165 research outputs found
The BMS/GCA correspondence
We find a surprising connection between asymptotically flat space-times and
non-relativistic conformal systems in one lower dimension. The BMS group is the
group of asymptotic isometries of flat Minkowski space at null infinity. This
is known to be infinite dimensional in three and four dimensions. We show that
the BMS algebra in 3 dimensions is the same as the 2D Galilean Conformal
Algebra which is of relevance to non-relativistic conformal symmetries. We
further justify our proposal by looking at a Penrose limit of a radially
infalling null ray inspired by non-relativistic scaling and obtain a flat
metric. The 4D BMS algebra is also discussed and found to be the same as
another class of GCA, called the semi-GCA, in three dimensions. We propose a
general BMS/GCA correspondence. Some consequences are discussed.Comment: 17 page
Noncommutativity Effects in FRW Scalar Field Cosmology
We study effects of noncommutativity on the phase space generated by a
non-minimal scalar field which is conformally coupled to the background
curvature in an isotropic and homogeneous FRW cosmology. These effects are
considered in two cases, when the potential of scalar field has zero and
nonzero constant values. The investigation is carried out by means of a
comparative detailed analysis of mathematical features of the evolution of
universe and the most probable universe wave functions in classically
commutative and noncommutative frames and quantum counterparts. The influence
of noncommutativity is explored by the two noncommutative parameters of space
and momentum sectors with a relative focus on the role of the noncommutative
parameter of momentum sector. The solutions are presented with some of their
numerical diagrams, in the commutative and noncommutative scenarios, and their
properties are compared. We find that impose of noncommutativity in the
momentum sector causes more ability in tuning time solutions of variables in
classical level, and has more probable states of universe in quantum level. We
also demonstrate that special solutions in classical and allowed wave functions
in quantum models impose bounds on the values of noncommutative parameters.Comment: 13 pages, 5 figure
Comparing user and community co-production approaches in local 'welfare' and 'law and order' services : does the governance mode matter?
This paper analyses the relationship between modes of governance at local level and the adoption of user and community co-production approaches in public safety and social care services, based on a German case study. The findings draw on a series of intensive focus groups with managers and staff of public services in four different regions in Germany, exploring existing levels of co-production and its potential in social care and public safety services, with particular focus on older and young people. The paper provides the first clear research evidence on how approaches to co-production are specific to the modes of governance within which they take place. The paper concludes with policy conclusions, both in the two programme areas concerned and in local public services more generally
О двухфотонном распаде частицы Хиггса в реликтовом излучении
A set of arguments is given that testify to two photon decay of the Higgs particle in the CMB radiation. These arguments are based on the analysis of the cosmological data in the framework of the Dirac scale-invariant formulation of General Relativity with a scalar dilaton that compensates scale transformation of all fields.В статье приведены аргументы, свидетельствующие о двухфотонном распаде частицы Хиггса с массой 118 ГэВ в реликтовом излучении. Аргументы основаны на анализе космологических данных в рамках дираковской масштабно-инвариантной формулировки ОТО со скалярным дилатоном, который компенсирует масштабные преобразования наблюдаемых полей
Вакуумное рождение частиц скалярного поля в конформно-инвариантной теории гравитации. Гамильтонов формализм и квантование релятивистских систем
model of gravitation in the frameworks of the Hamiltonian (Dirac) approach is considered. The equations, setting dependence of observable density of number of scalar particles on the initial data and invariant parametre of evolution, are constructed in an explicit form. Problems of unification of principles of the General Theory of Relativity (GTR) and the Quantum Theory of Fields (QTF) within a simple example of a vacuum creation of scalar particles in conformal-invariant model of gravitation [1-3,10-14] are considered. It is shown that such model can describe both possible mechanism of such creation, and ways of its generalisation to more complex models, including Standard Model (SM). It allows to formulate some new approach to quantization of the relativistic gravitational systems, which essence is in quantization of the phase space of initial quantities as integrals of motion of the system, obtained by Bogoljubov diagonalization of the motion equations in Hamiltonian formalism, and in the proof of equivalence of such quantization to transition from classical commutative variables to their noncommutative quantum analogues. The above described scheme can be applied to initial manifolds of any finite dimension and topology.В настоящей работе рассмотрена модель вакуумного рождения скалярных частиц в конформно-инвариантной модели гравитации в рамках гамильтонова (дираковского) подхода. Построены в явном виде уравнения, задающие в том числе зависимость наблюдаемой плотности числа частиц скалярного поля от начальных данных и инвариантного параметра эволюции. Рассмотрены проблемы объединения принципов общей теории относительности (ОТО) и квантовой теории поля (КТП) на простом примере вакуумного рождения скалярных частиц в конформно-инвариантной модели гравитации. Показано, что такая модель может описать как возможный механизм такого рождения, так и способы его обобщения на более сложные модели, в том числе и на Стандартную Модель (СМ). Сформулирован некоторый новый подход к квантованию релятивистских гравитирующих систем, суть которого заключается в квантовании фазового пространства начальных данных как интегралов движения системы, полученных путём Боголюбовской диагонализации уравнений гамильтонова формализма, и в доказательстве эквивалентности такого квантования переходу от классических пространственно-временных переменных к их некоммутирующим квантовым аналогам Вышеописанная схема может быть применена для исходного многообразия любой конечной мерности и топологии
Description of Friedmann Observables in Quantum Universe
The solution of the problem of describing the Friedmann observables (the
Hubble law, the red shift, etc.) in quantum cosmology is proposed on the basis
of the method of gaugeless Hamiltonian reduction in which the gravitational
part of the energy constraint is considered as a new momentum. We show that the
conjugate variable corresponding to the new momentum plays a role of the
invariant time parameter of evolution of dynamical variables in the sector of
the Dirac observables of the general Hamiltonian approach. Relations between
these Dirac observables and the Friedmann observables of the expanding Universe
are established for the standard Friedmann cosmological model with dust and
radiation. The presented reduction removes an infinite factor from the
functional integral, provides the normalizability of the wave function of the
Universe and distinguishes the conformal frame of reference where the Hubble
law is caused by the alteration of the conformal dust mass.Comment: 10 pages, LaTe
Conformal Hamiltonian Dynamics of General Relativity
The General Relativity formulated with the aid of the spin connection
coefficients is considered in the finite space geometry of similarity with the
Dirac scalar dilaton. We show that the redshift evolution of the General
Relativity describes the vacuum creation of the matter in the empty Universe at
the electroweak epoch and the dilaton vacuum energy plays a role of the dark
energy.Comment: 9 pages, 1 figure, submitted to PL
Heavy--light mesons in a bilocal effective theory
Heavy--light mesons are described in an effective quark theory with a
two--body vector--type interaction. The bilocal interaction is taken to be
instantaneous in the rest frame of the bound state, but formulated covariantly
through the use of a boost vector. The chiral symmetry of the light flavor is
broken spontaneously at mean field level. The framework for our discussion of
bound states is the effective bilocal meson action obtained by bosonization of
the quark theory. Mesons are described by 3--dimensional wave functions
satisfying Salpeter equations, which exhibit both Goldstone solutions in the
chiral limit and heavy--quark symmetry for . We present
numerical solutions for pseudoscalar -- and --mesons. Heavy--light meson
spectra and decay constants are seen to be sensitive to the description of
chiral symmetry breaking (dynamically generated vs.\ constant quark mass).Comment: (34 p., standard LaTeX, 7 PostScript figures appended)
UNITUE-THEP-17/9
Hamiltonian Cosmological Perturbation Theory
The Hamiltonian approach to cosmological perturbations in general relativity
in finite space-time is developed, where a cosmological scale factor is
identified with spatial averaging the metric determinant logarithm.
This identification preserves the number of variables and leads to a
cosmological perturbation theory with the scalar potential perturbations in
contrast to the kinetic perturbations in the Lifshitz version which are
responsible for the ``primordial power spectrum'' of CMB in the inflationary
model. The Hamiltonian approach enables to explain this ``spectrum'' in terms
of scale-invariant variables and to consider other topical problem of modern
cosmology in the context of quantum cosmological creation of both universes and
particles from the stable Bogoliubov vacuum.Comment: 10 pages, text was changed according to the version accepted for
publication in Physics Letters
and Polarizabilities from {} Data on the Base of S-Matrix Approach
We suggest the most model-independent and simple description of the
process near threshold in framework of S-matrix
approach. The amplitudes contain the pion polarizabilities and rather
restricted information about interaction. Application of these
formulae for description of MARK-II \cite{M2} and Crystal Ball \cite{CB} data
gives: ,
(in units system ) at the experimental values of scattering lengths. Both
values are compartible with current algebra predictions.Comment: LaTeX, 14 pages plus 6 figures (not included, available upon request)
, ISU-IAP.Th93-03, Irkuts
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