{"paper":{"title":"Update on pion weak decay constants in nuclear matter","license":"","headline":"","cross_cats":["nucl-th"],"primary_cat":"hep-ph","authors_text":"2), (2) Yonsei University), Hungchong Kim (1, Makoto Oka (1) ((1) Tokyo Institute of Technology","submitted_at":"2003-01-27T02:54:14Z","abstract_excerpt":"The QCD sum rule calculation of the in-medium pion decay constants using pseudoscalar-axial vector correlation function, $i \\int d^4x e^{ip\\cdot x} < \\rho| T[{\\bar d}(x) i \\gamma_5 u (x) {\\bar u}(0) \\gamma_\\mu \\gamma_5 d (0)] | \\rho>$ is revisited. In particular, we argue that the dimension 5 condensate, $<{\\bar q} (i D_0)^2 q >_N + {1\\over 8} < {\\bar q} g_s \\sigma \\cdot {\\cal G} q >_N$, which is crucial for splitting the time ($f_t$) and space ($f_s$) components of the decay constant, is not necessarily restricted to be positive. Its positive value is found to yield a tachyonic pion mass. Usi"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"hep-ph/0301227","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":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/hep-ph/0301227/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"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"}