3,111 research outputs found

### Quantum effects from a purely geometrical relativity theory

A purely geometrical relativity theory results from a construction that
produces from three-dimensional space a happy unification of Kaluza's
five-dimensional theory and Weyl's conformal theory. The theory can provide
geometrical explanations for the following observed phenomena, among others:
(a) lifetimes of elementary particles of lengths inversely proportional to
their rest masses; (b) the equality of charge magnitude among all charged
particles interacting at an event; (c) the propensity of electrons in atoms to
be seen in discretely spaced orbits; and (d) `quantum jumps' between those
orbits. This suggests the possibility that the theory can provide a
deterministic underpinning of quantum mechanics like that provided to
thermodynamics by the molecular theory of gases.Comment: 7 pages, LaTeX jpconf.cls (Institute of Physics Publishing), 6
Encapsulated PostScript figures (Fig. 6 is 1.8M uncompressed); Presented at
VI Mexican School on Gravitation and Mathematical Physics "Approaches to
Quantum Gravity

### Implication of Compensator Field and Local Scale Invariance in the Standard Model

We introduce Weyl's scale symmetry into the standard model (SM) as a local
symmetry. This necessarily introduces gravitational interactions in addition to
the local scale invariance group \tilde U(1) and the SM groups SU(3) X SU(2) X
U(1). The only other new ingredients are a new scalar field \sigma and the
gauge field for \tilde U(1) we call the Weylon. A noteworthy feature is that
the system admits the St\" uckelberg-type compensator. The \sigma couples to
the scalar curvature as (-\zeta/2) \sigma^2 R, and is in turn related to a St\"
uckelberg-type compensator \varphi by \sigma \equiv M_P e^{-\varphi/M_P} with
the Planck mass M_P. The particular gauge \varphi = 0 in the St\" uckelberg
formalism corresponds to \sigma = M_P, and the Hilbert action is induced
automatically. In this sense, our model presents yet another mechanism for
breaking scale invariance at the classical level. We show that our model
naturally accommodates the chaotic inflation scenario with no extra field.Comment: This work is to be read in conjunction with our recent comments
hep-th/0702080, arXiv:0704.1836 [hep-ph] and arXiv:0712.2487 [hep-ph]. The
necessary ingredients for describing chaotic inflation in the SM as
entertained by Bezrukov and Shaposhnikov [17] have been provided by our
original model [8]. We regret their omission in citing our original model [8

### Lukewarm black holes in quadratic gravity

Perturbative solutions to the fourth-order gravity describing
spherically-symmetric, static and electrically charged black hole in an
asymptotically de Sitter universe is constructed and discussed. Special
emphasis is put on the lukewarm configurations, in which the temperature of the
event horizon equals the temperature of the cosmological horizon

### The geometry of manifolds and the perception of space

This essay discusses the development of key geometric ideas in the 19th
century which led to the formulation of the concept of an abstract manifold
(which was not necessarily tied to an ambient Euclidean space) by Hermann Weyl
in 1913. This notion of manifold and the geometric ideas which could be
formulated and utilized in such a setting (measuring a distance between points,
curvature and other geometric concepts) was an essential ingredient in
Einstein's gravitational theory of space-time from 1916 and has played
important roles in numerous other theories of nature ever since.Comment: arXiv admin note: substantial text overlap with arXiv:1301.064

### Particle phenomenology on noncommutative spacetime

We introduce particle phenomenology on the noncommutative spacetime called
the Groenewold-Moyal plane. The length scale of spcetime noncommutativity is
constrained from the CPT violation measurements in $K^{0}-\bar{K}^{0}$ system
and $g-2$ difference of $\mu^+ - \mu^-$. The $K^{0}-\bar{K}^{0}$ system
provides an upper bound on the length scale of spacetime noncommutativity of
the order of $10^{-32} \textrm{m}$, corresponding to a lower energy bound $E$
of the order of $E \gtrsim 10^{16}\textrm{GeV}$. The $g-2$ difference of $\mu^+
- \mu^-$ constrains the noncommutativity length scale to be of the order of
$10^{-20} \textrm{m}$, corresponding to a lower energy bound $E$ of the order
of $E \gtrsim 10^{3}\textrm{GeV}$.
We also present the phenomenology of the electromagnetic interaction of
electrons and nucleons at the tree level in the noncommutative spacetime. We
show that the distributions of charge and magnetization of nucleons are
affected by spacetime noncommutativity. The analytic properties of
electromagnetic form factors are also changed and it may give rise to
interesting experimental signals.Comment: 10 pages, 3 figures. Published versio

### Conformal Invariance in Einstein-Cartan-Weyl space

We consider conformally invariant form of the actions in Einstein, Weyl,
Einstein-Cartan and Einstein-Cartan-Weyl space in general dimensions($>2$) and
investigate the relations among them. In Weyl space, the observational
consistency condition for the vector field determining non-metricity of the
connection can be obtained from the equation of motion. In Einstein-Cartan
space a similar role is played by the vector part of the torsion tensor. We
consider the case where the trace part of the torsion is the Kalb-Ramond type
of field. In this case, we express conformally invariant action in terms of two
scalar fields of conformal weight -1, which can be cast into some interesting
form. We discuss some applications of the result.Comment: 10 pages, version to appear MPL

### On the reduction of hypercubic lattice artifacts

This note presents a comparative study of various options to reduce the
errors coming from the discretization of a Quantum Field Theory in a lattice
with hypercubic symmetry. We show that it is possible to perform an
extrapolation towards the continuum which is able to eliminate systematically
the artifacts which break the O(4) symmetry.Comment: 15 pages. 4 figures. Minor changes (Appendix and refs added

### The Hawking temperature of expanding cosmological black holes

In the context of a debate on the correct expression of the Hawking
temperature of an expanding cosmological black hole, we show that the correct
expression in terms of the Hawking-Hayward quasi-local energy m of the hole is
T=1/(8\pi m(t)). This expression holds for comoving black holes and agrees with
a recent proposal by Saida, Harada, and Maeda.Comment: 5 latex pages, to appear in Phys. Rev. D. Some references adde

### New Models of General Relativistic Static Thick Disks

New families of exact general relativistic thick disks are constructed using
the ``displace, cut, fill and reflect'' method. A class of functions used to
``fill'' the disks is derived imposing conditions on the first and second
derivatives to generate physically acceptable disks. The analysis of the
function's curvature further restrict the ranges of the free parameters that
allow phisically acceptable disks. Then this class of functions together with
the Schwarzschild metric is employed to construct thick disks in isotropic,
Weyl and Schwarzschild canonical coordinates. In these last coordinates an
additional function must be added to one of the metric coefficients to generate
exact disks. Disks in isotropic and Weyl coordinates satisfy all energy
conditions, but those in Schwarzschild canonical coordinates do not satisfy the
dominant energy condition.Comment: 27 pages, 14 figure

### Universal entanglement concentration

We propose a new protocol of \textit{universal} entanglement concentration,
which converts many copies of an \textit{unknown} pure state to an \textit{%
exact} maximally entangled state. The yield of the protocol, which is outputted
as a classical information, is probabilistic, and achives the entropy rate with
high probability, just as non-universal entanglement concentration protocols
do.
Our protocol is optimal among all similar protocols in terms of wide
varieties of measures either up to higher orders or non-asymptotically,
depending on the choice of the measure. The key of the proof of optimality is
the following fact, which is a consequence of the symmetry-based construction
of the protocol: For any invariant measures, optimal protocols are found out in
modifications of the protocol only in its classical output, or the claim on the
product.
We also observe that the classical part of the output of the protocol gives a
natural estimate of the entropy of entanglement, and prove that that estimate
achieves the better asymptotic performance than any other (potentially global)
measurements.Comment: Revised a lot, especially proofs, though no change in theorems,
lemmas itself. Very long, but essential part is from Sec.I to Sec IV-C. Some
of the appendces are almost independent of the main bod

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