I have very basic question. In the LAMMPS documentation for eDPD (Description)

https://docs.lammps.org/pair_mesodpd.html

looking at the formulas, mass=1 and it does not appear in the Newtonian fromulas. However writing the input file and defining the beads we are able to have mass as an input.

My question is why the mass is defined as 1 in the formulas? if the masses are defined as one, then what are the masses we define the input file? what is the logic? I am confused.

Thank you so much.