{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2014:4QZ5O73ABIY6SPGPEPS3R6LEHC","short_pith_number":"pith:4QZ5O73A","canonical_record":{"source":{"id":"1406.4550","kind":"arxiv","version":4},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"hep-th","submitted_at":"2014-06-17T22:14:08Z","cross_cats_sorted":["astro-ph.CO","gr-qc","hep-ph"],"title_canon_sha256":"8f7af36769116509e4261d889419cdc816b5a76b4e240f8ac15b21a65dc9cb37","abstract_canon_sha256":"db8f71566384763f0c2aa6fdad572fd123364dfd5a6dbdd6cbb80914474d5766"},"schema_version":"1.0"},"canonical_sha256":"e433d77f600a31e93ccf23e5b8f96438aa70d014ecd62d06970467ab50342201","source":{"kind":"arxiv","id":"1406.4550","version":4},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1406.4550","created_at":"2026-05-18T00:15:53Z"},{"alias_kind":"arxiv_version","alias_value":"1406.4550v4","created_at":"2026-05-18T00:15:53Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1406.4550","created_at":"2026-05-18T00:15:53Z"},{"alias_kind":"pith_short_12","alias_value":"4QZ5O73ABIY6","created_at":"2026-05-18T12:28:14Z"},{"alias_kind":"pith_short_16","alias_value":"4QZ5O73ABIY6SPGP","created_at":"2026-05-18T12:28:14Z"},{"alias_kind":"pith_short_8","alias_value":"4QZ5O73A","created_at":"2026-05-18T12:28:14Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2014:4QZ5O73ABIY6SPGPEPS3R6LEHC","target":"record","payload":{"canonical_record":{"source":{"id":"1406.4550","kind":"arxiv","version":4},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"hep-th","submitted_at":"2014-06-17T22:14:08Z","cross_cats_sorted":["astro-ph.CO","gr-qc","hep-ph"],"title_canon_sha256":"8f7af36769116509e4261d889419cdc816b5a76b4e240f8ac15b21a65dc9cb37","abstract_canon_sha256":"db8f71566384763f0c2aa6fdad572fd123364dfd5a6dbdd6cbb80914474d5766"},"schema_version":"1.0"},"canonical_sha256":"e433d77f600a31e93ccf23e5b8f96438aa70d014ecd62d06970467ab50342201","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T00:15:53.056642Z","signature_b64":"jlcFCKQVI4slSDBZGXDyDUAh0tFtUBMkdWwYGZmusDxUe/56x+gks3Ea+rSZwDY9Pc6x6CN2qbZaUivox1fOAg==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"e433d77f600a31e93ccf23e5b8f96438aa70d014ecd62d06970467ab50342201","last_reissued_at":"2026-05-18T00:15:53.056028Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T00:15:53.056028Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"1406.4550","source_version":4,"attestation_state":"computed"},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T00:15:53Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"vGLNVFJPS+iB+6Gh0GR9Ju/Or1qMb4iAueMb0g+1ycFDk6CkzyGedyTHcFCjQzhgGNRXe0Gz/agOZUfx6FaTAw==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-27T10:12:04.443565Z"},"content_sha256":"095d29df6d1568b36dc0e8ad2c45c3d88871e90d73c8ba7cccb073faa706ad52","schema_version":"1.0","event_id":"sha256:095d29df6d1568b36dc0e8ad2c45c3d88871e90d73c8ba7cccb073faa706ad52"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2014:4QZ5O73ABIY6SPGPEPS3R6LEHC","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"Classical and quantum ghosts","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["astro-ph.CO","gr-qc","hep-ph"],"primary_cat":"hep-th","authors_text":"Fulvio Sbis\\`a","submitted_at":"2014-06-17T22:14:08Z","abstract_excerpt":"The aim of these notes is to provide a self-contained review of why it is generically a problem when a solution of a theory possesses ghost fields among the perturbation modes. We define what a ghost field is and we show that its presence is associated to a classical instability whenever the ghost field interacts with standard fields. We then show that the instability is more severe at quantum level, and that perturbative ghosts can exist only in low energy effective theories. However, if we don't consider very ad-hoc choices, compatibility with observational constraints implies that low energ"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1406.4550","kind":"arxiv","version":4},"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"},"verdict_id":null},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T00:15:53Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"CBp8FFghVUUBs2YPQ9fXrINP1LUKDtfh8cnGUxUThIlmKTjtDkSKDHqG7l28PbDJuk0oYcJz79qaHUCHEvpYCQ==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-05-27T10:12:04.444067Z"},"content_sha256":"d20da9c07c12e42f443c15cc66b9fc0872989f2bb8d2a0a5d266c4805703e7cd","schema_version":"1.0","event_id":"sha256:d20da9c07c12e42f443c15cc66b9fc0872989f2bb8d2a0a5d266c4805703e7cd"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/4QZ5O73ABIY6SPGPEPS3R6LEHC/bundle.json","state_url":"https://pith.science/pith/4QZ5O73ABIY6SPGPEPS3R6LEHC/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/4QZ5O73ABIY6SPGPEPS3R6LEHC/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":"2026-05-27T10:12:04Z","links":{"resolver":"https://pith.science/pith/4QZ5O73ABIY6SPGPEPS3R6LEHC","bundle":"https://pith.science/pith/4QZ5O73ABIY6SPGPEPS3R6LEHC/bundle.json","state":"https://pith.science/pith/4QZ5O73ABIY6SPGPEPS3R6LEHC/state.json","well_known_bundle":"https://pith.science/.well-known/pith/4QZ5O73ABIY6SPGPEPS3R6LEHC/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2014:4QZ5O73ABIY6SPGPEPS3R6LEHC","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":"db8f71566384763f0c2aa6fdad572fd123364dfd5a6dbdd6cbb80914474d5766","cross_cats_sorted":["astro-ph.CO","gr-qc","hep-ph"],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"hep-th","submitted_at":"2014-06-17T22:14:08Z","title_canon_sha256":"8f7af36769116509e4261d889419cdc816b5a76b4e240f8ac15b21a65dc9cb37"},"schema_version":"1.0","source":{"id":"1406.4550","kind":"arxiv","version":4}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1406.4550","created_at":"2026-05-18T00:15:53Z"},{"alias_kind":"arxiv_version","alias_value":"1406.4550v4","created_at":"2026-05-18T00:15:53Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1406.4550","created_at":"2026-05-18T00:15:53Z"},{"alias_kind":"pith_short_12","alias_value":"4QZ5O73ABIY6","created_at":"2026-05-18T12:28:14Z"},{"alias_kind":"pith_short_16","alias_value":"4QZ5O73ABIY6SPGP","created_at":"2026-05-18T12:28:14Z"},{"alias_kind":"pith_short_8","alias_value":"4QZ5O73A","created_at":"2026-05-18T12:28:14Z"}],"graph_snapshots":[{"event_id":"sha256:d20da9c07c12e42f443c15cc66b9fc0872989f2bb8d2a0a5d266c4805703e7cd","target":"graph","created_at":"2026-05-18T00:15:53Z","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"},"paper":{"abstract_excerpt":"The aim of these notes is to provide a self-contained review of why it is generically a problem when a solution of a theory possesses ghost fields among the perturbation modes. We define what a ghost field is and we show that its presence is associated to a classical instability whenever the ghost field interacts with standard fields. We then show that the instability is more severe at quantum level, and that perturbative ghosts can exist only in low energy effective theories. However, if we don't consider very ad-hoc choices, compatibility with observational constraints implies that low energ","authors_text":"Fulvio Sbis\\`a","cross_cats":["astro-ph.CO","gr-qc","hep-ph"],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"hep-th","submitted_at":"2014-06-17T22:14:08Z","title":"Classical and quantum ghosts"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1406.4550","kind":"arxiv","version":4},"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":"sha256:095d29df6d1568b36dc0e8ad2c45c3d88871e90d73c8ba7cccb073faa706ad52","target":"record","created_at":"2026-05-18T00:15:53Z","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":"db8f71566384763f0c2aa6fdad572fd123364dfd5a6dbdd6cbb80914474d5766","cross_cats_sorted":["astro-ph.CO","gr-qc","hep-ph"],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"hep-th","submitted_at":"2014-06-17T22:14:08Z","title_canon_sha256":"8f7af36769116509e4261d889419cdc816b5a76b4e240f8ac15b21a65dc9cb37"},"schema_version":"1.0","source":{"id":"1406.4550","kind":"arxiv","version":4}},"canonical_sha256":"e433d77f600a31e93ccf23e5b8f96438aa70d014ecd62d06970467ab50342201","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"e433d77f600a31e93ccf23e5b8f96438aa70d014ecd62d06970467ab50342201","first_computed_at":"2026-05-18T00:15:53.056028Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T00:15:53.056028Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"jlcFCKQVI4slSDBZGXDyDUAh0tFtUBMkdWwYGZmusDxUe/56x+gks3Ea+rSZwDY9Pc6x6CN2qbZaUivox1fOAg==","signature_status":"signed_v1","signed_at":"2026-05-18T00:15:53.056642Z","signed_message":"canonical_sha256_bytes"},"source_id":"1406.4550","source_kind":"arxiv","source_version":4}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:095d29df6d1568b36dc0e8ad2c45c3d88871e90d73c8ba7cccb073faa706ad52","sha256:d20da9c07c12e42f443c15cc66b9fc0872989f2bb8d2a0a5d266c4805703e7cd"],"state_sha256":"316309d01421e1a90c8abb5b3d55587c1ef3175f1060ee5772db50d660578d3a"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"ShBXrMo/YmHzQmJH8CBFX9NjpJDQ81P15BQQxr6qADvslWqwmDpeQDksoxAtVfQtaY4MwvrNpc3cfOXr6qxyBg==","signed_message":"bundle_sha256_bytes","signed_at":"2026-05-27T10:12:04.447394Z","bundle_sha256":"0232aa56da8bacef814656cba9709bbdc7d1b2cfbaf28fc39c8e89ca7da0003c"}}