{"id":"aac36fa7-de76-403d-be57-6431f77e914e","arxiv_id":"1104.5022","paper_version":2,"verdict":"CONDITIONAL","confidence":"MODERATE","novelty_score":5.0,"correctness_risk":"medium","formal_verification":"none","parameter_count":3,"one_line_summary":"Compressible quantum phases with Fermi surfaces, familiar from condensed matter, are argued to survive in the ABJM and N=4 super Yang-Mills theories when those theories are deformed by a chemical potential.","lead":"This survey argues that the same zero-temperature compressible phases (Fermi liquid, non-Fermi liquid, and fractionalized Fermi liquid) appear both in condensed matter models and in the supersymmetric gauge theories behind gauge-gravity duality once a chemical potential is added. It offers theorists a shared vocabulary for connecting holographic metals to real electron systems.","discovery_kind":"unclear","skeptic_critique":{"model":"selfhosted/deepseek-v4.1-flash","headline":"The bridge from toy Lagrangians L1/L3 to the full ABJM and N=4 SYM theories is asserted rather than derived; the sharpest unresolved gap is whether the d=2 U(1) gauge theory is deconfined with only two charged fermion flavors.","rationale":"The reader's weakest_assumption correctly identifies the toy-model bridge as the load-bearing premise, and the CONDITIONAL verdict is appropriate. I sharpen the concern to two concrete technical gaps that the paper does not resolve: (i) the deconfinement of the compact U(1) gauge theory in the d=2 model with only two charged fermion flavors, which is a standard necessary condition for the NFL and FL* phases to exist as such, and (ii) the pairing instability that the authors themselves flag but do not quantify. Neither gap is a hidden error; both are consequences of the stated modeling choices. The condensed matter sections (II-IV) are synthesis of published work and are presented as such; the mean-field computations in Sections V-VI are explicit and internally consistent, and the Luttinger counting in Eqs. (5.10), (6.25), and (6.28) checks out. The paper also candidly notes the absence of NFL/FL* phases for the μ1≠0, μ2=μ3=0 chemical potential assignment (Figs. 9-10), which is a partial qualification of the abstract's blanket claim. The verdict should remain CONDITIONAL: the paper establishes the phases in the toy models and argues plausibly for their presence in the full theories, but does not derive the bridge, and the deconfinement/stability gaps are the most concrete places where the argument could fail.","tokens_in":29422,"tokens_out":6822,"duration_ms":126798,"concrete_test":"Compute the deconfinement criterion for compact U(1) with N_f = 2 Dirac fermions in 2+1 dimensions (e.g., via the scaling dimension of the monopole operator or existing lattice/continuum results) and check whether the NFL and FL* phases of L1 lie in the deconfined regime. If N_f = 2 is below the critical value, the toy model does not realize these phases and the bridge to ABJM is unsupported.","verdict_should_be":"CONDITIONAL","load_bearing_attack":"The abstract's central claim (abstract:s4) is that the compressible phases found in condensed matter models are 'argued to also be present' in the full ABJM (d=2) and N=4 SYM (d=3) theories. The argument runs through toy Lagrangians L1 (Eq. 5.2) and L3 (Eq. 6.2), which reduce U(N)xU(N) to U(1) or SU(2), drop flavor indices, make the particles non-relativistic, and are analyzed at mean-field level with gauge fluctuations omitted. The authors acknowledge the simplifications openly (Section V: 'a simple toy model which can capture the possible compressible phases'), so the modeling choice itself is not a hidden error. What remains unresolved is whether the toy model's NFL and FL* phases survive in the full theory, and two specific gaps are load-bearing. First, in the d=2 model the NFL and FL* phases require a deconfined compact U(1) gauge field; with only two charged Dirac fermions (f_+, f_-) and gapped bosons, the standard expectation is that compact U(1) in 2+1 dimensions confines via monopole proliferation, and the paper does not check the deconfinement criterion or discuss monopole operators. Second, the paper itself notes (Section V, after Eq. 5.10) that the NFL and FL* phases are 'ultimately unstable to fermion pairing induced by exchange of gauge bosons,' but does not quantify the pairing scale or show that the intermediate-energy regime is wide; the phase diagrams of Figs. 4-8 present these phases as ground states. Both gaps bear directly on whether the phases are 'present' in the full theories rather than artifacts of the toy reduction.","agreement_with_reader":"partial"},"referee_report":{"model":"selfhosted/deepseek-v4.1-flash","summary":"This manuscript is a survey of zero-temperature compressible quantum matter — states with an unbroken global U(1) density Q and unbroken translations, which therefore host Fermi surfaces whose enclosed volumes are tied to <Q> by the Luttinger theorem. The paper reviews the Luttinger argument following Refs. 24 and 26, then walks through condensed-matter models: the doublon metal (Section II), Bose-Fermi mixtures (Section III), and the fractionalized Fermi liquid (Section IV). The original content is in Sections V and VI, where the authors write down toy Lagrangians L1 (Eq. 5.2) and L3 (Eq. 6.2) modeled on ABJM in d=2 and N=4 SYM in d=3 at nonzero chemical potential, compute mean-field energy functionals (Eqs. 5.5 and 6.19), and present phase diagrams (Figs. 4-12) containing Fermi liquid, non-Fermi liquid, fractionalized Fermi liquid, and superfluid phases. The abstract's central claim (abstract:s4) is that the compressible phases found in condensed-matter models are 'argued to also be present' in the holographic gauge theories.","tokens_in":29899,"tokens_out":8106,"duration_ms":177390,"significance":"The paper is a useful and timely unifying survey. The mean-field computations are explicit and reproducible: the energy functionals in Eqs. (5.5) and (6.19) are written out, the parameter choices (mf = mb = mc/2 = u = 1, g1 and g2 set to 0 or 1, v set to 0.85 or 4) are stated, and the Luttinger constraints in Eqs. (5.10), (6.25), and (6.28) are correctly derived from the charge assignments. The mapping between condensed-matter phases (FL, NFL, FL*) and the phases of the toy holographic models is a genuinely helpful organizing device, and the connection drawn to the holographic superfluid literature is well placed. The value of the paper is as a map and a guide to which phases one should look for in the gravity duals, and on that measure it succeeds.","major_comments":[{"comment":"The NFL and FL* phases are asserted to be deconfined — Section V.A.1(c) states 'the U(1) gauge force is deconfined' — but the manuscript nowhere discusses the compactness of the U(1) gauge field or monopole operators. With two charged Dirac fermions (f+ and f-) and gapped bosons, the standard deconfinement criterion in 2+1 dimensions needs to be checked or at least cited; the reader cannot tell whether the deconfined phase is stable against monopole proliferation. This is load-bearing for the d=2 half of the abstract's claim (abstract:s4), because if the compact U(1) confines, the NFL and FL* phases of Figs. 4-8 are not ground states of the theory. The manuscript should either supply the deconfinement argument or state explicitly that it is an assumption.","section":"Section V.A.1(c) and Section IV, Fig. 3","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The Discussion states that 'the basic phases were the same' between the condensed-matter models and the holographic toy models. This is stronger than what the toy Lagrangians establish. The abstract appropriately hedges with 'argued to also be present' (abstract:s4), but Section VII presents the correspondence as a finding. The toy models reduce U(N)xU(N) to U(1) or SU(2), drop flavor indices, make the particles non-relativistic, and are analyzed at mean-field level with gauge fluctuations omitted. The manuscript should temper the Section VII language and add an explicit list separating what is established (the mean-field phase diagrams of L1 and L3) from what is conjectured (the survival of these phases in full ABJM and N=4 SYM).","section":"Section VII, final paragraph","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The pairing instability of the NFL and FL* phases is acknowledged — Section II says these phases are 'ultimately unstable to fermion pairing induced by exchange of gauge bosons,' and Section V.A.1 repeats this — but Figs. 4-8 present NFL and FL* as ground states without a caveat in the figure captions. The manuscript should either estimate the pairing scale and the width of the intermediate-energy regime, or mark these phases in the figures as intermediate-energy regimes rather than ground states. As drawn, the phase diagrams invite the reader to read the NFL and FL* regions as zero-temperature ground states, which the text itself says they are not.","section":"Section II and Section V.A.1","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The truncation to non-relativistic particles 'which only carry charges favored by the chemical potential' drops the anti-particles, which in the relativistic ABJM theory have mass of order the chemical potential. The regime of validity of this truncation — whether it requires mu large compared to temperature and other scales, or mu small — should be stated. Without it, the relation between the toy model L1 and the relativistic ABJM theory at nonzero chemical potential is unclear, and the reader cannot judge how much of the phase structure survives when anti-particles are restored.","section":"Section V, opening paragraph","authors_acknowledge":null,"authors_acknowledge_p":null}],"minor_comments":[{"comment":"The sentence 'This feature differs from the ABJM-like model in Section VI' should read 'Section V'; the ABJM-like model is discussed in Section V, not Section VI.","section":"Section VI.A, paragraph after Eq. (6.25)","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The displayed expansion of sqrt(xi^2 + g1^2 Delta^2) appears to place the factor (k^2/2m2)^2 in the numerator of the correction term rather than the denominator. The subsequent subtraction in Eq. (6.17) is consistent with the denominator form, so this looks like a typographical slip; please check.","section":"Eq. (6.16)","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The text says 'the resulting phase diagrams in Figs. 11 and 12 are very similar to those in Figs. 9 and 10,' and then immediately says 'The new feature of Figs. 11 and 12 is the presence of deconfined phases ... such phases were absent ... in Figs. 9 and 10.' The two statements are in tension; please clarify in what sense the diagrams are similar and in what sense they differ.","section":"Section VI.B","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The caption says 'in the limit of very large epsilon1'; please state the sign of epsilon1 explicitly, since the boson mass term in Eq. (5.1) is epsilon1 - mu and the limit only gives <b±> = 0 for one sign.","section":"Fig. 4 caption","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The counterterm g1^2 |b+|^2 |b-|^2 mf/(k^2 + Lambda^2) in Eq. (5.5) and the renormalization of v in Eq. (5.7) should be cross-referenced in the text so the reader can see that the momentum integral in Eq. (5.5) is ultraviolet convergent as claimed.","section":"Eq. (5.5) and Eq. (5.7)","authors_acknowledge":null,"authors_acknowledge_p":null},{"comment":"The discussion of deconfinement would benefit from citations to the literature on compact U(1) gauge theory with two flavors of Dirac fermions in 2+1 dimensions, which is the relevant comparison for the doublon metal and the ABJM-like model.","section":"Section V.A.1(c) and Section IV","authors_acknowledge":null,"authors_acknowledge_p":null}],"recommendation":"major_revision","confidential_remarks":"This is a well-organized survey with sound and explicit mean-field computations, and the abstract is appropriately hedged. The main reason for major revision rather than minor is the deconfinement question in Section V: the NFL and FL* phases of the d=2 model are asserted to be deconfined without any discussion of monopoles, and that assertion is load-bearing for the d=2 half of the central claim. The Section VII overstatement and the unquantified pairing scale are secondary but should be addressed in the same pass. I expect these to be fixable with text changes and one or two added paragraphs rather than new computation."},"author_rebuttal":null,"desk_editor":{"model":"selfhosted/deepseek-v4.1-flash","letter":"The thing to know: this is two papers stapled together. Sections II–IV are a clean synthesis of published condensed matter work — doublon metal, Bose-Fermi mixtures, FL* — with the Luttinger theorem quoted properly from Powell et al. and Coleman et al. Sections V and VI are new: two toy Lagrangians, L1 modeled on ABJM in d=2 and L3 on N=4 SYM in d=3, with explicit mean-field energy functionals (Eqs. 5.5, 6.19) and phase diagrams in Figs. 4–12. The survey half is genuinely useful; I have not seen the FL*/NFL/FL taxonomy laid out this cleanly for a holography audience before. The new half has one result I think is real and worth attention: the contrast between L1 and L3. In L1 the pairing term is b+b−, so the one-loop correction goes as |b+|²|b−|² log(...) and can be minimized at b± = 0, which is why NFL and FL* survive in Figs. 4–8. In L3 the term is Φλλ, giving the standard BCS log that forces superfluid order, which is why Figs. 9–10 have no NFL or FL*. That is a sharp, checkable statement about which deformation of which theory permits which phase, and it is the best physics in the paper. The half-vortex arguments fixing the condensate charges at Q=2 and Q=4 are also nicely done. Where I would push back is on the stress-test's framing. The abstract says these phases are 'argued to also be present' — that is honest hedging, and Section V says outright it is 'a simple toy model which can capture the possible compressible phases.' Nobody is claiming a derivation. The pairing instability is likewise flagged twice, in Section II and after Eq. 5.10, with the width of the intermediate regime explicitly deferred to future work. So the reader's CONDITIONAL is right but slightly harsh on the bridge claim. The one gap the stress-test finds that the paper really does not address is monopole proliferation: the d=2 NFL and FL* phases need a deconfined compact U(1) with two charged flavors, and there is no discussion of the deconfinement criterion anywhere. That is a genuine omission, not an acknowledged one, and a referee should raise it. Minor: no code for the phase diagrams, though mean-field minimization is easy enough to redo. Who should read it: anyone in holography or strange metals who wants the condensed matter phase vocabulary and a concrete, honest toy model to argue with. Send it out.","headline":"A useful survey of compressible quantum matter with two new mean-field toy models; the bridge to full ABJM and N=4 SYM is explicitly a conjecture, not a derivation, and the paper mostly says so.","tokens_in":30558,"tokens_out":1347,"would_cite":true,"duration_ms":30922,"reading_group":"yes","serious_thinker":"yes","would_accept_peer_review":true},"pith_extraction":{"msc":[],"pacs":["11.25.Tq","71.10.Hf"],"model":"selfhosted/deepseek-v4.1-flash","headline":"The compressible phases of condensed matter — Fermi liquid, non-Fermi liquid, and fractionalized Fermi liquid — should also appear in the ABJM and $N=4$ super Yang-Mills theories once a chemical potential is turned on.","keywords":["gauge-gravity duality","Fermi surfaces","Luttinger theorem","non-Fermi liquid","fractionalized Fermi liquid","compressible quantum matter","ABJM model","N=4 super Yang-Mills"],"falsifier":"A calculation in the actual ABJM or $N=4$ SYM theory at nonzero chemical potential — for instance a large-$N$ resummation or a dual gravity solution — showing that the deconfined NFL or FL* phases are absent, for example because gauge-boson-induced pairing gaps every gauge-charged Fermi surface at the highest energy scale rather than leaving an intermediate window, would break the correspondence the paper argues for.","tokens_in":30734,"feed_emoji":"⚛️","tokens_out":3331,"duration_ms":70913,"temperature":0.7,"pith_summary":"The paper asks a bridging question: when a chemical potential is applied to the two gauge theories that anchor gauge-gravity duality — the ABJM theory in two spatial dimensions and $N=4$ super Yang-Mills in three — what zero-temperature phases result? Its organizing principle is the Luttinger theorem, which says that in any compressible state where the global charge symmetry and translation invariance survive, the total charge density is fixed by the momentum-space volumes enclosed by the Fermi surfaces of all fermions, whether or not those fermions are the original microscopic particles. Using that constraint, the authors survey the known compressible phases of condensed matter models — the doublon metal, Bose-Fermi mixtures, and the fractionalized Fermi liquid — and then write down simplified toy Lagrangians modelled on the particle content and symmetries of the two supersymmetric theories at nonzero chemical potential. Minimizing the mean-field free energy of those toys produces phase diagrams containing the same cast: ordinary Fermi liquids, non-Fermi liquids with Fermi surfaces coupled to gapless gauge fields, and fractionalized phases where some Fermi surfaces are hidden from charge-carrying probes. The claim a sympathetic reader should take away is that these are not curiosities of condensed-matter Lagrangians but a plausible guide to what the holographic theories do at finite density.","feed_headline":"Fermi surfaces may carry over to holographic gauge theories","feed_subtitle":"Chemical potentials in ABJM and N=4 SYM should reproduce Fermi liquid, non-Fermi liquid and fractionalized phases.","key_machinery":"The load-bearing tool is the generalized Luttinger theorem of Eq. (1.4), $langle Qrangle = sum_{ell,in,mathrm{fermions}} q_ell V_ell$, which ties the conserved charge density to the momentum-space volumes enclosed by every fermionic Fermi surface, including composite or fractionalized fermions introduced through a Hubbard-Stratonovich decoupling. A Fermi surface is defined precisely as the locus where the inverse Green's function vanishes at zero frequency, $G_ell^{-1}(k=k_F,omega=0)=0$, together with the mild condition that the imaginary part of the inverse Green's function vanish away from that locus as $omega to 0$. This definition is what lets the theorem apply beyond Landau Fermi liquid theory, to surfaces with non-Fermi liquid singularities of the form $G^{-1}(k,omega)=q^{1-eta}Phi(omega/q^{z/2})$. The theorem does the bookkeeping work of the whole paper: it converts a single number, the charge density, into a constraint on how many Fermi surfaces can exist and how large they are, and it is what makes the FL* phase distinctive, because there the Fermi volume seen by gauge-invariant probes is smaller than the total density, with the deficit carried by hidden gauge-charged surfaces.","core_discovery":"The paper's central claim is that the compressible phases already catalogued in condensed matter — Fermi liquid (FL), non-Fermi liquid (NFL) with Fermi surfaces blurred by gapless gauge fluctuations, and fractionalized Fermi liquid (FL*) with coexisting gauge-charged and gauge-neutral Fermi surfaces — are also present in models built from the symmetries and particle content of the ABJM theory in $d=2$ and $N=4$ super Yang-Mills in $d=3$ after a chemical potential is applied. The argument runs through two toy Lagrangians, $L_1$ in Eq. (5.2) and $L_3$ in Eq. (6.2), in which the gauge group is reduced to $U(1)$ or $SU(2)$, flavor indices are dropped, and the particles are treated non-relativistically. Minimizing the mean-field free energy subject to gauge-charge neutrality yields the phase diagrams of Figs. 4 through 12, and those diagrams contain FL, NFL, and FL* phases in the ABJM-inspired case, and FL plus superfluid phases in the SYM-inspired case. A sharp structural result separates the two: in $L_1$ the fermion pairing term couples to a boson pair $b_+b_-$, so the energy correction behaves as $g_1^2|b_+|^2|b_-|^2$ times a logarithm and can have a stable minimum at $b_+=b_-=0$, which is what permits NFL and FL* phases to survive; in $L_3$ the pairing couples to a single boson $g_1^2|Phi^a|^2$, giving the standard BCS logarithm that makes any phase with $lambda^a$ Fermi surfaces unstable to superfluidity, so no NFL or FL* appears there.","pith_inferences":["The pairing instability the paper flags as an affliction of every NFL and FL* phase — gauge-boson exchange driving Cooper pairing that gaps the Fermi surfaces — is the natural first thing a dual gravity computation should be checked against, since a classical bulk solution with a charged scalar condensate would be the gravity-side image of that instability.","Because the Luttinger constraint is stated for any unbroken global $U(1)$, it supplies a consistency check on holographic models independent of their details: any proposed gravity dual of a compressible state that reports a charge density inconsistent with its fermionic Fermi volumes is either not in the phase it claims or has broken the symmetry.","The paper's reduction to non-relativistic toy Lagrangians is a controlled-looking but undemonstrated step; a natural follow-up is to ask whether the same phase diagrams survive keeping the full $U(N)times U(N)$ or $SU(N)$ gauge group and relativistic dispersion at leading order in large $N$.","The distinction between the two models turns on whether the pairing term couples to one boson or a boson pair, which suggests a general selection rule: whether a holographic theory at finite density admits deconfined NFL phases depends on the charge assignment of its scalar sector under the residual symmetry, a criterion that could be applied to other supergravity truncations."],"forward_implications":["If the toy models are faithful, the zero-temperature phase diagrams of the ABJM theory in $d=2$ and $N=4$ SYM in $d=3$ at nonzero chemical potential contain NFL and FL* phases, not merely the superconducting or superfluid phases that holographic studies had already found.","The FL* phase offers a concrete target for gravity duals: gauge-neutral fermions scatter strongly off a gauge-charged sector, so a small Fermi volume seen by charge-carrying probes becomes a prediction to look for in a classical gravity solution.","The Luttinger count gives an experimentally checkable bookkeeping rule for any compressible state whose global charge symmetry is unbroken, even when the quasiparticles near the Fermi surface are not Fermi liquid-like.","Which chemical potential is turned on matters qualitatively: with $mu_1neq 0$ the scalar is doubly charged and cannot mix with fermion pairs, so no deconfined NFL or FL* phases appear, whereas with $mu_1=mu_2neq 0$ the scalar carries unit charge, the pairing term $g_1$ is forbidden, and deconfined FL* and NFL phases reappear in Figs. 11 and 12."],"supporting_citations":[{"why":"Supplies the generalized Luttinger theorem for arbitrary systems of fermions, bosons, and gauge fields, including composite fermions, which is the bookkeeping tool the whole paper rests on.","marker":"[24]"},{"why":"Provides the sum-rule and Ward-identity derivation showing that non-canonical, composite fermions also count in the Luttinger volume, justifying the inclusion of $c$ and $f$ Fermi surfaces.","marker":"[26]"},{"why":"Source of the doublon metal model with two opposite-charge fermions coupled to a $U(1)$ gauge field, the paper's simplest non-Fermi liquid example.","marker":"[34]"},{"why":"Introduces the fractionalized Fermi liquid (FL*) phase whose hidden Fermi volume deficit the paper identifies as the key link to holographic duals.","marker":"[48]"},{"why":"The ABJM theory itself, the $d=2$ superconformal gauge theory the paper deforms with a chemical potential in Section V.","marker":"[53]"},{"why":"Provides the explicit ABJM field content and $SU(4)$ generator conventions used to construct the toy Lagrangian $L_1$.","marker":"[54]"},{"why":"Supplies the assignment of the three chemical potentials to the $N=4$ SYM scalars and fermions, which fixes the residual symmetry and the charge assignments of the $d=3$ toy models.","marker":"[78]"},{"why":"The charged dilatonic black hole model identified as the most promising gravity dual for future study of the $d=3$ compressible phases.","marker":"[10]"}],"fun_headline_variants":["Toy mean-field models, not full ABJM or N=4 SYM, suggest FL/NFL/FL* phases","ABJM-inspired toy model hosts FL, NFL and FL* mean-field phases","Single-boson pairing makes SYM-inspired NFL phases unstable","Paired boson term lets NFL and FL* survive in ABJM toy model","Chemical potentials may extend Fermi surfaces to holographic toy models"],"cache_read_input_tokens":0,"weakest_assumption_plain":"The bridge from condensed matter to the supersymmetric theories runs entirely through simplified toy Lagrangians that reduce the gauge group to $U(1)$ or $SU(2)$, drop flavor indices, make the particles non-relativistic, and are analyzed at mean-field level with gauge fluctuations omitted; the paper assumes, without deriving it, that this reduction preserves the qualitative phase structure of the full theories.","fun_headline_variants_meta":{"raw":{"variants":["Toy mean-field models, not full ABJM or N=4 SYM, suggest FL/NFL/FL* phases","ABJM-inspired toy model hosts FL, NFL and FL* mean-field phases","Single-boson pairing makes SYM-inspired NFL phases unstable","Paired boson term lets NFL and FL* survive in ABJM toy model","Chemical potentials may extend Fermi surfaces to holographic toy models"]},"model":"selfhosted/deepseek-v4.1-flash","effort":"low","attempts":1,"cost_usd":0.0,"raw_usage":{"total_tokens":3565,"prompt_tokens":1107,"completion_tokens":2458,"prompt_tokens_details":null,"completion_tokens_details":{"reasoning_tokens":2367}},"tokens_in":1107,"tokens_out":2458,"duration_ms":54940,"image_pages":[],"temperature":1.0,"reasoning_budget":50,"reasoning_tokens":2367,"transport_provider":"selfhosted","cache_read_input_tokens":0,"cache_creation_input_tokens":0},"cache_creation_input_tokens":0},"created_at":"2026-11-10T17:26:52.222113+00:00","model_set":{"reader":"selfhosted/deepseek-v4.1-flash"},"falsifier":"A calculation in the actual ABJM or $N=4$ SYM theory at nonzero chemical potential — for instance a large-$N$ resummation or a dual gravity solution — showing that the deconfined NFL or FL* phases are absent, for example because gauge-boson-induced pairing gaps every gauge-charged Fermi surface at the highest energy scale rather than leaving an intermediate window, would break the correspondence the paper argues for.","supporting_citations":[{"cited_title":"Depletion of the Bose-Einstein condensate in Bose-Fermi mixtures","cited_arxiv_id":"cond-mat/0502299","evidence_quote":"Supplies the generalized Luttinger theorem for arbitrary systems of fermions, bosons, and gauge fields, including composite fermions, which is the bookkeeping tool the whole paper rests on."},{"cited_title":"Sum Rules and Ward Identities in the Kondo Lattice","cited_arxiv_id":"cond-mat/0503001","evidence_quote":"Provides the sum-rule and Ward-identity derivation showing that non-canonical, composite fermions also count in the Luttinger volume, justifying the inclusion of $c$ and $f$ Fermi surfaces."},{"cited_title":"Destruction of Neel order in the cuprates by electron-doping","cited_arxiv_id":"0804.1794","evidence_quote":"Source of the doublon metal model with two opposite-charge fermions coupled to a $U(1)$ gauge field, the paper's simplest non-Fermi liquid example."},{"cited_title":"Fractionalized Fermi liquids","cited_arxiv_id":"cond-mat/0209144","evidence_quote":"Introduces the fractionalized Fermi liquid (FL*) phase whose hidden Fermi volume deficit the paper identifies as the key link to holographic duals."},{"cited_title":"𝒩 = 6 superconformal Chern-Simons-matter theories, M2-branes and their gravity duals","cited_arxiv_id":"0806.1218","evidence_quote":"The ABJM theory itself, the $d=2$ superconformal gauge theory the paper deforms with a chemical potential in Section V."},{"cited_title":"Superconformal Chern-Simons Theories and AdS_4/CFT_3 Correspondence","cited_arxiv_id":"0806.1519","evidence_quote":"Provides the explicit ABJM field content and $SU(4)$ generator conventions used to construct the toy Lagrangian $L_1$."},{"cited_title":"Phase Diagram of N=4 Super-Yang-Mills Theory with R-Symmetry Chemical Potentials","cited_arxiv_id":"hep-th/0602074","evidence_quote":"Supplies the assignment of the three chemical potentials to the $N=4$ SYM scalars and fermions, which fixes the residual symmetry and the charge assignments of the $d=3$ toy models."},{"cited_title":"Peculiar properties of a charged dilatonic black hole in AdS_5","cited_arxiv_id":"0911.2898","evidence_quote":"The charged dilatonic black hole model identified as the most promising gravity dual for future study of the $d=3$ compressible phases."}],"review_version":1}