540 citations · 2.4k across the 44 of their papers we have counts for
44 papers
The End of the First Act: Spectral Running, Interacting Dark Radiation, and the Hubble Tension in Light of ACT DR6 Data
Mathias Garny, Florian Niedermann, Martin S. Sloth
We point out that constraints on reported by the ACT collaboration in their DR6 data release are surprisingly sensitive to the assumptions made about the initial…
Dark Acoustic Oscillations and the Hubble Tension
Mathias Garny, Florian Niedermann, Martin S. Sloth
The Hubble tension and the recently reported anomaly in data from the Dark Energy Spectroscopic Instrument (DESI) are considered to pose serious challenges to the standard CDM m…
Dark Acoustic Oscillations as an Early-Universe Explanation of the DESI Anomaly
Mathias Garny, Florian Niedermann, Martin S. Sloth
DESI DR2 data have been widely interpreted as evidence for late-time evolving dark energy (DE) with an apparent phantom crossing. Here we investigate an alternative explanation, ba…
String-induced vacuum decay and its gravitational wave signatures
Aleksandr Chatrchyan, Florian Niedermann, Phoebe Richman-Taylor
False vacuum decay typically proceeds via the nucleation of spherical bubbles of true vacuum, described by symmetric field configurations in Euclidean time. In this work, we…
Hot New Early Dark Energy: Dark Radiation Matter Decoupling
Mathias Garny, Florian Niedermann, Henrique Rubira +1
We present a microscopic model of the dark sector that resolves the Hubble tension within standard current data sets (Planck 2018, Pantheon+ and DESI DR2 BAO) based on well-known f…
Axions, Three-Forms, and M-Theory
Florian Niedermann, Ziqi Yan
Scalar fields with masses protected by global shift symmetries, commonly referred to as axions, are abundantly used in effective field theories in cosmology and particle physics. H…
Higher co-dimension de Sitter branes
Florian Niedermann, Antonio Padilla
We extend the arguments of Maldacena and Núñez to include higher co-dimension brane setups and derive a new no-go theorem. Specifically, we show that under reasonable assumptions o…
The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
Eleonora Di Valentino, Jackson Levi Said, Adam Riess +533
The standard model of cosmology has provided a good phenomenological description of a wide range of observations both at astrophysical and cosmological scales for several decades.…
Radiation Exposure from the Dark
Florian Niedermann, Martin S. Sloth
We explore the possibility that exotic forms of dark matter could expose humans on Earth or on prolonged space travel to a significant radiation dose. The radiation exposure from d…
Confronting Cold New Early Dark Energy and its Equation of State with Updated CMB, Supernovae, and BAO Data
Aleksandr Chatrchyan, Florian Niedermann, Vivian Poulin +1
Cold New Early Dark Energy (Cold NEDE) addresses the Hubble tension through a triggered vacuum phase transition in the dark sector. In this paper, we constrain a phenomenological f…
Hot New Early Dark Energy bridging cosmic gaps: Supercooled phase transition reconciles (stepped) dark radiation solutions to the Hubble tension with BBN
Mathias Garny, Florian Niedermann, Henrique Rubira +1
We propose a simple model that can alleviate the tension while remaining consistent with big bang nucleosynthesis (BBN). It is based on a dark sector described by a standard…
NANOGrav meets Hot New Early Dark Energy and the origin of neutrino mass
Juan S. Cruz, Florian Niedermann, Martin S. Sloth
It has recently been speculated that the NANOGrav observations point towards a first-order phase transition in the dark sector at the GeV scale [1]. Here, we show that such a phase…
New Early Dark Energy as a solution to the and tensions
Florian Niedermann, Martin S. Sloth
New Early Dark Energy introduces a new phase of dark energy that decays in a fast-triggered phase transition around matter-radiation equality. The presence of a trigger mechanism s…
Cold New Early Dark Energy pulls the trigger on the and tensions: a simultaneous solution to both tensions without new ingredients
Juan S. Cruz, Florian Niedermann, Martin S. Sloth
In this work, we show that the Cold New Early Dark Energy (Cold NEDE) model in its original form can solve both the Hubble tension and the tension without adding any new ingr…
Profiling Cold New Early Dark Energy
Juan S. Cruz, Steen Hannestad, Emil Brinch Holm +3
Recent interest in New Early Dark Energy (NEDE), a cosmological model with a vacuum energy component decaying in a triggered phase transition around recombination, has been sparked…
Modified gravity approaches to the cosmological constant problem
The FADE Collaboration, Heliudson Bernardo, Benjamin Bose +5
The cosmological constant and its phenomenology remain among the greatest puzzles in theoretical physics. We review how modifications of Einstein's general relativity could allevia…
A grounded perspective on New Early Dark Energy using ACT, SPT, and BICEP/Keck
Juan S. Cruz, Florian Niedermann, Martin S. Sloth
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…
Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies
Elcio Abdalla, Guillermo Franco Abellán, Amin Aboubrahim +200
In this paper we will list a few important goals that need to be addressed in the next decade, also taking into account the current discordances between the different cosmological…
Hot New Early Dark Energy
Florian Niedermann, Martin S. Sloth
New early dark energy (NEDE) makes the cosmic microwave background consistent with a higher value of the Hubble constant inferred from supernovae observations. It is an improvement…
Hot New Early Dark Energy: Towards a Unified Dark Sector of Neutrinos, Dark Energy and Dark Matter
Florian Niedermann, Martin S. Sloth
Hot new early dark energy describes a supercooled, first-order phase transition that takes place at sub-eV temperatures in the dark sector. It lowers the sound horizon, which provi…
Generalised scalar-tensor theories and self-tuning
Edmund J. Copeland, Sukhraj Ghataore, Florian Niedermann +1
We explore a family of generalised scalar-tensor theories that exhibit self-tuning to low scale anti de Sitter vacua, even in the presence of a large cosmological constant. We are…
Perturbative quantum consistency near black-hole horizon formation
Stefan Hofmann, Maximilian Koegler, Florian Niedermann
We study the prelude to black-hole formation using a suspended shell composed of physical matter that fulfills the dominant energy condition. Here, the collapse of the shell is bro…
Deconstructing higher order clockwork gravity
Anastasios Avgoustidis, Florian Niedermann, Antonio Padilla +1
We consider the higher order clockwork theory of gravitational interactions, whereby a number of gravitons are coupled together with TeV strength, but nevertheless generate a Planc…
New Early Dark Energy is compatible with current LSS data
Florian Niedermann, Martin S. Sloth
Recently a full-shape analysis of large-scale structure (LSS) data was employed to provide new constraints on a class of Early Dark Energy (EDE) models. In this note, we derive sim…