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Search: authors:"Malcolm Fairbairn"

8 papers found.
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Horizon feedback inflation

We consider the effect of the Gibbons–Hawking radiation on the inflaton in the situation where it is coupled to a large number of spectator fields. We argue that this will lead to two important effects – a thermal contribution to the potential and a gradual change in parameters in the Lagrangian which results from thermodynamic and energy conservation arguments. We present a...

Anomaly-free models for flavour anomalies

We explore the constraints imposed by the cancellation of triangle anomalies on models in which the flavour anomalies reported by LHCb and other experiments are due to an extra U(1)\(^\prime \) gauge boson Z\(^\prime \). We assume universal and rational U(1)\(^\prime \) charges for the first two generations of left-handed quarks and of right-handed up-type quarks but allow...

Anomaly-free dark matter models are not so simple

We explore the anomaly-cancellation constraints on simplified dark matter (DM) models with an extra U(1)′ gauge boson Z ′. We show that, if the Standard Model (SM) fermions are supplemented by a single DM fermion χ that is a singlet of the SM gauge group, and the SM quarks have non-zero U(1)′ charges, the SM leptons must also have non-zero U(1)′ charges, in which case LHC...

Glueball dark matter in non-standard cosmologies

Hidden sector glueball dark matter is well motivated by string theory, compactifications of which often have extra gauge groups uncoupled to the visible sector. We study the dynamics of glueballs in theories with a period of late time primordial matter domination followed by a low final reheating temperature due to a gravitationally coupled modulus. Compared to scenarios with a...

Constraints on Z′ models from LHC dijet searches and implications for dark matter

We analyse a combination of ATLAS and CMS searches for dijet resonances at run I and run II, presenting the results in a way that can be easily applied to a generic Z′ model. As an illustrative example, we consider a simple model of a Z′ coupling to quarks and dark matter. We first study a benchmark case with fixed couplings and then focus on the assumption that the Z′ is...

Physics from solar neutrinos in dark matter direct detection experiments

The next generation of dark matter direct detection experiments will be sensitive to both coherent neutrino-nucleus and neutrino-electron scattering. This will enable them to explore aspects of solar physics, perform the lowest energy measurement of the weak angle sin2 θ W to date, and probe contributions from new theories with light mediators. In this article, we compute the...

Dark stars at the Galactic Centre – the main sequence

In regions of very high dark matter density such as the Galactic Centre, the capture and annihilation of WIMP dark matter by stars has the potential to significantly alter their evolution. We describe the dark stellar evolution code DarkStars, and present a series of detailed grids of WIMP-influenced stellar models for main-sequence stars. We describe the changes in stellar...