721 research outputs found
Inclusive Four-jet Production at 7 and 13 TeV: Azimuthal Profile in Multi-Regge Kinematics
Recently, new observables in LHC inclusive events with three tagged jets were
proposed. Here, we extend that proposal to events with four tagged jets. The
events are characterised by one jet in the forward direction, one in the
backward direction with a large rapidity distance from the first one and
two more jets tagged in more central regions of the detector. In our setup,
non-tagged associated mini-jet multiplicity is present and needs to be
accounted for by the inclusion of BFKL gluon Green functions. The projection of
the cross section on azimuthal-angle components opens up the opportunity for
defining new ratios of correlation functions of the azimuthal angle differences
among the tagged jets that can be used as probes of the BFKL dynamics.Comment: 19 pages, 8 figures; v2: published versio
BFKL Azimuthal Imprints in Inclusive Three-jet Production at 7 and 13 TeV
We propose the study of new observables in LHC inclusive events with three
tagged jets, one in the forward direction, one in the backward direction and
both well-separated in rapidity from the each other (Mueller-Navelet jets),
together with a third jet tagged in central regions of rapidity. Since
non-tagged associated mini-jet multiplicity is allowed, we argue that
projecting the cross sections on azimuthal-angle components can provide several
distinct tests of the BFKL dynamics. Realistic LHC kinematical cuts are
introduced.Comment: 17 pages, 7 figure
The tragedy of the commons, the public goods dilemma, and the meaning of rivalry and excludability in evolutionary biology
Problem: In the study of conflicts, both economists and evolutionary biologists use the
concepts ‘tragedy of the commons’ and ‘public goods dilemma’. What is the relationship
between the economist and evolutionist views of these concepts?
Model features: The economics literature defines the tragedy of the commons and the public
goods dilemma in terms of rivalry and excludability of the good. In contrast, evolutionists
define these conflicts based on fitness functions with two components: individual and group
components of fitness.
Mathematical method: Evolutionary game theory and the calculation of evolutionarily stable
strategy trait values by standard optimization techniques and by replacing slopes of group
phenotype on individual genotype by coefficients of relatedness.
Conclusion: There is a direct relationship between rivalry and the individual component of
fitness and between excludability and the group component of fitness. Moreover, although the
prisoner’s dilemma constitutes a suitable metaphor to analyse both the public goods dilemma
and the tragedy of the commons, it gives the false idea that the two conflicts are symmetric since
they refer to situations in which individuals consume a common resource – tragedy of the
commons – or contribute to a collective action or common good – public goods dilemma.
However, the two situations are clearly not symmetric: from the economical point of view they
differ by rivalry, and from the evolutionary biology point of view the two conflicts differ by the
significance of the within-group competition in the fitness function
Nonequilibrium model for estimating parameters of deleterious mutations
Deleterious mutations are of extreme evolutionary importance because, even though they are eliminated by natural selection, their continuous pressure creates a pool of variability in natural populations. They are of potential relevance for the existence of several features in evolution, such as sexual reproduction, and pose a risk to small asexual populations. Despite their extreme importance, the deleterious mutation rate and the effects of each mutation on fitness are poorly known quantities. Here we analyze a simple model that can be applied to simple experiments, in microorganisms, aiming at the quantification of these values
Azimuthal-angle Observables in Inclusive Three-jet Production
We discuss the impact of corrections beyond the leading-logarithmic accuracy
on some recently proposed LHC observables that are based on azimuthal-angle
ratios in a kinematical setup that is an extension to the usual one for
Mueller-Navelet jets, after requiring an extra tagged jet in central regions of
rapidity. The corrections tend to be mild which suggests that these observables
are an excellent way to probe the onset of BFKL effects at hadronic colliders.Comment: 6 pages, presented by G. Chachamis at the 25th International Workshop
on Deep Inelastic Scattering and Related Topics, 3-7 April 2017, Birmingham,
U
Probing the BFKL dynamics in inclusive three jet production at the LHC
We propose the study of new observables in LHC inclusive events with three
tagged jets, one in the forward direction, one in the backward direction and
both well-separated in rapidity from the each other (Mueller-Navelet jets),
together with a third jet tagged in central regions of rapidity. Since
non-tagged associated mini-jet multiplicity is allowed, we argue that
projecting the cross sections on azimuthal-angle components can provide several
distinct tests of the BFKL dynamics. Realistic LHC kinematical cuts are
introduced.Comment: 8 pages. Talk given by G. Chachamis at the 5th International
Conference on New Frontiers in Physics (ICNFP2016), 6-14 July 2016,
Kolymbari, Crete, Greec
Conditional Image-Text Embedding Networks
This paper presents an approach for grounding phrases in images which jointly
learns multiple text-conditioned embeddings in a single end-to-end model. In
order to differentiate text phrases into semantically distinct subspaces, we
propose a concept weight branch that automatically assigns phrases to
embeddings, whereas prior works predefine such assignments. Our proposed
solution simplifies the representation requirements for individual embeddings
and allows the underrepresented concepts to take advantage of the shared
representations before feeding them into concept-specific layers. Comprehensive
experiments verify the effectiveness of our approach across three phrase
grounding datasets, Flickr30K Entities, ReferIt Game, and Visual Genome, where
we obtain a (resp.) 4%, 3%, and 4% improvement in grounding performance over a
strong region-phrase embedding baseline.Comment: ECCV 2018 accepted pape
An Efficient Approximate kNN Graph Method for Diffusion on Image Retrieval
The application of the diffusion in many computer vision and artificial
intelligence projects has been shown to give excellent improvements in
performance. One of the main bottlenecks of this technique is the quadratic
growth of the kNN graph size due to the high-quantity of new connections
between nodes in the graph, resulting in long computation times. Several
strategies have been proposed to address this, but none are effective and
efficient. Our novel technique, based on LSH projections, obtains the same
performance as the exact kNN graph after diffusion, but in less time
(approximately 18 times faster on a dataset of a hundred thousand images). The
proposed method was validated and compared with other state-of-the-art on
several public image datasets, including Oxford5k, Paris6k, and Oxford105k
Muller's ratchet in random graphs and scale free networks
Muller's ratchet is an evolutionary process that has been implicated in the extinction of asexual species, the evolution of mitochondria, the degeneration of the Y chromosome, the evolution of sex and recombination and the evolution of microbes. Here we study the speed of Muller's ratchet in a population subdivided into many small subpopulations connected by migration, and distributed on a network. We compare the speed of the ratchet in two distinct types of topologies: scale free networks and random graphs. The difference between the topologies is noticeable when the average connectivity of the network and the migration rate is large. In this situation we observe that the ratchet clicks faster in scale free networks than in random graphs. So contrary to intuition, scale free networks are more prone to loss of genetic information than random graphs. On the other hand, we show that scale free networks are more robust to the random extinction than random graphs. Since these complex networks have been shown to describe well real-life systems, our results open a framework for studying the evolution of microbes and disease epidemics
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