" }, { "subject": "dipolar modulation" }, { "subject": "Planck" }, { "subject": "quadratic estimator" }, { "subject": "Wheeler participatory universe" } ], "title": "Participatory horizons and the hemispherical power asymmetry: a curl evidence channel", "version": "1" }, "parent": { "access": { "owned_by": { "user": "1490775" }, "settings": { "accept_conditions_text": null, "allow_guest_requests": false, "allow_user_requests": false, "secret_link_expiration": 0 } }, "communities": { "default": "3744609d-c330-4e60-9ff1-54a7df845590", "entries": [ { "access": { "member_policy": "open", "members_visibility": "public", "record_submission_policy": "open", "review_policy": "closed", "visibility": "public" }, "children": { "allow": false }, "created": "2025-12-17T03:30:22.104568+00:00", "custom_fields": {}, "deletion_status": { "is_deleted": false, "status": "P" }, "id": "3744609d-c330-4e60-9ff1-54a7df845590", "links": {}, "metadata": { "description": "This programme explores cosmic anomalies and foundational problems through participatory principles. The project is emerging from its conceptual stages, and is now establishing feasibility and falsifiability. Enquiries welcome.", "organizations": [ { "id": "03b94tp07" } ], "page": "This is a highly exploratory programme exploring anomalies through participatory principles.
\nThe project is at its earliest conceptual stages, and is currently attempting to find its first steps in feasibility and falsifiability. The current studies can be considered simply as thought experiments, posed through phenomenological models.
Enquiries welcome.