Paper K: The Musical Architecture of the Primes: Perfect Fifths, Golden Ratios, and the Wästlund Circle

The prime gap ratio distribution has a striking property: the Hardy-Littlewood jump discontinuities at 2/3 and 3/2 — the perfect fourth and perfect fifth in Pythagorean music theory — straddle the golden probability levels phi^-2 approximately 0. 382 and phi^-1 approximately 0. 618 respectively. We explain why these specific intervals appear and no others. The answer connects three mathematical structures: the Farey sequence (which selects 2/3 and 3/2 as the unique level-3 Wästlund-dual pair closest to the golden levels), the circle of fifths (which generates all Pythagorean intervals from 3/2), and the Weil explicit formula (which converts between the language of primes and the language of Riemann zeros). The perfect fifth 3/2 is simultaneously the nearest rational approximation to phi^-1 with denominator at most 3, the second Wästlund iterate converging to phi, and the second Fibonacci convergent F₃/F₄. Its appearance in the prime gap distribution is not a coincidence: it is where the Pythagorean and Golden languages of arithmetic first resonate. We state the Harmonic Basis Change Conjecture: the Weil explicit formula is a harmonic basis change on the Wästlund circle between the Pythagorean basis (primes) and the Golden basis (Riemann zeros).