361 research outputs found
Gravity in Dynamically Generated Dimensions
A theory of gravity in dimensions is dynamically generated from a
theory in dimensions. As an application we show how dynamically coupled
gravity theories can reduce the effective Planck mass.Comment: 7 pages, LaTeX (Revtex
Unparticles: Scales and High Energy Probes
Unparticles from hidden conformal sectors provide qualitatively new
possibilities for physics beyond the standard model. In the theoretical
framework of minimal models, we clarify the relation between energy scales
entering various phenomenological analyses. We show that these relations always
counteract the effective field theory intuition that higher dimension operators
are more highly suppressed, and that the requirement of a significant conformal
window places strong constraints on possible unparticle signals. With these
considerations in mind, we examine some of the most robust and sensitive probes
and explore novel effects of unparticles on gauge coupling evolution and
fermion production at high energy colliders. These constraints are presented
both as bounds on four-fermion interaction scales and as constraints on the
fundamental parameter space of minimal models.Comment: 16 pages, 2 tables, 6 figures; reference added, published versio
The Role of in Determining the Weak Phase
The decay rates for , , and the
charge-conjugate processes were found to provide information on the weak phase
when the ratio of weak tree and penguin
amplitudes was taken from data on or semileptonic
decays. We show here that the rates for and can provide the necessary information on , and estimate the
statistical accuracy of forthcoming measurements at the Fermilab Tevatron.Comment: 8 pages, LaTeX, no figures, submitted to Physics Letters B,
corrections to discussion of SU(3) breaking adde
Discrete quantum gravity in the framework of Regge calculus formalism
An approach to the discrete quantum gravity based on the Regge calculus is
discussed which was developed in a number of our papers. Regge calculus is
general relativity for the subclass of general Riemannian manifolds called
piecewise flat ones. Regge calculus deals with the discrete set of variables,
triangulation lengths, and contains continuous general relativity as a
particular limiting case when the lengths tend to zero. In our approach the
quantum length expectations are nonzero and of the order of Plank scale
. This means the discrete spacetime structure on these scales.Comment: LaTeX, 16 pages, to appear in JET
Regge calculus in the canonical form
(3+1) (continuous time) Regge calculus is reduced to Hamiltonian form. The
constraints are classified, classical and quantum consequences are discussed.
As basic variables connection matrices and antisymmetric area tensors are used
supplemented with appropriate bilinear constraints. In these variables the
action can be made quasipolinomial with as the only deviation from
polinomiality. In comparison with analogous formalism in the continuum theory
classification of constraints changes: some of them disappear, the part of I
class constraints including Hamiltonian one become II class (and vice versa,
some new constraints arise and some II class constraints become I class). As a
result, the number of the degrees of freedom coincides with the number of links
in 3-dimensional leaf of foliation. Moreover, in empty space classical dynamics
is trivial: the scale of timelike links become zero and spacelike links are
constant.Comment: 24 pages,Plain LaTeX,BINP 93-4
Desperately Seeking Non-Standard Phases via Direct CP Violation in Process
Attributing the recent CLEO discovery of to originate
(primarily) from the fragmentation of an off-shell gluon () via , , we emphasize that many such states () should
materialize. Indeed the hadronic fragments () of states are closely
related to those seen in . A particular
final state of considerable interest is . Signals from such states
in decays can be combined to provide a very sensitive search for CP
violating phase(s) from non-standard physics. The method should work even if
the contribution of these source(s) to the rates is rather small () to
the point that a comparison between theory and experiment may find it extremely
difficult to reveal the presence of such a new physics.Comment: 16 pages, 5 figure
Coherent States and N Dimensional Coordinate Noncommutativity
Considering coordinates as operators whose measured values are expectations
between generalized coherent states based on the group SO(N,1) leads to
coordinate noncommutativity together with full dimensional rotation
invariance. Through the introduction of a gauge potential this theory can
additionally be made invariant under dimensional translations. Fluctuations
in coordinate measurements are determined by two scales. For small distances
these fluctuations are fixed at the noncommutativity parameter while for larger
distances they are proportional to the distance itself divided by a {\em very}
large number. Limits on this number will lbe available from LIGO measurements.Comment: 16 pqges. LaTeX with JHEP.cl
Expanding Cosmologies in Brane Geometries
Five dimensional gravity coupled, both in the bulk and on a brane, to a
scalar Liouville field yields a geometry confined to a strip around the brane
and with time dependent scale factors for the four geometry. In various limits
known models can be recovered as well as a temporally expanding four geometry
with a warp factor falling exponentially away from the brane. The effective
theory on the brane has a time dependent Planck mass and ``cosmological
constant''. Although the scale factor expands, the expansion is not an
acceleration.Comment: 7 pages, LaTex/RevTex
Brane World Cosmology In Jordan-Brans-Dicke Theory
We consider the embedding of 3+1 dimensional cosmology in 4+1 dimensional
Jordan-Brans-Dicke theory. We show that exponentially growing and power law
scale factors are implied. Whereas the 4+1 dimensional scalar field is
approximately constant for each, the effective 3+1 dimensional scalar field is
constant for exponentially growing scale factor and time dependent for power
law scale factor.Comment: 11 page
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