483,092 research outputs found
More Set-theory around the weak Freese-Nation property
In this paper, we introduce a very weak square principle which is even weaker
than the similar principle introduced by Foreman and Magidor. A
characterization of this principle is given in term of sequences of elementary
submodels of H(\chi). This is used in turn to prove a characterization of
kappa-Freese-Nation property under the very weak square principle and a weak
variant of the Singular Cardinals Hypothesis.
A typical application of this characterization shows that under
2^{\aleph_0}<\aleph_\omega and our very weak square for \aleph_\omega, the
partial ordering [omega_\omega]^{<\omega} (ordered by inclusion) has the
aleph_1-Freese-Nation property.
On the other hand we show that, under Chang's Conjecture for \aleph_\omega
the partial ordering above does not have the aleph_1-Freese-Nation property.
Hence we obtain the independence of our characterization of the
kappa-Freese-Nation property and also of the very weak square principle from
ZFC
Unification of Gravity and Electromagnetism I: Mach's Principle and Cosmology
The phenomenological consequences of unification of Einstein gravity and
electromagnetism in an early phase of a Machian universe with a very small and
uniform electrical charge density are explored. A form of the Strong
Equivalence Principle for unified electrogravity is first formulated, and it
immediately leads to (i) the empirical Schuster-Blackett law relating the
magnetic moments and angular momenta of neutral astronomical bodies, (ii) an
analogous relation between the linear acceleration of neutral massive bodies
and associated electric fields, (iii) gravitational lensing in excess of
Einstein gravity, and, with the additional assumption of scaling, to (iv) the
Wesson relation between the angular momentum and the square of the mass of
astronomical bodies. Incorporation of Sciama's version of Mach's principle
leads to a new post-Newtonian dynamics (in the weak field limit of gravity
alone without electromagnetism) that predicts flat rotation curves of galaxies
without the need of dark matter haloes. Finally, it is shown that the unified
theory with a broken symmetry predicts a flat expanding universe with a
cosmological term intimately related to electrogravity unification, and can
explain WMAP data with a single free parameter. WMAP data require C/cc which is too small to be detected atComment: 14 pages; some additional material; affiliation change
Is Cosmological Tuning Fine or Coarse?
The fine-tuning of the universe for life, the idea that the constants of
nature (or ratios between them) must belong to very small intervals in order
for life to exist, has been debated by scientists for several decades. Several
criticisms have emerged concerning probabilistic measurement of life-permitting
intervals. Herein, a Bayesian statistical approach is used to assign an upper
bound for the probability of tuning, which is invariant with respect to change
of physical units, and under certain assumptions it is small whenever the
life-permitting interval is small on a relative scale. The computation of the
upper bound of the tuning probability is achieved by first assuming that the
prior is chosen by the principle of maximum entropy (MaxEnt). The unknown
parameters of this MaxEnt distribution are then handled in such a way that the
weak anthropic principle is not violated. The MaxEnt assumption is "maximally
noncommittal with regard to missing information." This approach is sufficiently
general to be applied to constants of current cosmological models, or to other
constants possibly under different models. Application of the MaxEnt model
reveals, for example, that the ratio of the universal gravitational constant to
the square of the Hubble constant is finely tuned in some cases, whereas the
amplitude of primordial fluctuations is not.Comment: 19 pages, 1 figure. Substantial reorganization and expansion to make
it more clea
Complex Action Support from Coincidences of Couplings
Our model \cite{ownmMPP}\cite{SIMPP} with complex action in a functional
integral formulation with path integrals extending over all times, past and
future, is reviewed. Several numerical relations between coupling constants are
presented as supporting evidence. The new evidence is that some more
unexplained coincidences are explained in our model:
1) The "scale problem" is solved because the Higgs field expectation value is
predicted to be very small compared to say some fundamental scale, that might
be the Planck scale.
2) The Higgs VEV need not, however, to be just zero, but rather is predicted
to be so that the running top-Yukawa coupling just is about to be unity at this
scale; in this way the (weak) scale easily becomes "exponentially small".
Instead of the top-Yukawa we should rather say the highest flavour Yukawa
coupling here.
These predictions are only achieved by allowing the principle of minimization
of the imaginary part of the action SI(history) to to a certain extent adjust
some coupling constants in addition to the initial conditions.
If Susy-partners are not found in LHC, it would strengthen the need for
"solution" of the hierarchy or rather scale problem along the lines of the
present article.Comment: only text. Some printing mistakes corrected and a couple of new
subsections inserted and abstract stylistically changed a bi
F(750), We Miss You, as Bound State of 6 Top and 6 Anti top
We collect and estimate support for our long speculated "multiple point
principle" saying that there should be several vacua all having (compared to
the scales of high energy physics) very low energy densities. In pure Standard
Model we suggest there being three by "multiple point principle" low energy
density vacua, "present", "condensate" and "high field" vacuum. We fit the mass
of the in our picture since long speculated bound state of six top and six anti
top quarks in three quite {\em independent ways} and get remarkably within our
crude accuracy the {\em same} mass in all three fits! The new point of the
present article is to estimate the bound state mass in what we could call a bag
model estimation. The two other fits, which we review, obtain the mass of the
bound state by fitting to the multiple point principle prediction of degenerate
vacua.
Our remarkable agreement of our three mass-fits can be interpreted to mean,
that we have calculated at the end the energy densities of the two extra
speculated vacua and found that they are indeed very small!. Unfortunately the
recently much discussed statistical fluctuation peak F(750) has now been
revealed to be just a fluctuation, very accidentally matches our fitted mass of
the bound state remarkably well with the mass of this fluctuation 750 GeV.Comment: minor corrections in calculation and commas and a few references
added. arXiv admin note: text overlap with arXiv:1607.07907, adding few
citation
Two dimensional Dirac fermions and quantum magnetoresistance in CaMnBi
We report two dimensional Dirac fermions and quantum magnetoresistance in
single crystals of CaMnBi. The non-zero Berry's phase, small cyclotron
resonant mass and first-principle band structure suggest the existence of the
Dirac fermions in the Bi square nets. The in-plane transverse magnetoresistance
exhibits a crossover at a critical field from semiclassical weak-field
dependence to the high-field unsaturated linear magnetoresistance ( in 9 T at 2 K) due to the quantum limit of the Dirac fermions. The
temperature dependence of satisfies quadratic behavior, which is
attributed to the splitting of linear energy dispersion in high field. Our
results demonstrate the existence of two dimensional Dirac fermions in
CaMnBi with Bi square nets.Comment: 5 pages, 4 figure
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