1,281 research outputs found
Social Preference, Incomplete Information, and the Evolution of Ultimatum Game in the Small World Networks: An Agent-Based Approach
Certain social preference models have been proposed to explain fairness behavior in experimental games. Existing bodies of research on evolutionary games, however, explain the evolution of fairness merely through the self-interest agents. This paper attempts to analyze the ultimatum game's evolution on complex networks when a number of agents display social preference. Agents' social preference is modeled in three forms: fairness consideration or maintaining a minimum acceptable money level, inequality aversion, and social welfare preference. Different from other spatial ultimatum game models, the model in this study assumes that agents have incomplete information on other agents' strategies, so the agents need to learn and develop their own strategies in this unknown environment. Genetic Algorithm Learning Classifier System algorithm is employed to address the agents' learning issue. Simulation results reveal that raising the minimum acceptable level or including fairness consideration in a game does not always promote fairness level in ultimatum games in a complex network. If the minimum acceptable money level is high and not all agents possess a social preference, the fairness level attained may be considerably lower. However, the inequality aversion social preference has negligible effect on the results of evolutionary ultimatum games in a complex network. Social welfare preference promotes the fairness level in the ultimatum game. This paper demonstrates that agents' social preference is an important factor in the spatial ultimatum game, and different social preferences create different effects on fairness emergence in the spatial ultimatum game.Spatial Ultimatum Game, Complex Network, Social Preference, Agent Based Modeling
Mean motion resonances at high eccentricities: the 2:1 and the 3:2 interior resonances
Mean motion resonances [MMRs] play an important role in the formation and
evolution of planetary systems and have significantly influenced the orbital
properties and distribution of planets and minor planets in the solar system as
well as exo-planetary systems. Most previous theoretical analyses have focused
on the low-to-moderate eccentricity regime, but with new discoveries of high
eccentricity resonant minor planets and even exoplanets, there is increasing
motivation to examine MMRs in the high eccentricity regime. Here we report on a
study of the high eccentricity regime of MMRs in the circular planar restricted
three-body problem. Non-perturbative numerical analyses of the 2:1 and the 3:2
interior resonances are carried out for a wide range of secondary-to-primary
mass ratio, and for a wide range of eccentricity of the test particle. The
surface-of-section technique is used to study the phase space structure near
resonances. We identify transitions in phase space at certain critical
eccentricities related to the geometry of resonant orbits; new stable libration
zones appear at high eccentricity at libration centers shifted from those at
low eccentricities. We present novel results on the mass and eccentricity
dependence of the resonance libration centers and their widths in semi-major
axis. Our results show that MMRs have sizable libration zones at high
eccentricities, comparable to those at lower eccentricities.Comment: 16 pages. Submitted to AAS Journal
Effects of dissociation/recombination on the day-night temperature contrasts of ultra-hot Jupiters
Secondary eclipse observations of ultra-hot Jupiters have found evidence that
hydrogen is dissociated on their daysides. Additionally, full-phase light curve
observations of ultra-hot Jupiters show a smaller day-night emitted flux
contrast than that expected from previous theory. Recently, it was proposed by
Bell & Cowan (2018) that the heat intake to dissociate hydrogen and heat
release due to recombination of dissociated hydrogen can affect the atmospheric
circulation of ultra-hot Jupiters. In this work, we add cooling/heating due to
dissociation/recombination into the analytic theory of Komacek & Showman (2016)
and Zhang & Showman (2017) for the dayside-nightside temperature contrasts of
hot Jupiters. We find that at high values of incident stellar flux, the
day-night temperature contrast of ultra-hot Jupiters may decrease with
increasing incident stellar flux due to dissociation/recombination, the
opposite of that expected without including the effects of
dissociation/recombination. We propose that a combination of a greater number
of full-phase light curve observations of ultra-hot Jupiters and future General
Circulation Models that include the effects of dissociation/recombination could
determine in detail how the atmospheric circulation of ultra-hot Jupiters
differs from that of cooler planets.Comment: Accepted at Research Notes of the AA
Effects of Latent Heating on Atmospheres of Brown Dwarfs and Directly Imaged Planets
Growing observations of brown dwarfs have provided evidence for strong
atmospheric circulation on these objects. Directly imaged planets share similar
observations, and can be viewed as low-gravity versions of brown dwarfs.
Vigorous condensate cycles of chemical species in their atmospheres are
inferred by observations and theoretical studies, and latent heating associated
with condensation is expected to be important in shaping atmospheric
circulation and influencing cloud patchiness. We present a qualitative
description of the mechanisms by which condensational latent heating influence
the circulation, and then illustrate them using an idealized general
circulation model that includes a condensation cycle of silicates with latent
heating and molecular weight effect due to rainout of condensate. Simulations
with conditions appropriate for typical T dwarfs exhibit the development of
localized storms and east-west jets. The storms are spatially inhomogeneous,
evolving on timescale of hours to days and extending vertically from the
condensation level to the tropopause. The fractional area of the brown dwarf
covered by active storms is small. Based on a simple analytic model, we
quantitatively explain the area fraction of moist plumes, and show its
dependence on radiative timescale and convective available potential energy. We
predict that, if latent heating dominates cloud formation processes, the
fractional coverage area by clouds decreases as the spectral type goes through
the L/T transition from high to lower effective temperature. This is a natural
consequence of the variation of radiative timescale and convective available
potential energy with spectral type.Comment: 13 pages, 8 figures, accepted for publication in Ap
Extending Higgs Inflation with TeV Scale New Physics
Higgs inflation is among the most economical and predictive inflation models,
although the original Higgs inflation requires tuning the Higgs or top mass
away from its current experimental value by more than deviations, and
generally gives a negligible tensor-to-scalar ratio (if away
from the vicinity of critical point). In this work, we construct a minimal
extension of Higgs inflation, by adding only two new weak-singlet particles at
TeV scale, a vector-quark and a real scalar . The presence of singlets
significantly impact the renormalization group running of the Higgs
boson self-coupling. With this, our model provides a wider range of the
tensor-to-scalar ratio , consistent with the favored
values by either BICEP2 or Planck data, while keeping the successful prediction
of the spectral index . It further allows the Higgs and top
masses to fully fit the collider measurements. We also discuss implications for
searching the predicted TeV-scale vector-quark and scalar at the LHC
and future high energy pp colliders.Comment: 20pp, to match JCAP Final Versio
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