Events List

DateEvent TypeSpeaker
05/01/2024ArXiv DiscussionHEP/Pheno Journal Club [ + ]
05/01/2024HEP SeminarMichael Toomey [ -- ]

Title: Cosmic Tensions and Early Dark Energy
Abstract: Cosmological datasets consistently exhibit growing tension with the Λ Cold Dark Matter (ΛCDM) model of cosmology. The most striking discrepancy is between direct measurements of today's expansion rate (H0) using Cepheid-calibrated supernovae and the expansion rate inferred from ΛCDM fits to early-Universe data sets, namely the cosmic microwave background (CMB). This discrepancy now sits at a 5σ tension. More recently, measurements of galaxy clustering, as parameterized by the amplitude of dark matter density fluctuations (σ8), suggest further tension within the concordance model. One leading proposal to resolve the H0 tension is Early Dark Energy (EDE), which posits a slow-rolling scalar field active shortly before CMB formation. This field acts as a new, brief source of energy injection, modifying the size of the sound horizon—a critical standard ruler for constraining H0. In the first half of this talk, I will discuss the most recent constraints from combined analyses of CMB and large-scale structure datasets, which show that the original axion-like EDE model is strongly disfavored. I will also demonstrate that these constraints are not influenced by prior volume effects, which have been argued to artificially disfavor the model in Bayesian MCMC analyses of EDE. In the final part of the talk, I will present the first constraints on early dark energy using theory-informed priors in an analysis with CMB and large-scale structure datasets. Leveraging normalizing flows, a type of machine learning architecture, this represents the most stringent constraints on the model to date. Along the way, I will also comment on some general insights gained from the detailed analysis of the EDE scenario and how this should inspire model builders to construct future, well-motivated extensions of ΛCDM. (2:00 PM - 3:00 PM, 726 Broadway, 940, CCPP Seminar)
05/02/2024Oral DefenseXucheng Gan [ + ]
05/02/2024Oral DefenseConghuan Luo [ + ]
05/02/2024Physics Dept ColloquiumKathleen Stebe [ + ]
05/03/2024HEP Discussion SessionsZare [ + ]
05/03/2024Oral DefenseMilad Noorikuhani [ + ]
05/06/2024CCPP Brown BagPatrick Breysse [ + ]
05/07/2024Special SeminarAashay Pai [ + ]
05/07/2024Grad Pheno Journal Club [ + ]
05/10/2024HEP Discussion SessionsZare [ + ]
05/13/2024Special SeminarRiccardo Rattazzi [ + ]
05/14/2024Special SeminarRiccardo Rattazzi [ + ]
05/15/2024Special SeminarRiccardo Rattazzi [ + ]
05/16/2024Special SeminarRiccardo Rattazzi [ + ]
05/17/2024Special SeminarRiccardo Rattazzi [ + ]
05/20/2024Special SeminarMultiple Speakers [ + ]
05/27/2024Holiday [ + ]