Perceptions of research

The term 'research' is rarely questioned. It is a term whose meaning seems to be implicitly understood. Certainly there is an institutional bureaucracy which supports 'research', and academic staff are rewarded for their strength in 'research'. But what is this research? It is likely that there are multiple understandings of 'research', but unless this diversity of understanding is recognised, it is difficult to have meaningful dialogue about it

Recent results in chiral effective field theory for the NN system

I describe recent progress towards a theory of the NN force which captures the consequences of QCD's chiral symmetry and the pattern of its breaking, and is formulated as an expansion in a ratio of low and high mass scales, M_{lo}/M_{hi}. This "chiral effective field theory" of the NN system is a firm foundation for explorations of nuclear structure and reactions that are grounded in QCD's low-energy symmetries. While calculations that use a ChiPT expansion for the NN potential have proven very successful, they can only be used with a narrow range of momentum-space cutoffs, which leaves the expansion parameter for observable quantities somewhat murky. Here we seek a truly systematic effective field theory for the NN amplitude, that is manifestly renormalization-group invariant at each order in a demonstrably perturbative expansion.Comment: Invited talk at the 7th International Workshop on Chiral Dynamics, August 6-10, 2012, Jefferson Lab, Newport News, VA. To appear in the proceedings. 12 pages, 5 figure

Electron-deuteron scattering in a relativistic theory of hadrons

We review a three-dimensional formalism that provides a systematic way to include relativistic effects including relativistic kinematics, the effects of negative-energy states, and the boosts of the two-body system in calculations of two-body bound-states. We then explain how to construct a conserved current within this relativistic three-dimensional approach. This general theoretical framework is specifically applied to electron-deuteron scattering both in impulse approximation and when the $\rho \pi \gamma$ meson-exchange current is included. The experimentally-measured quantities $A$, $B$, and $T_{20}$ are calculated over the kinematic range that is probed in Jefferson Lab experiments. The role of both negative-energy states and meson retardation appears to be small in the region of interest.Comment: 17 pages, 4 figures, uses BoxedEPS.tex, lamuphys.sty, bibnorm.sty. To appear in the proceedings of the Workshop on Electron-Nucleus Scattering held at the Elba International Physics Center, June 199

The effect of helicopter configuration on the fluid dynamics of brownout

Brown’s Vorticity Transport Model, coupled to an additional particle transport model, is used to simulate the development of the dust cloud that can form around a helicopter when operating in dusty or desert conditions. The flow field around a tandem rotor configuration is simulated during the final stages of landing. The time-averaged flow field around the helicopter is characterised by the existence of two stationary points immediately adjacent to the ground plane. Almost all entrainment of dust into the flow takes place forward of the rearmost stationary point; the dust initially remains in a thin, sheet-like layer above the ground. As the dust sheet approaches the forward stationary point, the layer thickens and forms a characteristic wedge-shaped ‘separation zone’. The amount of sand that is subsequently drawn up away from the ground then appears to be critically dependent on the strength and position relative to the separation zone of strong regions of recirculation. VTM simulations suggest that, for a tandem rotor helicopter at least, the sudden growth of the dust cloud that is responsible for the onset of brownout may be due to a change in mode within the flow field surrounding the aircraft. At higher advance ratios the flow is dominated by a strong ground vortex that is created by the rear rotor. The forward extent of the resultant dust cloud is limited though by the absence of any strong recirculation within the flow below the front rotor of the system. At lower forward speed the ground vortex of the rear rotor is replaced by a strong vortex that lies just below the leading edge of the front rotor. This vortex is responsible for drawing a significant amount of dust out of the surface layer of entrained particulates to form a dense wall of dust some distance upstream of the helicopter. A study of the effect of blade twist on the strength and shape of the dust cloud formed in the flow surrounding helicopters with tandem rotors suggests that systems with smaller blade twist but the same disc loading might produce denser dust clouds than those with high blade twist

Tectonic connections to interior processes on Venus

The ultimate goal of geophysical/geological exploration of Venus is to relate the present tectonic (and volcanic) state of the lithosphere to interior processes, particularly mantle convection, operating both now and in the past. The Magellan mission has provided a spectacular view of the surface, and upcoming gravity measurements, particularly if the Magellan orbit is circularized, will provide significant constraints on the state of the interior. This extended abstract focuses on several controversial issues regarding venusian tectonics and its relationship to geodynamic mechanisms in the planet's interior. The origin of highlands, coronae diapir structures, and trenches and subduction are discussed

Is the Graviton a goldstone boson /ques/

Elementary particle theory for describing gravitation - Lorentz invariance - Graviton as boso