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Name

Sébastien Clesse

Position

External collaborator

UCL member card

http://www.uclouvain.be/sebastien.clesse

Projects

Research directions:

Cosmology and General Relativity
Data analysis in HEP, astroparticle and GW experiments

Experiments and collaborations:

Virgo

Non-active projects

Cosmic inflation

Christophe Ringeval

The first measurements of acoustic peaks in the CMB anisotropies strongly suggest that the birth of cosmological fluctuations may have taken place during an early inflationary era of the universe.
In this domain, our activities deal with the construction of explicit models of inflation as well as the extraction of their observable consequences. Our fields of expertise comprise some actively debated subjects as the existence of features (e.g. trans-Planckian effects), inflation with non-minimally coupled scalar fields, DBI- and brane inflation as in the context of String Theory.
For all these theories, we are maintaining various numerical tools such as the ASPIC and FieldInf librairies allowing to compute reheating-consistent predictions for comparison with cosmological data.

External collaborators: Jérôme Martin (IAP, Paris, France), Vincent Vennin (Portsmouth, U.K.), Sébastien Clesse (RWTH, Aachen, Germany).

Cosmological data

André Füzfa, Christophe Ringeval

Our expertise on inflation and cosmic strings is involved in the CMB data analysis of the PLANCK satellite.
Our current efforts concern the study of future CMB polarization experiments, ground based, and in space, as the CORE satellite.
We are part of the EUCLID collaboration and interested in the impact of high precision measurements of the matter power spectra of the large scale structures for cosmic inflation.
We are also involved in the LISA project, the giant space interferometer dedicated to gravitational wave astronomy, which should open a new window on cosmic string physics and other early universe phenomena.
Another direction concerns the 21cm cosmological radiation. This radiation is emitted by neutral hydrogen atoms and should shed light into the so-called "dark ages": from the recombination to the reionisation of the universe by the first stars. This new observable is expected to be sensitive to the nature of dark matter as well as to some properties of the inflationary era.

External collaborators: Sébastien Clesse (RWTH, Aachen), V. Vennin (Portsmooth, U.K.), CORE Coll., Euclid Coll., eLISA Coll.

Gravitational Wave Physics with Virgo

Giacomo Bruno, Antoine Depasse, Jan Govaerts, Jean-Marc Gérard, Vincent Lemaitre, Andrew Miller, Christophe Ringeval, Andres Tanasijczuk

In July 2018 CP3 members have joined the Virgo Collaboration at the European Gravitational Observatory (EGO) near Pisa in Italy. Virgo is the European laser interferometer for gravitational wave detection. After several years of instrument upgrades, Virgo went in observation mode in August 2017, about one year and half after the two LIGO interferometers in the US had detected for the first time gravitational waves. Virgo and LIGO work in close collaboration, sharing data, analysing data and publishing together. Fundamental research in gravitational wave experimental physics was funded for the first time in Belgium at the end of 2018 with a project led by UCLouvain and ULiege. On the data analysis side the plan is on one side to investigate the properties of binary black hole coalescence events, possibly relating them to theoretical models of dark matter and/or primordial black holes, and on the other to search for a stochastic gravitational wave background originating from the very early moments of the life of the Universe, a discovery that would be foundational for cosmology. On the instrumentation side, contributions to computing and the optical system of the Virgo interferometer are planned.
CP3 members are also actively supporting the Einstein Telescope project, a proposed underground laser interferometer project for gravitational wave detection that is expected to take over from LIGO and Virgo around 2030.

Publications in IRMP

All my publications on Inspire

Number of publications as IRMP member: 10
Last 5 publications

2018

CP3-18-15: Cosmology in the era of Euclid and the Square Kilometre Array

Sprenger, Tim and Archidiacono, Maria and Brinckmann, Thejs and Clesse, Sébastien and Lesgourgues, Julien

[Abstract] [PDF] [Journal] [Dial]
48 pages, 11 figures, 8 tables
Refereed paper. February 6.

2017

CP3-17-61: LIGO Lo(g)Normal MACHO: Primordial Black Holes survive SN lensing constraints

Garcia-Bellido, Juan and Clesse, Sebastien and Fleury, Pierre

[Abstract] [PDF] [Journal] [Dial]
7 pages, 7 figures
Refereed paper. December 21.

CP3-17-60: Seven Hints for Primordial Black Hole Dark Matter

Clesse, Sebastien and García-Bellido, Juan

[Abstract] [PDF] [Journal] [Dial]
11 pages, 3 figures
Refereed paper. December 21.

CP3-17-59: Constraints from microlensing experiments on clustered primordial black holes

García-Bellido, Juan and Clesse, Sebastien

[Abstract] [PDF] [Journal] [Dial]
6 pages, 3 figures
Refereed paper. December 21.

2011

CP3-11-16: Observational signatures of a non-singular bouncing cosmology

Marc Lilley, Larissa Lorenz, Sebastien Clesse

[Abstract] [PDF] [Journal] [Dial]
Published in JCAP 06 (2011) 004.
Refereed paper. April 19.

More publications

2010

CP3-10-24: Hybrid inflation along waterfall trajectories

Sébastien Clesse

[Abstract] [PDF] [Journal] [Dial]
updated version accepted for publication in Phys.Rev.D.
Refereed paper. June 23.

CP3-10-23: Initial conditions in hybrid inflation: exploration by MCMC technique

Sébastien Clesse

[Abstract] [PDF]
Proceedings of the 2010 Moriond Conference - Cosmology Session
Contribution to proceedings. June 23.

CP3-10-05: Anamorphosis in Hybrid Inflation: How to avoid fine-tuning of Initial Conditions?

Sébastien Clesse

[Abstract] [PDF] [Journal]
AIP Proceedings of the "Invisible Universe" conference, Palais de l'Unesco, Paris, 29th June to 4th July 2008.
Contribution to proceedings. February 2.

2009

CP3-09-43: Fractal initial conditions and natural parameter values in hybrid inflation

Sébastien Clesse, Christophe Ringeval, Jonathan Rocher

[Abstract] [PDF] [Journal] [Dial]
Published in Phys. Rev. D80, 123534 (2009)
Refereed paper. September 2.

2008

CP3-08-48: Avoiding the blue spectrum and the fine-tuning of initial conditions in hybrid inflation

Sébastien Clesse and Jonathan Rocher

[Abstract] [PDF] [Journal] [Dial]
Published in Phys. Rev. D79, 103507 (2009)
Refereed paper. September 26.