Heat capacity properties are often prefixed with the term "specific". International standards now recommend that specific heat capacity always refer to division by mass. The units for the specific heat capacity are formula_7. In chemistry, heat capacity is often specified relative to one mole, the unit of amount of substance, and is called the molar heat capacity. It has the unit formula_8. For some considerations it is useful to specify the volume-specific heat capacity, commonly called volumetric heat capacity, which is the heat capacity per unit volume and has SI units formula_9. This is used almost exclusively for liquids and solids, since
Cross section (physics) of the colliding system are , and , before and after the collision respectively, the differential cross section is given by where the on-shell matrix is defined by in terms of the S-matrix. Here is the Dirac delta function. The computation of the S-matrix is the main goal of the scattering theory. Although the SI unit of total cross sections is m, smaller units are usually used in practice. In nuclear and particle physics, the conventional unit is the barn b, where 1 b = 10 m = 100 fm. Smaller prefixed units such as mb and μb are also