arXiv subjects

Thomas Pignard

Publications and source records attributed to Thomas Pignard.

3 recordsLinked to original sources

arXiv2026

Variable-phase methods and data for long-range scattering

Long-range interactions play an important role in dark-matter phenomenology, affecting the relic abundance, indirect-detection signals, and structure formation on galactic scales. Reliable predictions often require nonperturbative solutions of the Schrödinger equation over broad parameter ranges and many partial waves. We present a numerical framework based on the variable-phase method, which recasts the radial Schrödinger equation as a system of first-order equations and allows both regular and irregular solutions to be computed efficiently. The former determine phase shifts and Sommerfeld factors, while the latter provide additional information relevant for the self-consistent unitarization of contact-like inelastic interactions. We discuss the numerical implementation, integration-domain selection, partial-wave convergence, and comparisons with analytic limits. We release the code together with tables for the Yukawa potential containing phase shifts, Sommerfeld factors, elastic and angularly weighted cross sections, and the irregular-solution information relevant for unitarization. These resources facilitate dark-matter studies without requiring repeated computationally intensive scans.

hep-ph↗

arXiv2026

Annihilation feedback on elastic scattering in self-interacting dark matter

Sizable dark-matter self-interactions, motivated by observations of galactic structure, often arise from the exchange of light force mediators. Light mediators can render scattering nonperturbative and make inelastic processes important. Unitarity, via the optical theorem, implies that elastic and inelastic interactions cannot be treated independently: inelasticity induces absorptive contributions to the two-particle self-energy kernel that determines the elastic amplitude, while the resulting incoming-state dynamics also modifies the inelastic amplitudes. We study the feedback of dark-matter annihilation on elastic scattering in the presence of a long-range force. Although annihilation is a short-distance process, it can be strongly enhanced by such a force. We find that its feedback becomes significant near Sommerfeld resonances, where it suppresses the low-velocity growth of the baseline elastic cross section. Near baseline elastic-scattering zeros, it may instead generate a nonzero elastic floor required by unitarity. A companion paper studies the feedback of radiative bound-state formation on elastic scattering, which can generate sizable self-interactions.

hep-ph↗

arXiv2026

Self-interacting dark matter from radiative bound-state-formation feedback

Observations of galactic structure motivate sizable dark-matter self-interactions at low velocities, naturally realized through light force mediators. Such mediators can also make inelastic processes very efficient. Unitarity then requires their absorptive contributions to the two-particle self-energy kernel to be resummed, which in turn feeds back into both the elastic and inelastic scattering amplitudes. We study the feedback of radiative bound-state formation on elastic scattering and its implications for self-interacting dark matter. We focus on capture processes through emission of a charged scalar; such transitions are particularly efficient because the scattering and bound states are governed by different effective potentials, a feature also shared by radiative capture through emission of a non-Abelian gauge boson. We show that their feedback can generate sizable elastic scattering relevant for halo dynamics, even when the baseline elastic amplitude vanishes. Notably, the generated elastic cross section can grow toward low velocities, resembling long-range scattering. A companion paper examines the feedback from annihilation processes.

hep-ph↗