Supersymmetric regularization, two-loop QCD amplitudes, and coupling shifts
By Z. Bern, A. Freitas, L. Dixon, H. L. Wong. 2002
163 citations recorded by the source corpus.
We present a definition of the four-dimensional helicity (FDH) regularization scheme valid for two or more loops. This scheme was previously defined and utilized at one loop. It amounts to a variation on the standard 't Hooft-Veltman scheme and is designed to be compatible with the use of helicity states for ''observed'' particles. It is similar to dimensional reduction in that it maintains an equal number of bosonic and fermionic states, as required for preserving supersymmetry. Supersymmetry Ward identities relate different helicity amplitudes in supersymmetric theories. As a check that the FDH scheme preserves supersymmetry, at least through two loops, we explicitly verify a number of these identities for gluon-gluon scattering (gg {yields} gg) in supersymmetric QCD. These results also cross-check recent non-trivial two-loop calculations in ordinary QCD. Finally, we compute the two-loop shift between the FDH coupling and the standard {bar M}{bar S} coupling, {alpha}{sub s}. The FDH shift is identical to the one for dimensional reduction. The two-loop coupling shifts are then used to obtain the three-loop QCD {beta} function in the FDH and dimensional reduction schemes.
Subfields: Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/a846bd54028eda3a1c774bfe045c7e9ab6987971
How researchers see this paper
The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.
In Nuclear and High Energy Physics
Citations in the corpus
- Two-Loop Helicity Amplitudes for Gluon-Gluon Scattering in QCD and Supersymmetric Yang-Mills Theory (2002, methodology): “) For completeness, we give the two-loop relation [23] between the MS coupling and that defined by an arbitrary value of”
- Scattering amplitudes over finite fields and multivariate functional reconstruction (2016, unknown): “r-helicity formalism as discussed in sect.4. We consider ‘-loop contributions to n-point scattering amplitudes in dimensional regularization. In particular we choose a regularization scheme such that [58] external momenta and polarizations are in four dimensions loop momenta are in ddimensions, with”
- A two-loop five-gluon helicity amplitude in QCD (2013, methodology): “in D6 dimensions but with the polarizations of gluons circulating in the loops living in Ds = 4 dimensions. We will now for a moment treat Ds as a free parameter. If Ds>D, a careful consideration [7,63] shows that each of the (DsD ) higher dimensional components will act as a scalar-like particle”
- Top-Quark Processes at NLO in Production and Decay (2012, unknown): “nctions, b(f) = (1−ω2 −β2) ω2 lnβ + 2P¯ 3 ω2 Y¯ p , c(f) = Li 2(1−P¯−)−Li2(1−P¯+) −Li2 1− P¯ − P¯ + +ln2 β −ln2 P¯ + . (B.5) The results for the coefficients in the four-dimensional helicity scheme [44] are, CL 0 = P¯ 0 P ¯ 3 Y¯ p −1 2 ǫ + 2P¯ 0 P3 c(f) −4+ln(β2) + 1 2P¯2 3 b(f) 1−β2ω2 −ω2 +β4 −2β2”
- Black hole binary dynamics from the double copy and effective theory (2019, methodology): “The four-dimensional helicity (FDH) scheme [61] is an alternative that meshes well with helicity methods.”