{"id":"4eb32168-d9c9-426f-9845-28c8a9e6e696","arxiv_id":"hep-ph/0311143","paper_version":1,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":6.0,"correctness_risk":"high","formal_verification":"none","parameter_count":0,"one_line_summary":"Two stable dark matter particles from an N=2 supersymmetry-inspired framework could jointly account for the 511 keV galactic bulge line and high-energy gamma-ray signals.","lead":"The paper proposes that two stable dark matter particles, one light and one heavy, could simultaneously explain the 511 keV gamma-ray line seen from the galactic bulge and very high energy gamma rays attributed to dark matter annihilations. It sketches how such a pair could arise from an N=2 supersymmetry-inspired framework with two discrete parities.","discovery_kind":"unclear","skeptic_critique":{"model":"selfhosted/deepseek-v4.1-flash","headline":"Eq. (1) gives Ω_LDM h² ≈ 0.095, essentially all of WMAP's Ω_dm h² ≈ 0.1; the heavy species is then forced to f ≲ 5%, so its gamma-ray flux scales as f²⟨σv⟩′ ≈ 0.0025⟨σv⟩′. The paper asserts ⟨σv⟩′ > 1 pb yields 'significant' flux but never checks this against the relic-density budget.","rationale":"The paper is a short proposal, and its central claim is conditional ('if such a signature is confirmed... we propose a way to accommodate'). The two-parity structure from N=2 SUSY is cited to Fayet's published work and is not the weak point. The U-boson velocity-suppression mechanism is cited to [9] and the neutrino-coupling suppression to [21], so the reader's concern about 'no concrete model' is partly addressed by citation, though the paper does not verify that a single parameter set satisfies 511 keV, relic density, and LAMPF/LSND simultaneously. The more load-bearing gap is internal: Eq. (1) shows LDM saturates the relic density, which quantitatively constrains the heavy species' abundance and hence its gamma-ray flux. The paper acknowledges the heavy species is subdominant but does not quantify the tension, invoking resonances without checking whether the required enhancement is consistent with the relic-density budget and observable flux. This is a real quantitative gap, but it does not falsify the scenario — it identifies a corner of parameter space that the paper asserts but does not demonstrate. Hence CONDITIONAL remains appropriate; the verdict is unchanged, though the specific gap is sharper than the reader's U-boson concern. Agreement with the reader is partial: the reader identified a related soft spot (the U-boson mechanism) but missed that it is cited and missed the more quantitative relic-density-budget tension.","tokens_in":9475,"tokens_out":10821,"duration_ms":189003,"concrete_test":"Recompute the two-component relic density and gamma-ray flux using the paper's own Eq. (1). Take m_LDM = 1-100 MeV with ⟨σv⟩_p = 1 pb (giving Ω_LDM h² ≈ 0.095) and m_heavy = 100 GeV. Solve for the ⟨σv⟩′ that keeps Ω_LDM h² + Ω_heavy h² = 0.1, obtaining ⟨σv⟩′ ≈ 10 pb and f ≈ 0.05. Then compute the predicted high-energy gamma-ray flux from heavy annihilations, Φ ∝ f² ⟨σv⟩′ × J(γ), for halo profiles γ = 0.4 and 0.8, and compare to the H.E.S.S. sensitivity quoted in [15]. If Φ falls below sensitivity for all resonance enhancement factors up to, say, 100, the paper's claim that the heavy component yields 'significant gamma ray fluxes' is not supported by its own relic-density budget.","verdict_should_be":"UNCHANGED","load_bearing_attack":"The central claim is that two stable DM particles can accommodate both the 511 keV line and high-energy gamma rays. The light species' relic density is fixed by the paper's own Eq. (1): for ⟨σv⟩_p ≈ 1 pb (the value needed to fit the 511 keV flux after v² suppression), Ω_LDM h² ≈ 0.095, essentially saturating WMAP's Ω_dm h² ≈ 0.1. The paper acknowledges this ('leaving little room for another weakly annihilating species') but then asserts that if the heavy species has ⟨σv⟩′ > 1 pb it 'would yield significant gamma ray fluxes.' This is not consistent with the paper's own numbers: at ⟨σv⟩′ = 1 pb, Eq. (1) gives Ω_heavy h² ≈ 0.05 for a 100 GeV particle, so the total would be ≈ 0.145, overclosing the universe by ~45%. To keep the total at 0.1, the heavy species must have ⟨σv⟩′ ≳ 10 pb and f ≡ Ω_heavy/Ω_dm ≲ 0.05. The gamma-ray flux scales as f²⟨σv⟩′ ≈ 0.0025 × 10 pb = 0.025 pb, i.e. ~40× below a single-component heavy species with ⟨σv⟩′ = 1 pb. The paper invokes resonances to enhance ⟨σv⟩′ but never quantifies whether the required enhancement (≳ 40×) is achievable in a concrete model, nor whether the resulting flux is above H.E.S.S./CANGAROO sensitivity for a realistic halo profile. This is the load-bearing gap: the 'both signals' claim rests on an unquantified resonance enhancement that must simultaneously satisfy the relic-density budget and produce an observable gamma-ray flux.","agreement_with_reader":"partial"},"referee_report":{"model":"selfhosted/deepseek-v4.1-flash","summary":"The manuscript proposes that two stable neutral dark matter particles, as can arise in theories inspired by N=2 supersymmetry with both R-parity and a new M-parity, could simultaneously account for the INTEGRAL/SPI 511 keV line from the galactic bulge and very high energy gamma rays of dark matter origin. The light M-odd spin-0 particle (LMP) is invoked to annihilate into e+e- and produce the 511 keV line, while the heavy R-odd neutralino (LSP) is invoked to produce the high-energy gamma rays. The paper reviews the relic-density and cross-section numerology in §II, sketches the two-Z2 particle spectrum in §III, and summarizes the scenario in §IV. No new calculation of the annihilation cross sections or of the gamma-ray fluxes is presented; the argument is a consistency proposal built on the authors' earlier work [8,9,10].","tokens_in":9946,"tokens_out":10553,"duration_ms":184225,"significance":"The proposal is timely and worth putting on record: the 511 keV detection is recent, and the idea that a single framework could host two stable dark matter candidates with different mass scales is a genuine particle-physics contribution rather than a purely phenomenological fit. The construction has the virtue of being falsifiable in two independent channels: the 511 keV line from dwarf spheroidals proposed in [14], and the high-energy gamma-ray flux from the heavy species. The paper is also appropriately modest in framing the claim as a proposal ('a way to accommodate') rather than a demonstration. The weakness is that the quantitative bridge between the two signals is asserted rather than computed, so the significance of the proposal currently rests on the plausibility of the N=2-inspired spectrum rather than on a worked-out prediction.","major_comments":[{"comment":"The sentence 'If the annihilation cross section of heavy DM particles (⟨σv⟩′) is larger than 1 pb at both early epochs and today, then these particles are likely to be subdominant but, on the other hand, they would yield significant gamma ray fluxes!' is in tension with the paper's own Eq. (1). For a cross section that is the same at freeze-out and today, the heavy relic fraction f ≡ Ω_heavy/Ω_dm scales as 1/⟨σv⟩′, so the present-day annihilation flux, which scales as f²⟨σv⟩′, scales as 1/⟨σv⟩′: a larger ⟨σv⟩′ reduces the gamma-ray flux rather than enhancing it. With the paper's own numbers, Eq. (1) gives Ω_LDM h² ≈ 0.095 at ⟨σv⟩_p ≈ 1 pb, leaving f ≲ 0.05; at f = 0.05 and ⟨σv⟩′ = 10 pb, f²⟨σv⟩′ ≈ 0.025 pb, roughly forty times below a single-component 1 pb species. The paper should either state explicitly that the required enhancement is velocity-dependent (a low-velocity resonance or Sommerfeld effect, so that the present-day cross section exceeds the primordial one) and quantify the required boost, or revise the claim. As written, the central 'both signals' argument rests on a scaling that runs the wrong way.","section":"§II, Eq. (1) and the sentence beginning 'If the annihilation cross section of heavy DM particles'","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The mechanism that makes the light species viable, a scalar coupled to a new light gauge boson U with a velocity-suppressed annihilation cross section, is asserted in §II ('One way to achieve this is to assume a scalar particle coupled to a new light gauge boson') and repeated in §III.C, but no coupling assignment is given in this Letter. The paper acknowledges in §IV that the U boson must avoid the LAMPF and LSND ν-e scattering constraints, requiring either a coupling dissymmetry or a suppressed neutrino coupling, but does not exhibit a consistent assignment. Since this mechanism is load-bearing for the LDM interpretation of the 511 keV line, the manuscript should either summarize the relevant parameter range from the companion paper [9] or give a minimal explicit example showing that the 511 keV flux, the relic density, and the LAMPF/LSND bounds can be satisfied simultaneously.","section":"§II and §III.C, the new light gauge boson U","authors_acknowledge":null,"authors_acknowledge_p":null}],"minor_comments":[{"comment":"The word 'accomodate' should be spelled 'accommodate'.","section":"Abstract","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The symbol g is introduced ('g and g⋆ are the numbers of internal and relativistic degrees of freedom') but does not appear in Eq. (1), and the sentence 'v is expressed in units of c' refers to a quantity that does not appear in the equation either. The notation Ω_thdm in Eq. (1) should be unified with Ω_LDM used elsewhere.","section":"§II, Eq. (1)","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The sentence 'unless the associated cross section turns out to be extremely small in the primordial universe (namely ≲ 10^-31 cm³ s^-1, which requires heavy mirror fermions and probably chiral couplings)' appears to contain a wording error: a primordial cross section of 10^-31 cm³ s^-1 would overclose the universe by roughly five orders of magnitude, whereas 10^-31 cm³ s^-1 is the order of the present-day cross section needed to fit the 511 keV line. Please clarify whether 'primordial' or 'present-day' is meant.","section":"§III.C","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The coannihilation argument in §I rests on reference [17], which is listed as 'in preparation'. Please cite a published version or soften the claim accordingly.","section":"§I, reference [17]","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The paper should state the assumed mass of the heavy species and the corresponding gamma-ray energy range, and compare the predicted flux to the H.E.S.S. and CANGAROO sensitivities cited in [15]. Without this comparison the 'both signals' claim cannot be assessed against the experiments the paper invokes.","section":"§II","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The phrase 'the DM velocity is ∼ 3 10^-3 the velocity in the primordial Universe' would read more clearly with the numerical values stated explicitly (v_today ∼ 10^-3 c, v_primordial ∼ c).","section":"§II","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The quoted LMP mass range of a few MeV to 100 MeV should be connected to the SPI angular resolution and the 511 keV line width; a sentence explaining why this range is compatible with the observed line would strengthen the section.","section":"§III.C","authors_acknowledge":null,"authors_acknowledge_p":null}],"recommendation":"major_revision","confidential_remarks":"The paper is a timely Letter and the two-Z2 construction is a genuine idea worth publishing. The main obstacle is that the quantitative link between the two signals in §II runs opposite to the paper's own Eq. (1) for a constant cross section; this is fixable with a paragraph distinguishing the primordial and present-day cross sections, but it should be fixed before acceptance. Reference [17] is unpublished and carries part of the §I argument."},"author_rebuttal":null,"desk_editor":{"model":"selfhosted/deepseek-v4.1-flash","letter":"Two things to know. First, the structural idea is real and clean: N=2-inspired SUSY gives two Z2 parities, R and M, so you get two absolutely stable neutral particles — a heavy neutralino LSP and a light M-odd spin-0 LMP. That is a specific, falsifiable two-component dark sector, not a vague gesture, and it is the part of the paper worth keeping. Second, the quantitative case that the heavy species produces detectable high-energy gamma rays is not made, and the stress-test's arithmetic on this is right. The paper's own Eq. (1) gives Omega_LDM h^2 ~ 0.095 at <sigma v>_p ~ 1 pb, essentially all of WMAP's 0.1. The authors see this — 'leaving little room for another weakly annihilating species' — and then say the heavy species is 'likely to be subdominant but ... would yield significant gamma ray fluxes.' Those two clauses do not sit together. Flux scales as f^2 <sigma v>', so at f <~ 0.05 you need <sigma v>' in the tens of pb to match a single-component 1 pb species. The paper mentions resonances as a possible enhancement but never checks whether the required factor is achievable, or whether the resulting flux clears H.E.S.S./CANGAROO for a realistic profile. That is the load-bearing gap, and it is not acknowledged in the text. Credit where due: the LMP-as-light-spin-0-coupled-to-a-new-U-boson is concrete enough to be worked out, and the paper is honest about the other soft spots — the v^2 suppression mechanism, the LAMPF/LSND neutrino-electron constraint, the 'extremely large' cross section needed for a flat halo. Those are flagged, not hidden. So: a good idea paper with one unexamined quantitative claim. Worth a serious referee, mainly to force the f^2 calculation and a real U-boson model. I would cite it for the two-parity structure; I would not cite it for the gamma-ray flux estimate.","headline":"The two-parity structure is a real, specific proposal; the claim that the heavy species yields detectable gamma rays is asserted, not computed, and the f-squared suppression is the gap.","tokens_in":10540,"tokens_out":2701,"would_cite":true,"duration_ms":44762,"reading_group":"maybe","serious_thinker":"yes","would_accept_peer_review":true},"pith_extraction":{"msc":[],"pacs":["07.85.Fv","52.38.Ph","95.35.+d","78.70.Bj","14.80.-j"],"model":"selfhosted/deepseek-v4.1-flash","headline":"Two stable dark matter particles could produce both the galactic 511 keV line and the highest-energy gamma rays, if both signals turn out to be annihilation products.","keywords":["dark matter","511 keV line","INTEGRAL/SPI","light dark matter","N=2 supersymmetry","R-parity","relic density","high-energy gamma rays"],"falsifier":"A dedicated INTEGRAL/SPI search for a 511 keV line from the Sagittarius dwarf spheroidal: a detection at the predicted flux would support the light dark matter interpretation, while a firm upper limit below it would exclude annihilating light dark matter as the source of the galactic bulge line.","tokens_in":10858,"feed_emoji":"🌌","tokens_out":2685,"duration_ms":51224,"temperature":0.7,"pith_summary":"The paper asks what happens if two different dark matter signals are both real: the bright 511 keV positron-annihilation line seen by INTEGRAL/SPI from the galactic bulge, and very high energy gamma rays of order a hundred GeV. A single dark matter particle struggles to do both, because the light particle needed for the 511 keV line annihilates too efficiently at early times to leave much room for a second species, and the heavy particle needed for the gamma rays has to be a subdominant relic with an unusually large annihilation rate. The authors propose that nature contains two stable neutral dark matter particles rather than one, a light spin-0 state at a few MeV to 100 MeV that annihilates into $e^+e^-$ and a heavy state such as the lightest neutralino that annihilates into high-energy gamma rays. The framework for this is supersymmetry with two supersymmetry generators, which can leave behind two independent discrete symmetries, so that both the lightest $R$-odd particle and the lightest $M$-odd particle are absolutely stable. If the picture holds, one model accounts for the relic density measured by WMAP, the 511 keV line, and a potentially detectable high-energy gamma-ray flux at the same time.","feed_headline":"Two dark matter particles could explain both signals","feed_subtitle":"A light scalar makes the galactic 511 keV line; a heavy neutralino makes the high-energy gamma rays.","key_machinery":"The load-bearing device is a pair of discrete $Z_2$ symmetries. In an $N=2$ extended supersymmetry the two supersymmetry generators $Q_1$ and $Q_2$ can be acted on independently by a global $R$-symmetry, which allows two separate $R$-parity operators $R_{1p}$ and $R_{2p}$ whose product is the ordinary $R$-parity, $R_p = R_{1p} R_{2p}$. Abandoning the full $N=2$ structure and keeping only one generator leaves the second discrete symmetry behind, reinterpreted as an $M$-parity that acts on the mirror sector. Ordinary and supersymmetric Standard Model particles carry $M=+1$, while mirror quarks and leptons, their superpartners, the new spin-0 states, the extra inos and the extra Higgs bosons carry $M=-1$. Both parities are preserved after electroweak symmetry breaking, so the lightest $R$-odd particle and the lightest $M$-odd particle are each stable. That is what makes two dark matter candidates possible in one theory instead of one. The second piece of machinery is a new light gauge boson $U$, coupled to the dark matter, whose exchange gives the light scalar the velocity-suppressed annihilation cross section needed to satisfy the 511 keV flux, the relic density, and the low-energy gamma-ray bounds simultaneously.","core_discovery":"The paper's claim is that the apparent tension between a low-energy and a high-energy dark matter signature dissolves if there are two stable neutral dark matter particles. The light one, a spin-0 particle with mass in the few MeV to 100 MeV range, annihilates into $e^+e^-$ and can reproduce both the flux ($9.9^{-4}$ photons cm$^{-2}$ s$^{-1}$) and the angular width of the SPI 511 keV line, provided its annihilation cross section is velocity-suppressed: about $10^{-4}$ to $10^{-5}$ pb in the galaxy today, against roughly 1 pb in the primordial universe. That early-time cross section is what fixes the relic abundance, and the authors estimate $0.095$ for the light species, close to the WMAP value of about $0.1$. The heavy particle is then a subdominant relic whose annihilation cross section can be larger than 1 pb at both epochs without violating the relic density, which is exactly what makes it able to generate a significant high-energy gamma-ray flux even for a relatively mild halo cusp. The authors stress that the required large cross sections are not absurd if resonances enhance them, and that the whole scheme is a proposal for how the two signals could coexist, not a demonstration that they do.","pith_inferences":["The proposal makes a sharp prediction about the spatial morphology of the two signals: the 511 keV emission should trace the same shallow profile that the high-energy gamma rays trace, so comparing their angular distributions would test the two-particle picture independently of any cross-section measurement.","If the light scalar couples to ordinary matter only through the new $U$ boson, then its mass and the $U$ coupling are constrained jointly by the relic density and the SPI flux, which turns the 511 keV line into a measurement of a particle-physics coupling rather than only an astrophysical observation.","The mirror-sector states that give the light scalar its couplings are expected at a few hundred GeV, so the same framework that explains the 511 keV line also predicts new states within reach of the LHC, tying the gamma-ray question to collider searches.","A null result from a dwarf spheroidal survey would not by itself kill the two-particle idea, but it would remove the cleanest test of the light component and leave the 511 keV line to astrophysical positron sources."],"forward_implications":["A 511 keV line from a dark-matter-dominated dwarf spheroidal such as Sagittarius, within reach of INTEGRAL/SPI, would confirm the light particle and rule out a purely astrophysical origin for the bulge line.","The heavy particle can give a diffuse high-energy gamma-ray flux even for a halo profile as shallow as $\\rho \\propto r^{-0.4}$, so a detection of such gamma rays need not require an extremely cuspy halo or a supermassive black hole at the galactic centre.","Direct detection would be difficult for both species: the light one because of its small mass, the heavy one because its residual number density is tiny.","The scenario can be checked against precision electroweak and low-energy data, since the new $U$ boson adds a contribution to $\\nu$-$e$ elastic scattering measured by LAMPF and LSND, and to the muon and electron $g-2$.","If the light species saturates the relic density, the cosmological parameter budget leaves little room for a second weakly annihilating species, so the heavy particle must remain subdominant."],"supporting_citations":[{"why":"Supplies the INTEGRAL/SPI detection of the 511 keV bulge line that the whole proposal is built around.","marker":"[2]"},{"why":"Provides the light dark matter model with a new light gauge boson that gives the velocity-suppressed annihilation cross section.","marker":"[9]"},{"why":"Supplies the halo profile $r^{-0.4}$ to $r^{-0.8}$ and the cross-section range needed to fit the SPI flux and angular width.","marker":"[10]"},{"why":"Supplies the $N=2$-inspired framework with mirror fermions and new spin-0 states that yields two stable neutral particles.","marker":"[18]"},{"why":"Supplies the WMAP relic density, about $0.1$, against which the light species' predicted abundance is compared.","marker":"[19]"},{"why":"Supplies the proposed dwarf-spheroidal test that would confirm or exclude a dark matter origin for the 511 keV line.","marker":"[14]"},{"why":"Supplies the LAMPF $nu$-$e$ scattering measurement that constrains the new gauge boson's couplings.","marker":"[25]"},{"why":"Supplies the LSND $nu$-$e$ scattering bound that the new gauge boson must also satisfy.","marker":"[26]"}],"fun_headline_variants":["Two dark matter particles could explain both signals","A light scalar and a heavy neutralino could fit both signals","Proposal only: two dark matter particles could fit both signals","Two dark matter relics could ease the 511 keV and gamma-ray tension","Light and heavy dark matter could share the 511 keV and gamma-ray roles"],"cache_read_input_tokens":0,"weakest_assumption_plain":"The scheme rests on the light scalar's annihilation being suppressed by a new light gauge boson badly enough to satisfy the 511 keV flux, the relic density, and the low-energy gamma-ray and neutrino-scattering bounds at once, and the paper asserts this route without constructing a concrete model or computing the couplings.","fun_headline_variants_meta":{"raw":{"variants":["Two dark matter particles could explain both signals","A light scalar and a heavy neutralino could fit both signals","Proposal only: two dark matter particles could fit both signals","Two dark matter relics could ease the 511 keV and gamma-ray tension","Light and heavy dark matter could share the 511 keV and gamma-ray roles"]},"model":"selfhosted/deepseek-v4.1-flash","effort":"low","attempts":1,"cost_usd":0.0,"raw_usage":{"total_tokens":1893,"prompt_tokens":896,"completion_tokens":997,"prompt_tokens_details":null,"completion_tokens_details":{"reasoning_tokens":923}},"tokens_in":896,"tokens_out":997,"duration_ms":17859,"image_pages":[],"temperature":1.0,"reasoning_budget":50,"reasoning_tokens":923,"transport_provider":"selfhosted","cache_read_input_tokens":0,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-11-11T09:05:25.823936+00:00","model_set":{"reader":"selfhosted/deepseek-v4.1-flash"},"falsifier":"A dedicated INTEGRAL/SPI search for a 511 keV line from the Sagittarius dwarf spheroidal: a detection at the predicted flux would support the light dark matter interpretation, while a firm upper limit below it would exclude annihilating light dark matter as the source of the galactic bulge line.","supporting_citations":[{"cited_title":"Early SPI/INTEGRAL contraints on the morphology of the 511 keV line emission in the 4th galactic quadrant","cited_arxiv_id":"astro-ph/0309442","evidence_quote":"Supplies the INTEGRAL/SPI detection of the 511 keV bulge line that the whole proposal is built around."},{"cited_title":"Scalar Dark Matter candidates","cited_arxiv_id":"hep-ph/0305261","evidence_quote":"Provides the light dark matter model with a new light gauge boson that gives the velocity-suppressed annihilation cross section."},{"cited_title":"MeV Dark Matter: Has It Been Detected?","cited_arxiv_id":"astro-ph/0309686","evidence_quote":"Supplies the halo profile $r^{-0.4}$ to $r^{-0.8}$ and the cross-section range needed to fit the SPI flux and angular width."},{"cited_title":"Nucl. Phys. B149, 137 (1979); Proc. 1980 Karpacz School (Harwood, 1981) p.115; Phys. Lett. B142, 263 (1984); Nucl. Phys. B246, 89","cited_arxiv_id":null,"evidence_quote":"Supplies the $N=2$-inspired framework with mirror fermions and new spin-0 states that yields two stable neutral particles."},{"cited_title":"First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Preliminary Maps and Basic Results","cited_arxiv_id":"astro-ph/0302207","evidence_quote":"Supplies the WMAP relic density, about $0.1$, against which the light species' predicted abundance is compared."},{"cited_title":"Possible Evidence for MeV Dark Matter In Dwarf Spheroidals","cited_arxiv_id":"astro-ph/0311150","evidence_quote":"Supplies the proposed dwarf-spheroidal test that would confirm or exclude a dark matter origin for the 511 keV line."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Supplies the LAMPF $nu$-$e$ scattering measurement that constrains the new gauge boson's couplings."},{"cited_title":null,"cited_arxiv_id":null,"evidence_quote":"Supplies the LSND $nu$-$e$ scattering bound that the new gauge boson must also satisfy."}],"review_version":1}