4,184 research outputs found
Spontaneous mass generation and the small dimensions of the Standard Model gauge groups U(1), SU(2) and SU(3)
The gauge symmetry of the Standard Model is SU(3)_c x SU(2)_L x U(1)_Y for
unknown reasons. One aspect that can be addressed is the low dimensionality of
all its subgroups. Why not much larger groups like SU(7), or for that matter,
SP(38) or E7? We observe that fermions charged under large groups acquire much
bigger dynamical masses, all things being equal at a high e.g. GUT scale, than
ordinary quarks. Should such multicharged fermions exist, they are too heavy to
be observed today and have either decayed early on (if they couple to the rest
of the Standard Model) or become reliquial dark matter (if they don't). The
result follows from strong antiscreening of the running coupling for those
larger groups (with an appropriately small number of flavors) together with
scaling properties of the Dyson-Schwinger equation for the fermion mass.Comment: 15 pages, 17 plots. This version incorporates community as well as
referee comments. Accepted for publication in Nuclear Physics
Portable Multi-Hypothesis Monte Carlo Localization for Mobile Robots
Self-localization is a fundamental capability that mobile robot navigation
systems integrate to move from one point to another using a map. Thus, any
enhancement in localization accuracy is crucial to perform delicate dexterity
tasks. This paper describes a new location that maintains several populations
of particles using the Monte Carlo Localization (MCL) algorithm, always
choosing the best one as the sytems's output. As novelties, our work includes a
multi-scale match matching algorithm to create new MCL populations and a metric
to determine the most reliable. It also contributes the state-of-the-art
implementations, enhancing recovery times from erroneous estimates or unknown
initial positions. The proposed method is evaluated in ROS2 in a module fully
integrated with Nav2 and compared with the current state-of-the-art Adaptive
ACML solution, obtaining good accuracy and recovery times.Comment: Submission for ICRA 202
Active Islanding Detection for Multiple Parallel-Connected Inverter-Based Distributed Generators Using High-Frequency Signal Injection
Rotating black holes in Eddington-inspired Born-Infeld gravity: an exact solution
We find an exact, rotating charged black hole solution within
Eddington-inspired Born-Infeld gravity. To this end we employ a recently
developed correspondence or {\it mapping} between modified gravity models built
as scalars out of contractions of the metric with the Ricci tensor, and
formulated in metric-affine spaces (Ricci-Based Gravity theories) and General
Relativity. This way, starting from the Kerr-Newman solution, we show that this
mapping bring us the axisymmetric solutions of Eddington-inspired Born-Infeld
gravity coupled to a certain model of non-linear electrodynamics. We discuss
the most relevant physical features of the solutions obtained this way, both in
the spherically symmetric limit and in the fully rotating regime. Moreover, we
further elaborate on the potential impact of this important technical progress
for bringing closer the predictions of modified gravity with the astrophysical
observations of compact objects and gravitational wave astronomy.Comment: 17 double column pages, 7 figures, revtex4-1 styl
Finite-gain-current repetitive controller for synchronverters with harmonic-sharing capabilities
FUSE Observations of Nebular O VI Emission from NGC 6543
NGC 6543 is one of the few planetary nebulae (PNe) whose X-ray emission has
been shown to be extended and originate from hot interior gas. Using FUSE
observations we have now detected nebular O VI emission from NGC 6543. Its
central star, with an effective temperature of ~50,000 K, is too cool to
photoionize O V, so the O VI ions must have been produced by thermal collisions
at the interface between the hot interior gas and the cool nebular shell. We
modeled the O VI emission incorporating thermal conduction, but find that
simplistic assumptions for the AGB and fast wind mass loss rates overproduce
X-ray emission and O VI emission. We have therefore adopted the pressure of the
interior hot gas for the interface layer and find that expected O VI emission
to be comparable to the observations.Comment: 4 pages, 4 figures, 1 table, using emulateapj.cls style. Accepted for
publication in ApJ Letter
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