1,170 research outputs found
Bounded fitness landscapes and the evolution of the linguistic diversity
A simple spatial computer simulation model was recently introduced to study
the evolution of the linguistic diversity. The model considers processes of
selective geographic colonization, linguistic anomalous diffusion and mutation.
In the approach, we ascribe to each language a fitness function which depends
on the number of people that speak that language. Here we extend the
aforementioned model to examine the role of saturation of the fitness on the
language dynamics. We found that the dependence of the linguistic diversity on
the area after colonization displays a power law regime with a nontrivial
exponent in very good agreement with the measured exponent associated with the
actual distribution of languages on the Earth.Comment: 10 pages, 3 figure
Quantum Black Holes as Holograms in AdS Braneworlds
We propose a new approach for using the AdS/CFT correspondence to study
quantum black hole physics. The black holes on a brane in an AdS
braneworld that solve the classical bulk equations are interpreted as duals of
{\it quantum-corrected} -dimensional black holes, rather than classical
ones, of a conformal field theory coupled to gravity. We check this explicitly
in D=3 and D=4. In D=3 we reinterpret the existing exact solutions on a flat
membrane as states of the dual 2+1 CFT. We show that states with a sufficiently
large mass really are 2+1 black holes where the quantum corrections dress the
classical conical singularity with a horizon and censor it from the outside. On
a negatively curved membrane, we reinterpret the classical bulk solutions as
quantum-corrected BTZ black holes. In D=4 we argue that the bulk solution for
the brane black hole should include a radiation component in order to describe
a quantum-corrected black hole in the 3+1 dual. Hawking radiation of the
conformal field is then dual to classical gravitational bremsstrahlung in the
AdS bulk.Comment: 28 pages, JHEP latex, 1 .eps figure, v2: references and comments
added, v3: comments and acknowledgements added to match the published pape
Evidence for the strangeness-changing weak decay
Using a collision data sample corresponding to an integrated luminosity
of 3.0~fb, collected by the LHCb detector, we present the first search
for the strangeness-changing weak decay . No
hadron decay of this type has been seen before. A signal for this decay,
corresponding to a significance of 3.2 standard deviations, is reported. The
relative rate is measured to be
, where and
are the and fragmentation
fractions, and is the branching
fraction. Assuming is bounded between 0.1 and
0.3, the branching fraction would lie
in the range from to .Comment: 7 pages, 2 figures, All figures and tables, along with any
supplementary material and additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-047.htm
flavour tagging using charm decays at the LHCb experiment
An algorithm is described for tagging the flavour content at production of
neutral mesons in the LHCb experiment. The algorithm exploits the
correlation of the flavour of a meson with the charge of a reconstructed
secondary charm hadron from the decay of the other hadron produced in the
proton-proton collision. Charm hadron candidates are identified in a number of
fully or partially reconstructed Cabibbo-favoured decay modes. The algorithm is
calibrated on the self-tagged decay modes and using of data collected by the LHCb
experiment at centre-of-mass energies of and
. Its tagging power on these samples of
decays is .Comment: All figures and tables, along with any supplementary material and
additional information, are available at
http://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-027.htm
Measurements of long-range near-side angular correlations in TeV proton-lead collisions in the forward region
Two-particle angular correlations are studied in proton-lead collisions at a
nucleon-nucleon centre-of-mass energy of TeV, collected
with the LHCb detector at the LHC. The analysis is based on data recorded in
two beam configurations, in which either the direction of the proton or that of
the lead ion is analysed. The correlations are measured in the laboratory
system as a function of relative pseudorapidity, , and relative
azimuthal angle, , for events in different classes of event
activity and for different bins of particle transverse momentum. In
high-activity events a long-range correlation on the near side, , is observed in the pseudorapidity range . This
measurement of long-range correlations on the near side in proton-lead
collisions extends previous observations into the forward region up to
. The correlation increases with growing event activity and is found
to be more pronounced in the direction of the lead beam. However, the
correlation in the direction of the lead and proton beams are found to be
compatible when comparing events with similar absolute activity in the
direction analysed.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-040.htm
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