标准模型在最简化的情况下展示了 17 种粒子，包含 12 种费米子、4 种传递力的玻色子以及赋予质量的希格斯玻色子。然而，如果将反粒子、八种不同的胶子、夸克的三种颜色，以及区分左右手性的手性与极化状态全部纳入计算，基本粒子的总数会迅速增加至 118 种，这些状态在物理行为和相互作用中扮演著截然不同的角色。
更深层的物理规律显示粒子的自由度取决于观测的能量尺度，物理学家施威默与科马尔戈茨基在 2011 年证实的「a定理」表明，有效自由度会随著尺度放大而减少。根据该定理的数学推导，标量场、物质场和力场分别被赋予了特定的自由度数值，这使得标准模型的总自由度达到了惊人的 995.5，揭示了量子场论中仍有许多未解之谜。
Regarding how many elementary particles exist in nature, physicists do not have a simple unified answer, with responses ranging from the textbook number of 17, to 118 when accounting for antiparticles, color, and chiral states, and even reaching 995.5 degrees of freedom in mathematical theory. It ultimately depends on one's taste for complexity and the scale of observation and calculation.
In its simplest representation, the Standard Model displays 17 particles, including 12 fermions, 4 force-carrying bosons, and the mass-giving Higgs boson. However, if antiparticles, eight distinct gluons, three quark colors, and the chiral and polarization states that distinguish left- and right-handedness are all factored into the count, the total number of elementary particles quickly escalates to 118, as these states play completely different roles in physical behaviors and interactions.
Deeper physical laws reveal that a particle's degrees of freedom depend on the energy scale of observation, and the "a-theorem" proved by physicists Schwimmer and Komargodski in 2011 shows that effective degrees of freedom must decrease as one zooms out. According to the mathematical derivation of the theorem, specific values of degrees of freedom are assigned to scalar, matter, and force fields, resulting in a staggering total of 995.5 degrees of freedom for the Standard Model and revealing that much remains misunderstood in quantum field theory.