{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:27:53Z","timestamp":1760059673425,"version":"build-2065373602"},"reference-count":57,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2025,7,4]],"date-time":"2025-07-04T00:00:00Z","timestamp":1751587200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Spanish Plan Nacional","award":["PGC2018-102021-B-100","CEX2020-001058-M"],"award-info":[{"award-number":["PGC2018-102021-B-100","CEX2020-001058-M"]}]},{"name":"Maria de Maeztu","award":["PGC2018-102021-B-100","CEX2020-001058-M"],"award-info":[{"award-number":["PGC2018-102021-B-100","CEX2020-001058-M"]}]},{"name":"The Royal Society","award":["PGC2018-102021-B-100","CEX2020-001058-M"],"award-info":[{"award-number":["PGC2018-102021-B-100","CEX2020-001058-M"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Symmetry"],"abstract":"<jats:p>Longstanding anomalies in the Cosmic Microwave Background (CMB), including the low quadrupole moment and hemispherical power asymmetry, have recently been linked to an underlying parity asymmetry. We show here how this parity asymmetry naturally arises within a quantum framework that explicitly incorporates the construction of a geometric quantum vacuum based on parity (P) and time-reversal (T) transformations. This framework restores unitarity in quantum field theory in curved spacetime (QFTCS). When applied to inflationary quantum fluctuations, this unitary QFTCS formalism predicts parity asymmetry as a natural consequence of cosmic expansion, which inherently breaks time-reversal symmetry. Observational data strongly favor this unitary QFTCS approach, with a Bayes factor, the ratio of marginal likelihoods associated with the model given the data pM|D, exceeding 650 times that of predictions from the standard inflationary framework. This Bayesian approach contrasts with the standard practice in the CMB community, which evaluates pD|M, the likelihood of the data under the model, which undermines the importance of low-\u2113 physics. Our results, for the first time, provide compelling evidence for the quantum gravitational origins of CMB parity asymmetry on large scales.<\/jats:p>","DOI":"10.3390\/sym17071056","type":"journal-article","created":{"date-parts":[[2025,7,4]],"date-time":"2025-07-04T04:51:17Z","timestamp":1751604677000},"page":"1056","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["CMB Parity Asymmetry from Unitary Quantum Gravitational Physics"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9632-0815","authenticated-orcid":false,"given":"Enrique","family":"Gazta\u00f1aga","sequence":"first","affiliation":[{"name":"Institute of Cosmology & Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth PO1 3FX, UK"},{"name":"Institute of Space Sciences (ICE, CSIC), 08193 Barcelona, Spain"},{"name":"Institut d\u2019Estudis Espacials de Catalunya (IEEC), 08034 Barcelona, Spain"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3126-8195","authenticated-orcid":false,"given":"K. Sravan","family":"Kumar","sequence":"additional","affiliation":[{"name":"Institute of Cosmology & Gravitation, University of Portsmouth, Dennis Sciama Building, Burnaby Road, Portsmouth PO1 3FX, UK"}]}],"member":"1968","published-online":{"date-parts":[[2025,7,4]]},"reference":[{"key":"ref_1","unstructured":"Chen, B.G., Derbes, D., Griffiths, D., Hill, B., Sohn, R., and Ting, Y.-S. (2018). Lectures of Sidney Coleman on Quantum Field Theory, WSP."},{"key":"ref_2","first-page":"532","article-title":"Quantum Fluctuations and a Nonsingular Universe","volume":"33","author":"Mukhanov","year":"1981","journal-title":"J. Exp. Theor. Phys. Lett."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1036","DOI":"10.1143\/PTP.76.1036","article-title":"Large Scale Quantum Fluctuations in the Inflationary Universe","volume":"76","author":"Sasaki","year":"1986","journal-title":"Prog. Theor. 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