Is there matter forming in the inflationary space?

Following the answers and the line of thinking from here Is there enough hydrogen left after a star dies so another star will have enough to light up?

I was wondering if is there any possibility to know if, where new space is created between the galaxies, is there also created any kind of new matter ( i.e. hydrogen, or subatomic particles that could eventually form atoms, which will lead to forming new stars and galaxies ) ?

Matter was formed when the universe was so compact that its temperature was billions and even trillions of Kelvin hot. The energy of the vacuum in any given volume was so high that matter-antimatter pairs were created, which usually quickly annihilated. Sometimes, however those short-lived particles collided, releasing large amounts of energy. For instance, to create an electron you need an energy of 0.5 MeV. The graph below shows that at a temperature of $10^{16}$ K collision energy could be as high as 1 TeV.