23,078 research outputs found
Euclidean-Minkowskian duality of Wilson-loop correlation functions
We discuss the analyticity properties of the Wilson--loop correlation
functions relevant to the problem of soft high-energy scattering, directly at
the level of the functional integral, in a genuinely nonperturbative way.Comment: 12 pages, 1 figure. To appear in the proceedings of the Tenth
Workshop on Non-Perturbative Quantum Chromodynamics, Paris, France, 8-12th
June 200
Recommended from our members
Coherent modeling of mortality patterns for age-specific subgroups
The recent actuarial literature has shown that mortality patterns and trajectories in closely related populations are similar in some respects and that small differences are unlikely to increase in the long run. The common feeling is that mortality forecasts for individual countries could be improved by taking into account the patterns from a larger group. Starting from this consideration, we apply the three-way Lee–Carter model to a group of countries, by extending the bilinear LC model to a three-way structure, which incorporates a further component in the decomposition of the log-mortality rates. From a methodological point of view, there are several issues to deal with when focusing on such kind of data. In the presence of a three-way data structure, several choices on the pretreatment of the data could affect the whole modeling process. This kind of analysis is useful to assess the source of variation in the raw mortality data, before the extraction of the rank-one components by the LC model. The proposed procedure is used to extract an ad hoc time mortality trend parameter for age-specific subgroups. The results show that the proposed strategy leads to a more coherent description of mortality for age-specific subgroups
Elastic anomalies in glasses: the string theory understanding in the case of Glycerol and Silica
We present an implementation of the analytical string theory recently applied
to the description of glasses. These are modeled as continuum media with
embedded elastic string heterogeneities, randomly located and randomly
oriented, which oscillate around a straight equilibrium position with a
fundamental frequency depending on their length. The existence of a length
distribution reflects then in a distribution of oscillation frequencies which
is responsible for the Boson Peak in the glass density of states. Previously,
it has been shown that such a description can account for the elastic anomalies
reported at frequencies comparable with the Boson Peak. Here we start from the
generalized hydrodynamics to determine the dynamic correlation function
associated with the coherent, dispersive and attenuated, sound
waves resulting from a sound-string interference. Once the vibrational density
of states has been measured, we can use it for univocally fixing the string
length distribution inherent to a given glass. The density-density correlation
function obtained using such distribution is strongly constrained, and able to
account for the experimental data collected on two prototypical glasses:
glycerol and silica. The obtained string length distribution is compatible with
the typical size of elastic heterogeneities previously reported for silica and
supercooled liquids, and the atomic motion associated to the string dynamics is
consistent with the soft modes recently identified in large scale numerical
simulations as non-phonon modes responsible for the Boson Peak. The theory is
thus in agreement with the most recent advances in the understanding of the
glass specific dynamics and offers an appealing simple understanding of the
microscopic origin of the latter, while raising new questions on the
universality or material-specificity of the string distribution properties.Comment: 15 pages, 8 figure
A Geometric Monte Carlo Algorithm for the Antiferromagnetic Ising model with "Topological" Term at
In this work we study the two and three-dimensional antiferromagnetic Ising
model with an imaginary magnetic field at . In order to
perform numerical simulations of the system we introduce a new geometric
algorithm not affected by the sign problem. Our results for the model are
in agreement with the analytical solutions. We also present new results for the
model which are qualitatively in agreement with mean-field predictions
- …