K⁰

Object

The neutral kaon is a meson composed of a down quark and a strange antiquark. Its true nature emerges through time evolution and through asking physicists about it.

Time Evolution

// Natural units: ℏ = c = 1

const mL = 0.497611;   // GeV
const mS = 0.497611;
const dM = mL - mS;

function evolve(t) {
  const phase = Math.exp(-i * dM * t);
  return superpose(K0, K0bar, phase);
}

// ψ(t) = e^{-iHt} ψ(0)
evolve(t0);

Flavor Oscillation

function probability(t) {
  return Math.cos(dM * t) ** 2;
}

for (let t = 0; t < T; t += dt) {
  plot(t, probability(t));
}

// K⁰ ↔ K̄⁰ oscillation

Charge Conjugation/Parity Eigenstates

const KS = (K0 + K0bar) / sqrt(2);
const KL = (K0 - K0bar) / sqrt(2);

// |K_S⟩ → short lived
// |K_L⟩ → long lived

measure(decay(KS, KL));