{"id":"cb9c9541-14f6-4e04-aa83-5e6f00494bf5","arxiv_id":"2505.01275","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":6,"one_line_summary":"COHERENT data can constrain flavor-general new physics in both neutrino production and detection once right-handed Dirac neutrinos are included, and the full rate reduces to a compact set of effective nuclear charges.","lead":"This paper lays out an effective field theory for how non-standard neutrino interactions show up in the COHERENT experiment, covering both the production of neutrinos in pion and muon decays and their detection by scattering off nuclei. It compresses all new physics into a few 'effective charges' and uses current and projected COHERENT data to set limits on the underlying operators.","discovery_kind":"extension","skeptic_critique":{"model":"deepseek-v4-flash","headline":"No significant objection identified","rationale":"The paper's central claim is the compact factorization of the COHERENT event rate and the new sensitivity to production-side right-handed neutrino parameters. I checked the key algebraic steps: cancellation of the PMNS matrix via unitarity when L≈0; the decomposition of the general muon-decay spectrum into the two SM spectral shapes, which makes Eq. (4.3) exact; the normalization of pion and muon decay widths to experimental values; and the non-relativistic reduction of nucleon bilinears in Eq. (2.8). All steps are internally consistent and reproduce known limits (SM, left-handed NSI, magnetic moment). The tensor non-enhancement follows from the standard vanishing of the spatial tensor matrix element for spin-0 nuclei. Subleading recoil and two-body corrections are suppressed by T/m_N≈10^-6 and are unlikely to shift bounds at current precision. The absence of released code and the local treatment of dark solutions are real limitations for reproduction and globality, but they do not invalidate the central framework. Therefore the CONDITIONAL verdict can remain unchanged.","tokens_in":27270,"tokens_out":38879,"duration_ms":390057,"concrete_test":"Compute the leading-order nuclear matrix element of the tensor current \\bar N \\sigma^{ij} N between the 0^+ ground state of 40Ar using the non-relativistic reduction of Eq. (2.8) and a realistic nuclear wave function; if the matrix element vanishes, the absence of tensor coherent enhancement is confirmed, settling the reader's concern.","verdict_should_be":"UNCHANGED","load_bearing_attack":"No significant objection identified. The central factorization in Eqs. (4.3)-(4.6) is mathematically consistent: with L->0 the PMNS matrices cancel by unitarity, the muon-decay neutrino spectrum is a linear combination of the two SM spectral shapes, and the generalized charges in Eq. (4.6) correctly encode production and detection WCs. The non-relativistic reduction in Eq. (2.8) is standard; tensor and axial operators are not coherently enhanced, and the neglected subleading corrections are O(T/m_N) ~ 10^-6 for COHERENT recoil energies, far below current experimental precision. The reader's concerns about missing code and dark solutions affect reproducibility and global bounds, but they do not undermine the central EFT result.","agreement_with_reader":"disagree"},"referee_report":{"model":"deepseek-v4-flash","summary":"This paper presents a νWEFT (weak effective field theory extended with light right-handed Dirac neutrinos) analysis of the COHERENT CEνNS data. It derives the full event rate for flavor-general new physics in pion decay, muon decay, and neutrino-nucleus detection, and shows that the rate can be written compactly as SM fluxes times effective cross sections with generalized nuclear charges (Eqs. (4.3)-(4.6)). The authors then use the COHERENT CsI and LAr datasets to set one-at-a-time bounds on these charges and on the underlying νWEFT Wilson coefficients, and estimate the sensitivity of the future CENNS-750 detector. They also argue, on the basis of a non-relativistic nuclear EFT, that tensor interactions do not receive the coherent enhancement assumed in much of the earlier CEνNS literature.","tokens_in":27455,"tokens_out":26660,"duration_ms":266554,"significance":"The compact factorization of the rate is a genuinely useful technical result: it encodes the full νWEFT prediction (with right-handed neutrinos, lepton-flavor violation, and simultaneous production and detection effects) in a few effective charges, and the derivation is checked against several known limits (SM, left-handed NSI, Lindner et al., magnetic moment, scalar, and interference). The paper provides the first constraints on production-side right-handed neutrino parameters from COHERENT, notably the muon-decay spectral parameters P_ν̄L and w_ν̄L, and corrects the literature on the absence of coherent enhancement of tensor operators. The numerical analysis is transparent about its own limitations (dark solutions, one-at-a-time fits, idealized projections), and the analytic part is self-contained. The main weakness is the lack of a public implementation, which limits direct reproducibility of the fits.","major_comments":[],"minor_comments":[{"comment":"The abstract and the introduction state that the analysis includes 'for the first time' flavor-general new physics in neutrino production and detection with right-handed neutrinos. Since Ref. [34] also treats general neutrino interactions with sterile neutrinos in meson decays and CEνNS, the authors should state explicitly which element is new (e.g., muon decay production, the treatment of lepton-flavor violation, or the complete operator basis), or soften the claim.","section":"Abstract; Sec. 1"},{"comment":"The three production factors xµ, x̄µ and xe are strongly correlated, and the paper reports their covariance matrix but not the full likelihood. Providing the fit results in a machine-readable form, or at least the exact χ² function, would allow interested readers to reproduce the derived bounds in Eqs. (5.7)-(5.10).","section":"Sec. 5.2, Eq. (5.5)"},{"comment":"The note that 'dark solutions' are omitted should be more precise: please state whether the quoted 90% CL intervals are local bounds around the SM and, if so, specify the range of each Wilson coefficient over which the bound applies; otherwise the global validity of the table is not clear.","section":"Sec. 5.3, Table 2"},{"comment":"The statement that axial-vector and tensor nucleon operators are 'not relevant for the remainder of our calculations' requires a quantitative justification for the CsI target, whose nuclei have nonzero spin; a short estimate of the spin-dependent contribution relative to the coherent vector rate would remove the ambiguity.","section":"Sec. 2.2, after Eq. (2.9)"},{"comment":"The sentence 'the bounds on the tensor quark-level coefficients e~ϵqq_T obtained in these works are incorrect by a factor N^2' is imprecise: the tensor contribution to the cross section was overestimated by a factor N^2, so the derived bounds on the Wilson coefficients are too strong by a factor N rather than N^2. Please rephrase.","section":"Sec. 4.2, tensor comparison"},{"comment":"The paper stresses that the rate parametrization is easy to implement, but no public code or data tables are provided; making the generalized-charge expressions and fit code available would significantly improve reproducibility. There are also several typos (e.g., the Appendix A title 'Kinematic fj X(T) functions', 'ννe' in Sec. 5.2, and a formatting issue in Eq. (2.1)).","section":"Throughout"}],"recommendation":"minor_revision","confidential_remarks":"The main concern is the novelty claim relative to Ref. [34], which is cited only in the tensor discussion; the authors should be asked to make the incremental contribution explicit before publication. The self-citations of Refs. [31] and [32] are appropriate given the line of work, but the paper should not rely on a silent distinction from [34]. I see no issue with the treatment of the experimental data or with the central factorization of the rate."},"author_rebuttal":null,"desk_editor":{"model":"deepseek-v4-flash","letter":"Worth a serious look. The genuinely new thing is a flavor-general νWEFT treatment of COHERENT with an arbitrary number of right-handed Dirac neutrinos, including non-standard effects in both production (pion and muon decay) and detection (CEνNS), all reduced to a compact SM-fluxes-times-effective-cross-sections form. The factorization in Eqs. (4.3)–(4.6) is clean enough that other groups will pick it up. The paper also makes a real correction to the tensor-interaction literature: at leading order in the non-relativistic pionless EFT, tensor operators map onto axial structure and do not receive coherent enhancement, so many previous bounds are off by N². I checked the reduction in Eq. (2.8); it is standard, and the neglected subleading terms are O(T/m_N) ~ 10⁻⁶, far below current precision. That part alone justifies refereeing.\n\nThe derivation is careful and self-consistent. It reduces properly to the SM, left-handed NSI, the Lindner et al. limit, magnetic moment, scalar, and interference cases. The PMNS matrices cancel at zero baseline, as they should. The muon-decay spectral parameterization with P_ν and w_ν for both chiralities is a natural generalization of Fetscher and of the authors' earlier letter. The numerical fits are plausible but less probative. There is no public code, the COHERENT implementation is inherited from the previous paper, and the one-at-a-time bounds leave out dark solutions at large couplings. Those are ordinary limitations, not cracks in the central EFT result.\n\nOne point to watch: the paper is blunt about the tensor error and cites a long list of papers that made it. The correction looks right, but the authors have skin in the game; a referee should independently verify the non-relativistic reduction and the agreement with Refs. [23,27,48] rather than take the footnote at face value. The novelty claim versus their own [32] is a modest extension, but the extension to arbitrary νR number and lepton-flavor violation is a clear step forward.\n\nIf I worked on CEνNS or neutrino EFT, I would cite this. The formalism is the contribution, and it is a good one. The fits are illustrative. The paper should go to peer review with a competent referee, not desk reject.","headline":"A genuinely reusable νWEFT framework for COHERENT with right-handed neutrinos, plus a correct and overdue fix to the tensor enhancement error; the fits are secondary.","tokens_in":28001,"tokens_out":2097,"would_cite":true,"duration_ms":21751,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"rs_alignment":null,"lean_confirmation":null,"pith_extraction":{"msc":[],"pacs":[],"model":"deepseek-v4-flash","headline":"COHERENT, through a flavor-general low-energy field theory with right-handed Dirac neutrinos, can constrain new physics in both neutrino production and detection, with all effects packaged into effective nuclear charges.","keywords":["CEνNS","COHERENT","νWEFT","right-handed Dirac neutrinos","effective nuclear charges","muon-decay parameters","tensor interactions","coherent enhancement"],"falsifier":"Compute the full nuclear response for scalar and tensor currents at the momentum transfers sampled by COHERENT, including subleading recoil corrections and two-body nuclear currents; if the coherent $N^2$ part of the tensor response is not negligible at these recoil energies, the bounds in Tables 2 and 3 shift outside their quoted uncertainties. A direct experimental check would be a high-precision measurement of the delayed-neutrino spectrum from muon decay by an independent charged-current detector, which should reproduce the extracted $P_{\\bar\\nu_L}$ and $w_{\\bar\\nu_L}$ within the reported 90% region.","tokens_in":27085,"feed_emoji":"⚛️","tokens_out":12134,"duration_ms":124147,"temperature":0.7,"pith_summary":"This paper argues that COHERENT's coherent elastic neutrino-nucleus scattering (CEνNS) data are sensitive not only to new physics in neutrino detection but also, once right-handed Dirac neutrinos are included, to new physics in neutrino production. Working in νWEFT, the most general low-energy effective theory with the Standard Model fields plus right-handed Dirac neutrinos, it keeps arbitrary lepton flavor and derives the full event rate for pion decay, muon decay, and CEνNS detection in compact form: Standard Model fluxes times effective cross sections built from a few generalized nuclear charges. The paper uses current COHERENT cesium-iodide and liquid-argon data to bound these charges and the underlying Wilson coefficients, including first constraints on the muon-decay antineutrino spectral parameters $P_{\\bar\\nu_L}$ and $w_{\\bar\\nu_L}$. It also establishes that tensor interactions are not coherently enhanced at leading nuclear order, correcting a long-standing assumption in earlier CEνNS analyses, and gives projections for the planned CENNS-750 detector. If right, the paper supplies a ready-made parametrization that any existing or future CEνNS experiment can use to constrain production-side new physics.","feed_headline":"Muon decay's neutrino spectrum is measurable at COHERENT","feed_subtitle":"All new physics folds into a few effective nuclear charges, giving first bounds on muon-decay antineutrinos.","key_machinery":"The central objects are the generalized nuclear charges of Eq. (3.3)—$Q_V$, $\\tilde Q_V$, $Q_S$, $Q_F$, and $Q_{SF}$—and their production-weighted combinations $(\\tilde Q^f_X)^2$ of Eq. (4.6), which bundle detection-side Wilson coefficients with muon-decay spectral matrices $H^{(i)}_x$ and pion-decay factors $P,\\tilde P$. The machinery is the νWEFT operator basis (including right-handed Dirac neutrinos) matched onto a pionless nonrelativistic nucleon EFT; the nonrelativistic reduction in Eq. (2.8) maps the scalar nucleon bilinear onto the coherent vector structure and the tensor bilinear onto the incoherent axial structure, which is the step that removes the coherent enhancement for tensor couplings. With that mapping in place, the rate factorizes into SM fluxes times effective cross sections, making the new physics implementation immediate for any target or experiment.","core_discovery":"The paper claims that the complete COHERENT event rate in the presence of flavor-general νWEFT new physics, including right-handed Dirac neutrinos in pion decay, muon decay, and CEνNS detection, can be written as the conventional Standard Model fluxes times effective cross sections, with all new physics collected in generalized nuclear charges $\\tilde Q^f_V$, $\\tilde Q^f_S$, $\\tilde Q^f_F$, and $\\tilde Q^f_{SF}$ of Eqs. (4.3)–(4.6). Production-side new physics enters through factors $x_\\mu$, $x_{\\bar\\mu}$, and $x_e$ multiplying the SM weak nuclear charge; in the presence of right-handed neutrinos these factors no longer cancel as they do in the SM-field-content case, which is why COHERENT can constrain them. The paper further claims first constraints on the muon-decay antineutrino spectral parameters $P_{\\bar\\nu_L}$ and $w_{\\bar\\nu_L}$, and shows, via the leading-order nonrelativistic reduction of the nucleon EFT, that scalar interactions mimic the coherent vector response while tensor interactions mimic the incoherent axial response. The tensor contribution therefore does not receive the $N^2$ coherent enhancement used in many previous CEνNS analyses, so the corresponding earlier bounds are not correct.","pith_inferences":["The same leading-order nonrelativistic rule that suppresses tensor coherence also governs dark-matter direct detection and muon-to-electron conversion, so the correction to CEνNS tensor bounds likely propagates to those processes; the paper notes the shared context but does not quantify that transfer.","If the muon-decay spectral parameters can be pinned down at CENNS-750, stopped-pion neutrino sources could become a broadly accessible laboratory for the Lorentz structure of the weak charged current, without needing to detect the charged lepton.","A multi-target global fit at fixed Wilson coefficients is a built-in consistency test of the factorization: cesium iodide and argon weight $Z$ and $N$ differently, so a disagreement between their inferred charges would point to nuclear-response or production physics missing from the leading-order EFT.","Extending the same method to reactor and solar CEνNS experiments, where neutrinos are born in beta decay, would open production-side sensitivity to charged-current operators that are hard to reach at spallation sources; the paper lists this as a direction to explore."],"forward_implications":["Earlier COHERENT bounds on tensor quark couplings that assumed an $N^2$ coherent enhancement should be revisited; those analyses overestimated the tensor rate by a factor $N^2$ and therefore quoted coefficient bounds that are too strong.","The delayed spectrum measured at COHERENT now yields constraints on the muon-decay spectral parameters $P_{\\bar\\nu_L}$ and $w_{\\bar\\nu_L}$ and their neutrino counterparts, without detecting the charged lepton in the decay.","All new physics can be implemented by replacing the SM weak charge with the generalized charges of Eqs. (4.3)–(4.6), so future CEνNS analyses at any target can reuse the same compact parametrization with little additional amplitude work.","Projections for the CENNS-750 detector show substantial improvements, including a projected lower bound $|[h^V_{LL}]_{\\alpha\\beta}| > 0.976$ at 90% CL, competitive with current values from global muon-decay analyses.","The same generalized-charge framework extends to CEνNS measurements with reactor and solar neutrinos, where the production side is nuclear beta decay rather than pion and muon decay."],"supporting_citations":[{"why":"Supplies the CEνNS rate formalism and the COHERENT experimental implementation for left-handed-only field content, which this paper extends to right-handed Dirac neutrinos.","marker":"[31]"},{"why":"Establishes the simpler lepton-flavor-conserving result that COHERENT can constrain muon-decay parameters; this paper generalizes that result to flavor-general νWEFT.","marker":"[32]"},{"why":"Defines the νWEFT operator framework (also called νLEFT/LNEFT) with right-handed Dirac neutrinos used throughout the calculation.","marker":"[33]"},{"why":"Shows that tensor interactions are not coherently enhanced under the nonrelativistic EFT treatment, a central correction used in this paper.","marker":"[23]"},{"why":"Provides the EFT analysis and nuclear-response treatment for CEνNS, including the non-coherent tensor response used here.","marker":"[27]"},{"why":"Gives the nonrelativistic nuclear reduction for tensor couplings in dark-matter detection and muon-to-electron conversion, supporting the tensor-interaction claim.","marker":"[48]"},{"why":"Supplies the COHERENT liquid-argon CEνNS data set used in the statistical fits.","marker":"[3]"},{"why":"Supplies the COHERENT cesium-iodide CEνNS data set used in the statistical fits.","marker":"[5]"},{"why":"Provides the muon-decay neutrino spectrum parametrization in terms of $P_{\\nu_L}$ and $w_{\\nu_L}$ on which the muon-decay analysis is built.","marker":"[38]"},{"why":"Gives the standard muon-decay parameter definitions and normalization conditions that connect the Wilson coefficients to measured quantities.","marker":"[40]"}],"fun_headline_variants":["COHERENT's first muon-decay antineutrino bounds from effective charges","All new physics at COHERENT packs into four nuclear charges","Tensor new physics lacks coherent boost in CEvNS, COHERENT shows","First constraints on muon-decay antineutrinos from COHERENT","Flavor-general new physics folds into four effective charges at COHERENT"],"cache_read_input_tokens":3200,"weakest_assumption_plain":"The load-bearing premise is the leading-order nonrelativistic pionless EFT of Section 2.2, which maps scalar and tensor nucleon bilinears onto vector and axial structures and assumes that subleading recoil corrections and two-body nuclear currents are negligible at COHERENT's recoil energies; the paper states that recoil corrections from tensor interactions are coherently enhanced but currently much smaller than experimental uncertainties, so if that hierarchy fails, the derived tensor and scalar limits shift.","fun_headline_variants_meta":{"raw":{"variants":["COHERENT's first muon-decay antineutrino bounds from effective charges","All new physics at COHERENT packs into four nuclear charges","Tensor new physics lacks coherent boost in CEvNS, COHERENT shows","First constraints on muon-decay antineutrinos from COHERENT","Flavor-general new physics folds into four effective charges at COHERENT"]},"model":"deepseek-v4-flash","effort":"low","cost_usd":0.00092,"raw_usage":{"total_tokens":3940,"prompt_tokens":932,"completion_tokens":3008,"prompt_tokens_details":{"cached_tokens":384},"prompt_cache_hit_tokens":384,"prompt_cache_miss_tokens":548,"completion_tokens_details":{"reasoning_tokens":2923}},"tokens_in":548,"tokens_out":3008,"duration_ms":21016,"temperature":1.0,"reasoning_tokens":2923,"cache_read_input_tokens":384,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-08-16T04:22:30.316741+00:00","model_set":{"reader":"deepseek-v4-flash"},"falsifier":"Compute the full nuclear response for scalar and tensor currents at the momentum transfers sampled by COHERENT, including subleading recoil corrections and two-body nuclear currents; if the coherent $N^2$ part of the tensor response is not negligible at these recoil energies, the bounds in Tables 2 and 3 shift outside their quoted uncertainties. A direct experimental check would be a high-precision measurement of the delayed-neutrino spectrum from muon decay by an independent charged-current detector, which should reproduce the extracted $P_{\\bar\\nu_L}$ and $w_{\\bar\\nu_L}$ within the reported 90% region.","supporting_citations":[{"cited_title":"Fetscher, Helicity dependence of the electron-neutrino energy spectrum from the decay of unpolarized muons,Phys","cited_arxiv_id":null,"evidence_quote":"Provides the muon-decay neutrino spectrum parametrization in terms of $P_{\\nu_L}$ and $w_{\\nu_L}$ on which the muon-decay analysis is built."}],"review_version":1}