Please apologise to my poor English, and I am the bigginner in this field. I have recently read about The inflation of the universe. It said that The Higgs Particles causes universe expansion with acceleration because of its negative density. Does it mean it has a negative mass or a negative volume? Can it be possible? Or It has some deep meaning about negative condensation? (In fact I don't even know what it plays role in standard model.) Moreover, the issue said that The Higgs Particle is one of a candidate to be dark matter. Dark matter is pushing space apart? I don't get it. Thanks a lot.