10,097 research outputs found
Limits on Lorentz violation in neutral-Kaon decay
The KLOE collaboration recently reported bounds on the directional dependence
of the lifetime of the short-lived neutral kaon K_S with respect to the cosmic
microwave background dipole anisotropy. We interpret their results in a general
framework developed to probe Lorentz violation in the weak interaction. In this
approach a Lorentz-violating tensor \chi_{\mu\nu} is added to the standard
propagator of the W boson. We derive the K_S decay rate in a naive tree-level
model and calculate the asymmetry for the lifetime. By using the KLOE data the
real vector part of \chi_{\mu\nu} is found to be smaller than 10^-2. We briefly
discuss the theoretical challenges concerning nonleptonic decays.Comment: Presented at the Sixth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 17-21, 2013
Testing Lorentz invariance in orbital electron capture
Searches for Lorentz violation were recently extended to the weak sector, in
particular neutron and nuclear decay [1]. From experiments on forbidden
-decay transitions strong limits in the range of -
were obtained on Lorentz-violating components of the -boson propagator [2].
In order to improve on these limits strong sources have to be considered. In
this Brief Report we study isotopes that undergo orbital electron capture and
allow experiments at high decay rates and low dose. We derive the expressions
for the Lorentz-violating differential decay rate and discuss the options for
competitive experiments and their required precision.Comment: accepted for publication as a Brief Report in Physical Review
Symmetry violations in nuclear and neutron decay
The role of decay as a low-energy probe of physics beyond the
Standard Model is reviewed. Traditional searches for deviations from the
Standard Model structure of the weak interaction in decay are discussed
in the light of constraints from the LHC and the neutrino mass. Limits on the
violation of time-reversal symmetry in decay are compared to the strong
constraints from electric dipole moments. Novel searches for Lorentz symmetry
breaking in the weak interaction in decay are also included, where we
discuss the unique sensitivity of decay to test Lorentz invariance. We
end with a roadmap for future -decay experiments.Comment: Accepted for publication in Rev. Mod. Phys. 86 pages, 13 figure
Nanophotonic hybridization of narrow atomic cesium resonances and photonic stop gaps of opaline nanostructures
We study a hybrid system consisting of a narrowband atomic optical resonance
and the long-range periodic order of an opaline photonic nanostructure. To this
end, we have infiltrated atomic cesium vapor in a thin silica opal photonic
crystal. With increasing temperature, the frequencies of the opal's
reflectivity peaks shift down by >20% due to chemical reduction of the silica.
Simultaneously, the photonic bands and gaps shift relative to the fixed
near-infrared cesium D1 transitions. As a result the narrow atomic resonances
with high finesse (f/df=8E5) dramatically change shape from a usual dispersive
shape at the blue edge of a stop gap, to an inverted dispersion lineshape at
the red edge of a stop gap. The lineshape, amplitude, and off-resonance
reflectivity are well modeled with a transfer-matrix model that includes the
dispersion and absorption of Cs hyperfine transitions and the
chemically-reduced opal. An ensemble of atoms in a photonic crystal is an
intriguing hybrid system that features narrow defect-like resonances with a
strong dispersion, with potential applications in slow light, sensing and
optical memory.Comment: 8 pages, 6 figure
Exploration of Lorentz violation in neutral-kaon decay
The KLOE collaboration recently reported bounds on the directional dependence
of the lifetime of the short-lived neutral kaon with respect to the
dipole anisotropy of the cosmic microwave background. We interpret their
results in an effective field theory framework developed to probe the violation
of Lorentz invariance in the weak interaction and previously applied to
semileptonic processes, in particular decay. In this approach a general
Lorentz-violating tensor is added to the standard propagator of
the boson. We perform an exploratory study of the prospects to search for
Lorentz violation in nonleptonic decays. For the kaon, we find that the
sensitivity to Lorentz violation is limited by the velocity of the kaons and by
the extent to which hadronic effects can be calculated. In a simple model we
derive the decay rate and calculate the asymmetry for the lifetime.
Using the KLOE data, limits on the values of are determined.Comment: accepted for publication in Physics Letters
Programmable two-photon quantum interference in channels in opaque scattering media
We investigate two-photon quantum interference in an opaque scattering medium
that intrinsically supports transmission channels. By adaptive spatial
phase-modulation of the incident wavefronts, the photons are directed at
targeted speckle spots or output channels. From experimentally available
coupled channels, we select two channels and enhance their transmission, to
realize the equivalent of a fully programmable beam splitter. By
sending pairs of single photons from a parametric down-conversion source
through the opaque scattering medium, we observe two-photon quantum
interference. The programmed beam splitter need not fulfill energy conservation
over the two selected output channels and hence could be non-unitary.
Consequently, we have the freedom to tune the quantum interference from
bunching (Hong-Ou-Mandel-like) to antibunching. Our results establish opaque
scattering media as a platform for high-dimensional quantum interference that
is notably relevant for boson sampling and physical-key-based authentication
Mapping individual electromagnetic field components inside a photonic crystal
We present a method to map the absolute electromagnetic field strength inside
photonic crystals. We apply the method to map the electric field component Ez
of a two-dimensional photonic crystal slab at microwave frequencies. The slab
is placed between two mirrors to select Bloch standing waves and a
subwavelength spherical scatterer is scanned inside the resulting resonator.
The resonant Bloch frequencies shift depending on the electric field at the
position of the scatterer. To map the electric field component Ez we measure
the frequency shift in the reflection and transmission spectrum of the slab
versus the scatterer position. Very good agreement is found between
measurements and calculations without any adjustable parameters.Comment: 12 pages, 7 figure
Note on the monodromy conjecture for a space monomial curve with a plane semigroup
Roughly speaking, the monodromy conjecture for a singularity states that every pole of its motivic Igusa zeta function induces an eigenvalue of its monodromy. In this note, we determine both the motivic Igusa zeta function and the eigenvalues of monodromy for a space monomial curve that appears as the special fiber of an equisingular family whose generic fiber is a plane branch. In particular, this yields a proof of the monodromy conjecture for such a curve.
En gros, la conjecture de la monodromie pour une singularité dit que chaque pôle de sa fonction zêta d’Igusa motivique induit une valeur propre de sa monodromie. Dans cette note, nous déterminons la fonction zêta d’Igusa motivique ainsi que les valeurs propres de la monodromie pour une courbe d’espace monomiale qui apparaît comme fibre spéciale d’une famille équisingulière dont la fibre générique est une branche plane. En particulier, il en résulte une démonstration de la conjecture de la monodromie pour une telle courb
Recent Developments and Practical Feasibility of Polymer-Based Antifouling Coatings
While nature has optimized its antifouling strategies over millions of years, synthetic antifouling coatings have not yet reached technological maturity. For an antifouling coating to become technically feasible, it should fulfill many requirements: high effectiveness, long-term stability, durability, ecofriendliness, large-scale applicability, and more. It is therefore not surprising that the search for the perfect antifouling coating has been going on for decades. With the discovery of metal-based antifouling paints in the 1970s, fouling was thought to be a problem of the past, yet its untargeted toxicity led to serious ecological concern, and its use became prohibited. As a response, research shifted focus toward a biocompatible alternative: polymer-based antifouling coatings. This has resulted in numerous advanced and innovative antifouling strategies, including fouling-resistant, fouling-release, and fouling-degrading coatings. Here, these novel and exciting discoveries are highlighted while simultaneously assessing their antifouling performance and practical feasibility
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