Yang-Mills theory is one of the Millennium problems, which are doped by the Clay institute with a million dollars. Yang-Mills theory is concerned with the quantum theory and was confirmed in many experiments, although it assumes that quantum particles that move with the speed of light have mass. According to Einstein, photons or quanta have the rest mass of zero, if they have a mass that he has left open.
After mass conservation law results, in both nuclear fission and nuclear fusion, in which gamma rays are produced, which move with the speed of light, as well as the annihilation of an electron and its antiparticle positron, that photons and thus quanta have mass. The mass of a quantum particle is calculated from the relationship between rest mass and mass according to Einstein. The mass is therefore the rest mass divided by the relativistic root. The relativistic root is again the square root of 1 minus the ratio of the square of the velocity and the speed of light squared. For particles moving at light speed, is that the relativistic root becomes 0. The rest mass is also zero, so the mass of a quantum is 0/0. According to the previous mathematics, this is not defined. In particular, the obvious assumption that 0/0 equals 1, just as any other real number divided by itself is one, cannot be handled with the previous definition of zero. Simple counter-evidence would be 2 * 0 = 0 = 1 * 0. Dividing this equation by 0, and assumed that 0/0 = 1 would come out, that 2 equals 1, which is of course a contradiction. However, if one defines the 0 by taking the factor as an index, you can divide by zero. This idea is analogous to that of imaginary numbers, the roots of negative numbers. 2 * 0 is not equal to 0 then it is 0(2). And 1 * 0 equals 0(1). So 0(1) not equals 0(2). Accordingly, the conventional counter-evidence fails against the assumption that 0/0 = 1. You can read more at the division by zero. With this redefinition of the number 0, we see that the mass of a quantum 0/0 = 1. Thus the particle which moves with the highest speed, which can achieve a particle, has the elementary mass. Accordingly, Yang-Mills theory is confirmed and the problem is not really a big problem.