The quantum spin of a particle is a fundamental property that characterizes its intrinsic angular momentum. The possible combinations of quantum spin depend on the type of particle and its spin value.
- Fermions: Fermions are particles that have half-integer spin values (such as 1/2, 3/2, etc.) and obey the Pauli exclusion principle, which states that no two identical fermions can occupy the same quantum state simultaneously.
For a fermion with spin 1/2, such as an electron, the possible combinations of quantum spin are:
- Spin-up: The spin projection along a chosen axis is +1/2.
- Spin-down: The spin projection along the same axis is -1/2.
These two states form a spinor, and any linear combination of these states is also a valid spin state.
- Bosons: Bosons are particles that have integer spin values (such as 0, 1, 2, etc.) and do not obey the Pauli exclusion principle. Multiple bosons can occupy the same quantum state.
For a boson with spin 1, the possible combinations of quantum spin are:
- Spin-up: The spin projection along a chosen axis is +1.
- Spin-zero: The spin projection along the same axis is 0.
- Spin-down: The spin projection along the same axis is -1.
These three states form a triplet, and linear combinations of these states can also be valid spin states.
For bosons with higher integer spin values, additional spin states can exist.
It's important to note that the actual physical interpretation and behavior of particles with different spin values depend on the specific laws and interactions of the underlying quantum field theory, such as the Standard Model of particle physics. The possible combinations of quantum spin described above represent the basic mathematical framework for spin states.