In [[Minimal Supersymmetric Standard Model|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 prettyrather light for the [[electroweak theory]] to work. At the same momentHowever, the loop corrections to the mass are naturally much greater; whichthis 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 [[superpartner]]s dodoes 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 as to whether the little hierarchy problem is serious.
