Little hierarchy problem

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In MSSM, the little hierarchy problem is a refinement of the hierarchy problem, namely a puzzle whose existence is already pretty well established. According to quantum field theory, the mass of the Higgs boson must be pretty light for the electroweak theory to work. At the same moment, the loop corrections to the mass are naturally much greater which is known as the hierarchy problem. New physical effects such as supersymmetry may in principle reduce the size of the loop corrections, making the theory natural. However, it is known from experiments that new physics such as superpartners does not occur at very low energy scales, so even if these new particles reduce the Higgs mass, they do not reduce it enough to make the required value completely natural. The expected value of the Higgs mass is about 10 percent of the size of the loop corrections which shows that a certain "little" amount of fine-tuning seems necessary.

Particle physicists have different opinions whether the little hierarchy problem is serious.