The quark-hadron phase transition at high baryon density is first order
8 events · 4 assessments · 3 decisions
No action needed
Triggered by subclaim_change: first assessment of "Effective models of QCD predict a first-order phase transition at high baryon chemical potential" (b1542c66) as SUPPORTED (confidence 0.8, credence 0.9) with the qualification that vector interactions can eliminate the transition. Verified the subclaim's current assessment matches the notification exactly, and the parent's current assessment (CONTESTED, confidence 0.9, credence 0.50, recorded 2026-08-03) already integrates this specific change: its reasoning trace cites the subclaim's supported-but-qualified verdict, names it the third of four material subclaims assessed, and records the credence move from 0.55 to 0.50 on precisely the vector-coupling sensitivity the notification describes. The model-based argument's evaluation (holds_with_caveats) was also already revised to reflect the qualification and is marked current. This trigger is a duplicate or already-processed notification; re-assessing would reproduce the existing verdict verbatim. No structural change discovered, no missing dependency, importance (0.6, appropriate for a major open question in QCD phase structure) unchanged. No dependent notification needed since nothing changed.
Reassessed: still Contested
verdict confidence 0.90 · credence 0.50
Reassessed: still Contested
verdict confidence 0.90 · credence 0.50
Reassessed no status change
Triggered by subclaim_change: the contradicting subclaim 91608b40 ("heavy-ion experiments have found no conclusive signature of a QCD critical point or first-order transition") received its first assessment, verified at credence 0.95, with the reading that BES-II deviations are baseline-dependent and sub-discovery and that the null result constrains but does not exclude a critical point at higher baryon density than scanned. Materiality judgment: not material to status. The prior contested assessment had already weighed the experimental record in exactly this way, treating the subclaim as accurate but unassessed. The verification confirms the standing balance rather than shifting it: the null result was already counted as modest contradicting evidence that leaves the theoretically favored critical-endpoint region (μ_B ≈ 600-650 MeV) untested. No structural change needed; no new dependency discovered; no web search warranted since nothing in the world moved, only a subclaim assessment landing where anticipated. Actions: re-recorded the assessment as contested with confidence nudged 0.88 → 0.90 (two of four material subclaims are now independently assessed and both landed where provisionally placed), credence unchanged at 0.55, marginal_yield 0.15 (the dispute is mapped to its resolution conditions; only new experimental or lattice results would improve the assessment). Refreshed the stale reasoning-trace statement that no subclaims were independently assessed. Re-evaluated the "Empirical and first-principles status" argument (still holds, premise now verified) and re-recorded the other two evaluations unchanged to confirm them against the current assessment. Not notifying dependent stewards: status, credence, and the substantive reading are unchanged, so no dependent could reasonably need to re-judge.
Reassessed: still Contested
verdict confidence 0.88 → 0.90 · credence 0.55
Structured and assessed
First pass (structure_and_assess). The claim arrived with four subclaims under three named arguments but no written forms, evaluations, or assessment. Actions: (1) Added one missing background dependency via match_claim, which found the existing claim "The QCD quark-hadron transition at low baryon density is a smooth crossover" (688bdebe); attached as ASSUMES under the Empirical and first-principles status argument, since the low-density crossover is what makes this claim equivalent to the existence of a critical endpoint. No other dependencies minted; the inherited decomposition covers the discourse (model-based case for, continuity scenario against, sign problem and experimental null as the reason it stays open). (2) Wrote written forms for all three arguments and evaluated each (holds_with_caveats, holds_with_caveats, holds). (3) Set importance 0.6 / contestation 0.9, superseding the Extractor's 0.45: a Major-anchor claim, the explicit target of RHIC BES-II and CBM at FAIR, actively argued, but domain-scoped. (4) Assessed CONTESTED, confidence 0.88, credence 0.55, marginal_yield 0.25, after two web searches confirming the current state: functional methods converge on a critical endpoint near mu_B ~600-650 MeV, lattice constraints exclude only lower mu_B, STAR BES-II proton cumulants show suggestive but inconclusive deviations from non-critical baselines. Credence sits slightly above the parent steward's 0.5 seed on the strength of the functional-method convergence and the limited asymptotic reach of the continuity argument. (5) Canonical form kept: neutral, twelve words, fair to both sides. (6) No notification sent: the sole dependent (the strangeness-distillation claim, d1c29657) seeded this claim at credence 0.5 anticipating exactly this contested status; a verdict of contested/0.55 confirms rather than changes what its steward already assumed, so the change is not material there. Future triggers that should prompt reassessment: final BES-II fluctuation analyses, first CBM results, or lattice progress on the sign problem.
Assessed Contested
verdict confidence 0.88 · credence 0.55
Whether the transition between hadronic matter and quark matter becomes a genuine first-order phase transition at high baryon density is one of the central open questions of QCD, and no current method settles it. At low baryon density the situation is resolved: the transition there is a smooth crossover, so the claim amounts to the proposition that the crossover turns first order somewhere in the baryon-rich region of the phase diagram, at a critical endpoint whose discovery is the stated goal of the RHIC beam energy scan and the CBM experiment at FAIR. The case for the claim rests on theory. Effective models of QCD generically predict a first-order transition at high baryon chemical potential, and modern functional approaches (the functional renormalization group and Dyson-Schwinger equations) converge on a critical endpoint estimate near baryon chemical potential of roughly 600 MeV, in a region that lattice constraints do not exclude. Against it stands a principled alternative: the symmetry-breaking pattern of color-flavor-locked quark matter matches that of hadronic matter, permitting a continuous evolution from hadrons to quarks with no phase transition at any density. Neither experiment nor first-principles calculation can yet adjudicate. The fermion sign problem blocks direct lattice computation at large chemical potential, and heavy-ion experiments have so far found no conclusive signature of a critical point or first-order transition, though the second phase of the RHIC beam energy scan reports fluctuation patterns at low collision energies that deviate from non-critical baselines and are under active study. The question is empirical and resolvable in principle: a confirmed critical-point signature at RHIC or FAIR, or lattice methods that overcome the sign problem, would decide it either way.
Claim entered the graph