14,074 research outputs found
Photonic crystal nanofiber using an external grating
We implement a photonic crystal nanofiber device by reversibly combining an
optical nanofiber and a nanofabricated grating. Using the finite-difference
time-domain method, we design the system for minimal optical loss while
tailoring the resonant wavelength and bandwidth of the device. Experimentally
we demonstrate that the combined system shows a strong photonic stop-band in
good agreement with numerical predictions. The resulting device may be used to
realize strong light-matter coupling near to the nanofiber surface
Study of dynamical charge fluctuations in the hadronic medium
The dynamical charge fluctuations have been studied in ultra-relativistic
heavy-ion collisions by using hadronic model simulations, such as UrQMD and
HIJING. The evolution of fluctuations has been calculated at different time
steps during the collision as well as different observation window in
pseudorapidity (\DelEta). The final state effects on the fluctuations have been
investigated by varying ~ and the time steps with the aim
of obtaining an optimum observation window for capturing maximum fluctuations.
It is found that ~ between 2.0 and 3.5 gives the best
coverage for the fluctuations studies. The results of these model calculations
for Au+Au collisions at ~=~7.7 to 200~GeV and for Pb+Pb
collisions at 2.76 TeV are presented and compared with available experimental
data from the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron
Collider (LHC).Comment: 6 pages, 4 Figure
Standard Coupling Unification in SO(10), Hybrid Seesaw Neutrino Mass and Leptogenesis, Dark Matter, and Proton Lifetime Predictions
We discuss gauge coupling unification of the SM descending directly from
SO(10) while providing solutions to the three outstanding problems: neutrino
masses, dark matter, and the baryon asymmetry of the universe. Conservation of
matter parity as gauged discrete symmetry in the model calls for high-scale
spontaneous symmetry breaking through Higgs representation. This
naturally leads to the hybrid seesaw formula for neutrino masses mediated by
heavy scalar triplet and right-handed neutrinos. The seesaw formula predicts
two distinct patterns of RH masses, one hierarchical and another not so
hierarchical (or compact) when fitted with the neutrino oscillation data.
Predictions of the baryon asymmetry via leptogenesis are investigated through
the decays of both the patterns of RH masses. A complete flavor analysis
has been carried out to compute CP-asymmetries and solutions to Boltzmann
equations have been utilized to predict the baryon asymmetry. The additional
contribution to vertex correction mediated by the heavy left-handed triplet
scalar is noted to contribute as dominantly as other Feynman diagrams. We have
found successful predictions of the baryon asymmetry for both the patterns of
RH masses. The triplet fermionic dark matter at the TeV scale carrying
even matter parity is naturally embedded into the non-standard fermionic
representation of SO(10). In addition to the triplet scalar and the
triplet fermion, the model needs a nonstandard color octet fermion of mass
GeV to achieve precision gauge coupling unification. Threshold
corrections due to superheavy components of and other representations
are estimated and found to be substantial. It is noted that the proton life
time predicted by the model is accessible to the ongoing and planned
experiments over a wide range of parameter space.Comment: 58 pages PDFLATEX, 19 Figures, Revised as suggested by JHEP Revie
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R-PEKS: RBAC Enabled PEKS for Secure Access of Cloud Data
In the recent past, few works have been done by combining attribute-based access control with multi-user PEKS, i.e., public key encryption with keyword search. Such attribute enabled searchable encryption is most suitable for applications where the changing of privileges is done once in a while. However, to date, no efficient and secure scheme is available in the literature that is suitable for these applications where changing privileges are done frequently. In this paper our contributions are twofold. Firstly, we propose a new PEKS scheme for string search, which, unlike the previous constructions, is free from bi-linear mapping and is efficient by 97% compared to PEKS for string search proposed by Ray et.al in TrustCom 2017. Secondly, we introduce role based access control (RBAC) to multi-user PEKS, where an arbitrary group of users can search and access the encrypted files depending upon roles. We termed this integrated scheme as R-PEKS. The efficiency of R-PEKS over the PEKS scheme is up to 90%. We provide formal security proofs for the different components of R-PEKS and validate these schemes using a commercial dataset
Direct measurements of the magnetocaloric effect in pulsed magnetic fields: The example of the Heusler alloy NiMnIn
We have studied the magnetocaloric effect (MCE) in the shape-memory Heusler
alloy NiMnIn by direct measurements in pulsed magnetic
fields up to 6 and 20 T. The results in 6 T are compared with data obtained
from heat-capacity experiments. We find a saturation of the inverse MCE,
related to the first-order martensitic transition, with a maximum adiabatic
temperature change of K at 250 K and a conventional
field-dependent MCE near the second-order ferromagnetic transition in the
austenitic phase. The pulsed magnetic field data allow for an analysis of the
temperature response of the sample to the magnetic field on a time scale of
to 100 ms which is on the order of typical operation frequencies (10
to 100 Hz) of magnetocaloric cooling devices. Our results disclose that in
shape-memory alloys the different contributions to the MCE and hysteresis
effects around the martensitic transition have to be carefully considered for
future cooling applications.Comment: 5 pages, 4 figure
Broken-symmetry-adapted Green function theory of condensed matter systems:towards a vector spin-density-functional theory
The group theory framework developed by Fukutome for a systematic analysis of
the various broken symmetry types of Hartree-Fock solutions exhibiting spin
structures is here extended to the general many body context using spinor-Green
function formalism for describing magnetic systems. Consequences of this theory
are discussed for examining the magnetism of itinerant electrons in nanometric
systems of current interest as well as bulk systems where a vector spin-density
form is required, by specializing our work to spin-density-functional
formalism. We also formulate the linear response theory for such a system and
compare and contrast them with the recent results obtained for localized
electron systems. The various phenomenological treatments of itinerant magnetic
systems are here unified in this group-theoretical description.Comment: 17 page
New mechanism for Type-II seesaw dominance in SO(10) with low-mass Z-prime, RH neutrinos, and verifiable LFV, LNV, and proton decay
Dominance of type-II seesaw mechanism for neutrino masses has attracted
considerable attention because of a number of advantages. We show a novel
approach to achieve Type-II seesaw dominance in non-supersymmetric
grand unification where a low mass boson and specific patterns of
right-handed neutrino masses are predicted within the accessible energy range
of the Large Hadron Collider. In spite of the high value of the seesaw scale,
GeV, the model predicts new dominant
contributions to neutrino-less double beta decay in the channel close
to the current experimental limits via exchanges of heavier singlet fermions
used as essential ingredients of this model even when the light active neutrino
masses are normally hierarchical or invertedly hierarchical. We obtain upper
bounds on the lightest sterile neutrino mass GeV, GeV,
and GeV for normally hierarchical, invertedly hierarchical, and
quasi-degenerate patterns of light neutrino masses, respectively. The
underlying non-unitarity effects lead to lepton flavor violating decay
branching ratios within the reach of ongoing or planned experiments and the
leptonic CP-violation parameter nearly two orders larger than the quark sector.
Some of the predicted values on proton lifetime for are found
to be within the currently accessible search limits. Other aspects of model
applications including leptogenesis etc. are briefly indicated.Comment: 44 pages, 16 figures, hep-ph, hep-ex.Section 8 on leptogenesis added;
figures and references adde
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