Discussion Overview
The discussion revolves around the highest known spin of particles, both theoretical and experimentally observed. Participants explore the spin values of elementary particles, composite systems, and the implications of theoretical frameworks like the Weinberg-Witten theorem.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
Main Points Raised
- One participant inquires about the highest spin known for particles, referencing an older source that mentions a spin of 11/2.
- Another participant states that for elementary particles in the Standard Model, the highest spin is 1 for particles like photons and gluons, while the theorized graviton has spin 2.
- A different participant mentions that composite systems can achieve higher spins through angular momentum addition, citing the ability to excite nuclei up to about 80 units of angular momentum.
- One participant defines spin as the angular momentum of an object in its rest frame, using a spinning tennis ball as an example.
- In the absence of supersymmetry, a participant claims that the highest possible spin for an elementary particle is 2, referring to the graviton and the Weinberg-Witten theorem.
- Another participant questions whether the Weinberg-Witten theorem applies only to massless particles, which is confirmed by subsequent replies.
- A participant notes that a macroscopic magnet could have spins on the order of 10^23 due to the addition of many electronic spins, and suggests that the 11/2 spin corresponds to the dysprosium 3+ ion.
- One participant clarifies that the theorem discussed pertains to helicity rather than spin.
Areas of Agreement / Disagreement
Participants express differing views on the highest spin values, particularly regarding the distinction between elementary and composite particles, as well as the implications of the Weinberg-Witten theorem. No consensus is reached on the highest spin known.
Contextual Notes
The discussion includes references to theoretical frameworks and specific particles, but lacks clarity on the definitions and assumptions regarding spin and angular momentum in different contexts.