Radioactive isotypes of atoms naturally experience alpha, beta and gamma decay at particular characteristic rates tied to fundamental laws of physics and the structure of very large atomic nuclei.
Detectors that try to measure gamma decay rates show seasonal and daily variation matching differences in the angle with which the suns rays hit the laboratory site.
Lubos Motl, correctly in my view, reasons that the variations in gamma decay rates observed by the detectors don't actually involve seasonal and daily shifts in gamma decay rates. Instead, he reasons, seasonal and daily variation probably actually involve collisions between something emitted by the sun and the radioactive materials that varies with the directness of angular exposure to the sun, that merely looks like gamma decay to the detector, when it is in fact something entirely different.
The thing that is triggering the collisions could be (1) photons (of wavelengths that can penetrate the materials containing the radioactive isotypes, or that trigger collisions outside the containing materials that in turn generate secondary effects that reach the detectors), (2) neutrinos (which he disfavors on the theory that neutrinos would disproportionately influence beta rather than gamma decay, which is a neutrino generating process), or (3) something else emitted by the sun. Neutrinos also ought to have peaks twice a day, rather than once, because the Earth provides little shielding from them since they are so unreactive, and so should peak when the sun is mostly directly above and below the experiment, rather than merely once a day as shown.
The finding matters not just because a previously unknown source of collisions related to sun exposure was discovered, but also because the study suggests that prior measurements of gamma decay rates that don't account for the influence of sun exposure and simply rely on average gamma decay rates, systemically overestimate true gamma decay rates due to false positives from sun exposure correlated collisions. Without this correction, we might misinterpret future deep space experiments measuring gamma decay rates that lack this sun exposure induced collision effect. The systemic error of experiments that don't account for this factor could even lead to incorrect parameter estimation of Standard Model constants that give rise to gamma decay, although most of these parameters are estimated are far "cleaner" experiments than the decay of large radioactive isotypes.
The results may very well be the source of "new physics", but probably not new "fundamental physics." Instead, it may help us better understand what the sun emits and at what energies and how those emitted products interact with the kind of materials found in radioactive decay measurement laboratories. This may tell us more about the complex structure of a fairly typical star, but doesn't tell us much about the fundamental physics of radioactive decay, other than to use trough rather than average values for many purposes.