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Search for new physics and cosmology measurements

The standard model of particle physics is verified experimentally with a high precision. However it presents some limitations from a theoretical point of view: it does not provide a dark matter candidate, it does not explain why no CP violation is observed in strong interaction, it does not provide a candidate to be the particle responsible for the primordial inflationary phase, and it does not describe gravitation in a common framework with other interactions. The goal of the project is to search for new particles predicted in beyond standard model theories, to constrain some aspects of the structure of the universe related to the inflation, and to search for violations of Lorentz invariance that can appear in particle physics theories that include gravtiation.

Use of extragalactic gamma-ray observations

The observations of distant gamma-ray allow to have access to powerful sources, with large magnetic fields, high energies and important propagation distances. One key point of the CosmoTeV project is that these extragalactic gamma-ray observations give access to fundamental subjects:
- transparency of the universe and axions: axions are particles predicted in beyond standard model theories explaining CP conservation in strong interactions. The existence of axion like particles could modify the optical depth of the TeV photons. Such a scenario might explain the observation of blazars up to redshitfs of 0.6.
- turbulent magnetic fields and axions: If axion-like particles exist, turbulent magnetic fields in TeV photon emission regions could induce effects in the source energy spectra. The observation of TeV blazars can lead to constraints the coupling of axion-like particles to photons by searching for irregularity in their energy spectra.
- large-scale magnetic fields: TeV photons from distant sources can be destroyed by pair creation on the extragalactic background light. Observations of TeV blazars can test the fact that these particles induce an electromagnetic cascade. Some characteristics of the cascade depend on the ambient magnetic field. These observations therefore allow constraining the strength of inter-galactic magnetic fields.
- photon time-of-flight and Lorentz invariance: TeV blazars are variable on short time scales, of the order of one minute.This feature can be used to search for an energy dependent speed of light.logos, abstract, link to the ANR page

Achievements

In the contect of this ANR project, 7 papers were published in peer-reviewed journals, results were presented in 4 international conferences. Results concern the search for axions, tests of Lorentz invariance and measurement of the extragalactic background light. Find out more in the pages on papers and conferences.

P. Brun - last updated Sept 2015