{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2023:5S2T3WKTGKJ4IINBKGW7CCO4XB","merge_version":"pith-open-graph-merge-v1","event_count":2,"valid_event_count":2,"invalid_event_count":0,"equivocation_count":0,"current":{"canonical_record":{"metadata":{"abstract_canon_sha256":"c467403e951ff349e2d9597fb92b88f026d5a452023ec19a4024b2eff9f540c5","cross_cats_sorted":["hep-th"],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"gr-qc","submitted_at":"2023-03-31T11:13:43Z","title_canon_sha256":"055f476672a821602e2a57a8d7c8bc67d4d685f41d146bc226d7d8c0b94bccaa"},"schema_version":"1.0","source":{"id":"2303.17969","kind":"arxiv","version":2}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"2303.17969","created_at":"2026-07-05T06:55:22Z"},{"alias_kind":"arxiv_version","alias_value":"2303.17969v2","created_at":"2026-07-05T06:55:22Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.2303.17969","created_at":"2026-07-05T06:55:22Z"},{"alias_kind":"pith_short_12","alias_value":"5S2T3WKTGKJ4","created_at":"2026-07-05T06:55:22Z"},{"alias_kind":"pith_short_16","alias_value":"5S2T3WKTGKJ4IINB","created_at":"2026-07-05T06:55:22Z"},{"alias_kind":"pith_short_8","alias_value":"5S2T3WKT","created_at":"2026-07-05T06:55:22Z"}],"graph_snapshots":[{"event_id":"sha256:93ae450884b37345b87e385e23d8b82f6c029342b3bc34dda0aefd9855e5abf0","target":"graph","created_at":"2026-07-05T06:55:22Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"graph_snapshot":{"author_claims":{"count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","strong_count":0},"builder_version":"pith-number-builder-2026-05-17-v1","claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"integrity":{"available":true,"clean":true,"detectors_run":[],"endpoint":"/pith/2303.17969/integrity.json","findings":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938","summary":{"advisory":0,"by_detector":{},"critical":0,"informational":0}},"paper":{"abstract_excerpt":"We study the classical dynamics of the Nambu-Goto strings with a null symmetry in curved spacetimes admitting a null Killing vector field. The Nambu-Goto equation is reduced to first order ordinary differential equations and is always integrable in contrast to the case of non-null symmetries where integrability requires additional spacetime symmetries. It is found that in the case of null symmetry, an almost contact structure associated with the metric dual 1-form $\\eta$ of the null Killing vector field emerges naturally. This structure determines the allowed class of string worldsheets in suc","authors_text":"Hideki Ishihara, Hiroshi Kozaki, Tatsuhiko Koike, Yoshiyuki Morisawa","cross_cats":["hep-th"],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"gr-qc","submitted_at":"2023-03-31T11:13:43Z","title":"Nambu-Goto Strings with a null symmetry and contact structure"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2303.17969","kind":"arxiv","version":2},"verdict":{"created_at":null,"id":null,"model_set":{},"one_line_summary":"","pipeline_version":null,"pith_extraction_headline":"","strongest_claim":"","weakest_assumption":""}},"verdict_id":null}}],"author_attestations":[],"timestamp_anchors":[],"storage_attestations":[],"citation_signatures":[],"replication_records":[],"corrections":[],"mirror_hints":[],"record_created":{"event_id":"sha256:7d1071d8fcc92384d891ecfcfb59bb6dedbd3b5de7693e13b915632c5440ef1d","target":"record","created_at":"2026-07-05T06:55:22Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"attestation_state":"computed","canonical_record":{"metadata":{"abstract_canon_sha256":"c467403e951ff349e2d9597fb92b88f026d5a452023ec19a4024b2eff9f540c5","cross_cats_sorted":["hep-th"],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"gr-qc","submitted_at":"2023-03-31T11:13:43Z","title_canon_sha256":"055f476672a821602e2a57a8d7c8bc67d4d685f41d146bc226d7d8c0b94bccaa"},"schema_version":"1.0","source":{"id":"2303.17969","kind":"arxiv","version":2}},"canonical_sha256":"ecb53dd9533293c421a151adf109dcb87b5530b6331a0b6d0635c686204d9ba3","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"ecb53dd9533293c421a151adf109dcb87b5530b6331a0b6d0635c686204d9ba3","first_computed_at":"2026-07-05T06:55:22.984265Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-07-05T06:55:22.984265Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"clhCRTn7+jjBNhY3KTpPRQWHJF2fp3TdA6s33acZ6MHrqGfUuX6fujl2rh/aJ9Ghv1XxN9V/dHTj5WxYM8WwBQ==","signature_status":"signed_v1","signed_at":"2026-07-05T06:55:22.984749Z","signed_message":"canonical_sha256_bytes"},"source_id":"2303.17969","source_kind":"arxiv","source_version":2}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:7d1071d8fcc92384d891ecfcfb59bb6dedbd3b5de7693e13b915632c5440ef1d","sha256:93ae450884b37345b87e385e23d8b82f6c029342b3bc34dda0aefd9855e5abf0"],"state_sha256":"ef66b888f11d714f55d67931266939f8273f8c55897ac626082fa4a39f9893db"}