{"schema":"pubphys.bundle/1","record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"ed5c9edfd4bc06a80bb24ad66ae2bd3dc3fa1db9a808a85a5a6d4ba928c5a344","created":"2026-10-03T07:18:05Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"8258dfb0ee02763fd377bf9c301baa10a1f56130a55f02cc3f3c0462d4a4748f","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"hep.higgs-couplings.second-generation","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"The Higgs has been seen decaying to the heavy third-generation fermions, but its decays to the muon and to the charm quark (second-generation particles) are rare and only hinted at. Confirming them would show that the Higgs gives mass the same way across generations.","posed_since":"","precise":"Measure the coupling modifiers $\\kappa_{\\mu}$ and $\\kappa_c$ relative to the SM. ATLAS Run 2 plus Run 3 $H \\to \\mu\\mu$ gives $3.4\\sigma$ ($2.5\\sigma$ expected) with signal strength $1.4 \\pm 0.4$ (Phys. Rev. Lett. 135, 231802, 2025), CMS Run 2 gives $3.0\\sigma$; the best direct charm bound is $\\left|\\kappa_c\\right| < 4.2$ at 95 percent CL (ATLAS VH, JHEP 04 (2025) 075). An answer is a $\\ge 5\\sigma$ observation of $H \\to \\mu\\mu$ with $\\kappa_{\\mu}$ to $\\sim 10\\ \\mathrm{percent}$, and a $\\kappa_c$ measurement that separates 1 from 0.","problem_ref":null,"references":"","settled_by":"HL-LHC $H \\to \\mu \\mu$ and H -> c cbar analyses, followed by percent-level BR(H -> c cbar) and $\\operatorname{BR}(H \\to \\mu \\mu)$ measurements at a Higgs factory.","status_note":"Evidence-level $H \\to \\mu\\mu$ from ATLAS (2025) and CMS (2020); $H \\to c\\,\\mathrm{cbar}$ not observed, with limits about 11 times the SM rate as of 2025.","title":"Do the muon and charm quark couple to the Higgs with SM 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