{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"bd9e87021f4b2e6854c841f84f994bbe2c8ed7fc77e399383fceeff93a73f838","created":"2026-10-03T07:18:05Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011","b5a6eed4777c84a1bba368f984fc123270b9316dd4ad87ddd50aa6379d8d0ddd"],"salt":"d58730ab8fc4e4eebc681698a44effc4ba384b9fe26a87a891fbf03780138843","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"hep.grand-unification.proton-lifetime","kind":"well-posed","literature_status":"open","n":"1","parents":[{"note":"","parent_revision":"b5a6eed4777c84a1bba368f984fc123270b9316dd4ad87ddd50aa6379d8d0ddd","relation":"special_case"}],"plain":"Grand unified theories predict a proton can decay into a positron and a neutral pion. Huge water detectors watch for this rare event.","posed_since":"1974","precise":"Measure or bound $\\tau(p \\to e+ \\pi0)/B$, currently $> 2.4e34\\,\\mathrm{yr}$ (Super-Kamiokande, 2020, 90 percent CL). Non-supersymmetric $\\mathrm{SO}(10)$ models with intermediate scales typically predict $1e34\\text{ to }1e36\\,\\mathrm{yr}$. An answer is a detection or a limit near $1e35\\,\\mathrm{yr}$.","problem_ref":null,"references":"","settled_by":"Hyper-Kamiokande exposure of about 1 to 2 Mt-yr reaching $\\sim 1\\mathrm{e}35\\,\\mathrm{yr}$ sensitivity.","status_note":"Hyper-Kamiokande construction is under way, with data expected late in the 2020s.","title":"Is the proton lifetime to $e+ \\pi0$ below $1e35\\,\\mathrm{years}$?","topic_ref":"4ab26fd00d33deeca52b12d9aa2bb5b76a58cde8ecf899d995d016d99ca5ba55"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"e26a954814709de6a21c0c6742078135befff4d202e9194d2771193699e31948","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"5eddd591585ed88509990182cdd514d17fb58c857a07f4feb54408d3cc48bbd9","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"UL8mVgZfAIckPzNKLTfCbiNoiQhWCnVj8S7az8TSLi-7rqBKaAZoP-Kaa9VzNB-pzCHDrXFxq4XntZSvmFccBw"},"schema":"pubphys.envelope/1"},"record_hash":"e26a954814709de6a21c0c6742078135befff4d202e9194d2771193699e31948","leaf_index":1547}