11,386 research outputs found
Chiral behavior of baryon magnetic moments
The utility of chiral effective field theory, constructed in a manner in
which loop contributions are suppressed as one moves outside the power-counting
regime, is explored for baryon magnetic moments. Opportunities for the study of
significant chiral curvature in valence and full QCD and the nontrivial
behavior of strange- and light-quark contributions to the magnetic moment of
the Lambda baryon are highlighted.Comment: 7 pages, 5 figures; prepared for the proceedings of Achievements and
New Directions in Subatomic Physics: Workshop in Honour of Tony Thomas' 60th
Birthda
QCD Shear Viscosity at (almost) NLO
We compute the shear viscosity of QCD with matter, including almost all
next-to-leading order corrections -- that is, corrections suppressed by one
power of relative to leading order. We argue that the still missing terms
are small. The next-to-leading order corrections are large and bring
down by more than a factor of 3 at physically relevant couplings. The
perturbative expansion is problematic even at GeV. The largest
next-to-leading order correction to arises from modifications to the
qhat parameter, which determines the rate of transverse momentum diffusion. We
also explore quark number diffusion, and shear viscosity in pure-glue QCD and
in QED.Comment: 36 pages plus appendices, 11 figures. The main results are summarized
in the introduction (Fig. 1
Something of a Paradox: The Curious Neglect of Agriculture in Development
This paper argues that investment in agriculture has a large and continuing developmental importance in terms of both economic growth and poverty reduction. Moreover, targeted public resources have proven to be indispensable in achieving these results. Both arguments are supported with novel analyses which update and strengthen the traditional case for agriculture-led development with public-sector involvement. But despite the strong case for agriculture-led development strategies, the authors find that over the last three decades the financial resources allocated towards this sector have strongly declined. It is suggested that a shift towards new development paradigms since 1980 might be a significant explanation for this apparent Agricultural Paradox. This conjecture is tested with data on market reform impacts, PRSP contents and analyses of the intellectual resources devoted to the study of agriculture in development by both practitioners and researchers. The authors conclude with a critical discussion of these disturbing trends.
Jet-Medium Interactions at NLO in a Weakly-Coupled Quark-Gluon Plasma
We present an extension to next-to-leading order in the strong coupling
constant of the AMY effective kinetic approach to the energy loss of high
momentum particles in the quark-gluon plasma. At leading order, the transport
of jet-like particles is determined by elastic scattering with the thermal
constituents, and by inelastic collinear splittings induced by the medium. We
reorganize this description into collinear splittings, high-momentum-transfer
scatterings, drag and diffusion, and particle conversions (momentum-preserving
identity-changing processes). We show that this reorganized description remains
valid to NLO in , and compute the appropriate modifications of the drag,
diffusion, particle conversion, and inelastic splitting coefficients. In
addition, a new kinematic regime opens at NLO for wider-angle collinear
bremsstrahlung. These semi-collinear emissions smoothly interpolate between the
leading order high-momentum-transfer scatterings and collinear splittings. To
organize the calculation, we introduce a set of Wilson line operators on the
light-cone which determine the diffusion and identity changing coefficients,
and we show how to evaluate these operators at NLO.Comment: 37 pages plus appendices, 15 figures. A pedagogical review has been
presented in arXiv:1502.03730. v2: minor changes, matches journal versio
Something of a Paradox: The Neglect of Agriculture in Economic Development
This paper argues that investment in agriculture has a large and continuing developmental importance in terms of both economic growth and poverty reduction. Moreover, targeted public resources have proven to be indispensable in achieving these results. Both arguments are supported with novel analyses which update and strengthen the traditional case for agriculture-led development with public-sector involvement. But despite the strong case for agriculture-led development strategies, the authors find that the financial resources allocated towards this sector have strongly declined over the last three decades, and they suggest that a shift towards new development paradigms since 1980 might be a significant explanation for this apparent Agricultural Paradox. This conjecture is tested with data on foreign aid, public expenditure, PRSP contents, and empirical analyses of the intellectual resources devoted to the study of agriculture in development by World Bank researchers. The authors conclude with a critical discussion of these disturbing trends.Agricultural Productivity, Economic Growth, Poverty Alleviation, Urban Biases, Public Expenditure, Foreign Aid, Washington Consensus., International Development,
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