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Lepton-pair scattering with an off-shell and an on-shell photon at two loops in massless QED (2023)
Journal Article
Badger, S., Kryś, J., Moodie, R., & Zoia, S. (2023). Lepton-pair scattering with an off-shell and an on-shell photon at two loops in massless QED. Journal of High Energy Physics, 2023(11), Article 41. https://doi.org/10.1007/jhep11%282023%29041

We compute the two-loop QED helicity amplitudes for the scattering of a lepton pair with an off-shell and an on-shell photon, 0 → ℓℓ¯γγ*, using the approximation of massless leptons. We express all master integrals relevant for the scattering of four... Read More about Lepton-pair scattering with an off-shell and an on-shell photon at two loops in massless QED.

Machine learning and LHC event generation (2023)
Journal Article
Butter, A., Plehn, T., Schumann, S., Badger, S., Caron, S., Cranmer, K., …Zupan, J. (2023). Machine learning and LHC event generation. SciPost Physics, 14(4), Article 079. https://doi.org/10.21468/scipostphys.14.4.079

First-principle simulations are at the heart of the high-energy physics research program. They link the vast data output of multi-purpose detectors with fundamental theory predictions and interpretation. This review illustrates a wide range of applic... Read More about Machine learning and LHC event generation.

Using neural networks for efficient evaluation of high multiplicity scattering amplitudes (2020)
Journal Article
Badger, S., & Bullock, J. (2020). Using neural networks for efficient evaluation of high multiplicity scattering amplitudes. Journal of High Energy Physics, 2020(6), Article 114. https://doi.org/10.1007/jhep06%282020%29114

Precision theoretical predictions for high multiplicity scattering rely on the evaluation of increasingly complicated scattering amplitudes which come with an extremely high CPU cost. For state-of-the-art processes this can cause technical bottleneck... Read More about Using neural networks for efficient evaluation of high multiplicity scattering amplitudes.

A numerical evaluation of planar two-loop helicity amplitudes for a W-boson plus four partons (2019)
Journal Article
Hartanto, H. B., Badger, S., Brønnum-Hansen, C., & Peraro, T. (2019). A numerical evaluation of planar two-loop helicity amplitudes for a W-boson plus four partons. Journal of High Energy Physics, 2019(9), Article 119. https://doi.org/10.1007/jhep09%282019%29119

We present the first numerical results for the two-loop helicity amplitudes for the scattering of four partons and a W-boson in QCD. We use a finite field sampling method to reduce directly from Feynman diagrams to the coefficients of a set of master... Read More about A numerical evaluation of planar two-loop helicity amplitudes for a W-boson plus four partons.

Analytic Form of the Full Two-Loop Five-Gluon All-Plus Helicity Amplitude (2019)
Journal Article
Badger, S., Chicherin, D., Gehrmann, T., Heinrich, G., Henn, J., Peraro, T., Wasser, P., Zhang, Y., & Zoia, S. (2019). Analytic Form of the Full Two-Loop Five-Gluon All-Plus Helicity Amplitude. Physical Review Letters, 123(7), Article 071601. https://doi.org/10.1103/physrevlett.123.071601

We compute the full-color two-loop five-gluon amplitude for the all-plus helicity configuration. In order to achieve this, we calculate the required master integrals for all permutations of the external legs, in the physical scattering region. We ver... Read More about Analytic Form of the Full Two-Loop Five-Gluon All-Plus Helicity Amplitude.

Analytic helicity amplitudes for two-loop five-gluon scattering: the single-minus case (2019)
Journal Article
Badger, S., Brønnum-Hansen, C., Hartanto, H. B., & Peraro, T. (2019). Analytic helicity amplitudes for two-loop five-gluon scattering: the single-minus case. Journal of High Energy Physics, 2019(1), Article 186. https://doi.org/10.1007/jhep01%282019%29186

We present a compact analytic expression for the leading colour two-loop five-gluon amplitude in Yang-Mills theory with a single negative helicity and four positive helicities. The analytic result is reconstructed from numerical evaluations over fini... Read More about Analytic helicity amplitudes for two-loop five-gluon scattering: the single-minus case.

Applications of integrand reduction to two-loop five-point scattering amplitudes in QCD (2018)
Presentation / Conference Contribution
Badger, S., Bronnum-Hansen, C., Gehrmann, T., Hartanto, H. B., Henn, J., Lo Presti, A., & Peraro, T. (2023, April). Applications of integrand reduction to two-loop five-point scattering amplitudes in QCD. Presented at Loops and Legs in Quantum Field Theory (LL2018), St. Goar, Germany

We review the current state-of-the-art in integrand level reduction for five-point scattering amplitudes at two loops in QCD. We present some benchmark results for the evaluation of the leading colour two-loop five-gluon amploitudes in the physical r... Read More about Applications of integrand reduction to two-loop five-point scattering amplitudes in QCD.

First Look at Two-Loop Five-Gluon Scattering in QCD (2018)
Journal Article
Badger, S., Brønnum-Hansen, C., Hartanto, H. B., & Peraro, T. (2018). First Look at Two-Loop Five-Gluon Scattering in QCD. Physical Review Letters, 120(9), Article 092001. https://doi.org/10.1103/physrevlett.120.092001

We compute the leading-color contributions to five-gluon scattering at two loops in massless QCD. The integrands of all independent helicity amplitudes are evaluated using d -dimensional generalized unitarity cuts and finite field reconstruction tech... Read More about First Look at Two-Loop Five-Gluon Scattering in QCD.

A unitarity compatible approach to one-loop amplitudes with massive fermions (2017)
Journal Article
Badger, S., Brønnum-Hansen, C., Buciuni, F., & O’Connell, D. (2017). A unitarity compatible approach to one-loop amplitudes with massive fermions. Journal of High Energy Physics, 2017(6), Article 141. https://doi.org/10.1007/jhep06%282017%29141

We explain how one-loop amplitudes with massive fermions can be computed using only on-shell information. We first use the spinor-helicity formalism in six dimensions to perform generalised unitarity cuts in d dimensions. We then show that divergent... Read More about A unitarity compatible approach to one-loop amplitudes with massive fermions.

Local integrands for two-loop all-plus Yang-Mills amplitudes (2016)
Journal Article
Badger, S., Mogull, G., & Peraro, T. (2016). Local integrands for two-loop all-plus Yang-Mills amplitudes. Journal of High Energy Physics, 2016(8), Article 63. https://doi.org/10.1007/jhep08%282016%29063

We express the planar five- and six-gluon two-loop Yang-Mills amplitudes with all positive helicities in compact analytic form using D-dimensional local integrands that are free of spurious singularities. The integrand is fixed from on-shell tree amp... Read More about Local integrands for two-loop all-plus Yang-Mills amplitudes.