LiteBIRD is a satellite that will search for primordial gravitational waves emitted during the cosmic inflation era (around 10–38 sec after the beginning of the Universe). It goal is to test representative inflationary models (single-ﬁeld slow-role models with large ﬁeld variation) by performing an all-sky CMB polarization survey.
Primordial gravitational waves are expected to be imprinted in the CMB polarization map as special patterns, called the “B-mode”. If we succeed to detect them, it will provide entirely new and profound knowledge on how our Universe began.
From the viewpoint of high-energy physics or elementary particle physics, the observation of the CMB B-mode is very important because it will allow us to search for physics in ultra high-energy scales, which are not accessible with man-made accelerators. Measurements of CMB polarization will open a new era of testing theoretical predictions of quantum gravity, including those by the superstring theory.