1,167 research outputs found
Towards a Bell-Kochen-Specker theorem of identity
In contrast to conventional, dynamical entanglement, in which particles with
definite identity have uncertain properties, in so-called statistical
entanglement, which arises between indistinguishable particles because of
quantum symmetry rules, even particle identities are uncertain. The Bell and
Kochen-Specker theorems imply that quantum properties either lack realism or
possess it with a caveat of contextuality or nonlocality. In the matter of
identity of multi-particle states of indistinguishable particles, these
contrasting ontological attitudes are mirrored by the "bundle" vs. haecceity
views. We offer some arguments aimed at importing the above theorems to the
issue of identity in quantum theory, with the conclusion (under certain
assumptions) that indistinguishable particles either lack individualism or
possess a definite identity with a caveat of contextuality or nonlocality.Comment: 3 page
Van der Waerden's Colouring Theorem and Classical Spin Systems
We find a non-invertible matrix representation for Van der Waerden's
colouring theorem for two distinct colours in a one dimensional periodic
lattice. Using this,an infinite one dimensional antiferromagnetic Ising system
is mapped to a pseudo-ferromagnetic one, thereby relating the couplings. All
this is reminiscent of renormalisation group.Comment: Latex, 10 page
Spacetime Dependent Lagrangians and Electrogravity Duality
We apply the spacetime dependent lagrangian formalism [1] to the action in
general relativity. We obtain a Barriola-Vilenkin type monopole solution by
exploiting theelectrogravity duality of the vacuum Einstein equations and using
a modified definition of empty space. An {\it upper bound} is obtained on the
monopole mass , where is the global monopole charge.
Keywords: global monopole, electrogravity duality, holographic principle.
PACS: 11.15.-q, 11.27.+d, 14.80.Hv, 04.Comment: 4 pages, late
Confronting K\"ahler moduli inflation with CMB data
In models of inflation obtained from string compactification, moduli vacuum
misalignment leads to an epoch in the post-inflationary history of the universe
when the energy density is dominated by cold moduli particles. This effect
leads to a modification in the number of -foldings () between
horizon exit of the CMB modes and the end of inflation. Taking K\"ahler moduli
inflation as a prototype, the shift in -foldings turns out to be a function
of the model parameters which also determines the inflationary observables. We
analyse this scenario numerically using publicly available {\sc{ModeChord}} and
{\sc{CosmoMC}} with the latest \emph{Planck+BICEP2/Keck array} data to
constrain the model parameters and . In light of the present and
future precision data, the results show the importance of careful consideration
of any post-inflationary non-standard epoch, as well as of the effects of
reheating.Comment: 9 pages, 8 figures, new section added with analysis for different
values of the equation of state during reheating, references added. PRD
published versio
Self-organized synthesis of patterned magnetic nanostructures with in-plane and perpendicular to the plane magnetization
Patterned arrays of ferromagnetic nanoparticles of Co, Ni, and Fe_{\text{50}}
Co_{\text{50}} have been synthesized from their ultrathin metal films on
SiO_{\text{2}} substrate by nanosecond laser-induced self-organization. The
morphology, nanostructure, and magnetic behavior of the nanoparticle arrays
were investigated by a combination of electron, atomic force, and magnetic
force microscopy techniques. Transmission electron microscopy investigations
revealed a granular polycrystalline nanostructure, with the number of grains
inside the nanoparticle increasing with their diameter. Magnetic force
measurements showed that the magnetization direction of the Co and Ni
nanoparticles was predominantly out-of-plane while those for the
Fe_{\text{50}}Co_{\text{50}} alloy was in the plane of the substrate. This
difference in behavior is due to the dominating influence of magnetostrictive
energy on the magnetization as a result of residual thermal strain following
fast laser processing. Since the magnetostriction coefficient is negative for
polycrystalline Co and Ni, and positive for Fe_{\text{50}}Co_{\text{50}}, the
tensile residual strain forces the magnetization direction of the negative
magnetostriction materials out-of-plane and the positive magnetostriction
materials in-plane. This demonstrates a cost-effective non-epitaxial technique
for the fabrication of patterned arrays of magnetic nanoparticles with tailored
magnetization orientations.Comment: 22 pages, 6 figure
Thermodynamic potential for quark-gluon plasma with finite quark masses and chemical potential
We summarize the derivation of the finite temperature, finite chemical
potential thermodynamic potential in the bag-model approximation to quantum
chromodynamics (QCD) that includes a finite -quark mass in the Feynman
diagram contributions for both zero-order and two-loop corrections to the quark
interaction. The thermodynamic potential for quarks in QCD is a desired
ingredient for computations of the equation of state in the early universe,
supernovae, neutron stars, and heavy-ion collisions. The 2-loop contributions
are normally divergent and become even more difficult in the limit of finite
quark masses and finite chemical potential. We introduce various means to
interpolate between the low and high chemical potential limits. Although
physically well motivated, we show that the infinite series Pad\'e rational
polynomial interpolation scheme introduces spurious poles. Nevertheless, we
show that lower order interpolation schemes such as polynomial interpolation
reproduce the Pad\'e result without the presence of spurious poles. We propose
that in this way one can determine the equation of state for the two-loop
corrections for arbitrary chemical potential, temperature and quark mass. This
provides a new realistic bag-model treatment of the QCD equation of state. We
compute the QCD phase diagram with up to the two-loop corrections. We show that
the two-loop corrections decrease the pressure of the quark-gluon plasma and
therefore increase the critical temperature and chemical potential of the phase
transition. We also show, however, that the correction for finite -quark
mass in the two-loop correction serves to decrease the critical temperature for
the quark-hadron phase transition in the early universe.Comment: 16 pages, 6 figures, Matches published versio
Evidence for Planck-scale resonant particle production during inflation from the CMB power spectrum
The power spectrum of the cosmic microwave background from both the {\it
Planck} and {\it WMAP} data exhibits a slight dip for multipoles in the range
of . We show that such a dip could be the result of the resonant
creation of massive particles that couple to the inflaton field. For our
best-fit models, the epoch of resonant particle creation reenters the horizon
at a wave number of ( Mpc). The
amplitude and location of this feature corresponds to the creation of a number
of degenerate fermion species of mass
during inflation where is the coupling
constant between the inflaton field and the created fermion species, while
is the number of degenerate species. Although the evidence is of marginal
statistical significance, this could constitute new observational hints of
unexplored physics beyond the Planck scaleComment: 6 pages, 1 figure , Fourteenth Marcel Grossmann Meeting, July, 2015.
arXiv admin note: substantial text overlap with arXiv:1508.0121
Limits on Brane-World and Particle Dark Radiation from Big Bang Nucleosynthesis and the CMB
The term dark radiation is used both to describe a noninteracting neutrino
species and as a correction to the Friedmann Equation in the simplest
five-dimensional RS-II brane-world cosmology. In this paper we consider the
constraints on both meanings of dark radiation based upon the newest results
for light-element nuclear reaction rates, observed light-element abundances and
the power spectrum of the Cosmic Microwave Background (CMB). Adding dark
radiation during big bang nucleosynthesis (BBN) alters the Friedmann expansion
rate causing the nuclear reactions to freeze out at a different temperature.
This changes the final light element abundances at the end of BBN. Its
influence on the CMB is to change the effective expansion rate at the surface
of last scattering. We find that the BBN constraint reduces the allowed range
for both types of dark radiation at 10 Mev to between and of
the {\bf total} background energy density at 10 Mev. Combining this result with
fits to the CMB power spectrum, produces different results for particle vs.
brane-world dark radiation. In the brane-world, the range decreases to
to . Thus, we find, that the ratio of dark radiation to the background
total relativistic mass energy density is consistent with
zero although there remains a very slight preference for a positive (rather
than negative) contribution.Comment: arXiv admin note: substantial text overlap with arXiv:1607.0685
Possible Evidence for Planck-Scale Resonant Particle Production during Inflation from the CMB Power Spectrum
The power spectrum of the cosmic microwave background from both the Planck
and WMAP data exhibits a slight dip in for multipoles in the range of l=10-30.
We show that such a dip could be the result of resonant creation of a massive
particle that couples to the inflaton field. For our best-fit models, epochs of
resonant particle creation reenters the horizon at wave numbers of k* ~ 0.00011
(h/Mpc). The amplitude and location of these features correspond to the
creation of a number of degenerate fermion species of mass ~ 15 times the
planck mass during inflation with a coupling constant between the inflaton
field and the created fermion species of near unity. Although the evidence is
marginal, if this interpretation is correct, this could be one of the first
observational hints of new physics at the Planck scale.Comment: 5 pages, 3 figures. arXiv admin note: substantial text overlap with
arXiv:astro-ph/0406046. Updated mass estimat
Construction of Lagrangians Exhibiting Duality
Electromagnetic duality seems to be a fundamental principle of nature. Although there exist a lot of work on various aspects of duality, a general derivation from the lagrangian formalism has been elusive except that of Gaillard and Zumino [1] who showed that duality follows from certain transformation properties of a lagrangian. Here, starting from lagrangian field theory and the variational principle, we show that duality can be obtained by introducing explicit spacetime dependence of the lagrangian. As illustrations, we show how one can understand (1) the Dirac string solution and (2) the t'Hooft-Polyakov monopole solution. We also outline a procedure for obtaining new classical solutions of Yang-Mills theory
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