2,690 research outputs found
Light-Cone Quantization of the Liouville Model
We present the quantization of the Liouville model defined in light-cone
coordinates in (1,1) signature space. We take advantage of the representation
of the Liouville field by the free field of the Backl\"{u}nd transformation and
adapt the approch by Braaten, Curtright and Thorn.
Quantum operators of the Liouville field ,
, , are constructed consistently in
terms of the free field. The Liouville model field theory space is found to be
restricted to the sector with field momentum , , which
is a closed subspace for the Liouville theory operator algebra.Comment: 16 p, EFI-92-6
On-Farm Food Safety and Environmental Farm Plans: A Conceptual Framework for Identifying and Classifying Benefits and Costs
This series of six reports entitled: "On-Farm Food Safety and Environmental Farm Plans: Identifying and Classifying Benefits and Costs" was initiated soon after the launch of the Agricultural Policy Framework (APF) in 2002. The APF recognized the importance of food safety and environmental concerns for the future growth of the agriculture and Agri-food sector. For this reason, Agriculture and Agri-Food Canada (AAFC) commissioned this series of reports to develop a conceptual framework to strengthen our understanding of the potential benefit and cost implications of On-farm Food Safety (OFFS) and Environmental Farm Plans (EFP) that were key components of the APF. The reports were prepared by a group of academics with extensive knowledge of the agriculture and Agri-food sector and issues related to food safety, traceability and the environment. The first report presents a summary of the findings in the five main reports in the series. The second report presents the conceptual framework that was developed to help identify qualitatively the potential benefits and costs that the various players in the agriculture and agri-food supply chain would face in implementing OFFS and EFP programs. The third report applies this framework to pork, the fourth, to beef, the fifth, to grains and the sixth, to dairy. In general, benefits and costs are divided into both demand and supply side effects. In addition, both public and private costs and benefits are considered, especially since they help indicate where a role for government might be required and where markets are not working as well as they might. Based on these preliminary qualitative assessments, the beef and pork sector have more to gain from HACCP-based OFFS and EFP initiatives, due to their ability to gain market share from marketing their products internationally, while the grains sector already benefits internationally from its high quality reputation and the dairy sector is restricted to produce only for the domestic market. However, more work is required in these areas to validate and quantify costs and benefits.Agribusiness, Agricultural and Food Policy, Environmental Economics and Policy, Food Consumption/Nutrition/Food Safety, Production Economics, Resource /Energy Economics and Policy,
Intrinsic Gap of the nu=5/2 Fractional Quantum Hall State
The fractional quantum Hall effect is observed at low field, in a regime
where the cyclotron energy is smaller than the Coulomb interaction. The nu=5/2
excitation gap is measured to be 262+/-15 mK at ~2.6 T, in good agreement with
previous measurements performed on samples with similar mobility, but with
electronic density larger by a factor of two. The role of disorder on the
nu=5/2 gap is examined. Comparison between experiment and theory indicates that
a large discrepancy remains for the intrinsic gap extrapolated from the
infinite mobility (zero disorder) limit. In contrast, no such large discrepancy
is found for the nu=1/3 Laughlin state. The observation of the nu=5/2 state in
the low-field regime implies that inclusion of non-perturbative Landau level
mixing may be necessary to better understand the energetics of half-filled
fractional quantum hall liquids.Comment: 5 pages, 4 figures; typo corrected, comment expande
Contrasting Behavior of the 5/2 and 7/3 Fractional Quantum Hall Effect in a Tilted Field
Using a tilted field geometry, the effect of an in-plane magnetic field on
the even denominator nu = 5/2 fractional quantum Hall state is studied. The
energy gap of the nu = 5/2 state is found to collapse linearly with the
in-plane magnetic field above ~0.5 T. In contrast, a strong enhancement of the
gap is observed for the nu = 7/3 state. The radically distinct tilted-field
behaviour between the two states is discussed in terms of Zeeman and
magneto-orbital coupling within the context of the proposed Moore-Read pfaffian
wavefunction for the 5/2 fractional quantum Hall effect
From Zwiebach invariants to Getzler relation
We introduce the notion of Zwiebach invariants that generalize Gromov-Witten
invariants and homotopical algebra structures. We outline the induction
procedure that induces the structure of Zwiebach on the subbicomplex, that
gives the structure of Gromov-Witten invariants on subbicomplex with zero
diffferentials. We propose to treat Hodge dGBV with 1/12 axiom as the simplest
set of Zwiebach invariants, and explicitely prove that it induces WDVV and
Getzler equations in genera 0 and 1 respectively.Comment: 35 page
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