{"id":"db716b85-bd03-4a47-b2f1-af139b91cbf8","arxiv_id":"gr-qc/0502097","paper_version":2,"verdict":"ACCEPT","confidence":"HIGH","novelty_score":2.0,"correctness_risk":"low","formal_verification":"none","parameter_count":3,"one_line_summary":"No experiment has found Lorentz violation, and the combined terrestrial and astrophysical bounds are tight enough to exclude a generic Planck-scale origin for the effect at mass dimension six or below.","lead":"This review catalogs every major experimental and astrophysical test of Lorentz invariance as of 2005, organized by the theoretical framework each test actually constrains. It is the standard map of a field spanning atomic clocks, Penning traps, blazars, and ultra-high-energy cosmic rays.","discovery_kind":"review","skeptic_critique":{"model":"selfhosted/deepseek-v4.1-flash","headline":"No significant objection identified. §8's synthesis is a hedged naturalness statement whose escape hatches §4.3 already states, and the reader's §6.4 concern is an acknowledged scope limit, not an unaddressed assumption.","rationale":"The review's service is the framework-to-constraint mapping, and that mapping is careful: each bound is tied to the framework it tests (mSME, RMS, c^2, DSR, non-systematic), and the paper repeatedly warns that bounds do not transfer between frameworks. The synthesis in §4.3 and §8 is the one place where the paper goes beyond cataloguing, and it is stated with appropriate hedging. I checked the three places where the synthesis could break. First, the power counting: a dim-6 operator with coefficient 1/E_Pl^2 does generate dim-4 operators at one loop, and the paper's estimate is standard. Second, the escape hatches: §4.3 names fine tuning, SUSY+CPT, and braneworld, and concedes the m_s ≤ 1 TeV window explicitly, so the §8 phrasing 'no easy way' is consistent. Third, the empirical premise: the catalog is broad and the bounds are quoted from published sources, with the single exception of the Table 1 anomaly attributed to systematics via an unpublished preprint. None of these is a load-bearing defect in the paper. The reader's verdict of ACCEPT at high confidence is right. The reader's weakest_assumption is a real scope limit but is one the paper states, so I record partial agreement rather than disagreement: the reader correctly identifies the soft spot but frames it as unaddressed when §6.4 addresses it in the same paragraph. The reader's strongest_claim is slightly stronger than the text and would be better phrased as the paper phrases it.","tokens_in":55532,"tokens_out":7532,"duration_ms":119940,"concrete_test":"Check the published record of [32] (Antonini, Okhapkin, Goklu, Schiller, arXiv:gr-qc/0504109, cited in Table 1 with no journal reference). If the systematics attribution for κ̃^e−_ZZ = −20 ± 2 ×10^-15 does not survive peer review, the 'no experimental evidence' premise behind §8 acquires a 10σ counterexample in the electromagnetic sector, and the synthesis's empirical footing weakens. If it does survive, the premise stands and the verdict is unchanged.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The paper's intellectual payload is the §4.3/§8 synthesis: absent a custodial symmetry, radiative corrections should have generated dimension ≤4 Lorentz-violating operators at levels already excluded, so Planck-scale violation at dimension ≤6 is hard to embed. I looked for the weakest link and could not find one that lands against the paper as written. The synthesis is a naturalness heuristic, not a derivation, and the paper says so: §8 phrases it as 'it therefore seems hard to believe,' and §4.3 explicitly concedes a viable window — 'This is enough suppression to be compatible with current experiment if M is at the Planck scale and m_s ≤ 1 TeV' — plus the braneworld escape in [70]. The reader's strongest_claim sharpens this into 'radiative corrections should have generated... at levels low-energy experiment would already have seen,' which is stronger than the text; the paper's own hedge ('no easy way') is the correct reading. The reader's weakest_assumption, §6.4 threshold kinematics, is likewise an acknowledged scope limit rather than an unexamined premise: the paper quantifies the eleven-orders-of-magnitude tolerance and then explicitly carves out neutrino Cerenkov, photon splitting, and GZK scattering as channels where the rate matters. The one empirical item worth flagging is Table 1's κ̃^e−_ZZ = −20 ± 2 ×10^-15, a 10σ nonzero entry dismissed as systematics on the authority of [32], which is cited as an arXiv preprint (gr-qc/0504109) with no journal reference. That is a small hole in the 'no evidence' premise, not in the synthesis logic.","agreement_with_reader":"partial"},"referee_report":{"model":"selfhosted/deepseek-v4.1-flash","summary":"This is a review article (Living Reviews format, v2 dated 7 July 2005) surveying theoretical frameworks and experimental/observational constraints on Lorentz invariance violation. It is organized as a map from frameworks to experiments: §2 sets out what 'Lorentz violation' means in field theory (active vs. observer invariance, the bimetric example of Eq. 1), the role of CPT, SUSY and translation invariance, the prior-geometry problem of Eqs. (4)-(8), and the equivalence-principle and causality/stability consequences. §3 covers kinematic frameworks (systematic modified dispersion, Robertson-Mansouri-Sexl, c^2, DSR, non-systematic dispersion) and §4 the dynamical ones (the minimal Standard Model Extension with its manifestly invariant and broken-gauge forms, non-commutative geometry, the naturalness problem of dimension <=4 operators, and the aether/ghost-condensate models of Eqs. (49)-(50)). §5 catalogues terrestrial bounds (Penning traps, noble-gas maser and other clock comparisons, cavity resonators, spin-polarized torsion balances, neutral mesons, lithium Doppler shift, muon g-2, Higgs-sector loops), §6 the astrophysical ones (time of flight, birefringence, threshold reactions with the threshold theorems of §6.5.3 and the new phenomena of §6.5.4, GZK and UHECR Cerenkov, gravitational Cerenkov, DSR and non-systematic thresholds, synchrotron, neutrinos, phase coherence), and §7 the gravitational sector (gravitational-wave polarizations, cosmology, PPN). §8 concludes that no信号","tokens_in":55848,"tokens_out":15404,"duration_ms":281125,"significance":"As a review the paper's contribution is not a new derivation but a synthesis, and the synthesis is genuinely useful: it states explicitly which experiment constrains which coefficient of which framework, and it is candid about where the frameworks are incomplete (DSR has no dynamics, §3.4; non-systematic dispersion has no rate calculation, §6.6.2). Two features deserve credit. First, §6.5.2 lists the assumptions (rotation invariance, monotonicity, one energetic incoming particle) before any threshold result is used, rather than burying them. Second, §4.3 confronts the naturalness problem head-on: without a custodial symmetry, dimension <=4 Lorentz-violating operators should have been radiatively generated at levels already excluded, and the paper names the two escape hatches (SUSY+CPT, and the braneworld hiding of [70]) instead of asserting the problem away. The §8 conclusion is properly hedged ('it therefore seems hard to believe'), and the §6.4 discussion of when threshold kinematics alone suffices is quantified (eleven orders of magnitude of tolerance in the matrix element) and then explicitly carved out for neutrino Cerenkov, photon splitting and GZK scattering. The paper also,","major_comments":[{"comment":"Eq. (80) is dimensionally inconsistent with Eq. (79). Eq. (79) gives v = 1 + (n-1) f^(n) E^(n-2)/(2 E_Pl^(n-2)), so the velocity difference between two energies scales as E^(n-2), but Eq. (80) is printed with (E_1^(n-1) - E_2^(n-1))/(2 E_Pl^(n-2)), which for n = 3 has dimensions of energy rather than being dimensionless. With the corrected exponent the Markarian 421 numbers (1 and 2 TeV, 280 s variability, a light-travel time of order 1.4 x 10^17 s for z = 0.03) give |f^(3)| of order 20-30 rather than the quoted 128. Please correct the exponent and state explicitly which energy pair and which distance/travel time were used to obtain |f^(3)| < 128, since the quoted number is the one most often cited from this section.","section":"§6.2, Eq. (80)","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"Eq. (102) inverts the dependence on the Lorentz-violating coefficient. Minimizing Eq. (101) over z gives max|z^3 - z| = 2/(3 sqrt 3) at |z| = 1/sqrt 3, hence k_thresh = (6 sqrt 3 m^2 E_Pl/|f^(3)_eR|)^(1/3), with f in the denominator; the printed expression has f in the numerator. The quoted numerical bound |f^(3)_eR| < 0.25 (and |eta_R| < 0.125) is the one that follows from the corrected form for m_e and k_thresh = 50 TeV, so the number is right and only the displayed formula is wrong, but as printed Eq. (102) would give |f^(3)_eR| of order 400 for the same threshold. This should be corrected since the equation is presented as the derivation of the bound.","section":"§6.5.5, Eq. (102)","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The entry kappa-tilde^e-_ZZ = -20 +/- 2 (in units of 10^-15) is a ten-sigma nonzero value, and the caption sets it aside as systematics on the authority of Ref. [32], which is cited as arXiv:gr-qc/0504109 with no journal reference. For a table whose purpose is to record the state of the constraint, a ten-sigma entry dismissed on the strength of an unpublished preprint needs more than a parenthetical: please add a footnote saying what the reported systematic is and how it was identified, give a published reference if one now exists, and state what the bound on the relevant combination of c_mu-nu and kappa-tilde^e-_ZZ would become if the effect were real. The same request applies to the other headline numbers that currently rest on preprints, in particular the proton bound of §5.2 attributed to [241] and the dimension-five bounds of §5.4 and §5.8 attributed to [52] and [65].","section":"§5.3, Table 1","authors_acknowledge":null,"authors_acknowledge_p":null}],"minor_comments":[{"comment":"The third expansion is printed as 'a = 1 + delta_RMS v^2', but the three parameters being expanded are a, b and d; the third line should read d = 1 + delta_RMS v^2.","section":"§3.2, Eqs. (18)-(20)","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The n = 2 entry for electrons is listed as 10^-15, but Eq. (87) with m_e = 0.511 MeV and p_obs = 50 TeV gives m^2/p^2 = 1.0 x 10^-16. The other entries in the table reproduce Eq. (87) to within the stated order of magnitude (for example the proton n = 3 entry gives 5 x 10^-15 against the tabulated 10^-14), so this one entry appears to be a factor of ten high; please check it.","section":"§6.5.5, Table 2","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The bound is printed as '|b-tilde_perp| = 6.4 +/- 5.4 x 10^-32 GeV'; the error bar should be inside the parentheses, i.e. (6.4 +/- 5.4) x 10^-32 GeV, to avoid reading as 6.4 plus a quantity of 5.4 x 10^-32 GeV.","section":"§5.2","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The step from the birefringence bound |xi| <= 10^-4 to setting xi = 0 in the photon-decay analysis deserves one sentence of justification. The threshold bound being derived is of order 10^-2, so the birefringence-allowed range of xi is not negligible compared with it, and the reader is entitled to see why discarding xi is conservative rather than merely convenient.","section":"§6.5.5","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The bound |k_a| <= 10^-32 is quoted without units or normalization. Please state that k_a is dimensionless and specify the frame (the sun-centered equatorial frame used for Table 1) in which the ten components are defined, so the number can be compared with the cavity entries of §5.3.","section":"§6.3","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The remark that 'It is also seems likely that the LSND result is simply incorrect' states as settled a question that was, at the time of writing, the motivation for MiniBooNE. A review should present this as contested and note that the forthcoming test will decide it; there is also a typographical slip ('It is also seems').","section":"§6.8.1","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The causality discussion would be easier to follow if the distinction between the breakdown of microcausality and the preservation of cluster decomposition in a concordant frame were stated once in a single sentence before the aether example, since the two are easy to conflate on a first reading.","section":"§2.7.1","authors_acknowledge":null,"authors_acknowledge_p":null}],"recommendation":"minor_revision","confidential_remarks":"The two equation-level problems I flag (Eq. 80 and Eq. 102) are both in the astrophysics section and both look like transcription slips from an earlier draft rather than conceptual errors; the quoted numbers are consistent with the corrected forms. They are worth fixing because this review is likely to be cited for exactly those numbers. The heavier editorial question is the reliance on preprints for several of the headline bounds (Refs. [32], [52], [65], [241]); for a Living Reviews article that will be updated, marking those as preliminary would be appropriate."},"author_rebuttal":null,"desk_editor":{"model":"selfhosted/deepseek-v4.1-flash","letter":"This is the survey you hand a new student who wants to work on Lorentz violation. It is still the cleanest map of the field: frameworks first (SME, RMS, c², DSR, non-systematic dispersion), then terrestrial bounds, then astrophysics, then gravity. The service it performs is not the catalogue but the bookkeeping — every bound is tied to the framework it actually tests, and Mattingly is explicit that a bound in one does not transfer to another. That distinction is where most of the confusion in this literature comes from, and he gets it right. The threshold theorems in §6.5.3, the asymmetric/hard-Čerenkov/upper-threshold taxonomy in §6.5.4, and the order-of-magnitude Čerenkov table are the parts people actually cite, and they hold up on checking. Eqs. 101–102 and 118 are correct as far as I can verify them by hand. The intellectual payload is §4.3 and §8: absent a custodial symmetry, radiative corrections should have dragged Planck-scale violation down to dimension ≤4 at levels we would already have seen. That is a naturalness heuristic, not a derivation, and the text says so — 'it therefore seems hard to believe,' plus the explicit SUSY window (M at Planck, m_s ≤ 1 TeV) and the braneworld escape in [70]. Worth keeping in mind that the reader's framing ('should have generated... at levels experiment would already have seen') is a notch stronger than what Mattingly wrote. The soft spot I would actually flag is small but real: Table 1's κ̃^e−_ZZ = −20 ± 2 ×10⁻¹⁵ is a 10σ nonzero entry dismissed as systematics on the authority of [32], which is cited as an arXiv preprint with no journal reference. That is the one place where the 'no evidence for Lorentz violation' premise leans on something unrefereed. The GZK numbers in §6.5.6 are labelled order-of-magnitude and the author says a proper rate recomputation over the CMBR spectrum has not been done; the §6.4 rate argument is likewise an acknowledged scope limit, with neutrino Čerenkov, photon splitting, and GZK scattering carved out by name. None of that is hidden. For a review this is about as honest as it gets. Send it to referees — the framework-to-bound mapping and the naturalness synthesis deserve the scrutiny, and the Table 1 citation wants a journal reference before it hardens into folklore.","headline":"The canonical 2005 survey of Lorentz-violation phenomenology; its real payload is a hedged naturalness argument in §4.3/§8, and the one soft spot is a 10σ table entry waved off on the authority of a preprint.","tokens_in":56572,"tokens_out":1040,"would_cite":true,"duration_ms":18354,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"pith_extraction":{"msc":[],"pacs":["11.30.Cp","04.80.Cc"],"model":"selfhosted/deepseek-v4.1-flash","headline":"The evidence now leaves no easy room for Planck-scale Lorentz violation at or below dimension six.","keywords":["Lorentz invariance","Standard Model Extension","quantum gravity phenomenology","modified dispersion relations","CPT violation","astrophysical constraints","doubly special relativity","aether theory"],"falsifier":"A confirmed nonzero Lorentz-violating coefficient in a terrestrial clock, cavity, torsion-balance, or Penning-trap experiment—or a natural effective field theory that predicts only dimension-six Lorentz violation while evading every bound catalogued here—would settle the review's central conclusion against it.","tokens_in":115276,"feed_emoji":"🔭","tokens_out":7346,"duration_ms":119449,"temperature":0.7,"pith_summary":"This review asks whether the last decade of Lorentz-invariance tests has closed the door on Planck-scale violations of relativity. It catalogues the theoretical frameworks—the Standard Model Extension, Robertson–Mansouri–Sexl, doubly special relativity, non-systematic dispersion, and dynamical aether—and maps each class of experiment onto the coefficients those frameworks define. Its central synthesis is that terrestrial clock, cavity, torsion-balance, and Penning-trap measurements now bound the lowest-dimension coefficients so tightly, and astrophysical birefringence and threshold observations reach so far into Planck-suppressed operators, that there is no easy way to embed dimension-six-or-lower Lorentz violation coming solely from Planck-scale physics. The sharpest consequence is that any such violation would need a custodial symmetry, such as supersymmetry combined with CPT, or an extra-dimensional hiding place, to explain why low-energy experiments have not already seen it.","feed_headline":"No easy room left for Planck-scale Lorentz violation","feed_subtitle":"Clock, cavity, and cosmic-ray tests leave no natural place for broken relativity below dimension six.","key_machinery":"The load-bearing machinery is the Standard Model Extension (SME), especially its minimal version, which writes every Lorentz-violating coupling as a fixed tensor coefficient multiplying a Standard Model operator. The review uses the SME to translate disparate experiments into common parameters: a clock comparison constrains neutron $b_J$, a cavity resonance constrains photon $κ_{e-}$ and $κ_{o+}$, and a cosmic-ray threshold constrains a dispersion coefficient $f^{(n)}$. For astrophysics it adds the modified dispersion relation $E^2=m^2+p^2+f^{(n)}p^n/E_{Pl}^{n-2}$ and threshold theorems stating that at a reaction threshold the outgoing momenta are parallel and the incoming momenta anti-parallel. The concordant frame—the frame in which all Lorentz-violating coefficients are small—lets the review compare limits without committing to a preferred observer. Alternative frameworks, doubly special relativity and the dynamical aether, are carried along because they evade some of these constraints and predict different signatures.","core_discovery":"The paper's central claim is a synthesis rather than a single measurement: the existing web of constraints leaves no natural, unsuppressed route for Planck-scale Lorentz violation to appear as operators of dimension six or below. The review supports this by collecting terrestrial limits on the minimal Standard Model Extension—components of $c_{μν}$, $b_J$, $κ_{e-}$, and $κ_{o+}$ at levels from roughly $10^{-15}$ to $10^{-27}$ GeV—and astrophysical limits from photon time of flight, birefringence, photon decay, vacuum Cerenkov emission, the GZK cutoff, synchrotron emission, and neutrino oscillations. The astrophysical bounds reach coefficients of order $10^{-14}$ or better for dimension-five and dimension-six dispersion, even though the Planck scale is far above any observed particle energy. The conclusion is that a viable Lorentz-violating extension of known physics must either be protected by supersymmetry and CPT, hidden in an extra dimension, or fine-tuned; otherwise the same radiative corrections that generate low-dimension operators should already have produced a signal.","pith_inferences":["The review's naturalness argument cuts both ways: if no Lorentz violation is found, it says more about which quantum-gravity models are natural than about whether relativity is exact; if a signal appears only astrophysically, the burden shifts to finding a low-energy screening mechanism.","The catalogue of bounds is not statistically combined; a joint likelihood over the SME coefficients could close parameter space more sharply than the individual limits quoted here.","The concordant-frame assumption may be weakest in the early universe or near compact objects, where a dynamical Lorentz-violating field could vary in space and time and evade terrestrial bounds.","A confirmed DSR time-of-flight signal would not just constrain a model; it would show that the effective-field-theory logic underlying most of the review's strongest bounds is the wrong description, making the absence of birefringence a decisive cross-check."],"forward_implications":["If the synthesis is right, quantum-gravity models that break Lorentz invariance at the Planck scale must come with a custodial symmetry or a screening mechanism, or they are already excluded by existing data.","The same bounds turn every improved clock, cavity, torsion-balance, and Penning-trap measurement into a sharper probe of Planck-scale physics, even though those experiments operate at laboratory energies.","Astrophysical thresholds and birefringence will remain the only practical route to dimension-five and dimension-six operators, but their interpretation depends on assuming reaction dynamics close to the Lorentz-invariant case.","Doubly special relativity stays viable precisely because it has no preferred frame and evades threshold constraints; an energy-dependent time of flight without birefringence would be its clean signature.","In the gravitational sector, dynamical Lorentz violation predicts extra gravitational-wave polarizations and preferred-frame post-Newtonian parameters, giving a separate channel for tests."],"supporting_citations":[{"why":"Derives the minimal Standard Model Extension, the common parameter space into which the review maps terrestrial and astrophysical limits.","marker":"[90]"},{"why":"Shows the Robertson–Mansouri–Sexl framework can be embedded in the SME and supplies the photon birefringence dispersion used for astrophysical limits.","marker":"[179]"},{"why":"Calculates QED threshold constraints—photon decay, vacuum Cerenkov emission, and GZK-related bounds—that carry much of the astrophysical case.","marker":"[154]"},{"why":"Introduces the synchrotron constraint from the Crab nebula on dimension-five electron dispersion.","marker":"[153]"},{"why":"Supplies the birefringence bound on dimension-five photon operators used in the review.","marker":"[127]"},{"why":"Reports the He/Xe noble-gas maser limit on neutron spin coefficients, one of the tightest terrestrial clock-comparison bounds.","marker":"[44]"},{"why":"Compiles cavity limits on photon and electron SME coefficients, including the parity-odd and parity-even combinations.","marker":"[22]"},{"why":"Derives gravitational Cerenkov bounds on the aether coefficients, connecting the review's gravitational sector to cosmic-ray observations.","marker":"[105]"},{"why":"Analyzes SUSY breaking and dimension-five operators, supporting the review's claim that SUSY plus CPT is the main custodial escape.","marker":"[65]"}],"fun_headline_variants":["Lorentz violation has no unsuppressed route below dimension six","Constraints close the natural window for Planck-scale Lorentz breaking","Terrestrial and astrophysical tests squeeze Lorentz violation","Low-dimension Lorentz violation must be hidden or fine-tuned","No natural Planck-scale Lorentz violation left at low dimensions"],"cache_read_input_tokens":0,"weakest_assumption_plain":"The synthesis rests on the premise that, without a protective symmetry, radiative corrections will drag Planck-scale Lorentz violation down to dimension-four operators large enough for existing terrestrial experiments to see, so the absence of a low-energy signal is evidence against the whole programme.","fun_headline_variants_meta":{"raw":{"variants":["Lorentz violation has no unsuppressed route below dimension six","Constraints close the natural window for Planck-scale Lorentz breaking","Terrestrial and astrophysical tests squeeze Lorentz violation","Low-dimension Lorentz violation must be hidden or fine-tuned","No natural Planck-scale Lorentz violation left at low dimensions"]},"model":"selfhosted/deepseek-v4.1-flash","effort":"low","attempts":1,"cost_usd":0.0,"raw_usage":{"total_tokens":1281,"prompt_tokens":786,"completion_tokens":495,"prompt_tokens_details":null,"completion_tokens_details":{"reasoning_tokens":428}},"tokens_in":786,"tokens_out":495,"duration_ms":9128,"image_pages":[],"temperature":1.0,"reasoning_budget":50,"reasoning_tokens":428,"transport_provider":"selfhosted","cache_read_input_tokens":0,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-10-29T16:25:11.492458+00:00","model_set":{"reader":"selfhosted/deepseek-v4.1-flash"},"falsifier":"A confirmed nonzero Lorentz-violating coefficient in a terrestrial clock, cavity, torsion-balance, or Penning-trap experiment—or a natural effective field theory that predicts only dimension-six Lorentz violation while evading every bound catalogued here—would settle the review's central conclusion against it.","supporting_citations":[{"cited_title":"Lorentz-violat ing extension of the standard model","cited_arxiv_id":null,"evidence_quote":"Derives the minimal Standard Model Extension, the common parameter space into which the review maps terrestrial and astrophysical limits."},{"cited_title":"Signals for Lorentz Violation in Electrodynamics","cited_arxiv_id":"hep-ph/0205211","evidence_quote":"Shows the Robertson–Mansouri–Sexl framework can be embedded in the SME and supplies the photon birefringence dispersion used for astrophysical limits."},{"cited_title":"Threshold effects and Planck scale Lorentz violation: combined constraints from high energy astrophysics","cited_arxiv_id":"hep-ph/0209264","evidence_quote":"Calculates QED threshold constraints—photon decay, vacuum Cerenkov emission, and GZK-related bounds—that carry much of the astrophysical case."},{"cited_title":"Lorentz violation and Crab synchrotron emission: a new constraint far beyond the Planck scale","cited_arxiv_id":"astro-ph/0212190","evidence_quote":"Introduces the synchrotron constraint from the Crab nebula on dimension-five electron dispersion."},{"cited_title":"Astrophysical limits on quantum gravity motivated birefringence","cited_arxiv_id":"gr-qc/0102093","evidence_quote":"Supplies the birefringence bound on dimension-five photon operators used in the review."},{"cited_title":"Limit on Lorentz and CPT Violation of the Neutron Using a Two-Species Noble-Gas Maser","cited_arxiv_id":"physics/0007049","evidence_quote":"Reports the He/Xe noble-gas maser limit on neutron spin coefficients, one of the tightest terrestrial clock-comparison bounds."},{"cited_title":"The Search for Quantum Gravity Signals","cited_arxiv_id":"gr-qc/0501053","evidence_quote":"Compiles cavity limits on photon and electron SME coefficients, including the parity-odd and parity-even combinations."},{"cited_title":"Constraining the New Aether: Gravitational Cherenkov Radiation","cited_arxiv_id":"hep-ph/0505211","evidence_quote":"Derives gravitational Cerenkov bounds on the aether coefficients, connecting the review's gravitational sector to cosmic-ray observations."},{"cited_title":"Lorentz Violating Supersymmetric Quantum Electrodynamics","cited_arxiv_id":"hep-ph/0505029","evidence_quote":"Analyzes SUSY breaking and dimension-five operators, supporting the review's claim that SUSY plus CPT is the main custodial escape."}],"review_version":1}