{"id":"ea56e54f-f85f-47f7-abf0-7ecb279096af","arxiv_id":"2605.24466","paper_version":1,"verdict":"UNVERDICTED","confidence":"LOW","novelty_score":5.0,"correctness_risk":"unknown","formal_verification":"none","parameter_count":0,"one_line_summary":"Non-axial deformations in TDDFT fission trajectories broaden spin-projection distributions, permit tilting rotations, and reduce axial spin-spin correlations while leaving perpendicular ones more stable.","lead":"The paper simulates spontaneous fission of 252Cf with time-dependent density functional theory, comparing axially symmetric and non-axial deformation paths to track how fission fragments acquire spin and quantum correlations. A smart generalist might read it to see how nuclear models now quantify intrinsic angular momentum and entanglement that affect observable gamma emission and fragment properties.","discovery_kind":"new_application","skeptic_critique":{"model":"grok-4.3","headline":"TDDFT mean-field trajectories may not capture quantum fluctuations or pairing dynamics needed to reliably produce the reported spin distributions and mutual information changes","rationale":"The load-bearing assumption identified by the reader is precisely the one that must hold for the numerical results on spin modes and entanglement to translate into physical conclusions. No other internal inconsistency is visible from the abstract-level description, and the paper supplies no independent verification (e.g., machine-checked proofs or parameter-free limits) that would bypass the mean-field limitation. The UNVERDICTED verdict therefore remains appropriate.","tokens_in":1657,"tokens_out":372,"duration_ms":15624,"concrete_test":"Re-run the spontaneous-fission trajectories for 252Cf with an augmented TDDFT that adds stochastic one-body fluctuations (or explicit pairing restoration via a Bogoliubov extension) at the same Skyrme functional; recompute the spin-projection distributions and mutual-information matrices for axial vs. non-axial cases. If the axial-correlation reduction changes by >15% or the tilting-mode population disappears, the headline claim weakens.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim—that non-axial deformations broaden fission-fragment spin projections on the fission axis, enable tilting modes, and reduce axial spin-spin correlations via mutual information—rests on the TDDFT evolution (Skyrme or similar) directly generating these collective spin modes and entanglement. Standard TDDFT is a mean-field framework whose single-particle orbitals and collective trajectories do not automatically incorporate beyond-mean-field quantum fluctuations, dynamical pairing restoration, or dissipation; these omissions are known to affect angular-momentum generation in fission. If the observed broadening and correlation resilience are sensitive to the missing physics, the reported differences between axial and non-axial trajectories could be artifacts of the approximation rather than robust predictions.","agreement_with_reader":"agree"},"referee_report":{"model":"grok-4.3","summary":"The manuscript applies nuclear time-dependent density functional theory (TDDFT) to spontaneous fission of 252Cf, contrasting axially symmetric trajectories with those including non-axial deformations. It reports that non-axial modes broaden fission-fragment spin-projection distributions along the fission axis, permit axial tilting rotations forbidden under axial symmetry, and that mutual-information analysis shows axial-symmetry breaking reduces axial spin-spin correlations (while perpendicular correlations remain resilient); the impact on spin opening-angle distributions is also examined.","tokens_in":1806,"tokens_out":450,"duration_ms":33059,"significance":"If robust, the work supplies a dynamical, parameter-free illustration of how triaxial degrees of freedom influence collective spin modes and fragment entanglement, a topic of interest in fission theory. The use of direct TDDFT evolution to generate the reported distributions and mutual-information values without additional fitted corrections is a methodological strength.","major_comments":[{"comment":"Results section on spin-projection distributions and mutual information: the central claim that non-axial trajectories produce broader axial spin projections and reduced axial correlations rests on the untested fidelity of the chosen Skyrme functional within mean-field TDDFT; the manuscript supplies neither comparison to measured fission-fragment spin data nor error estimates on the reported distributions.","section":"Results (spin distributions and mutual information)"},{"comment":"Method section describing the TDDFT trajectories: no discussion is given of how post-scission de-excitation, dynamical pairing restoration, or beyond-mean-field quantum fluctuations are (or are not) incorporated, yet these effects are known to influence angular-momentum generation and could alter the reported differences between axial and non-axial cases.","section":"Method (TDDFT setup)"}],"minor_comments":[{"comment":"Abstract: the specific Skyrme parametrization employed is not named, which would aid reproducibility.","section":"Abstract"},{"comment":"Figure captions for the mutual-information plots: axis labels and units for the mutual-information values should be stated explicitly.","section":"Figures (mutual information)"}],"recommendation":"major_revision","confidential_remarks":null},"author_rebuttal":{"model":"grok-4.3","summary":"We thank the referee for the constructive feedback. We address each major comment below and have revised the manuscript to better articulate the scope and limitations of our TDDFT calculations.","responses":[{"response":"The central claims concern the relative changes induced by breaking axial symmetry (broadening of axial spin projections, emergence of tilting modes, and reduction in axial mutual information) within a single, consistent TDDFT framework. These differences are generated dynamically by the same functional and initial conditions, so they do not rely on absolute fidelity to experiment. We agree that direct comparison to measured fragment spins and quantitative error bars are absent; such benchmarks lie outside the present scope. In revision we will add an explicit paragraph in the discussion section stating the model limitations and noting that future work should include functional benchmarking and uncertainty quantification. This is a partial revision.","revision_made":"partial","referee_comment":"Results section on spin-projection distributions and mutual information: the central claim that non-axial trajectories produce broader axial spin projections and reduced axial correlations rests on the untested fidelity of the chosen Skyrme functional within mean-field TDDFT; the manuscript supplies neither comparison to measured fission-fragment spin data nor error estimates on the reported distributions."},{"response":"The calculations follow the TDDFT evolution only up to the scission point, where the fragments separate while still connected by a neck. Post-scission de-excitation, dynamical pairing restoration, and beyond-mean-field fluctuations are not included. We will revise the method section to state this scope explicitly and to note that these omitted processes may modify absolute spin values and possibly the magnitude of the reported differences, although the qualitative effect of non-axial degrees of freedom on allowed collective modes is expected to remain. This is a full revision.","revision_made":"yes","referee_comment":"Method section describing the TDDFT trajectories: no discussion is given of how post-scission de-excitation, dynamical pairing restoration, or beyond-mean-field quantum fluctuations are (or are not) incorporated, yet these effects are known to influence angular-momentum generation and could alter the reported differences between axial and non-axial cases."}],"tokens_in":1268,"tokens_out":462,"duration_ms":35464,"standing_objections":[]},"desk_editor":{"model":"grok-4.3","letter":"The main thing to know is that adding triaxial deformations to TDDFT fission trajectories for 252Cf produces broader distributions of fragment spin projections along the fission axis, allows tilting collective rotations that axial paths forbid, and reduces axial spin-spin correlations according to mutual information while perpendicular correlations hold up better. The effect on opening-angle distributions between the two fragments is also mapped out.\n\nThis extends earlier axial-only TDDFT studies by running the same framework with non-axial shapes and then applying mutual-information measures to the resulting spin entanglement. The numbers come from the dynamical evolution rather than from any fitted parameters, so there is no obvious circularity.\n\nThe calculations look internally consistent and the choice to quantify entanglement via mutual information is a reasonable way to make the spin correlations concrete. That part is new enough to be worth noting for people tracking fission fragment angular momenta.\n\nThe main limitations are the ones the stress-test note flags. Standard TDDFT is mean-field, so it omits quantum fluctuations, dynamical pairing restoration, and dissipation that are known to influence angular-momentum generation. The paper supplies no comparison to measured gamma multiplicities or fragment spins, no error estimates on the distributions, and no discussion of how post-scission de-excitation is handled. If those missing pieces alter the reported broadening or the differential resilience of axial versus perpendicular correlations, the claimed differences between axial and triaxial cases could change. The functional dependence is also untested in the supplied information.\n\nThis is for nuclear theorists who already work with TDDFT fission or who need quantitative spin distributions for 252Cf. A reader in that narrow area can extract usable numbers and correlation measures even if the broader claims need more support.\n\nIt is coherent enough and grounded enough in the method to deserve a serious referee, though the review should focus on validation against data and on the robustness to beyond-mean-field effects.","headline":"Triaxial TDDFT trajectories for 252Cf fission broaden spin projections, enable tilting modes, and weaken axial correlations while perpendicular ones stay resilient, but the mean-field setup lacks validation or uncertainty checks.","tokens_in":2316,"tokens_out":461,"would_cite":false,"duration_ms":18520,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"grok-4.3","headline":"Non-axial deformations in fission of 252Cf broaden spin projections on the fission axis, enable tilting rotations, and reduce axial spin-spin correlations.","keywords":["fission","spin generation","entanglement","non-axial deformation","time-dependent density functional theory","252Cf","mutual information","tilting mode"],"falsifier":"Direct measurement of the width of spin-projection distributions along the fission axis and the mutual information between fragment spins in 252Cf fission events, compared against predictions from axial-only versus non-axial trajectories.","tokens_in":2574,"feed_emoji":"☢","tokens_out":673,"duration_ms":31917,"temperature":0.7,"pith_summary":"The paper applies nuclear time-dependent density functional theory to spontaneous fission of 252Cf while allowing both axial and non-axial deformations. Axially symmetric paths restrict rotations to counter-rotation along the fission axis and equiprobable bending or wriggling modes perpendicular to it. Non-axial paths remove these restrictions, widen the distribution of spin projections along the axis, and permit tilting collective rotations. Mutual information between fragment spins drops along the fission axis when axial symmetry is broken, yet perpendicular correlations stay largely intact. The work therefore supplies a microscopic route to intrinsic angular momentum and entanglement that depends on the degree of symmetry breaking.","feed_headline":"Non-axial paths broaden fission fragment spins and weaken axial correlations","feed_subtitle":"In 252Cf fission, breaking axial symmetry permits tilting rotations and reduces spin correlations along the fission axis while perpendicular","key_machinery":"Time-dependent density functional theory trajectories that include non-axial deformations, with mutual information used to quantify spin-spin entanglement.","core_discovery":"Nuclear time-dependent density functional theory is used to investigate spin generation and entanglement of fission fragments in spontaneous fission of 252Cf, incorporating both axial and non-axial deformations. Axially symmetric fission trajectories enforce strict constraints: counter rotation (twisting mode) along the fission axis and equiprobable bending/wriggling modes perpendicular to it. Non-axial modes broaden the distributions of fission fragment spin projection on the fission axis, and allow for axial (tilting) collective rotations, which are forbidden on axially symmetric trajectories. Mutual information analysis reveals that axial-symmetry breaking reduces spin-spin correlations a","pith_inferences":["Models that enforce axial symmetry throughout the fission path may systematically underestimate the spread in observed fragment spins.","Measurements that separate spin correlations parallel and perpendicular to the fission axis could distinguish the contribution of non-axial trajectories.","The resilience of perpendicular correlations suggests that certain angular observables in fission may be less sensitive to symmetry breaking than others."],"forward_implications":["Non-axial paths produce wider distributions of fission-fragment spin projections along the fission axis.","Tilting collective rotations appear only when axial symmetry is broken.","Spin-spin correlations measured along the fission axis decrease once axial symmetry is lost in symmetric fission.","Perpendicular spin correlations between fragments remain largely unchanged by the symmetry breaking.","Triaxial degrees of freedom modify the opening-angle distribution between the two fragment spins."],"fun_headline_variants":["Non-axial modes broaden fission fragment spins in 252Cf","Breaking axial symmetry permits tilting collective rotations","Axial symmetry breaking reduces spin correlations along fission axis","Non-axial trajectories leave perpendicular correlations intact"],"cache_read_input_tokens":2112,"weakest_assumption_plain":"The chosen Skyrme-type interaction in time-dependent density functional theory produces the observed collective spin modes and entanglement without extra fitted terms for pairing, dissipation, or fluctuations beyond mean field.","fun_headline_variants_meta":{"raw":{"variants":["Non-axial modes broaden fission fragment spins in 252Cf","Breaking axial symmetry permits tilting collective rotations","Axial symmetry breaking reduces spin correlations along fission axis","Non-axial trajectories leave perpendicular correlations intact"]},"model":"grok-4.3","cost_usd":0.007817,"raw_usage":{"total_tokens":3544,"prompt_tokens":619,"num_sources_used":0,"completion_tokens":58,"cost_in_usd_ticks":78174500,"prompt_tokens_details":{"text_tokens":619,"audio_tokens":0,"image_tokens":0,"cached_tokens":256},"completion_tokens_details":{"audio_tokens":0,"reasoning_tokens":2867,"accepted_prediction_tokens":0,"rejected_prediction_tokens":0}},"tokens_in":619,"tokens_out":58,"duration_ms":39262,"temperature":1.0,"reasoning_tokens":2867,"cache_read_input_tokens":256,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-06-30T12:29:19.706066+00:00","model_set":{"reader":"grok-4.3"},"falsifier":"Direct measurement of the width of spin-projection distributions along the fission axis and the mutual information between fragment spins in 252Cf fission events, compared against predictions from axial-only versus non-axial trajectories.","supporting_citations":[],"review_version":1}