410 research outputs found
The Nonlinear Field Space Theory
In recent years the idea that not only the configuration space of particles,
i.e. spacetime, but also the corresponding momentum space may have nontrivial
geometry has attracted significant attention, especially in the context of
quantum gravity. The aim of this letter is to extend this concept to the domain
of field theories, by introducing field spaces (i.e. phase spaces of field
values) that are not affine spaces. After discussing the motivation and general
aspects of our approach we present a detailed analysis of the prototype
(quantum) Nonlinear Field Space Theory of a scalar field on the Minkowski
background. We show that the nonlinear structure of a field space leads to
numerous interesting predictions, including: non-locality, generalization of
the uncertainty relations, algebra deformations, constraining of the maximal
occupation number, shifting of the vacuum energy and renormalization of the
charge and speed of propagation of field excitations. Furthermore, a compact
field space is a natural way to implement the "Principle of Finiteness" of
physical theories, which once motivated the Born-Infeld theory. Thus the
presented framework has a variety of potential applications in the theories of
fundamental interactions (e.g. quantum gravity), as well as in condensed matter
physics (e.g. continuous spin chains), and can shed new light on the issue of
divergences in quantum field theories.Comment: 7 pages, v2 additional content and references added, title changed,
presentation improve
Deformed Carroll particle from 2+1 gravity
We consider a point particle coupled to 2+1 gravity, with de Sitter gauge
group SO(3,1). We observe that there are two contraction limits of the gauge
group: one resulting in the Poincare group, and the second with the gauge group
having the form AN(2) \ltimes \an(2)^*. The former case was thoroughly
discussed in the literature, while the latter leads to the deformed particle
action with de Sitter momentum space, like in the case of kappa-Poincare
particle. However, the construction forces the mass shell constraint to have
the form p_0^2 = m^2, so that the effective particle action describes the
deformed Carroll particle.Comment: 10 page
Beyond Fock space in three dimensional semiclassical gravity
Quantization of relativistic point particles coupled to three-dimensional
Einstein gravity naturally leads to field theories living on the Lorentz group
in their momentum representation. The Lie group structure of momentum space can
be traced back to the classical phase space of the particles coupled to
topological gravity. In this work we show how the non-trivial structure of
momentum space leads to an unusual description of Fock space. The latter is
reflected in a deformed algebra of creation and annihilation operators which
reduces to the ordinary algebra when momentum space "flattens" to Minkowski
space in the limit in which the three-dimensional Newton's constant vanishes.
The construction is covariant under the action of relativistic symmetries
acting on the Lorentz group-momentum space. This shows how it is possible to
build a Fock space on a group manifold momentum space in a way consistent with
the underlying (deformed) relativistic symmetries.Comment: 11 pages, v2 typos corrected and presentation improve
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Addressing Theoretical Gaps in Positive Youth Development for Diverse Youth
One in a series of fact sheets for 4-H and youth development professionals to use when designing a program to increase diversity in program participation
Diffusion on -Minkowski space
We study the spectral dimension associated with diffusion processes on
Euclidean -Minkowski space. We start by describing a geometric
construction of the "Euclidean" momentum group manifold related to
-Minkowski space. On such space we identify various candidate Laplacian
functions, i.e. deformed Casimir invariants, and calculate the corresponding
spectral dimension for each case. The results obtained show a variety of
running behaviours for the spectral dimension according to the choice of
deformed Laplacian, from dimensional reduction to super-diffusion.Comment: 12 pages, 8 figures; v2 short comments and references adde
Parental CoâConstruction of 5â to 13âYearâOlds\u27 Global SelfâEsteem Through Reminiscing About Past Events
The current study explored parental processes associated with children\u27s global selfâesteem development. Eighty 5â to 13âyearâolds and one of their parents provided qualitative and quantitative data through questionnaires, openâended questions, and a laboratoryâbased reminiscing task. Parents who included more explanations of emotions when writing about the lowest points in their lives were more likely to discuss explanations of emotions experienced in negative past events with their child, which was associated with child attachment security. Attachment was associated with concurrent selfâesteem, which predicted relative increases in selfâesteem 16 months later, on average. Finally, parent support also predicted residual increases in selfâesteem. Findings extend prior research by including younger ages and uncovering a process by which two theoretically relevant parenting behaviors impact selfâesteem development
Mentalizing Deficits Constrain Belief in a Personal God
Religious believers intuitively conceptualize deities as intentional agents with mental states who anticipate and respond to human beliefs, desires and concerns. It follows that mentalizing deficits, associated with the autistic spectrum and also commonly found in men more than in women, may undermine this intuitive support and reduce belief in a personal God. Autistic adolescents expressed less belief in God than did matched neuro-typical controls (Study 1). In a Canadian student sample (Study 2), and two American national samples that controlled for demographic characteristics and other correlates of autism and religiosity (Study 3 and 4), the autism spectrum predicted reduced belief in God, and mentalizing mediated this relationship. Systemizing (Studies 2 and 3) and two personality dimensions related to religious belief, Conscientiousness and Agreeableness (Study 3), failed as mediators. Mentalizing also explained the robust and well-known, but theoretically debated, gender gap in religious belief wherein men show reduced religious belief (Studies 2â4)
Volunteerism in Youth Development Programs: Editors' Note
Youth development programs are varied and diverse. Some rely on paid staff to deliver programming, but many rely on volunteers. While there is quite a bit of research on volunteers and volunteerism in general, there is little that goes in depth covering the nuances of volunteers in youth development organizations. The editors of this special issue introduce the articles, which cover themes of understanding the impacts of volunteers, volunteer competencies and skill development, support and motivation of volunteers, and evaluation of programs. In addition, a book review and a closing reflection are included. Finally, the editors close with their thoughts about exciting directions for the future of volunteer development research and practice
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