Participatory horizons and the CMB parity anomaly: a smoothed antipodal evidence operator
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| Formato: | Recurso digital |
| Lenguaje: | inglés |
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2026
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| _version_ | 1866902237153853440 |
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| author | O'Grady, Gregory |
| author_facet | O'Grady, Gregory |
| contents | <p>The $\Lambda$CDM model accounts for the cosmic microwave background with remarkable precision, yet persistent anomalies at the largest angular scales remain unexplained. Among these, the low-multipole temperature spectrum exhibits an even/odd parity asymmetry at the $0.2$--$0.3\%$ level across $\ell \lesssim 30$. This programme hypothesises that such anomalies reflect the observer's causal diamond acting as a recording aperture on the observed sky, while retaining $\Lambda$CDM as the underlying cosmology.</p> <p>Companion papers derived an angular recording filter, a radial kernel, and a variance decoder from the `Participatory Modular Hamiltonian (PMH)'. The angular filter demonstrated it can resolve the low-power anomaly and the decoder reproduces the quadrupole--octopole alignment, but both channels record only unsigned threshold events and are provably parity-even. Here we show that all local recording-rate mechanisms are blocked from producing parity asymmetry by an exact spherical-harmonic identity, and that the rotationally covariant evasion within the present scalar pairing framework is a nonlocal antipodal kernel for which $P_\ell(-1) = (-1)^\ell$ preserves the parity sign. Three structural principles, namely the antipodal pairing map, the negative sign from evidence optimality, and a heat-kernel smoothing envelope, fix the form of the operator; a geometric scale closure then reduces the model to a single fitted parameter, the contrast amplitude~$\rho$.</p> <p>The one-parameter model gives $2\Delta\ln\mathcal{L} = 5.6$ over $\Lambda$CDM ($\Delta\chi^2 = -7.4$; $\Delta\mathrm{AIC} = -3.6$). The geometric closure retains nearly the full likelihood of the freely fitted model, losing only $\Delta(2\ln\mathcal{L})\simeq0.28$ while reducing the fit from three parameters to one. The parity ratio anomaly moves from the $1$--$3\%$ tail to the $26$--$54\%$ bulk at every tested $\ell_{\max}$, and the $S_{1/2}$ resolution of the angular filter is preserved.</p> <p>The extended unified model is favoured over $\Lambda$CDM by information criteria in its present construction. However, the contrast amplitude $\rho = 0.27$ remains a single fitted parameter. Resolving the programme's amplitude gap from first principles remains the framework's central open problem.</p> |
| format | Recurso digital |
| id | zenodo_https___doi_org_10_5281_zenodo_19840796 |
| institution | Zenodo |
| language | eng |
| publishDate | 2026 |
| publisher | Zenodo |
| record_format | zenodo |
| spellingShingle | Participatory horizons and the CMB parity anomaly: a smoothed antipodal evidence operator O'Grady, Gregory CMB CMB Anomalies Cosmic Microwave Background parity asymmetry low-multipole power spectrum participatory horizon modular Hamiltonian antipodal operator angular recording filter Planck TT Participatory Universe quantum measurement <p>The $\Lambda$CDM model accounts for the cosmic microwave background with remarkable precision, yet persistent anomalies at the largest angular scales remain unexplained. Among these, the low-multipole temperature spectrum exhibits an even/odd parity asymmetry at the $0.2$--$0.3\%$ level across $\ell \lesssim 30$. This programme hypothesises that such anomalies reflect the observer's causal diamond acting as a recording aperture on the observed sky, while retaining $\Lambda$CDM as the underlying cosmology.</p> <p>Companion papers derived an angular recording filter, a radial kernel, and a variance decoder from the `Participatory Modular Hamiltonian (PMH)'. The angular filter demonstrated it can resolve the low-power anomaly and the decoder reproduces the quadrupole--octopole alignment, but both channels record only unsigned threshold events and are provably parity-even. Here we show that all local recording-rate mechanisms are blocked from producing parity asymmetry by an exact spherical-harmonic identity, and that the rotationally covariant evasion within the present scalar pairing framework is a nonlocal antipodal kernel for which $P_\ell(-1) = (-1)^\ell$ preserves the parity sign. Three structural principles, namely the antipodal pairing map, the negative sign from evidence optimality, and a heat-kernel smoothing envelope, fix the form of the operator; a geometric scale closure then reduces the model to a single fitted parameter, the contrast amplitude~$\rho$.</p> <p>The one-parameter model gives $2\Delta\ln\mathcal{L} = 5.6$ over $\Lambda$CDM ($\Delta\chi^2 = -7.4$; $\Delta\mathrm{AIC} = -3.6$). The geometric closure retains nearly the full likelihood of the freely fitted model, losing only $\Delta(2\ln\mathcal{L})\simeq0.28$ while reducing the fit from three parameters to one. The parity ratio anomaly moves from the $1$--$3\%$ tail to the $26$--$54\%$ bulk at every tested $\ell_{\max}$, and the $S_{1/2}$ resolution of the angular filter is preserved.</p> <p>The extended unified model is favoured over $\Lambda$CDM by information criteria in its present construction. However, the contrast amplitude $\rho = 0.27$ remains a single fitted parameter. Resolving the programme's amplitude gap from first principles remains the framework's central open problem.</p> |
| title | Participatory horizons and the CMB parity anomaly: a smoothed antipodal evidence operator |
| topic | CMB CMB Anomalies Cosmic Microwave Background parity asymmetry low-multipole power spectrum participatory horizon modular Hamiltonian antipodal operator angular recording filter Planck TT Participatory Universe quantum measurement |
| url | https://doi.org/10.5281/zenodo.19840796 |