439 research outputs found
Renormalization of noncommutative phi 4-theory by multi-scale analysis
In this paper we give a much more efficient proof that the real Euclidean phi
4-model on the four-dimensional Moyal plane is renormalizable to all orders. We
prove rigorous bounds on the propagator which complete the previous
renormalization proof based on renormalization group equations for non-local
matrix models. On the other hand, our bounds permit a powerful multi-scale
analysis of the resulting ribbon graphs. Here, the dual graphs play a
particular r\^ole because the angular momentum conservation is conveniently
represented in the dual picture. Choosing a spanning tree in the dual graph
according to the scale attribution, we prove that the summation over the loop
angular momenta can be performed at no cost so that the power-counting is
reduced to the balance of the number of propagators versus the number of
completely inner vertices in subgraphs of the dual graph.Comment: 34 page
Disparity in the natural cycles of Borrelia burgdorferi and the agent of human granulocytic ehrlichiosis.
We studied the prevalence of Borrelia burgdorferi and the agent of human granulocytic ehrlichiosis (HGE) among questing nymphal and adult Ixodes scapularis ticks of the same generation and the infectivity of wild white-footed mice for ticks feeding on them. The prevalence of B. burgdorferi infection in host-seeking ticks increased less than twofold from nymphal (31% to 33%) to adult (52% to 56%) stage, and 52% of white-footed mice were infected. Prevalence of the agent of HGE increased 4.5- to 10.6-fold from nymphal (1.5% to 1.8%) to adult stage (7.6% to 19.0%), while only 18% of mice were infectious to ticks. B. burgdorferi infection was more common in mouse-fed ticks than in ticks collected from vegetation, whereas the agent of HGE was half as common in mouse-fed ticks as in ticks collected from vegetation. The different prevalence in nature of these pathogens in ticks suggests that their maintenance cycles are also different
Bipartite partial duals and circuits in medial graphs
It is well known that a plane graph is Eulerian if and only if its geometric
dual is bipartite. We extend this result to partial duals of plane graphs. We
then characterize all bipartite partial duals of a plane graph in terms of
oriented circuits in its medial graph.Comment: v2: minor changes. To appear in Combinatoric
Sample Uncertainty Analysis of Daily Flood Quantiles Using a Weather Generator
[EN] The combined use of weather generators (WG) and hydrological models (HM) in what is
called synthetic continuous simulation (SCS) has become a common practice for carrying out flood
studies. However, flood quantile estimations are far from presenting relatively high confidence levels,
which mostly relate to the uncertainty of models¿ input data. The main objective of this paper is to
assess how different precipitation regimes, climate extremality, and basin hydrological characteristics
impact the uncertainty of daily flood quantile estimates obtained by SCS. A Monte Carlo simulation
from 18 synthetic populations encompassing all these scenarios was performed, evaluating the
uncertainty of the simulated quantiles. Additionally, the uncertainty propagation of the quantile
estimates from the WG to the HM was analyzed. General findings show that integrating the regional
precipitation quantile (XT,P) in the WG model calibration clearly reduces the uncertainty of flood
quantile estimates, especially those near the regional XT,P. Basin size, climate extremality, and the
hydrological characteristics of the basin have been proven not to affect flood quantiles¿ uncertainty
substantially. Furthermore, it has been found that uncertainty clearly increases with the aridity of
the climate and that the HM is not capable of buffering the uncertainty of flood quantiles, but rather
increases it.The authors thank AEMET and the UC for the data provided to carry out this work (Spain02 dataset).
This work was supported by the Spanish Ministry of Science and Innovation through the
research projects TETISCHANGE (RTI2018-093717-B-100) and TETISPREDICT (PID2022-141631OBI00). Funding for the open-access charge has been provided by Universitat Politècnica de ValènciaBeneyto, C.; Vignes, G.; Aranda Domingo, JÁ.; Francés, F. (2023). Sample Uncertainty Analysis of Daily Flood Quantiles Using a Weather Generator. Water. 15(19):1-16. https://doi.org/10.3390/w15193489116151
On the Effective Action of Noncommutative Yang-Mills Theory
We compute here the Yang-Mills effective action on Moyal space by integrating
over the scalar fields in a noncommutative scalar field theory with harmonic
term, minimally coupled to an external gauge potential. We also explain the
special regularisation scheme chosen here and give some links to the Schwinger
parametric representation. Finally, we discuss the results obtained: a
noncommutative possibly renormalisable Yang-Mills theory.Comment: 19 pages, 6 figures. At the occasion of the "International Conference
on Noncommutative Geometry and Physics", April 2007, Orsay (France). To
appear in J. Phys. Conf. Se
One-loop Beta Functions for the Orientable Non-commutative Gross-Neveu Model
We compute at the one-loop order the beta-functions for a renormalisable
non-commutative analog of the Gross Neveu model defined on the Moyal plane. The
calculation is performed within the so called x-space formalism. We find that
this non-commutative field theory exhibits asymptotic freedom for any number of
colors. The beta-function for the non-commutative counterpart of the Thirring
model is found to be non vanishing.Comment: 16 pages, 9 figure
Generalization of the Bollob\'as-Riordan polynomial for tensor graphs
Tensor models are used nowadays for implementing a fundamental theory of
quantum gravity. We define here a polynomial encoding the
supplementary topological information. This polynomial is a natural
generalization of the Bollob\'as-Riordan polynomial (used to characterize
matrix graphs) and is different of the Gur\uau polynomial, (R. Gur\uau,
"Topological Graph Polynomials in Colored Group Field Theory", Annales Henri
Poincare {\bf 11}, 565-584 (2010)) defined for a particular class of tensor
graphs, the colorable ones. The polynomial is defined for both
colorable and non-colorable graphs and it is proved to satisfy the
contraction/deletion relation. A non-trivial example of a non-colorable graphs
is analyzed.Comment: 22 pages, 20 figure
Exorcizing the Landau Ghost in Non Commutative Quantum Field Theory
We show that the simplest non commutative renormalizable field theory, the
model on four dimensional Moyal space with harmonic potential is
asymptotically safe to all orders in perturbation theor
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