Colóquios

Smooth reheating via non-Abelian dark sector | Colóquio DFMA

Data: 
quinta-feira, 19 Setembro, 2024 - 14:00 até 15:00
Palestrante: 
Dr. Simona Procacci (Universidade de Genebra)
Resumo: 

 

Abstract: We consider a model, where a single inflaton interacts weakly as an axion with Yang-Mills gauge bosons. As these rapidly thermalize, the friction felt by the inflaton field is increased, leading to a self-amplifying process. If the gauge bosons of the thermal bath represent a dark sector, the reheating of the Standard Model is then realised through portal interactions. The dark relic abundance in this scenario depends mostly on the departure from equilibrium after the universe cools down below the critical temperature, when the dark vectors confine into composite states. This constrains the confinement scale of the dark sector. Moreover, indirect detection and Big-Bang nucleosynthesis set bounds on the portal interactions, revealing a predictive parameter space.

 

 

Bootstrapping the relativistic two-body problem | Colóquio DFMA

Data: 
quinta-feira, 22 Agosto, 2024 - 16:00 até 17:00
Palestrante: 
Dr. Rafael Porto (DESY, Alemanha)
Resumo: 

Abstract: I review the state of the art of modern approaches to gravitational wave physics that leverage ideas and tools from scattering amplitudes and quantum field theory to tackle the gravitational binary problem in (classical) general relativity.

Emulators for beyond-LCDM models and photometric probes | Colóquio DFMA

Data: 
terça-feira, 20 Agosto, 2024 - 16:00 até 17:00
Palestrante: 
Dr. Guilherme Brando (Max Planck Institute for Astrophysics -- Munique. Alemanha)
Resumo: 

Abstract: In this talk, I will discuss the current effort of creating emulators for the non-linear power spectrum in beyond-LCDM models. I will present a pipeline that has been developed to model the matter power spectrum from large to small scales, with a focus on stage-IV photometric galaxy surveys. I will delve into the fundamental components of this pipeline, the consistency checks performed to validate it, and how effectively this new tool performs when conducting a full Bayesian parameter estimation analysis with a survey similar to LSST.
 

 

 

Post-Newtonian observables for aligned-spin binaries from gravitational self-force and Compton amplitudes | Colóquio DFMA

Data: 
quinta-feira, 15 Agosto, 2024 - 16:00 até 17:00
Palestrante: 
Dr. Yilber Fabian Bautista (IPhT-Saclay)
Resumo: 

Abstract: Accurate modeling of compact binaries is essential for gravitational-wave detection and parameter estimation, with spin being an important effect to include in waveform models. In this seminar, I will show how to derive new post-Newtonian (PN) results for the conservative aligned-spin dynamics at next-to-next-to-leading order for the spin3 and spin4 contributions, in addition to the next-to-leading order (NLO) spin5 and spin6 contributions. One approach we follow is the Tutti Frutti method, which relates PN and gravitational self-force (GSF) results through the redshift and spin-precession invariants, by making use of the simple dependence of the scattering angle on the binary mass ratio. However, an ambiguity arises at the NLO spin5 contribution, due to transcendental  functions of the Kerr spin in the redshift; this is also the order at which Compton amplitudes calculations are affected by spurious poles. Therefore, we discuss an additional approach to determine the NLO spin5 and spin6 dynamics: using on-shell Compton amplitudes dictated by homogeneous solutions of the Teukolsky equation, the later solved non-perturbative in terms of the Nekrasov-Shatashvili Function.

Dia 15/08/2024 (quinta-feira), às 16h, na Sala Jayme Tiomno

 

Distillation of quantum non-Markovianity | Colóquio DFMA

Data: 
quinta-feira, 15 Agosto, 2024 - 14:00 até 17:00
Palestrante: 
Profa. Nadja Bernardes - UFPE
Resumo: 

Resumo: Non-Markovianty of open quantum systems dynamics is a physically relevant property which is usually associated with the backflow of (quantum) information. Using this paradigmatic marker, we develop an operational framework to investigate how non-Markovianity for qubit dynamics can be distilled when many copies of the channels are used, possibly allowing for a stronger effect on the backflow of information.

 
 
 

 

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