Spin is defined as intrinsic angular momentum, independent of spatial dimensions, and is deduced from the magnetic moment of particles. Current experimental evidence, particularly from the Large Hadron Collider (LHC) at ~10 TeV, indicates that fundamental particles like electrons do not exhibit substructure down to distances of at least 10-17 cm. The notion of internal components contributing to spin is ruled out, as the evidence does not support the idea of smaller particles with half-integer spin existing within electrons. The established concept of intrinsic angular momentum remains robust and would require significant evidence to challenge.
PREREQUISITESPhysicists, students of quantum mechanics, and researchers in particle physics seeking to understand the nature of spin and its implications for fundamental particles.
Simon Bridge said:The calculation shows that the possible internal particles are not so internal.
Orbital angular momentum cannot be half-integer. If the electron were made of "smaller" particles, at least one of those particles would have to have half-integer spin.Idoubt said:We say that spin is an intrinsic angular momentum which does not have anything to do with space. But is it possible that it is the orbital angular momentum of some internal constituent particles (a yet unknown fine structure)?
To probe shorter distances you need higher energy. The highest energy we've explored in detail is ~ 10 TeV by the LHC, and there's no indication that the particles we currently believe are elementary might instead be composite. The electron is still pointlike, it shows no substructure down to a distance of at least 10-17 cm.Idoubt said:Are you saying that the observed experimental data rules out a further fine structure for elementary particles in the standard model? I know that the existence of quarks were confirmed from high energy scattering from nucleons. My question is with the current experimental evidence how strongly will we say that a further fine structure is not possible.
No - I am being much more specific than that: I am saying that the evidence is not consistent with the intrinsic magnetic moment being produced by internal components having some kind of rotation. The evidence so far pretty much rules out turning internal components as the source of the spin. Fundamental particles are just not big enough.Idoubt said:Could you elaborate a little? Are you saying that the observed experimental data rules out a further fine structure for elementary particles in the standard model?
This is quite a different question from the one you started out asking - I will echo Bill_K on this one. Any sub-structure is certainly on scales less than 10-17cm.I know that the existence of quarks were confirmed from high energy scattering from nucleons. My question is with the current experimental evidence how strongly will we say that a further fine structure is not possible.