{"record_type":"pith_number_record","schema_url":"https://pith.science/schemas/pith-number/v1.json","pith_number":"pith:2019:KI4YYBDV5P2N2UG7PM5EGCQUEX","short_pith_number":"pith:KI4YYBDV","schema_version":"1.0","canonical_sha256":"52398c0475ebf4dd50df7b3a430a1425dc90bd797bc27e086aa655af7b78b6d3","source":{"kind":"arxiv","id":"1905.04290","version":1},"attestation_state":"computed","paper":{"title":"Diagrammatic Expansion for Positive Spectral Functions in the Steady-State Limit","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"cond-mat.stat-mech","authors_text":"Daniel Karlsson, Markku J. Hyrk\\\"as, Robert van Leeuwen","submitted_at":"2019-05-07T13:49:05Z","abstract_excerpt":"Recently, a method was presented for constructing self-energies within many-body perturbation theory that are guaranteed to produce a positive spectral function for equilibrium systems, by representing the self-energy as a product of half-diagrams on the forward and backward branches of the Keldysh contour. We derive an alternative half-diagram representation that is based on products of retarded diagrams. Our approach extends the method to systems out of equilibrium. When a steady-state limit exists, we show that our approach yields a positive definite spectral function in the frequency domai"},"verification_status":{"content_addressed":true,"pith_receipt":true,"author_attested":false,"weak_author_claims":0,"strong_author_claims":0,"externally_anchored":false,"storage_verified":false,"citation_signatures":0,"replication_records":0,"graph_snapshot":true,"references_resolved":false,"formal_links_present":false},"canonical_record":{"source":{"id":"1905.04290","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"cond-mat.stat-mech","submitted_at":"2019-05-07T13:49:05Z","cross_cats_sorted":[],"title_canon_sha256":"73fbfff4416e735af9dd97a35260cb9b3a37abf3f3dbdbf40180f76a9620fdae","abstract_canon_sha256":"295d28c142be436b19f327110b2d868ecbfb06788b307c424bec8d7b9c13f139"},"schema_version":"1.0"},"receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-17T23:46:25.421649Z","signature_b64":"MUbQuT4JH6VXZRPNvza9orTrX03hyYql+lgmjgewJ7Rsi4S1kIxFKJjldKqbBKxviir0Xc8/zs1pRw4cQXsjBg==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"52398c0475ebf4dd50df7b3a430a1425dc90bd797bc27e086aa655af7b78b6d3","last_reissued_at":"2026-05-17T23:46:25.420988Z","signature_status":"signed_v1","first_computed_at":"2026-05-17T23:46:25.420988Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"graph_snapshot":{"paper":{"title":"Diagrammatic Expansion for Positive Spectral Functions in the Steady-State Limit","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"cond-mat.stat-mech","authors_text":"Daniel Karlsson, Markku J. Hyrk\\\"as, Robert van Leeuwen","submitted_at":"2019-05-07T13:49:05Z","abstract_excerpt":"Recently, a method was presented for constructing self-energies within many-body perturbation theory that are guaranteed to produce a positive spectral function for equilibrium systems, by representing the self-energy as a product of half-diagrams on the forward and backward branches of the Keldysh contour. We derive an alternative half-diagram representation that is based on products of retarded diagrams. Our approach extends the method to systems out of equilibrium. When a steady-state limit exists, we show that our approach yields a positive definite spectral function in the frequency domai"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1905.04290","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"},"aliases":[{"alias_kind":"arxiv","alias_value":"1905.04290","created_at":"2026-05-17T23:46:25.421091+00:00"},{"alias_kind":"arxiv_version","alias_value":"1905.04290v1","created_at":"2026-05-17T23:46:25.421091+00:00"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1905.04290","created_at":"2026-05-17T23:46:25.421091+00:00"},{"alias_kind":"pith_short_12","alias_value":"KI4YYBDV5P2N","created_at":"2026-05-18T12:33:21.387695+00:00"},{"alias_kind":"pith_short_16","alias_value":"KI4YYBDV5P2N2UG7","created_at":"2026-05-18T12:33:21.387695+00:00"},{"alias_kind":"pith_short_8","alias_value":"KI4YYBDV","created_at":"2026-05-18T12:33:21.387695+00:00"}],"events":[],"event_summary":{},"paper_claims":[],"inbound_citations":{"count":0,"internal_anchor_count":0,"sample":[]},"formal_canon":{"evidence_count":0,"sample":[],"anchors":[]},"links":{"html":"https://pith.science/pith/KI4YYBDV5P2N2UG7PM5EGCQUEX","json":"https://pith.science/pith/KI4YYBDV5P2N2UG7PM5EGCQUEX.json","graph_json":"https://pith.science/api/pith-number/KI4YYBDV5P2N2UG7PM5EGCQUEX/graph.json","events_json":"https://pith.science/api/pith-number/KI4YYBDV5P2N2UG7PM5EGCQUEX/events.json","paper":"https://pith.science/paper/KI4YYBDV"},"agent_actions":{"view_html":"https://pith.science/pith/KI4YYBDV5P2N2UG7PM5EGCQUEX","download_json":"https://pith.science/pith/KI4YYBDV5P2N2UG7PM5EGCQUEX.json","view_paper":"https://pith.science/paper/KI4YYBDV","resolve_alias":"https://pith.science/api/pith-number/resolve?arxiv=1905.04290&json=true","fetch_graph":"https://pith.science/api/pith-number/KI4YYBDV5P2N2UG7PM5EGCQUEX/graph.json","fetch_events":"https://pith.science/api/pith-number/KI4YYBDV5P2N2UG7PM5EGCQUEX/events.json","actions":{"anchor_timestamp":"https://pith.science/pith/KI4YYBDV5P2N2UG7PM5EGCQUEX/action/timestamp_anchor","attest_storage":"https://pith.science/pith/KI4YYBDV5P2N2UG7PM5EGCQUEX/action/storage_attestation","attest_author":"https://pith.science/pith/KI4YYBDV5P2N2UG7PM5EGCQUEX/action/author_attestation","sign_citation":"https://pith.science/pith/KI4YYBDV5P2N2UG7PM5EGCQUEX/action/citation_signature","submit_replication":"https://pith.science/pith/KI4YYBDV5P2N2UG7PM5EGCQUEX/action/replication_record"}},"created_at":"2026-05-17T23:46:25.421091+00:00","updated_at":"2026-05-17T23:46:25.421091+00:00"}