{"schema":"pubphys.bundle/1","record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"316db19423b15078afb81799067e3ffd7515b1014f58f0054ff0113a60909cc8","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":["ai:gpt-5.5"],"kind":"seed"},"parents":["b793902ee46d89c2debafedd035e923dec7ba326cfd61f77f96f67c6b2de7b92","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"bca4ba7793a5111e3c0853fd79e561f556bc631f505f619b107326417f90142a","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":["ai:gpt-5.5"],"external_id":"hep.higgs-couplings.second-generation","kind":"well-posed","literature_status":"open","n":"2","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 $\\sim 10\\%$, and a $\\kappa_c$ measurement that separates 1 from 0.","problem_ref":"b793902ee46d89c2debafedd035e923dec7ba326cfd61f77f96f67c6b2de7b92","references":"","settled_by":"HL-LHC $H \\to \\mu \\mu$ and $H \\to c\\ \\mathrm{cbar}$ analyses, followed by percent-level $\\mathrm{BR}(H \\to c\\ \\mathrm{cbar})$ 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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