Double-logarithms in Einstein-Hilbert gravity and supergravity

We study the interplay between graviton reggeization and double-logarithmic in energy contributions to four-graviton scattering in theories with and without supersymmetry. Predictions to all orders in the gravitational coupling are given for these double-logarithms. As the number of supersymmetries grows these terms generate a convergent behaviour for the amplitudes at very high energies. At two-loop level, we find agreement with previous exact results for N=8 supergravity and with those of Boucher-Veronneau and Dixon, who studied the N=4,5,6 supergravities using a conjectured double-copy structure of gravity

An integrated systematic analysis of uncertainties in UK energy transition pathways

Policy goals to transition national energy systems to meet decarbonisation and security goals must contend with multiple overlapping uncertainties. These uncertainties are pervasive through the complex nature of the system, the long term consequences of decisions, and in the models and analytical approaches used. These greatly increase the challenges of informing robust decision making. Energy system studies have tended not to address uncertainty in a systematic manner, relying on simple scenario or sensitivity analysis. This paper utilises an innovative UK energy system model, ESME, which characterises multiple uncertainties via probability distributions and propagates these uncertainties to explore trade-offs in cost effective energy transition scenarios. A linked global sensitivity analysis is used to explore the uncertainties that have most impact on the transition. The analysis highlights the strong impact of uncertainty on delivering the required emission reductions, and the need for an appropriate carbon price. Biomass availability, gas prices and nuclear capital costs emerge as critical uncertainties in delivering emission reductions. Further developing this approach for policy requires an iterative process to ensure a complete understanding and representation of different uncertainties in meeting mitigation policy objectives

An integrated systematic analysis of uncertainties in UK energy transition pathways

Policy goals to transition national energy systems to meet decarbonisation and security goals must contend with multiple overlapping uncertainties. These uncertainties are pervasive through the complex nature of the system, the long term consequences of decisions, and in the models and analytical approaches used. These greatly increase the challenges of informing robust decision making. Energy system studies have tended not to address uncertainty in a systematic manner, relying on simple scenario or sensitivity analysis. This paper utilises an innovative UK energy system model, ESME, which characterises multiple uncertainties via probability distributions and propagates these uncertainties to explore trade-offs in cost effective energy transition scenarios. A linked global sensitivity analysis is used to explore the uncertainties that have most impact on the transition. The analysis highlights the strong impact of uncertainty on delivering the required emission reductions, and the need for an appropriate carbon price. Biomass availability, gas prices and nuclear capital costs emerge as critical uncertainties in delivering emission reductions. Further developing this approach for policy requires an iterative process to ensure a complete understanding and representation of different uncertainties in meeting mitigation policy objectives

The critical role of the industrial sector in reaching long-term emission reduction, energy efficiency and renewable targets

This paper evaluates the critical contribution of the industry sector to long-term decarbonisation, efficiency and renewable energy policy targets. Its methodological novelty is the incorporation of a process-oriented modelling approach based on a comprehensive technology database for the industry sector in a national energy system model for the UK (UKTM), allowing quantification of the role of both decarbonisation of upstream energy vectors and of mitigation options in the industrial sub-categories. This enhanced model is then applied in a comparative policy scenario analysis that explores various target dimensions on emission mitigation, renewable energy and energy efficiency at both a national and European level. The results show that ambitious emission cuts in the industry sector of up to 77% until 2050 compared to 2010 can be achieved. Moreover, with a reduction in industrial energy demand of up to 31% between 2010 and 2050, the sector is essential for achieving the overall efficiency commitments. The industry sector also makes a moderate contribution to the expansion of renewable energies mostly through the use of biomass for low-temperature heating services. However, additional sub-targets on renewable sources and energy efficiency need to be assessed critically, as they can significantly distort the cost-efficiency of the long-term mitigation pathway

A semi-infinite matrix analysis of the BFKL equation

The forward BFKL equation is discretised in virtuality space and it is shown that the diffusion into infrared and ultraviolet momenta can be understood in terms of a semi-infinite matrix. The square truncation of this matrix can be exponentiated leading to asymptotic eigenstates sharing many features with the BFKL gluon Green's function in the limit of large matrix size. This truncation is closely related to a representation of the XXX Heisenberg spin $= - \frac{1}{2}$ chain with SL(2) invariance where the Hamiltonian acts on a symmetric double copy of the harmonic oscillator. A simple modification of the BFKL matrix suppressing the infrared modes generates evolution with energy compatible with unitarity.Comment: Small changes, same conclusions, matching the published version in EPJ

W production at large transverse momentum at the Large Hadron Collider

We study the production of W bosons at large transverse momentum in pp collisions at the Large Hadron Collider (LHC). We calculate the complete next-to-leading order (NLO) corrections to the differential cross section. We find that the NLO corrections provide a large increase to the cross section but, surprisingly, do not reduce the scale dependence relative to leading order (LO). We also calculate next-to-next-to-leading-order (NNLO) soft-gluon corrections and find that, although they are small, they significantly reduce the scale dependence thus providing a more stable theoretical prediction.Comment: 12 pages, 7 figure

BFKL Pomeron, Reggeized gluons and Bern-Dixon-Smirnov amplitudes

After a brief review of the BFKL approach to Regge processes in QCD and in supersymmetric (SUSY) gauge theories we propose a strategy for calculating the next-to-next-to-leading order corrections to the BFKL kernel. They can be obtained in terms of various cross-sections for Reggeized gluon interactions. The corresponding amplitudes can be calculated in the framework of the effective action for high energy scattering. In the case of N=4 SUSY it is also possible to use the Bern-Dixon-Smirnov (BDS) ansatz. For this purpose the analytic properties of the BDS amplitudes at high energies are investigated, in order to verify their self-consistency. It is found that, for the number of external particles being larger than five, these amplitudes, beyond one loop, are not in agreement with the BFKL approach which predicts the existence of Regge cuts in some physical channels.Comment: 41 pages, expanded version with many clarifications and new references, conclusions unchanged. Note adde

Global Marine Fuel Trends 2030

Global Marine Fuel Trends 2030 central objective is to unravel the landscape of fuels used by commercial shipping over the next 16 years. The problem has many dimensions: a fuel needs to be available, cost-effective, compatible with existing and future technology and compliant with current and future environmental requirements. In a way, one cannot evaluate the future of marine fuels without evaluating the future of the marine industry. And the future of the marine industry itself is irrevocably linked with the global economic, social and political landscape to 2030

W hadroproduction at large transverse momentum beyond next-to-leading order

We study the production of W bosons at large transverse momentum in p pbar collisions. We show that the next-to-leading order cross section at large transverse momentum is dominated by threshold soft-gluon corrections. We add next-to-next-to-leading-order soft-gluon corrections to the exact next-to-leading-order differential cross sections. We find that these higher-order corrections provide modest enhancements to the transverse momentum distribution of the W at the Tevatron, and reduce significantly the dependence on the factorization and renormalization scales.Comment: 17 pages, 8 figure