What does this equation mean?

A parallel, quieter history has run through direct dark-matter detection. Weakly Interacting Massive Particles (WIMPs) were, for two decades, the theoretically favored dark-matter candidate, in large part because a stable, weak-scale supersymmetric partner would naturally produce roughly the right relic abundance — the same theoretical structure that motivated collider SUSY searches also motivated underground WIMP searches, and the two literatures grew up together. The XENONnT experiment’s first WIMP search results, published in 2023, found no significant excess of nuclear-recoil events in its blinded analysis and set an upper limit on the spin-independent WIMP-nucleon scattering cross-section of 2.58$\times$10^{-47}\,$\text{cm}^2$ for a 28 GeV/ $c^2$ WIMP at 90% confidence, achieved with a background rate roughly five times lower than its XENON1T predecessor [ 8 ] . This is, again, an exclusion, not a disproof: it rules out an increasingly large region of WIMP mass and coupling parameter space, pressing the community toward lighter dark-matter candidates, axions, or entirely different production mechanisms, rather than closing the dark-matter question outright.