When matter and antimatter collide, they annihilate each other, releasing a tremendous amount of energy in the process. According to our current understanding of physics, the collision of matter and antimatter should result in the complete conversion of their mass into energy. However, it's important to note that our understanding of the universe is based on the laws of physics as we currently know them, and there are still many mysteries and unanswered questions.
While the annihilation of matter and antimatter is believed to result in the conversion of mass into energy, it's also possible that there may be some remnants or products of the annihilation process. These remnants could potentially include particles such as photons, which are particles of light, or other elementary particles. Additionally, in certain scenarios, it's conceivable that some matter-antimatter asymmetry could exist, which could lead to a small excess of matter particles surviving the annihilation.
However, it's important to emphasize that our current understanding of physics suggests that the complete annihilation of matter and antimatter should result in the conversion of their mass into energy, without any substantial remnants remaining. This understanding is supported by extensive experimental evidence and the successful predictions of particle physics theories.