{"paper":{"title":"Upper Bound on R_b in Two Higgs Doublet Model from Lepton Universality","license":"","headline":"","cross_cats":[],"primary_cat":"hep-ph","authors_text":"Hitoshi Murayama (UC Berkeley, Junji Hisano (Univ of Minnesota), Kek), LBNL), Shingo Kiyoura (Tokyo Inst of Tech","submitted_at":"1997-02-02T19:31:16Z","abstract_excerpt":"It has been known that $R_b$ can be enhanced in the two Higgs doublet model if $\\tan \\beta$ is large. We point out that a similar enhancement in $\\Gamma(Z \\to \\tau^+ \\tau^-)$ is large enough to place a constraint on such a possibility. We obtain a 95% CL upper bound $\\Delta R_b/R_{b} < 0.73%$ in this model for the $\\overline{MS}$ mass $m_{b} (m_{Z}) = 3.0$ GeV. The 1996 world average is $\\Delta R_{b}/R_{b}$ = $0.97% \\pm 0.51%$. We used the $m_{b}(m_{Z})$ to determine the bottom Yukawa coupling instead of $m_b(m_{b})$ unlike in previous analyses, and also an improved experimental test of the le"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"hep-ph/9702202","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}