536 research outputs found
Constituent Gluon Content of the Static Quark-Antiquark State in Coulomb Gauge
Motivated by the gluon-chain model of flux tube formation, we compute and
diagonalize the transfer matrix in lattice SU(2) gauge theory for states
containing heavy static quark-antiquark sources, with separations up to one
fermi. The elements of the transfer matrix are calculated by variational Monte
Carlo methods, in a basis of states obtained by acting on the vacuum state with
zero, one, and two-gluon operators in Coulomb gauge. The color Coulomb
potential is obtained from the zero gluon to zero gluon element of the transfer
matrix, and it is well-known that while this potential is asymptotically
linear, it has a slope which is two to three times larger than the standard
asymptotic string tension. We show that the addition of one and two gluon
states results in a potential which is still linear, but the disagreement with
the standard asymptotic string tension is reduced to 38% at the largest lattice
coupling we have studied
What are the Confining Field Configurations of Strong-Coupling Lattice Gauge Theory?
Starting from the strong-coupling SU(2) Wilson action in D=3 dimensions, we
derive an effective, semi-local action on a lattice of spacing L times the
spacing of the original lattice. It is shown that beyond the adjoint
color-screening distance, i.e. for , thin center vortices are stable
saddlepoints of the corresponding effective action. Since the entropy of these
stable objects exceeds their energy, center vortices percolate throughout the
lattice, and confine color charge in half-integer representations of the SU(2)
gauge group. This result contradicts the folklore that confinement in
strong-coupling lattice gauge theory, for D>2 dimensions, is simply due to
plaquette disorder, as is the case in D=2 dimensions. It also demonstrates
explicitly how the emergence and stability of center vortices is related to the
existence of color screening by gluon fields.Comment: 17 pages, 5 figures, latex2
Present and Future Estimates of Evapotranspiration and Runoff for Europe
One of the objectives of IIASA's study "The Future Environments for Europe: Some Implications of Alternative Development Paths" is to characterize the large-scale and long-term environmental transformations that could be associated with plausible scenarios of Europe's socio-economic development over the next century. Special attention is being given to a few low-probability, high-impact transformations. Changes in hydrological cycles and climatic factors are some of the key environmental components being considered.
This Working Paper describes the present conditions of evapo-transpiration and runoff for Europe, as well as their future conditions as based on a scenario for climate change
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