REVIEW
MHV Rules for Higgs Plus Multi-Gluon Amplitudes
High Energy Physics - Theory · Submitted 8 Nov 2004 · 58 references
Pith's verdict: A genuinely new MHV construction for Higgs-plus-gluons, well benchmarked through n=5, with the general-n vertex and the tr G^3 section carrying acknowledged gaps.
T0 · AI review
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Referee report
The paper
The paper claims
The paper claims that a Higgs boson coupled to gluons through the heavy-top operator can be described by two MHV towers, one holomorphic and one anti-holomorphic, whose sum gives the physical amplitude.
The reading
What carries the argument
The load-bearing device is the split of the dimension-five operator into selfdual and anti-selfdual field strengths, $H$ tr $G^{2} to varphi$ tr $G_{mathrm{SD}}^{2} + varphi^{dagger}$ tr $G_{mathrm{ASD}}^{2}$. This turns one interaction that produces many helicity configurations into two interactions with a definite holomorphic or anti-holomorphic character. The holomorphic piece gives an MHV vertex identical in form to the pure-gauge Parke-Taylor amplitude, except that momentum conservation includes the Higgs momentum; the anti-holomorphic piece gives its parity conjugate. Scalar propagators connect these new vertices to standard MHV vertices, and the two towers are added at the end. The same split is motivated by an $N=1$ supersymmetric completion in which the holomorphic interaction is an $F$-term.
Extended reading notes
Core claim
The central claim is that the heavy-top effective interaction $H$ tr $G^{2}$ can be decomposed into a selfdual part, which generates a $varphi$-MHV tower, and an anti-selfdual part, which generates the parity-conjugate $varphi^{dagger}$-anti-MHV tower. The $varphi$-MHV vertices are asserted to have exactly the Parke-Taylor form $langle pq rangle^{4}/prod_{i}langle i,i+1 rangle$ for any number of gluons, with the Higgs carrying the recoil momentum, and to admit the same CSW off-shell continuation as pure QCD. Combining these vertices with ordinary MHV vertices produces amplitudes with more than two negative helicities; parity gives the tower with more than two positive helicities. The physical Higgs amplitude is then $mathcal{A}_{n}(H)=mathcal{A}_{n}(varphi)+mathcal{A}_{n}(varphi^{dagger})$. The paper checks this construction against all available analytic Higgs-plus-$n$-gluon formulas for $n le 5$ and derives the all-$n$ same-helicity amplitude in closed form.
Load-bearing premise
The load-bearing premise is that the $varphi$-MHV building block (2.12) has exactly the Parke-Taylor form for every $n$ and admits the same CSW off-shell continuation, which the paper argues from collinear and multi-particle factorization and says should be provable recursively rather than proving in general.
Editorial extensions
If this is right
- The rules reproduce the known $H+4$-gluon and $H+5$-gluon formulas and in several cases give shorter expressions, so they can replace older expressions in numerical codes.
- They give a closed all-$n$ formula for the same-helicity amplitude $A_n(H,1^+,ldots,n^+) propto m_H^4/prod_i langle i,i+1 rangle$.
- The pseudoscalar $A$ coupling to $G$ times its dual follows by taking the difference of the $varphi$ and $varphi^{dagger}$ amplitudes instead of the sum.
- The construction supplies a template for the $G^{3}$ effective operator, where the holomorphic and anti-holomorphic towers overlap first at six gluons.
- It provides compact tree-level input for next-to-leading-order and next-to-next-to-leading-order calculations of Higgs production with jets.
Reading between the lines
- The two-tower recipe looks portable: any effective operator that can be split into a selfdual piece with a supersymmetric $F$-term completion and an anti-selfdual conjugate may admit an analogous MHV construction.
- The soft-Higgs limit offers a sharp consistency test: as the Higgs momentum goes to zero, the $varphi$ tower should approach $(n_- -1)$ times the pure-gauge amplitude and the $varphi^{dagger}$ tower $(n_+ -1)$ times it, so a numerical mismatch there would expose an error in the off-shell continuation.
- If the all-$n$ $varphi$-MHV vertex is correct, the same off-shell continuation should extend to Higgs amplitudes with external quarks, since massless quarks can be added supersymmetrically without changing the bosonic tree-level story.
Original abstract
We use tree-level perturbation theory to show how non-supersymmetric one-loop scattering amplitudes for a Higgs boson plus an arbitrary number of partons can be constructed, in the limit of a heavy top quark, from a generalization of the scalar graph approach of Cachazo, Svrcek and Witten. The Higgs boson couples to gluons through a top quark loop which generates, for large top mass, a dimension-5 operator H tr G^2. This effective interaction leads to amplitudes which cannot be described by the standard MHV rules; for example, amplitudes where all of the gluons have positive helicity. We split the effective interaction into the sum of two terms, one holomorphic (selfdual) and one anti-holomorphic (anti-selfdual). The holomorphic interactions give a new set of MHV vertices -- identical in form to those of pure gauge theory, except for momentum conservation -- that can be combined with pure gauge theory MHV vertices to produce a tower of amplitudes with more than two negative helicities. Similarly, the anti-holomorphic interactions give anti-MHV vertices that can be combined with pure gauge theory anti-MHV vertices to produce a tower of amplitudes with more than two positive helicities. A Higgs boson amplitude is the sum of one MHV-tower amplitude and one anti-MHV-tower amplitude. We present all MHV-tower amplitudes with up to four negative-helicity gluons and any number of positive-helicity gluons (NNMHV). These rules reproduce all of the available analytic formulae for Higgs + n-gluon scattering (n<=5) at tree level, in some cases yielding considerably shorter expressions.
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 use tree-level perturbation theory to show how non-supersymmetric one-loop scattering amplitudes for a Higgs boson plus an arbitrary number of partons can be constructed, in the limit of a heavy top quark, from a generalization of the scalar graph approach of Cachazo, Svrcek and Witten. The Higgs boson couples to gluons through a top quark loop which generates, for large top mass, a dimension-5 operator H tr G^2. This effective interaction leads to amplitudes which cannot be described by the standard MHV rules; for example, amplitudes where all of the gluons have positive helicity. We split the effective interaction into the sum of two terms, one holomorphic (selfdual) and one anti-holomorphic (anti-selfdual). The holomorphic interactions give a new set of MHV vertices -- identical in form to those of pure gauge theory, except for momentum conservation -- that can be combined with pure gauge theory MHV vertices to produce a tower of amplitudes with more than two negative helicities. Similarly, the anti-holomorphic interactions give anti-MHV vertices that can be combined with pure gauge theory anti-MHV vertices to produce a tower of amplitudes with more than two positive helicities. A Higgs boson amplitude is the sum of one MHV-tower amplitude and one anti-MHV-tower amplitude. We present all MHV-tower amplitudes with up to four negative-helicity gluons and any number of positive-helicity gluons (NNMHV). These rules reproduce all of the available analytic formulae for Higgs + n-gluon scattering (n<=5) at tree level, in some cases yielding considerably shorter expressions.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We use tree-level perturbation theory to show how non-supersymmetric one-loop scattering amplitudes for a Higgs boson plus an arbitrary number of partons can be constructed, in the limit of a heavy top quark, from a generalization of the scalar graph approach of Cachazo, Svrcek and Witten. | contribution 0.94 | 0.93 | 0.38 | asserted 1.00 |
| s1 | The Higgs boson couples to gluons through a top quark loop which generates, for large top mass, a dimension-5 operator H tr G^2. | background 0.99 | 0.12 | 0.03 | asserted 1.00 |
| s2 | This effective interaction leads to amplitudes which cannot be described by the standard MHV rules; for example, amplitudes where all of the gluons have positive helicity. | background 0.47 | 0.24 | 0.08 | asserted 1.00 |
| s3 | We split the effective interaction into the sum of two terms, one holomorphic (selfdual) and one anti-holomorphic (anti-selfdual). | method 0.94 | 0.88 | 0.05 | asserted 1.00 |
| s4 | The holomorphic interactions give a new set of MHV vertices -- identical in form to those of pure gauge theory, except for momentum conservation -- that can be combined with pure gauge theory MHV vertices to produce a tower of amplitudes with more than two negative helicities. | contribution 0.43 | 0.88 | 0.31 | asserted 1.00 |
| s5 | Similarly, the anti-holomorphic interactions give anti-MHV vertices that can be combined with pure gauge theory anti-MHV vertices to produce a tower of amplitudes with more than two positive helicities. | method 0.48 | 0.82 | 0.11 | asserted 1.00 |
| s6 | A Higgs boson amplitude is the sum of one MHV-tower amplitude and one anti-MHV-tower amplitude. | method 0.41 | 0.81 | 0.34 | asserted 1.00 |
| s7 | We present all MHV-tower amplitudes with up to four negative-helicity gluons and any number of positive-helicity gluons (NNMHV). | contribution 0.78 | 0.94 | 0.19 | asserted 1.00 |
| s8 | These rules reproduce all of the available analytic formulae for Higgs + n-gluon scattering (n<=5) at tree level, in some cases yielding considerably shorter expressions. | result 0.98 | 0.90 | 0.19 | asserted 1.00 |
What was examined, and what was not
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Figures
Figures reproduced from arXiv:hep-th/0411092 by the authors.
References
How later papers used it
73 later papers cite it
3 later papers by other authors are listed below: 3 used its method or tool. 2 more papers by the same authors are listed: 2 used its method or tool.
Uses its method or tool 5 of 11 papers with this label · 2 by the same authors
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Introduced a complex scalar field following this paper to write the effective Lagrangian with the gluon field strength split into self-dual and anti-self-dual components.
Analytic results for the one-loop NMHV Hqqgg amplitude (2009) · 0.93 · paraphrased: the licence does not allow quoting
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Split the Higgs field into a field and its conjugate as advocated in this paper to derive the CSW rules from the space-time action.
Deriving CSW rules for massive scalar legs and pure Yang-Mills loops (2008) · 0.91 · paraphrased: the licence does not allow quoting
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Simplified the effective Lagrangian for Higgs plus four parton amplitudes by introducing a complex scalar field as in this paper, separating the gluon field strength into self-dual and anti-self-dual components.
MCFM for the Tevatron and the LHC (2010) · 0.96 · paraphrased: the licence does not allow quoting
By the same authors
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Introduced a complex field and its conjugate following this paper, splitting the effective interaction into a piece with the self-dual field strengths and another with the anti-self-dual ones.
One-loop Higgs plus four gluon amplitudes: Full analytic results (2009) (same authors) · 0.82 · paraphrased: the licence does not allow quoting
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Split the interaction into selfdual and anti-selfdual pieces following this paper.
One-loop phi-MHV amplitudes using the unitarity bootstrap (2007) (same authors) · 0.96 · paraphrased: the licence does not allow quoting
How the literature uses it
74 arXiv papers cite this in 138 sentences
Papers citing it · 91 sentences without a confident label
Builds on it 1 paper
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As a further example of the derivation of CSW-rules we derive the rules of [ref] resulting from an effective Higgs-gluon coupling and obtain additional multi-Higgs-gluon CSW vertices not noted in the previous literature.
Deriving CSW rules for massive scalar legs and pure Yang-Mills loops · Introduction · 0.96
Uses its method or tool 11 papers
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This is achieved by splitting the real Higgs scalar into two complex scalars ($ϕ$ and $ϕ^†$) such that the Higgs amplitude is recovered in the sum [ref] .
Analytic results for the one-loop NMHV Hqqgg amplitude · Introduction · 0.98
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Compact analytic forms for the tree-level amplitudes relevant for $A_4^(1)(ϕ,1^+,2^-,3^-,4^-)$ have been computed using both MHV rules [ref] and BCFW recursion [ref] .
One-loop Higgs plus four gluon amplitudes: Full analytic results · Tree-level amplitudes · 0.91
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The calculation is performed within the parton-level event generator NNLOJET [ref] , which combines the tree-level double real radiation corrections (RR, [ref] ), the one-loop single real radiation corrections (RV, [ref] ) and the two-loop virtual corrections (VV, [ref] ) with appropriate antenna subtraction terms.
Precise QCD Description of the Higgs Boson Transverse Momentum Spectrum · Introduction · 0.99
Uses its data or values 1 paper
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The form factor of $(F^2)$ is known for an arbitrary number of gluons and is given by [ref] [equation]
Form factors of $\mathscr{N}=4$ self-dual Yang-Mills from the chiral algebra bootstrap · Two points and renormalization · 0.84
Compares with it 9 papers
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It is satisfying to see that in all these cases [ref] gives the same results as those from CSW rules [ref] .
Connected formulas for amplitudes in standard model · Higgs plus multi-parton amplitudes · 0.98
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We note that similar results were obtained in [ref] considering MHV amplitude in a certain chiral scalar coupled to Yang-Mills theory [ref] .
Celestial holography and AdS3/CFT2 from a scaling reduction of twistor space · The correlator · 0.87
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The $D=4$ helicity components of the CHY expressions[See [ref] for a systematic study of the reduction of CHY formulae to $D=4$ dimensions.] in turn have been verified to agree with the results of [ref] .
Berends-Giele currents in Bern-Carrasco-Johansson gauge for $F^3$- and $F^4$-deformed Yang-Mills amplitudes · Berends–Giele recursions for $F^3$ and $F^4$ · 0.97
Cites it as background 20 papers
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The tree-level QCD amplitudes have been known for some time [ref] and the relevant $n$-point tree-level $ϕ$-amplitudes have been recently computed using the CSW method [ref] .
Higgs Amplitudes From Twistor Inspired Methods · Cut Constructible Contributions · 0.85
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Since the CSW rules were originally motivated by arguments from twistor-string theory [ref] , they were thought to be limited mainly to massless particles, although extensions to currents with single color-neutral external massive particles, i.e. electroweak gauge bosons [ref] or Higgs bosons [ref] , have been found.
Twistor-inspired construction of massive quark amplitudes · Introduction · 0.87
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Amplitudes with fewer (but more than two) negative helicities have been computed with Feynman diagrams (up to 4 partons) in Ref. [ref] and using MHV rules and on-shell recursion relations in Refs. [ref] .
One-loop phi-MHV amplitudes using the unitarity bootstrap: the general helicity case · The Higgs Model · 0.87
Discussion
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