Short Answer
The tunnelling probability through the Coulomb barrier (exponential suppression at low energy) is the best answer.
Nuclear and particle questions tend to hinge on conservation laws, decay rules, interaction types, or scale. A clean answer usually comes from identifying the process before the details.
Gamow factor: P_tunnel ∝ exp(−2πZ₁Z₂e²/ℏv) — the quantum tunnelling probability through the Coulomb barrier; it dominates stellar reaction rates.
Why This Answer Is Correct
This is a Hard-level question in Nuclear & Particle Physics. The prompt is really testing whether you can connect the concept to its defining physical relationship instead of picking a nearby-but-wrong term.
Track conserved quantities carefully: energy, momentum, charge, lepton number, baryon number, and spin-like constraints when relevant.
Choices At A Glance
- A. Nuclear binding energy
- B. The tunnelling probability through the Coulomb barrier (exponential suppression at low energy)
- C. Fission cross-section
- D. Neutrino flux
When similar options appear on an exam, eliminate the ones that break the core law, use the wrong units, or confuse a definition with a consequence.
Study Next
Review the related formula library
review the theoretical physics hub
Topic Snapshot
Topic: Nuclear & Particle Physics
Difficulty: Hard
Best next move: Re-state the governing law in your own words, then solve one more example from the same topic before moving on.