The Planck mass is not considered to be the most massive particle possible. The Planck mass, denoted as MPlM_{ ext{Pl}}MPl, is a fundamental constant in physics that arises from the combination of fundamental constants such as the speed of light, gravitational constant, and Planck's constant. It is defined as approximately 2.176×10−82.176 imes 10^{ -8}2.176×10−8 kilograms.
The Planck mass sets the scale at which quantum gravitational effects are expected to become significant. However, it does not represent the maximum mass of a particle. In fact, the concept of a maximum mass for a particle is not well-defined in current physics.
Particle masses observed in nature span a wide range, from very light particles like neutrinos with masses on the order of 10−210^{ -2}10−2 electron volts (eV) to the Higgs boson with a mass of around 125 giga-electron volts (GeV). There is ongoing research and exploration in particle physics to discover new particles and understand their properties, but there is no theoretical or experimental evidence to suggest that there is an upper limit on particle masses.
It is worth noting that within the framework of the Standard Model of particle physics, the Higgs boson is associated with the generation of particle masses. However, the maximum mass of a particle is not determined by the Higgs boson or the Planck mass alone. It depends on various factors, including the specific theoretical framework, interactions, and phenomena that are yet to be discovered or understood.