Swampland conjectures and infinite flop chains

PHYSICAL REVIEW D 104:4 (2021) ARTN 046008

Authors:

Callum R Brodie, Andrei Constantin, Andre Lukas, Fabian Ruehle

Spin correlations in final-state parton showers and jet observables

European Physical Journal C Springer 81:8 (2021) 681

Authors:

Gavin P Salam, Alexander Karlberg, Ludovic Scyboz, Rob Verheyen

Abstract:

As part of a programme to develop parton showers with controlled logarithmic accuracy, we consider the question of collinear spin correlations within the PanScales family of parton showers. We adapt the well-known Collins–Knowles spin-correlation algorithm to PanScales antenna and dipole showers, using an approach with similarities to that taken by Richardson and Webster. To study the impact of spin correlations, we develop Lund-declustering based observables that are sensitive to spin-correlation effects both within and between jets and extend the MicroJets collinear single-logarithmic resummation code to include spin correlations. Together with a 3-point energy correlation observable proposed recently by Chen, Moult and Zhu, this provides a powerful set of constraints for validating the logarithmic accuracy of our shower results. The new observables and their resummation further open the pathway to phenomenological studies of these important quantum mechanical effects.

Two-loop leading-colour QCD helicity amplitudes for two-photon plus jet production at the LHC

JOURNAL OF HIGH ENERGY PHYSICS (2021) ARTN 164

Authors:

Herschel A Chawdhry, Michal Czakon, Alexander Mitov, Rene Poncelet

Topological formulae for the zeroth cohomology of line bundles on del Pezzo and Hirzebruch surfaces

Complex Manifolds De Gruyter Open 8:1 (2021) 223-229

Authors:

Callum R Brodie, Andrei Constantin, Rehan Deen, Andre Lukas

Abstract:

We show that the zeroth cohomology of effective line bundles on del Pezzo and Hirzebruch surfaces can always be computed in terms of a topological index.

Framing energetic top-quark pair production at the LHC

Journal of High Energy Physics Scuola Internazionale Superiore di Studi Avanzati 2021:7 (2021) 40

Authors:

Fabrizio Caola, Frédéric Dreyer, Ross McDonald, Gavin Salam

Abstract:

Top-quark pair production is central to many facets of LHC physics. At leading order, the top and anti-top are produced in a back-to-back topology, however this topology accounts only for a minority of the events with TeV-scale momentum transfer that contain a tt¯ pair. The remaining events instead involve the splitting of an initial or final-state gluon to tt¯. We provide simple quantitative arguments that explain why this is the case, and examine the interplay between different topologies and a range of variables that characterise the event hardness. We then develop a method to classify the topologies of individual events and use it to illustrate our findings in the context of simulated events, using both top partons and suitably defined fiducial tops. For events with large tt¯ invariant mass, we comment on additional features that have important experimental and theoretical implications.