REVIEW
The Minimal Model of Nonbaryonic Dark Matter: A Singlet Scalar
High Energy Physics - Phenomenology · Submitted 28 Nov 2000 · 44 references
Pith's verdict: The paper that turned the singlet scalar into a benchmark Higgs-portal dark matter model; the physics chain is sound, but the headline cross section is quoted as a point when the hadronic input makes it a range.
T0 · AI review
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Referee report
The paper
The paper claims
One real scalar field, neutral under all Standard Model forces and coupled to ordinary matter only through the Higgs, can account for the dark matter; requiring its relic abundance to match observation pins its coupling to the Higgs at $O(0
The reading
What carries the argument
The load-bearing object is the Higgs-portal vertex $lambda S^2 H^dagger H$. Expanded about the electroweak vacuum it produces both a shift of the singlet mass, $m_S^2 = m_0^2 + lambda v_{EW}^2$, and a three-point $lambda v_{EW} S^2 h$ interaction that mediates $s$-channel Higgs exchange. That single graph does all the work: it sets $S$-pair annihilation in the early universe through $sigma_{ann} v_{rel} = 8lambda^2 v_{EW}^2 / [(4m_S^2 - m_h^2)^2 + m_h^2 Gamma_h^2] F_X$, it sets elastic $S$-nucleon scattering, and it sets the invisible width $Gamma_{h to SS}$. The relic density follows from the standard freeze-out expression $Omega_s h^2 = (1.07 times 10^9), x_f / (g_*^{1/2} M_{Pl}, text{GeV}, langle sigma v_{rel} rangle)$, and inverting it turns $lambda$ into a function of $m_S$ for each $m_h$.
Extended reading notes
Core claim
The central claim is that the minimal renormalizable singlet-scalar model is predictive enough to be tested. With only a mass $m_S$, a self-coupling $lambda_S$, and a Higgs-portal coupling $lambda$, the requirement that $S$ freeze out with the observed relic density imposes a definite relation $lambda(m_S)$ for each assumed Higgs mass. Over the range $10$ GeV $lesssim m_S lesssim 100$ GeV and $100$ GeV $leq m_h leq 200$ GeV, that relation gives $lambda sim O(0.1-1)$ almost everywhere, except in a narrow strip near the Higgs pole where resonance annihilation suppresses $lambda$ to $10^{-4}$ to $10^{-3}$. Since $lambda$ also fixes the Higgs-nucleon coupling that mediates elastic scattering, the same relation yields $sigma_{el}(text{nucleon}) sim 10^{-43}$ cm$^2$, a factor of roughly twenty below the DAMA and CDMS reach at $m_S = 40$ GeV and $m_h = 120$ GeV but within reach of the next generation of detectors for $m_S leq 50$ GeV. The identical vertex makes the Higgs decay invisibly for $2m_S < m_h$, cutting the visible Higgs signal by a factor of ten or more when $m_S approx 0.3 m_h$, which the authors flag as a threat to Higgs discovery at the Tevatron and the LHC.
Load-bearing premise
The whole prediction chain rests on the relic density being set by ordinary thermal freeze-out of $S$ particles that stayed in equilibrium with the plasma down to the electroweak epoch, with no large pre-inflationary condensate and no non-renormalizable operators contributing to annihilation.
Editorial extensions
If this is right
- Direct detection: for $m_h = 120$ GeV and $m_S = 40$ GeV the abundance condition gives $0.05 lesssim lambda lesssim 0.085$ and hence $5 times 10^{-44} lesssim sigma_{el}(text{nucleon}) lesssim 1.5 times 10^{-43}$ cm$^2$, so the projected CDMS-Soudan and Genius sensitivities would cover $m_S leq 50$ GeV for Higgs masses between 110 and 140 GeV.
- Indirect detection: the same elastic cross section feeds capture in the Sun, giving an upward muon flux $phi_mu approx 0.8 times 10^{-14}$ cm$^{-2}$ s$^{-1}$ for $sigma_{el} = 10^{-44}$ cm$^2$, right at the level of the Kamiokande, MACRO and Baksan limits of about $1.4 times 10^{-14}$ cm$^{-2}$ s$^{-1}$.
- Higgs searches: whenever $2m_S < m_h$ the invisible width can exceed the $tau^+tau^-$ width by up to a factor of a thousand, and the ratio $R$ of visible signal to the Standard Model expectation falls below one tenth for $m_S approx 0.3 m_h$, so a Standard-Model-like Higgs search could miss the Higgs entirely; existing LEP searches already exclude an invisibly decaying Higgs below about 106.7 GeV.
- Colliders: pair production $e^+e^- to ZSS$ via virtual Higgs exchange gives a missing-energy signal with a kinematic reach in the $S$-pair invariant mass no better than about 100 GeV for $m_h$ near 100 GeV, and hadron machines are not useful because of the two-jets-plus-missing-energy background.
- Strongly self-interacting dark matter: cross sections of order $10^{-24}$ cm$^2$ require $m_S lesssim 1$ GeV, which in this model demands a part-per-million cancellation between $lambda v_{EW}^2$ and $m_0^2$ and pushes $lambda$ to the edge of perturbation theory.
Reading between the lines
- The portal coupling makes the model a bridge between two otherwise unrelated measurements: an invisible Higgs width measured at a lepton collider would fix $lambda$ independently of cosmology, and therefore predict the direct detection rate outright, so a future invisible-Higgs measurement and a future nuclear recoil signal can be checked against each other rather than interpreted separately.
- The predictions are sharpest exactly where the calculation is least controlled, near the Higgs pole where $lambda$ drops to $10^{-4}$ to $10^{-3}$; a higher-order or resummed treatment of annihilation in that strip would tell us whether the 'hiding' window $0.4 m_h lesssim m_S leq 0.5 m_h$ is genuinely as unreachable as the paper estimates.
- If a spin-independent signal near $10^{-43}$ cm$^2$ were seen without any accompanying invisible Higgs width, the minimal portal would be in trouble and an additional annihilation channel, for instance a dimension-six operator, would be the natural repair; conversely a null result at that sensitivity for $m_S leq 50$ GeV would close the most natural part of the parameter space.
- The fine tuning needed for sub-GeV masses suggests the strongly self-interacting variant of this idea is better pursued in composite or non-thermal constructions, where the Higgs coupling can be suppressed without forcing a cancellation in the scalar mass.
Original abstract
We propose the simplest possible renormalizable extension of the Standard Model - the addition of just one singlet scalar field - as a minimalist model for non-baryonic dark matter. Such a model is characterized by only three parameters in addition to those already appearing within the Standard Model: a dimensionless self-coupling and a mass for the new scalar, and a dimensionless coupling, \lambda, to the Higgs field. If the singlet is the dark matter, these parameters are related to one another by the cosmological abundance constraint, implying that the coupling of the singlet to the Higgs field is large, \lambda \sim O(0.1 - 1). Since this parameter also controls couplings to ordinary matter, we obtain predictions for the elastic cross section of the singlet with nuclei. The resulting scattering rates are close to current limits from both direct and indirect searches. The existence of the singlet also has implications for current Higgs searches, as it gives a large contribution to the invisible Higgs width for much of parameter space. These scalars can be strongly self-coupled in the cosmologically interesting sense recently proposed by Spergel and Steinhardt, but only for very low masses (< 1 GeV), which is possible only at the expense of some fine-tuning of parameters.
The compiled record
The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
The abstract, sentence by sentence
We propose the simplest possible renormalizable extension of the Standard Model - the addition of just one singlet scalar field - as a minimalist model for non-baryonic dark matter. Such a model is characterized by only three parameters in addition to those already appearing within the Standard Model: a dimensionless self-coupling and a mass for the new scalar, and a dimensionless coupling, \lambda, to the Higgs field. If the singlet is the dark matter, these parameters are related to one another by the cosmological abundance constraint, implying that the coupling of the singlet to the Higgs field is large, \lambda \sim O(0.1 - 1). Since this parameter also controls couplings to ordinary matter, we obtain predictions for the elastic cross section of the singlet with nuclei. The resulting scattering rates are close to current limits from both direct and indirect searches. The existence of the singlet also has implications for current Higgs searches, as it gives a large contribution to the invisible Higgs width for much of parameter space. These scalars can be strongly self-coupled in the cosmologically interesting sense recently proposed by Spergel and Steinhardt, but only for very low masses (< 1 GeV), which is possible only at the expense of some fine-tuning of parameters.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We propose the simplest possible renormalizable extension of the Standard Model - the addition of just one singlet scalar field - as a minimalist model for non-baryonic dark matter. | contribution 0.99 | 0.87 | 0.29 | asserted 0.78 |
| s1 | Such a model is characterized by only three parameters in addition to those already appearing within the Standard Model: a dimensionless self-coupling and a mass for the new scalar, and a dimensionless coupling, \lambda, to the Higgs field. | method 0.55 | 0.36 | 0.07 | asserted 1.00 |
| s2 | If the singlet is the dark matter, these parameters are related to one another by the cosmological abundance constraint, implying that the coupling of the singlet to the Higgs field is large, \lambda \sim O(0.1 - 1). | result 0.79 | 0.59 | 0.21 | asserted 0.81 |
| s3 | Since this parameter also controls couplings to ordinary matter, we obtain predictions for the elastic cross section of the singlet with nuclei. | interpretation 0.45 | 0.75 | 0.07 | asserted 0.99 |
| s4 | The resulting scattering rates are close to current limits from both direct and indirect searches. | result 0.99 | 0.78 | 0.17 | asserted 0.99 |
| s5 | The existence of the singlet also has implications for current Higgs searches, as it gives a large contribution to the invisible Higgs width for much of parameter space. | interpretation 0.64 | 0.71 | 0.10 | asserted 0.97 |
| s6 | These scalars can be strongly self-coupled in the cosmologically interesting sense recently proposed by Spergel and Steinhardt, but only for very low masses (< 1 GeV), which is possible only at the expense of some fine-tuning of parameters. | limitation 0.60 | 0.61 | 0.07 | asserted 0.55 |
What was examined, and what was not
- arXiv listing abstract v3
- full text
- figures and tables
- references and citing sentences
- relations to other papers
- P abstract
- S sections
- T body sentences
- C citations
- R cross-paper relations
Figures
Figures reproduced from arXiv:hep-ph/0011335 by the authors.
References
How later papers used it
388 later papers cite it
2 later papers by other authors are listed below: 2 used its data or values.
Uses its data or values 2 of 4 papers with this label
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Used this paper's Higgs-nucleon coupling value of about 340 MeV/246 GeV.
Warped Radion Dark Matter (2011) · 0.95 · paraphrased: the licence does not allow quoting
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Used this paper's effective Higgs-nucleon coupling of about 0.3 (g m_N)/(2 m_W), with m_N the nucleon mass.
Electroweak Baryogenesis and Dark Matter with an approximate R-symmetry (2011) · 0.90 · paraphrased: the licence does not allow quoting
How the literature uses it
368 arXiv papers cite this in 512 sentences
Papers citing it · 257 sentences without a confident label
Builds on it 2 papers
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The expression for $σ_II^$ due to Higgs-exchange diagrams follows from its real darkon counterpart [ref] , and so [equation] where $h̃$ is a virtual Higgs with the same couplings as the physical $h$, but with the invariant mass $√(s)=2m_D^$, and $h̃→X_i$ is any kinematically allowed decay mode of $h̃$.
Dark Matter and Higgs Boson in a Model with Discrete Gauge Symmetry · Relic abundance · 0.86
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Here, we provide the phenomenological expressions for these interactions which can be viewed as a generalization of the Higgs portal model [ref] .
Leptoquarks and Real Singlets: A Richer Scalar Sector Behind the Origin of Dark Matter · Higgs and LQ portals to Dark Matter · 0.89
Uses its method or tool 3 papers
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In Fig. [ref](b) we display the corresponding reduction factor [ref] [equation] which lowers all the SM3 (SM4) Higgs branching ratios in the SM3+D (SM4+D) in the same way.
Hints of Standard Model Higgs Boson at the LHC and Light Dark Matter Searches · Standard model plus darkon · 0.87
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From this Lagrangian and $L_D^$ in Eq. ([ref]), one can derive for $|t|≪m^2_h$ the darkon-nucleon elastic cross-section [ref] [equation] having used the approximation $(p_D^+p_N^)^2≃(m_D^+m_N^)^2$.
Scalar Dark Matter and Standard Model with Four Generations · Constraints from dark-matter direct searches · 0.84
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Given the model parameters $M_h$, $M_S$, and $a_2$, we calculate the annihilation cross section $σ_ann$ and relic density $Ω_S h^2$ for singlet cold dark matter (CDM), following the discussions in Refs. [ref] [We have also made use of the Higgs decay width program HDECAY of Ref. [ref] .].
Vacuum Stability, Perturbativity, and Scalar Singlet Dark Matter · Results & Discussion · 0.91
Uses its data or values 4 papers
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The thermalization condition of dark matter scalar particles is $λ_I ≥√(m_W/M_p)∼10^-8$ [ref] .
Theoretical Probes of Higgs-Axion non-perturbative Couplings · Non-perturbative Higgs-Axion Couplings, Higher Order non-renormalizable Operators and the Misalignment Mechanism · 0.80
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In the above, we neglected the coupling of the radion to the nucleon compared to the Higgs-nucleon coupling, $g_hNN ≈340 MeV/246 GeV$ [ref] .
Warped Radion Dark Matter · Direct and Indirect Detection · 0.95
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The low mass region may explain the right relic density $Ωh^2=0.1198±0.0026$ [ref] , however, the direct detection data exclude most of them [ref] .
The stability analysis of the extended singlet scalar model with two high scale minima · Introduction · 0.85
Compares with it 14 papers
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This is similar to the real darkon case [ref] , in which the Higgs can be hidden from sight for sufficiently low $m_h^>2m_D^$.
Dark Matter and Higgs Boson in a Model with Discrete Gauge Symmetry · Invisible decay of the Higgs boson · 0.88
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Unlike in the Higgs-portal scalar DM [ref] based on freeze-out mechanism, where only a narrow scalar mass window near a half of the Higgs mass is not excluded [ref] , the FIDM due to a small $λ$ in eq.([ref]) allows us to reopen the scalar mass window above GeV scale.
LHC-friendly freeze-in dark matter via Higgs portal · Introduction · 0.88
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As long as dark matter properties are concerned, this model is very similar to the real singlet (darkon) model [ref] and therefore similar dark matter properties [ref] and identical to the complex scalar singlet model [ref] with degenerate mass for the real and imaginary parts of S.
Radiative Two Loop Inverse Seesaw and Dark Matter · Dark Matter Candidate · 0.88
Cites it as support 2 papers
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A large coupling to the Higgs leads to a large Higgs boson decay rate to a scalar DM pair [ref] .
WIMP dark matter, Higgs exchange and DAMA · Introduction · 0.96
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We are motivated to study this model, in part, because it arises in a wide range of cosmological and particle-physics model building: providing a possible dark matter candidate [ref] , acting as the inflaton [ref] and providing for electroweak baryogenesis [ref] .
Real scalar phase transitions: a nonperturbative analysis · Introduction · 0.96
Cites it as background 211 papers
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Requiring that the darkon Lagrangian be renormalizable then implies that it has the form [ref] [equation] where $λ_D^$, $m_0^$, and $λ$ are free parameters and $H$ is the Higgs doublet containing the physical Higgs field $h$, in the notation of Ref. [ref] which has additional details on the model.
Hints of Standard Model Higgs Boson at the LHC and Light Dark Matter Searches · Standard model plus darkon · 0.87
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One of the most simple and minimal SM extension to describe the particle candidate of DM is made by adding a real singlet scalar particle such that it can reach the equilibrium with the bath particles and plays the role of WIMP DM [ref] .
Singlet scalar dark matter in the non-commutative space-time: a viable hypothesis to explain the gamma-ray excess in the galactic center · Singlet Scalar DM in the NCST · 0.87
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In the limit $= 0$ and $λ_sh ≠0$, the model behaves effectively much like the singlet scalar dark matter model [ref] , which has been extensively studied in the literature – including the case of a low reheating temperature [ref] [Note, however, that with the given particle content this limit would be problematic since the heavy, charged fermions $F$ would also be cosmologically stable.].
Freeze-in at all couplings · The model · 0.92
Discussion
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