{"about":{"site":"https://codewithpapers.app","non_affiliation":"Code with Papers and Syntology are not affiliated with, endorsed by, or sponsored by Papers with Code, Meta, or the pwc-archive mirror.","licence":"CC BY-SA 4.0","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","attribution":"https://codewithpapers.app/attribution","modified":"archive material modified by Syntology; see the attribution page"},"url":"/paper/a-grounded-perspective-on-new-early-dark","title":"A grounded perspective on New Early Dark Energy using ACT, SPT, and BICEP/Keck","arxiv_id":"2209.02708","date":"2022-09-06","proceeding":null,"authors":["Juan S. Cruz","Florian Niedermann","Martin S. Sloth"],"abstract":"We examine further the ability of the New Early Dark Energy model (NEDE) to resolve the current tension between the Cosmic Microwave Background (CMB) and local measurements of $H_0$ and the consequences for inflation. We perform new Bayesian analyses, including the current datasets from the ground-based CMB telescopes Atacama Cosmology Telescope (ACT), the South Pole Telescope (SPT), and the BICEP/Keck telescopes, employing an updated likelihood for the local measurements coming from the S$H_0$ES collaboration. Using the S$H_0$ES prior on $H_0$, the combined analysis with Baryonic Acoustic Oscillations (BAO), Pantheon, Planck and ACT improves the best-fit by $\\Delta\\chi^2 = -15.9$ with respect to $\\Lambda$CDM, favors a non-zero fractional contribution of NEDE, $f_{\\rm NEDE} > 0$, by $4.8\\sigma$, and gives a best-fit value for the Hubble constant of $H_0 = 72.09$ km/s/Mpc (mean $71.48_{-0.81}^{+0.79}$ with $68\\%$ C.L.). A similar analysis using SPT instead of ACT yields consistent results with a $\\Delta \\chi^2 = - 23.1$ over $\\Lambda$CDM, a preference for non-zero $f_{\\rm NEDE}$ of $4.7\\sigma$ and a best-fit value of $H_0=71.77$ km/s/Mpc (mean $71.43_{-0.84}^{+0.84}$ with $68\\%$ C.L.). We also provide the constraints on the inflation parameters $r$ and $n_s$ coming from NEDE, including the BICEP/Keck 2018 data, and show that the allowed upper value on the tensor-scalar ratio is consistent with the $\\Lambda$CDM bound, but, as also originally found, with a more blue scalar spectrum implying that the simplest curvaton model is now favored over the Starobinsky inflation model.","url_abs":"https://arxiv.org/abs/2209.02708v2","url_pdf":"https://arxiv.org/pdf/2209.02708v2.pdf","source":{"archive":"pwc-archive (Hugging Face), CC BY-SA 4.0","snapshot":"2025-07-28","licence_url":"https://creativecommons.org/licenses/by-sa/4.0/legalcode","row_kind":"links_only","authors_date_abstract":"arXiv metadata, CC0 1.0 (https://info.arxiv.org/help/license), from the Kaggle arXiv metadata snapshot of 2026-09-12"},"code_links":[{"paper_slug":"a-grounded-perspective-on-new-early-dark","repo_url":"https://github.com/flo1984/TriggerClass","is_official":1,"mentioned_in_paper":1,"mentioned_in_github":0,"framework":"none","reach":null}],"tasks":[],"methods":[],"datasets_introduced":[],"methods_introduced":[],"results":[],"syntology":{"syntology_url":null,"atlas_url":null,"mcp":null,"developers":"https://syntology.ai/developers"},"arxiv_metadata":null,"syntology_extracted_results":null}