REVIEW
Heavy Baryon Chiral Perturbation Theory with Light Deltas
High Energy Physics - Phenomenology · Submitted 22 Dec 1997 · 53 references
Pith's verdict: A solid, explicit formalism paper for pi-N-Delta HBChPT; the O(ε²) construction holds up, but the 'to all orders' phrasing in Section 4.4 outruns what the paper actually proves.
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Referee report
The paper
The paper claims
A consistent heavy-baryon chiral Lagrangian is constructed for pions, nucleons, and the Delta(1232), with the mass splitting treated as a small expansion parameter.
The reading
Extended reading notes
Core claim
The central claim is that heavy-mass methods can be extended to a coupled pion-nucleon-Delta system in a single systematic expansion. The paper states that it gives 'a consistent chiral perturbative scheme for the joint interactions of pions, nucleons, and deltas to all orders' (Section 4.4) and constructs the Lagrangians explicitly through O(ε²). If correct, the Delta(1232) can be kept as an explicit degree of freedom rather than integrated out into counterterms, and the resulting power counting treats soft momenta, the pion mass, and the nucleon-Delta splitting on the same footing.
Load-bearing premise
The load-bearing premise is that the expansion is controlled when Δ = MΔ - MN ≈ 300 MeV is counted as O(ε) alongside soft momenta and mπ. The authors call this 'a phenomenological extension of pure (HB)ChPT' in the Introduction because Δ does not vanish in the chiral limit. If the series in Δ/Λχ converges poorly, the formalism is still a consistent bookkeeping scheme, but the word 'systematic' does not imply a small error. The paper does not provide a convergence test or an error estimate for truncated orders.
Original abstract
We demonstrate how heavy mass methods, previously applied to chiral perturbation theory calculations involving the interactions of nucleons and pions, can be generalized to include interactions with the $\Delta(1232)$ in a systematic formalism which we call the "small scale expansion."
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 demonstrate how heavy mass methods, previously applied to chiral perturbation theory calculations involving the interactions of nucleons and pions, can be generalized to include interactions with the $\Delta(1232)$ in a systematic formalism which we call the "small scale expansion."
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We demonstrate how heavy mass methods, previously applied to chiral perturbation theory calculations involving the interactions of nucleons and pions, can be generalized to include interactions with the $\Delta(1232)$ in a systematic formalism which we call the "small scale expansion." | contribution 0.99 | 0.91 | 0.71 | asserted 1.00 |
What was examined, and what was not
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References
How later papers used it
73 later papers cite it
7 later papers by other authors are listed below: 7 used its method or tool.
Uses its method or tool 7 of 16 papers with this label
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Based its calculations on Weinberg's power counting utilizing the small scale expansion.
Delta-excitations and the three-nucleon force (2007) · 1.00 · paraphrased: the licence does not allow quoting
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Adopted the small-scale expansion in the presence of explicit Delta degrees of freedom.
Radiative corrections to neutron $\beta$ decay with explicit $\Delta (1232)$ degrees of freedom (2026) · 0.98 · paraphrased: the licence does not allow quoting
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Analyzed radiative pion photoproduction utilizing the covariant Delta-full chiral perturbation theory framework within the small scale expansion scheme.
Radiative pion photoproduction in covariant chiral perturbation theory (2020) · 0.98 · paraphrased: the licence does not allow quoting
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Used the small scale expansion counting scheme in the Delta-full case.
Pion photoproduction in chiral perturbation theory with explicit treatment of the $\Delta(1232)$ resonance (2021) · 0.92 · paraphrased: the licence does not allow quoting
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Employed the scheme of this paper.
Redundancy of the off-shell parameters in chiral effective field theory with explicit spin-3/2 degrees of freedom (2009) · 0.98 · paraphrased: the licence does not allow quoting
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Adopted the small scale expansion scheme.
Chiral Lagrangians with $\Delta(1232)$ to one loop (2017) · 0.99 · paraphrased: the licence does not allow quoting
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Used the small scale expansion to treat the octet and decuplet mass difference.
Recent developments in SU(3) covariant baryon chiral perturbation theory (2013) · 0.98 · paraphrased: the licence does not allow quoting
How the literature uses it
62 arXiv papers cite this in 132 sentences
Papers citing it · 80 sentences without a confident label
Uses its method or tool 14 papers
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Our calculations are based on Weinberg's power counting [ref] utilizing the small scale expansion [ref] .
Delta-excitations and the three-nucleon force · $Δ$-contributions to the three-nucleon force up to NNLO · 1.00
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We use the standard power counting [ref] , extended to diagrams with $Δ$ baryons following small scale expansion (SSE) of Refs. [ref] .
Light-quark mass dependence of the nucleon axial charge and pion-nucleon scattering phenomenology · The nucleon axial charge in relativistic BChPT · 0.93
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In the presence of explicit $Δ$ degrees of freedom, we adopt the small-scale expansion (SSE) [ref] , [equation] with $Λ_χ∼4πF_π∼m_N$ the chiral-symmetry-breaking scale that numerically is close to the nucleon mass.
Radiative corrections to neutron $\beta$ decay with explicit $\Delta (1232)$ degrees of freedom · Power counting and decoupling · 0.98
Uses its data or values 2 papers
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Regarding the coupling constants related to baryons, the following values are utilized [ref] [equation] Other coupling constants of those type can be derived from $SU(4)$ symmetry.
Strong decays of the $\Lambda_{c}(2910)$ and $\Lambda_{c}(2940)$ in the $ND^{*}$ molecular frame · Coupling constants under SU(4) symmetry · 1.00
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A fit to the decay width of $Δ$ resonance leads to $h=1.05$ [ref] .
Neutrinoless double-beta decay of the $\Delta^-$ resonance · Chiral effective field Lagrangians · 0.98
Compares with it 2 papers
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For the $𝒪(p^2)$ $πNΔ$ chiral Lagrangian, we obtain three independent terms, [equation] From Ref. [ref] , a different set of relativistic terms is, [equation] We find the following correspondence between these two sets of terms: $d_1^(2)↔b_4$, $d_2^(2)↔b_5$, and $d_3^(2)↔b_1$.
Chiral Lagrangians with $\Delta(1232)$ to one loop · $𝒪(p^2)$ order · 1.00
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When $k_1=1$, the relation is consistent with Refs. [ref] .
Relations for low-energy constants in baryon chiral perturbation theory with explicit $\Delta(1232)$ derived from the chiral quark model · Values of $k$'s · 0.95
Cites it as support 3 papers
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This suggests that the convergence of the $Δ$-less chiral expansion could potentially be improved by treating the nearby $Δ(1232)$ resonance, with a mass only $300$ MeV larger than the nucleon, as an explicit degree of freedom, rather than integrating it out into the low-energy constants (LECs) [ref] .
Radiative corrections to neutron $\beta$ decay with explicit $\Delta (1232)$ degrees of freedom · Introduction · 0.96
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These findings were confirmed in the explicit calculation by Fettes and Meißner [ref] based on the so-called small scale expansion (SSE) [ref] .
Redundancy of the off-shell parameters in chiral effective field theory with explicit spin-3/2 degrees of freedom · Introduction and Summary · 0.99
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This was confirmed in the explicit calculation by Fettes and Meißner [ref] based on the so-called small scale expansion [ref] .
On-shell consistency of the Rarita-Schwinger field formulation · Dependence on off-shell parameters · 1.00
Cites it as background 19 papers
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ℒ_πΔ^(1) = ψ̅^μ_i ( [i D]^i j_μν - m_μν^ij - g_1/2 g_μν u^ij γ_5 - g_2/2 ( γ_μu_ν^ij + u_μ^ij γ_ν) - g_3/2 γ_μu^ij γ_5 γ_ν) ψ^ν_j , where the $g_i$ are LECs, $u_μ^ij = u_μδ^ij$, $u_μ= i (u^†∂_μu - i ∂_μu^†)$ and the matrix $U(x) = u^2 (x)$ collects the pion fields, see [ref] for more details.
Redundancy of the off-shell parameters in chiral effective field theory with explicit spin-3/2 degrees of freedom · Redundancy of the off-shell parameters in chiral EFT · 0.81
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The chiral perturbation theory with explicit \(Δ\) degrees of freedom has been extensively developed over the past decades [ref] .
$\Delta$ resonance contributions to QED radiative corrections in neutron and inverse beta decay · Introduction · 0.98
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A widely adopted power counting scheme is the small scale expansion (the mass difference $Δ$ and the soft momentum $p$ belong to the same order) [ref] , but the $δ=Δ/Λ_χ∼m_π/Δ$ expansion [ref] was also used.
Relations for low-energy constants in baryon chiral perturbation theory with explicit $\Delta(1232)$ derived from the chiral quark model · Introduction · 0.94
Discussion
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