326 research outputs found
The geometric role of symmetry breaking in gravity
In gravity, breaking symmetry from a group G to a group H plays the role of
describing geometry in relation to the geometry the homogeneous space G/H. The
deep reason for this is Cartan's "method of equivalence," giving, in
particular, an exact correspondence between metrics and Cartan connections. I
argue that broken symmetry is thus implicit in any gravity theory, for purely
geometric reasons. As an application, I explain how this kind of thinking gives
a new approach to Hamiltonian gravity in which an observer field spontaneously
breaks Lorentz symmetry and gives a Cartan connection on space.Comment: 4 pages. Contribution written for proceedings of the conference
"Loops 11" (Madrid, May 2011
Factors and outcomes in primary care physician retention in rural areas
Background: This paper examines factors influencing physicians’ decisions to practise in rural communities as well as the results of a programme focused on rural recruitment and retention. Methods: Data from two sources were analysed and discussed: 1) telephone interviews with 20 of 33 (61%) recently located rural physicians regarding practice and community factors influencing their practice decisions and 2) a database of 107 graduates of a rural medical education programme who have been in practice for at least three years to examine specialty choice and practice location(s), including moves from their original practice sites.Results: Most rural physicians in this study decided to practise in rural areas because of family ties. Eighty per cent of the physicians participating in the interviews mentioned no negative personal or family factors related to their community of practice. Outcome data on graduates from the rural medical education programme are encouraging. Over 70% opt for primary care and rural practice. Over 80% have remained in their original rural practice location. Conclusion: Keys to success in rural physician retention seem to include identifying and recruiting medical students of rural origin and focusing on a healthy practice environment. Policy makers need to work with local government, schools and employers to offer programmes that provide information on health careers in rural areas and begin to identify local youth for induction in rural health care. Keywords: retention; rural; primary care; physicians; workforc
Coupling of Gravity to Matter via SO(3,2) Gauge Fields
We consider gravity from the quantum field theory point of view and introduce
a natural way of coupling gravity to matter by following the gauge principle
for particle interactions. The energy-momentum tensor for the matter fields is
shown to be conserved and follows as a consequence of the dynamics in a
spontaneously broken SO(3,2) gauge theory of gravity. All known interactions
are described by the gauge principle at the microscopic level.Comment: 12 latex page
Riemann-Einstein Structure from Volume and Gauge Symmetry
It is shown how a metric structure can be induced in a simple way starting
with a gauge structure and a preferred volume, by spontaneous symmetry
breaking. A polynomial action, including coupling to matter, is constructed for
the symmetric phase. It is argued that assuming a preferred volume, in the
context of a metric theory, induces only a limited modification of the theory.Comment: LaTeX, 13 pages; Added additional reference in Reference
Ring diagrams and electroweak phase transition in a magnetic field
Electroweak phase transition in a magnetic field is investigated within the
one-loop and ring diagram contributions to the effective potential in the
minimal Standard Model. All fundamental fermions and bosons are included with
their actual values of masses and the Higgs boson mass is considered in the
range . The effective potential is real at
sufficiently high temperature. The important role of fermions and -bosons in
symmetry behaviour is observed. It is found that the phase transition for the
field strengths G is of first order but the baryogenesis
condition is not satisfied. The comparison with the hypermagnetic field case is
done.Comment: 16 pages, Latex, changed for a mistake in the numerical par
“You made me look bad. And that’s not good”:The millennial cultification of Fatal Deviation, Ireland’s only martial arts film
Examples of Embedded Defects (in Particle Physics and Condensed Matter)
We present a series of examples designed to clarify the formalism of the
companion paper `Embedded Vortices'. After summarising this formalism in a
prescriptive sense, we run through several examples: firstly, deriving the
embedded defect spectrum for Weinberg-Salam theory, then discussing several
examples designed to illustrate facets of the formalism. We then calculate the
embedded defect spectrum for three physical Grand Unified Theories and conclude
with a discussion of vortices formed in the superfluid He-A phase
transition.Comment: final corrections. latex fil
Snyder's Quantized Space-time and De Sitter Special Relativity
There is a one-to-one correspondence between Snyder's model in de Sitter
space of momenta and the \dS-invariant special relativity. This indicates that
physics at the Planck length and the scale should be
dual to each other and there is in-between gravity of local \dS-invariance
characterized by a dimensionless coupling constant .Comment: 8 page
Self-Dual Conformal Supergravity and the Hamiltonian Formulation
In terms of Dirac matrices the self-dual and anti-self-dual decomposition of
a conformal supergravity is given and a self-dual conformal supergravity theory
is developed as a connection dynamic theory in which the basic dynamic variabes
include the self-dual spin connection i.e. the Ashtekar connection rather than
the triad. The Hamiltonian formulation and the constraints are obtained by
using the Dirac-Bergmann algorithm.
PACS numbers: 04.20.Cv, 04.20.Fy,04.65.+
Quantum Gravity, the Origin of Time and Time's Arrow
The local Lorentz and diffeomorphism symmetries of Einstein's gravitational
theory are spontaneously broken by a Higgs mechanism by invoking a phase
transition in the early Universe, at a critical temperature below which
the symmetry is restored. The spontaneous breakdown of the vacuum state
generates an external time and the wave function of the Universe satisfies a
time dependent Schrodinger equation, which reduces to the Wheeler-deWitt
equation in the classical regime for , allowing a semi-classical WKB
approximation to the wave function. The conservation of energy is spontaneously
violated for and matter is created fractions of seconds after the big
bang, generating the matter in the Universe. The time direction of the vacuum
expectation value of the scalar Higgs field generates a time asymmetry, which
defines the cosmological arrow of time and the direction of increasing entropy
as the Lorentz symmetry is restored at low temperatures.Comment: 37 page
- …