Prime Self-Superposition Structures in the Riemann Explicit Formula

This preprint studies prime and prime-power structures in the Riemann explicit formula through the language of self-superposition. A prime power p^k is interpreted as the k-fold self-superposition of a prime p, and log(p^k)=k log p is interpreted as a self-superposition frequency ladder. The product phase T log(p^k)=T k log p is treated as a structural interpretation of the product phase already present in the standard explicit-formula term sin(T k log p). The paper synthesizes a sequence of SPIR/ABS numerical experiments. V11-V12 identify structural bias in the inverse of the Riemann-von Mangoldt mean term. V13-V16 examine the arithmetic background spectrum in post-bias residuals and test false-positive, random-target, composite-target, and density-corrected controls. V17-V21 study prime self-superposition ladders and the time-prime-space product phase. V22-V25 test frozen held-out validation, expanded held-out validation, window-size robustness, and multiple testing correction. V26 compares ABS/product-phase models with fixed explicit-formula coefficients, and V27 decomposes the coefficients into a dominant repeated explicit-formula structure and smaller local variations. The package also includes a numerical validation of character-twisted prime-power structures for selected Dirichlet L-functions. The contribution is not a replacement of the explicit formula. It is an interpretive and numerical program that clarifies how the explicit formula's prime and prime-power terms can be read as a repetition-with-variation structure of prime self-superposition, and how this structure is implemented in the Riemann zeta function and related Euler-product L-functions.