What is a graviton and how does the graviton interact with matter?
The existence of gravitons has not been established. In fact, a graviton detector would be beyond any technology we’re likely to be able to construct in the next few centuries. However, gravitons are theoretically attractive to complete the standard model with a bosonic carrier of the gravitational interaction. The only theoretical construct so far proposed that avoids ultra-violet divergence (i.e. infinities in higher-order loop calculations) is superstring theory, in which gravitons are closed loop strings. If gravitons exist, they must interact with matter because gravitons mediate gravitation, and we know gravity affects matter (particles with mass).
