MICROSCOPE, the Equivalence Principle and the search for a fifth force

• Joël Bergé (ONERA)

Room: 100/-1-A900 - Auditorium Joliot Curie The MICROSCOPE mission allowed for an unprecedented precision on the test of the Weak Equivalence Principle (WEP). The WEP states that all bodies fall at the same rate, independently of their mass and composition, and is the cornerstone of General Relativity (GR). MICROSCOPE’s measurement concept relied on comparing the free fall of two test masses of different compositions as they orbited the Earth. Beside testing GR’s foundation, it allowed us to shed light on modified gravity models involving the existence of a putative fifth force. For instance, the test of the equivalence principle in the Earth orbit sets constraints on long-range (of order a thousand kilometres and more) fifth force, while the interaction of MICROSCOPE’s test masses with each other provides clues on a shorter (of order 0.1 m) fifth force. In this talk, I will first present the MICROSCOPE experiment and test of the WEP. I will then discuss how MICROSCOPE could set new constraints on fifth force models such as a Yukawa deviation from Newtonian gravity, a light dilaton and a chameleon field.