478 research outputs found
The flat limit of three dimensional asymptotically anti-de Sitter spacetimes
In order to get a better understanding of holographic properties of
gravitational theories with a vanishing cosmological constant, we analyze in
detail the relation between asymptotically anti-de Sitter and asymptotically
flat spacetimes in three dimensions. This relation is somewhat subtle because
the limit of vanishing cosmological constant cannot be naively taken in
standard Fefferman-Graham coordinates. After reformulating the standard anti-de
Sitter results in Robinson-Trautman coordinates, a suitably modified Penrose
limit is shown to connect both asymptotic regimes.Comment: 11 pages revtex fil
Towards a bulk description of higher spin SYK
We consider on the bulk side extensions of the Sachdev--Ye--Kitaev (SYK)
model to Yang--Mills and higher spins. To this end we study generalizations of
the Jackiw--Teitelboim (JT) model in the BF formulation. Our main goal is to
obtain generalizations of the Schwarzian action, which we achieve in two ways:
by considering the on-shell action supplemented by suitable boundary terms
compatible with all symmetries, and by applying the Lee--Wald--Zoupas formalism
to analyze the symplectic structure of dilaton gravity. We conclude with a
discussion of the entropy (including log-corrections from higher spins) and a
holographic dictionary for the generalized SYK/JT correspondence.Comment: 42 pages; v2: Typos correcte
Revisiting the asymptotic dynamics of General Relativity on AdS
The dual dynamics of Einstein gravity on AdS supplemented with boundary
conditions of KdV-type is identified. It corresponds to a two-dimensional field
theory at the boundary, described by a novel action principle whose field
equations are given by two copies of the "potential modified KdV equation". The
asymptotic symmetries then transmute into the global Noether symmetries of the
dual action, giving rise to an infinite set of commuting conserved charges,
implying the integrability of the system. Noteworthy, the theory at the
boundary is non-relativistic and possesses anisotropic scaling of Lifshitz
type.Comment: 18 page
Nonlinearly charged Lifshitz black holes for any exponent
Charged Lifshitz black holes for the Einstein-Proca-Maxwell system with a
negative cosmological constant in arbitrary dimension are known only if the
dynamical critical exponent is fixed as . In the present work, we
show that these configurations can be extended to much more general charged
black holes which in addition exist for any value of the dynamical exponent
by considering a nonlinear electrodynamics instead of the Maxwell theory.
More precisely, we introduce a two-parametric nonlinear electrodynamics defined
in the more general, but less known, so-called -formalism and
obtain a family of charged black hole solutions depending on two parameters. We
also remark that the value of the dynamical exponent turns out to be
critical in the sense that it yields asymptotically Lifshitz black holes with
logarithmic decay supported by a particular logarithmic electrodynamics. All
these configurations include extremal Lifshitz black holes. Charged topological
Lifshitz black holes are also shown to emerge by slightly generalizing the
proposed electrodynamics
The cognitive basis of social behavior: cognitive reflection overrides antisocial but not always prosocial motives
Even though human social behavior has received considerable scientific attention in the last decades, its cognitive underpinnings are still poorly understood. Applying a dual-process framework to the study of social preferences, we show in two studies that individuals with a more reflective/deliberative cognitive style, as measured by scores on the Cognitive Reflection Test (CRT), are more likely to make choices consistent with “mild” altruism in simple non-strategic decisions. Such choices increase social welfare by increasing the other person's payoff at very low or no cost for the individual. The choices of less reflective individuals (i.e., those who rely more heavily on intuition), on the other hand, are more likely to be associated with either egalitarian or spiteful motives. We also identify a negative link between reflection and choices characterized by “strong” altruism, but this result holds only in Study 2. Moreover, we provide evidence that the relationship between social preferences and CRT scores is not driven by general intelligence. We discuss how our results can reconcile some previous conflicting findings on the cognitive basis of social behavior
Deliberation favours social efficiency by making people disregard their relative shares: evidence from USA and India
Groups make decisions on both the production and the distribution of resources. These decisions typically involve a tension between increasing the total level of group resources (i.e. social efficiency) and distributing these resources among group members (i.e. individuals’ relative shares). This is the case because the redistribution process may destroy part of the resources, thus resulting in socially inefficient allocations. Here we apply a dual-process approach to understand the cognitive underpinnings of this fundamental tension. We conducted a set of experiments to examine the extent to which different allocation decisions respond to intuition or deliberation. In a newly developed approach, we assess intuition and deliberation at both the trait level (using the Cognitive Reflection Test, henceforth CRT) and the state level (through the experimental manipulation of response times). To test for robustness, experiments were conducted in two countries: the USA and India. Despite absolute-level differences across countries, in both locations we show that: (i) time pressure and low CRT scores are associated with individuals’ concerns for their relative shares and (ii) time delay and high CRT scores are associated with individuals’ concerns for social efficiency. These findings demonstrate that deliberation favours social efficiency by overriding individuals’ intuitive tendency to focus on relative shares
Kac-Moody symmetry in the light front of gauge theories
We discuss the emergence of a new symmetry generator in a Hamiltonian
realisation of four-dimensional gauge theories in the flat space foliated by
retarded (advanced) time. It generates an asymptotic symmetry that acts on the
asymptotic fields in a way different from the usual large gauge
transformations. The improved canonical generators, corresponding to gauge and
asymptotic symmetries, form a classical Kac-Moody charge algebra with a
non-trivial central extension. In particular, we describe the case of
electromagnetism, where the charge algebra is the current
algebra with a level proportional to the coupling constant of the theory,
. We construct bilinear generators yielding Virasoro
algebras on the null boundary. We also provide a non-Abelian generalization of
the previous symmetries by analysing the evolution of Yang-Mills theory in
Bondi coordinates.Comment: 31 pages, no figures; in V2 text clarified and references adde
To trust or not to trust: cognitive reflection in trust game
We present results from two studies that show a positive relation between cognitive reflection and trusting behavior, but no significant relation with trustworthy behavior. Our finding holds regardless of individual distributional social preferences and risk aversion. Our results add to a growing body of literature that illustrates the role of cognitive ability in helping explain outcomes in economic experiments
- …