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Existing continuum theories often inherit assumptions from equilibrium liquid-crystal physics, motivating explicit nonequilibrium formulations. Here, we develop a minimal continuum model of two-dimensional monolayers based on odd mechanics, accounting for broken symmetries and nonequilibrium dynamics. We show that nematic order can support an odd viscous modulus generated by broken time-reversal symmetry and spatial anisotropy, without chirality. The model reproduces half-integer defect motion and stress profiles in Madin\u2013Darby canine kidney (MDCK) monolayers, as well as defect-associated cell accumulation and depletion in neural progenitor and ovarian mesothelium systems. Finally, we estimate the viscous-moduli tensor from measured stress, velocity, and orientation fields in MDCK monolayers and identify a nonzero odd modulus. Our results show that odd mechanics provides a minimal framework for nonequilibrium cell monolayers, complementing conventional active-nematic theories.<\/jats:p>","DOI":"10.64898\/2026.07.25.740723","type":"posted-content","created":{"date-parts":[[2026,7,27]],"date-time":"2026-07-27T20:45:12Z","timestamp":1785185112000},"source":"Crossref","is-referenced-by-count":0,"title":["Achiral Odd Mechanics in Cell Monolayers"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5278-6277","authenticated-orcid":false,"given":"Sreejith","family":"Santhosh","sequence":"first","affiliation":[{"name":"Department of Physics, University of California San Diego"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6007-5878","authenticated-orcid":false,"given":"Mattia","family":"Serra","sequence":"additional","affiliation":[{"name":"Department of Physics, University of California San Diego"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026072918450847000_2026.07.25.740723v1.1","doi-asserted-by":"publisher","DOI":"10.1038\/nrm2720"},{"key":"2026072918450847000_2026.07.25.740723v1.2","doi-asserted-by":"publisher","DOI":"10.1088\/1361-6633\/aa65ef"},{"key":"2026072918450847000_2026.07.25.740723v1.3","doi-asserted-by":"publisher","DOI":"10.1146\/annurev-conmatphys-031218-013516"},{"key":"2026072918450847000_2026.07.25.740723v1.4","doi-asserted-by":"publisher","DOI":"10.1101\/cshperspect.a041653"},{"key":"2026072918450847000_2026.07.25.740723v1.5","doi-asserted-by":"publisher","DOI":"10.1038\/s41580-021-00424-z"},{"key":"2026072918450847000_2026.07.25.740723v1.6","doi-asserted-by":"publisher","DOI":"10.1016\/j.cell.2019.05.052"},{"key":"2026072918450847000_2026.07.25.740723v1.7","doi-asserted-by":"publisher","DOI":"10.1038\/nmat4848"},{"key":"2026072918450847000_2026.07.25.740723v1.8","doi-asserted-by":"publisher","DOI":"10.1038\/nrm.2017.98"},{"key":"2026072918450847000_2026.07.25.740723v1.9","doi-asserted-by":"crossref","first-page":"426","DOI":"10.1038\/nphys1269","article-title":"Physical forces during collective cell migration","volume":"5","year":"2009","journal-title":"Nature physics"},{"key":"2026072918450847000_2026.07.25.740723v1.10","doi-asserted-by":"publisher","DOI":"10.1038\/nmat3025"},{"key":"2026072918450847000_2026.07.25.740723v1.11","doi-asserted-by":"publisher","DOI":"10.1103\/RevModPhys.85.1143"},{"key":"2026072918450847000_2026.07.25.740723v1.12","doi-asserted-by":"crossref","unstructured":"V. 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