{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2021:6MCA3OSRBVVYDANKPV2V5KROW2","short_pith_number":"pith:6MCA3OSR","canonical_record":{"source":{"id":"2108.06294","kind":"arxiv","version":1},"metadata":{"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"gr-qc","submitted_at":"2021-08-13T15:57:49Z","cross_cats_sorted":["astro-ph.CO","hep-th"],"title_canon_sha256":"6726c14b9270e90c99b462c636f7704068622af4c05b1b460b31a7a999dd224a","abstract_canon_sha256":"c75744f60b19d3cc7613209532369084ec639d8f9a87b4e6f9cd7e98faf4f294"},"schema_version":"1.0"},"canonical_sha256":"f3040dba510d6b8181aa7d755eaa2eb68bd1d87dab8a03dcfd5349aa557d1c96","source":{"kind":"arxiv","id":"2108.06294","version":1},"source_aliases":[{"alias_kind":"arxiv","alias_value":"2108.06294","created_at":"2026-07-05T03:05:39Z"},{"alias_kind":"arxiv_version","alias_value":"2108.06294v1","created_at":"2026-07-05T03:05:39Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.2108.06294","created_at":"2026-07-05T03:05:39Z"},{"alias_kind":"pith_short_12","alias_value":"6MCA3OSRBVVY","created_at":"2026-07-05T03:05:39Z"},{"alias_kind":"pith_short_16","alias_value":"6MCA3OSRBVVYDANK","created_at":"2026-07-05T03:05:39Z"},{"alias_kind":"pith_short_8","alias_value":"6MCA3OSR","created_at":"2026-07-05T03:05:39Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2021:6MCA3OSRBVVYDANKPV2V5KROW2","target":"record","payload":{"canonical_record":{"source":{"id":"2108.06294","kind":"arxiv","version":1},"metadata":{"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"gr-qc","submitted_at":"2021-08-13T15:57:49Z","cross_cats_sorted":["astro-ph.CO","hep-th"],"title_canon_sha256":"6726c14b9270e90c99b462c636f7704068622af4c05b1b460b31a7a999dd224a","abstract_canon_sha256":"c75744f60b19d3cc7613209532369084ec639d8f9a87b4e6f9cd7e98faf4f294"},"schema_version":"1.0"},"canonical_sha256":"f3040dba510d6b8181aa7d755eaa2eb68bd1d87dab8a03dcfd5349aa557d1c96","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-07-05T03:05:39.475329Z","signature_b64":"nFzWRxDVFCsK6Xi5Sij9jbtsHx8EYZP+KJVbolPp+I9JmVHy9T28dWV2NJ8f+k+yeHk6ViCJiU5CuPz0mFN/AQ==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"f3040dba510d6b8181aa7d755eaa2eb68bd1d87dab8a03dcfd5349aa557d1c96","last_reissued_at":"2026-07-05T03:05:39.474889Z","signature_status":"signed_v1","first_computed_at":"2026-07-05T03:05:39.474889Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"2108.06294","source_version":1,"attestation_state":"computed"},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-07-05T03:05:39Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"6oRl0gK3lnbSjOq0tHtzD2kfSNTqdLF6plaFk1lyJuV/n4zJCCkR9xWl9wxMwPhDjLOc+Vie+my2hDe4gTRYAw==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-08-03T11:16:23.906338Z"},"content_sha256":"fbbd311fc72cda74beb783da31503fc6db213fa9a41a035b60041a52f9a50cff","schema_version":"1.0","event_id":"sha256:fbbd311fc72cda74beb783da31503fc6db213fa9a41a035b60041a52f9a50cff"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2021:6MCA3OSRBVVYDANKPV2V5KROW2","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"Ghosts without runaway","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":["astro-ph.CO","hep-th"],"primary_cat":"gr-qc","authors_text":"Alexander Vikman, C\\'edric Deffayet, Shinji Mukohyama","submitted_at":"2021-08-13T15:57:49Z","abstract_excerpt":"We present a simple class of mechanical models where a canonical degree of freedom interacts with another one with a negative kinetic term, i.e. with a ghost. We prove analytically that the classical motion of the system is completely stable for all initial conditions, notwithstanding that the conserved Hamiltonian is unbounded from below and above. This is fully supported by numerical computations. Systems with negative kinetic terms often appear in modern cosmology, quantum gravity and high energy physics and are usually deemed as unstable. Our result demonstrates that for mechanical systems"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2108.06294","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/2108.06294/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"},"verdict_id":null},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-07-05T03:05:39Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"enQ2BBFB6CUEmFjOMpyWv1Mbl04LSRmUGb0mUhyz0qteJ/nqwhW94M4Lr0kFOxVZ7HfmTrRTANhGxjt0SurWAA==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-08-03T11:16:23.906719Z"},"content_sha256":"c087a4f6c3455188ef3f6623eafd0ebb7be1fd6245e999853e38a0cb56cb4509","schema_version":"1.0","event_id":"sha256:c087a4f6c3455188ef3f6623eafd0ebb7be1fd6245e999853e38a0cb56cb4509"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/6MCA3OSRBVVYDANKPV2V5KROW2/bundle.json","state_url":"https://pith.science/pith/6MCA3OSRBVVYDANKPV2V5KROW2/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/6MCA3OSRBVVYDANKPV2V5KROW2/bundle.json","status":"primary"}],"public_keys":[{"key_id":"pith-v1-2026-05","algorithm":"ed25519","format":"raw","public_key_b64":"stVStoiQhXFxp4s2pdzPNoqVNBMojDU/fJ2db5S3CbM=","public_key_hex":"b2d552b68890857171a78b36a5dccf368a953413288c353f7c9d9d6f94b709b3","fingerprint_sha256_b32_first128bits":"RVFV5Z2OI2J3ZUO7ERDEBCYNKS","fingerprint_sha256_hex":"8d4b5ee74e4693bcd1df2446408b0d54","rotates_at":null,"url":"https://pith.science/pith-signing-key.json","notes":"Pith uses this Ed25519 key to sign canonical record SHA-256 digests. Verify with: ed25519_verify(public_key, message=canonical_sha256_bytes, signature=base64decode(signature_b64))."}],"merge_version":"pith-open-graph-merge-v1","built_at":"2026-08-03T11:16:23Z","links":{"resolver":"https://pith.science/pith/6MCA3OSRBVVYDANKPV2V5KROW2","bundle":"https://pith.science/pith/6MCA3OSRBVVYDANKPV2V5KROW2/bundle.json","state":"https://pith.science/pith/6MCA3OSRBVVYDANKPV2V5KROW2/state.json","well_known_bundle":"https://pith.science/.well-known/pith/6MCA3OSRBVVYDANKPV2V5KROW2/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2021:6MCA3OSRBVVYDANKPV2V5KROW2","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":"c75744f60b19d3cc7613209532369084ec639d8f9a87b4e6f9cd7e98faf4f294","cross_cats_sorted":["astro-ph.CO","hep-th"],"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"gr-qc","submitted_at":"2021-08-13T15:57:49Z","title_canon_sha256":"6726c14b9270e90c99b462c636f7704068622af4c05b1b460b31a7a999dd224a"},"schema_version":"1.0","source":{"id":"2108.06294","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"2108.06294","created_at":"2026-07-05T03:05:39Z"},{"alias_kind":"arxiv_version","alias_value":"2108.06294v1","created_at":"2026-07-05T03:05:39Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.2108.06294","created_at":"2026-07-05T03:05:39Z"},{"alias_kind":"pith_short_12","alias_value":"6MCA3OSRBVVY","created_at":"2026-07-05T03:05:39Z"},{"alias_kind":"pith_short_16","alias_value":"6MCA3OSRBVVYDANK","created_at":"2026-07-05T03:05:39Z"},{"alias_kind":"pith_short_8","alias_value":"6MCA3OSR","created_at":"2026-07-05T03:05:39Z"}],"graph_snapshots":[{"event_id":"sha256:c087a4f6c3455188ef3f6623eafd0ebb7be1fd6245e999853e38a0cb56cb4509","target":"graph","created_at":"2026-07-05T03:05:39Z","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/2108.06294/integrity.json","findings":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938","summary":{"advisory":0,"by_detector":{},"critical":0,"informational":0}},"paper":{"abstract_excerpt":"We present a simple class of mechanical models where a canonical degree of freedom interacts with another one with a negative kinetic term, i.e. with a ghost. We prove analytically that the classical motion of the system is completely stable for all initial conditions, notwithstanding that the conserved Hamiltonian is unbounded from below and above. This is fully supported by numerical computations. Systems with negative kinetic terms often appear in modern cosmology, quantum gravity and high energy physics and are usually deemed as unstable. Our result demonstrates that for mechanical systems","authors_text":"Alexander Vikman, C\\'edric Deffayet, Shinji Mukohyama","cross_cats":["astro-ph.CO","hep-th"],"headline":"","license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"gr-qc","submitted_at":"2021-08-13T15:57:49Z","title":"Ghosts without runaway"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2108.06294","kind":"arxiv","version":1},"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:fbbd311fc72cda74beb783da31503fc6db213fa9a41a035b60041a52f9a50cff","target":"record","created_at":"2026-07-05T03:05:39Z","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":"c75744f60b19d3cc7613209532369084ec639d8f9a87b4e6f9cd7e98faf4f294","cross_cats_sorted":["astro-ph.CO","hep-th"],"license":"http://creativecommons.org/licenses/by/4.0/","primary_cat":"gr-qc","submitted_at":"2021-08-13T15:57:49Z","title_canon_sha256":"6726c14b9270e90c99b462c636f7704068622af4c05b1b460b31a7a999dd224a"},"schema_version":"1.0","source":{"id":"2108.06294","kind":"arxiv","version":1}},"canonical_sha256":"f3040dba510d6b8181aa7d755eaa2eb68bd1d87dab8a03dcfd5349aa557d1c96","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"f3040dba510d6b8181aa7d755eaa2eb68bd1d87dab8a03dcfd5349aa557d1c96","first_computed_at":"2026-07-05T03:05:39.474889Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-07-05T03:05:39.474889Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"nFzWRxDVFCsK6Xi5Sij9jbtsHx8EYZP+KJVbolPp+I9JmVHy9T28dWV2NJ8f+k+yeHk6ViCJiU5CuPz0mFN/AQ==","signature_status":"signed_v1","signed_at":"2026-07-05T03:05:39.475329Z","signed_message":"canonical_sha256_bytes"},"source_id":"2108.06294","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:fbbd311fc72cda74beb783da31503fc6db213fa9a41a035b60041a52f9a50cff","sha256:c087a4f6c3455188ef3f6623eafd0ebb7be1fd6245e999853e38a0cb56cb4509"],"state_sha256":"35448aa417e040755d22f665eeb9e8f0fdafaa6ee0e4866c097e7002e451ed9b"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"QYZUXUj5Frjsa6sbDnzWhOG56k39lELGa6U5EgERalSR6xLBH+MC4apqD3yUxlfaKkNhmrS45Ip8VzQ58Ec0CQ==","signed_message":"bundle_sha256_bytes","signed_at":"2026-08-03T11:16:23.909327Z","bundle_sha256":"8afd69da52223d1512230a2e3d53d3f823e48265b4151bf33d9fa78a48e1621d"}}