New Matter Effects and BBN Constraints for Mass Varying Neutrinos

The presence of light (m_a ~ 10^-6 ev) scalar fields in the early universe can modify the cosmology of neutrinos considerably by allowing their masses to vary on cosmological times. In this paper, we consider the effect of Planck-suppressed couplings of this scalar to electrons and show that such couplings can easily make new sterile states thermally inaccessible in the early universe, preserving the successes of big bang nucleosynthesis predictions. We consider the circumstances under which these effects give the proper initial conditions for recently considered models of neutrino dark energy, and consider limits from tests of the equivalence principle. The parameters which satisfy cosmological constraints naturally give rise to interesting signals in terrestrial neutrino oscillation experiments.Comment: 6 pages. References added, minor modification

Visible Cascade Higgs Decays to Four Photons at Hadron Colliders

The presence of a new singlet scalar particle a can open up new decay channels for the Higgs boson, through cascades of the form h -> 2a -> X, possibly making discovery through standard model channels impossible. If a is CP-odd, its decay products are particularly sensitive to physics beyond the standard model. Quantum effects from heavy fields can naturally make gluonic decay, a -> 2g, the dominant decay mode, resulting in a h -> 4 g decay which is difficult to observe at hadron colliders, and is allowed by LEP for m_h > 82 GeV. However, there are usually associated decays with photons, either h -> 2g 2gamma or h -> 4gamma, which are more promising. The decay h -> 2g 2gamma only allows discovery of the a particle and not the Higgs whereas h -> 4gamma is a clean channel that can discover both particles. We determine what branching ratios are required for discovery at LHC and find that with 300 fb^-1 of luminosity, a branching ratio of order 10^-4 is sufficient for a large region of Higgs masses. Due to a lower expected luminosity of ~ 8 fb^-1, discovery at the Tevatron requires more than 5 x 10^-3 in branching ratio.Comment: 6 pages, 2 color figures, revtex4 forma

You’re trouble you are, just like your mother! An intergenerational autobiographical narrative on activism in Higher Education

This paper draws on autobiographical interviews of a mother and daughter concerning their experiences of working in higher education to explore the changes in university teaching and research in the UK and also the possibilities of challenging prevalent normative assumptions about aims and purpose. It uses the qualitative methodology of narrative enquiry, particularly in its focus on temporality, sociality and place, to create a co-constructed account which is able to expose critical events, possibilities and limitations for higher education ‘activists’ in the recent past and present. It will be shown that the quality of the relationship between the two researcher-participants had a significant impact on the quality of the data generated, and that together the relationship and methodology promoted interpretation and analysis in ‘uncommonly accelerated ways’ (Carillo & Baguley, 2011). At the same time, it created moments of discomfort and misunderstandings about ideological perceptions. It was found that while there were some similarities at least initially between the experiences of the two interviewees in their capacities both to perform to work expectations and to take an activist position, substantial differences were identified due, in particular, to generational intellectual schisms as well as shifts in higher education from elitist institutions promoting public good to mass, neo-liberal institutions with performative and institutional goals and practices. The European dream of becoming ‘the most competitive and knowledge-based economy of the world’ (European Council, 2000) has marked the transformation and modernisation of social welfare and education systems…. When policies and institutional practices based on competence, efficiency and competition are stressed, ideals such as equity and social community tend to become secondary (Arnesan, 2011

Transient behavior of surface plasmon polaritons scattered at a subwavelength groove

We present a numerical study and analytical model of the optical near-field diffracted in the vicinity of subwavelength grooves milled in silver surfaces. The Green's tensor approach permits computation of the phase and amplitude dependence of the diffracted wave as a function of the groove geometry. It is shown that the field diffracted along the interface by the groove is equivalent to replacing the groove by an oscillating dipolar line source. An analytic expression is derived from the Green's function formalism, that reproduces well the asymptotic surface plasmon polariton (SPP) wave as well as the transient surface wave in the near-zone close to the groove. The agreement between this model and the full simulation is very good, showing that the transient "near-zone" regime does not depend on the precise shape of the groove. Finally, it is shown that a composite diffractive evanescent wave model that includes the asymptotic SPP can describe the wavelength evolution in this transient near-zone. Such a semi-analytical model may be useful for the design and optimization of more elaborate photonic circuits whose behavior in large part will be controlled by surface waves.Comment: 12 pages, 10 figure

The Bose-Einstein correlation function C2(Q)C_2(Q) from a Quantum Field Theory point of view

We show that a recently proposed derivation of Bose-Einstein correlations (BEC) by means of a specific version of thermal Quantum Field Theory (QFT), supplemented by operator-field evolution of the Langevin type, allows for a deeper understanding of the possible coherent behaviour of the emitting source and a clear identification of the origin of the observed shape of the BEC function $C_2(Q)$. Previous conjectures in this matter obtained by other approaches are confirmed and have received complementary explanation.Comment: Some misprints corrected. To be publishe in Phys. Rev.