The low energy effective Lagrangian for photon interactions in any dimension

The subject of low energy photon-photon scattering is considered in arbitrary dimensional space-time and the interaction is widened to include scattering events involving an arbitrary number of photons. The effective interaction Lagrangian for these processes in QED has been determined in a manifestly invariant form. This generalisation resolves the structure of the weak-field Euler-Heisenberg Lagrangian and indicates that the component invariant functions have coefficients related, not only to the space-time dimension, but also to the coefficients of the Bernoulli polynomial.Comment: In the revised version, the results have been expressed in terms of Bernoulli polynomials instead of generalized zeta functions; they agree for spinor QED with those of Schubert and Schmidt (obtained differently by path integral methods)

Signatures of sub-GeV dark matter beams at neutrino experiments

We study the high-luminosity fixed-target neutrino experiments at MiniBooNE, MINOS and T2K and analyze their sensitivity to light stable states, focusing on MeV--GeV scale dark matter. Thermal relic dark matter scenarios in the sub-GeV mass range require the presence of light mediators, whose coupling to the Standard Model facilitates annihilation in the early universe and allows for the correct thermal relic abundance. The mediators in turn provide a production channel for dark matter at colliders or fixed targets, and as a consequence the neutrino beams generated at fixed targets may contain an additional beam of light dark matter. The signatures of this beam include elastic scattering off electrons or nucleons in the (near-)detector, which closely mimics the neutral current scattering of neutrinos. We determine the event rate at modern fixed target facilities and the ensuing sensitivity to sub-GeV dark matter.Comment: 18 pages, 13 figures, revtex4-

Climate targets, executive compensation, and corporate strategy

Since the 2015 Paris Agreement, climate change – and wider environmental, social and governance (ESG) issues – have risen to board-level on the corporate agenda. Under increasing pressure from institutional investors, companies are reformulating their strategies for a climate-constrained world. A novel aspect of the emerging corporate response is that executive compensation is being linked to climate targets. At the world’s largest energy companies, climate metrics now make up 8% of CEO’s short-term incentive plans. This paper explains the case for corporate climate action, summarizes the use to date of climate-linked management incentives, and presents a framework for understanding their benefits and design challenges

Probing a Secluded U(1) at B-factories

A secluded U(1) gauge field, kinetically mixed with Standard Model hypercharge, provides a `portal' mediating interactions with a hidden sector at the renormalizable level, as recently exploited in the context of WIMP dark matter. The secluded U(1) symmetry-breaking scale may naturally be suppressed relative to the weak scale, and so this sector is efficiently probed by medium energy electron-positron colliders. We study the collider signatures of the minimal secluded U(1) model, focusing on the reach of B-factory experiments such as BaBar and BELLE. In particular, we show that Higgs-strahlung in the secluded sector can lead to multi-lepton signatures which probe the natural range for the kinetic mixing angle of 10^(-2)-10^(-3) over a large portion of the kinematically accessible parameter space.Comment: 14 pages, 3 figure

An evaluation of the IDEEA™ activity monitor for estimating energy expenditure

Peer reviewedPublisher PD

Optimal Altruism in Public Good Provision

We present a model of altruistically-minded-yet rational-players contributing to a public good. A key feature is the tension between altruism and "crowding-out" effects (players' efforts are strategic substitutes). We find that more altruistic behaviour can raise or reduce welfare, depending on the fine details of the environment. It is almost always optimal for a player to act more selfishly than her true preference. We discuss applications to a range of public good problems, including global climate policy. Our results highlight that it may be difficult to infer social preferences from observed behaviour