10,464 research outputs found
Study of direct CP violation for decay in Perturbative QCD
We investigate the direct CP violation for the charmless three-body decay
process of . The mechanisms of ,
and mixing are considered in perturbative QCD
approach. Isospin symmetry breaking from the decays of and are known to be tiny. However, we
find the direct CP violation of the decay processes of
and
can reach and
from isospin symmetry breaking, respectively. To better compare with
experimental data in the future, the localized integrated direct CP violation
of the decay processes are presented. The mechanism can provide a new way to
explore CP violation from the three-body decay processes of meson for the
LHC experiment.Comment: arXiv admin note: text overlap with arXiv:2201.0238
Interacting agegraphic tachyon model of dark energy
Scalar-field dark energy models like tachyon are often regarded as an
effective description of an underlying theory of dark energy. In this Letter,
we implement the interacting agegraphic dark energy models with tachyon field.
We demonstrate that the interacting agegraphic evolution of the universe can be
described completely by a single tachyon scalar field. We thus reconstruct the
potential as well as the dynamics of the tachyon field according to the
evolutionary behavior of interacting agegraphic dark energy.Comment: 11 pages, to appear in Phys. Lett.
Thermally activated and aggregation-regulated excitonic coupling enable emissive high-lying triplet excitons
Funding: Horizon 2020 Framework Programme (Grant Number(s): 897098; Grant recipient(s): Tao Wang, Eli Zysman-Colman); Horizon 2020 Framework Programme (Grant Number(s): 101025143; Grant recipient(s): Eli Zysman-Colman, Joydip De); Engineering and Physical Sciences Research Council (Grant Number(s): EP/P010482/1; Grant recipient(s): Eli Zysman-Colman); Royal Society (Grant Number(s): SRF\R1\201089; Grant recipient(s): Abhishek Kumar Gupta, Eli Zysman-Colman); China Scholarship Council (GrantNumber(s): 201906250199; Grant recipient(s): Sen Wu)Room-temperature phosphorescence (RTP) originating from higher-lying triplet excitons remains a rather rarely documented occurrence for purely organic molecular systems. Here, we report two naphthalene-based RTP luminophores whose phosphorescence emission is enabled by radiative decay of high-lying triplet excitons. In contrast, upon cooling the dominant phosphorescence originates from the lowest-lying triplet excited state, which is manifested by a red-shifted emission. Photophysical and theoretical studies reveal that the unusual RTP results from thermally activated excitonic coupling between different conformations of the compounds. Aggregation-regulated excitonic coupling is observed when increasing the doping concentration of the emitters in poly(methylmethacrylate) (PMMA). Further, the RTP quantum efficiency improves more than 80-fold in 1,3-bis(N-carbazolyl)benzene (mCP) compared to that in PMMA. This design principle offers important insight into triplet excited state dynamics and has been exploited in afterglow-indicating temperature sensing.Publisher PDFPeer reviewe
Adaptive low-level control of autonomous underwater vehicles using deep reinforcement learning
Low-level control of autonomous underwater vehicles (AUVs) has been extensively addressed by classical control techniques. However, the variable operating conditions and hostile environments faced by AUVs have driven researchers towards the formulation of adaptive control approaches. The reinforcement learning (RL) paradigm is a powerful framework which has been applied in different formulations of adaptive control strategies for AUVs. However, the limitations of RL approaches have lead towards the emergence of deep reinforcement learning which has become an attractive and promising framework for developing real adaptive control strategies to solve complex control problems for autonomous systems. However, most of the existing applications of deep RL use video images to train the decision making artificial agent but obtaining camera images only for an AUV control purpose could be costly in terms of energy consumption. Moreover, the rewards are not easily obtained directly from the video frames. In this work we develop a deep RL framework for adaptive control applications of AUVs based on an actor-critic goal-oriented deep RL architecture, which takes the available raw sensory information as input and as output the continuous control actions which are the low-level commands for the AUV's thrusters. Experiments on a real AUV demonstrate the applicability of the stated deep RL approach for an autonomous robot control problem.Fil: Carlucho, Ignacio. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; ArgentinaFil: de Paula, Mariano. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; ArgentinaFil: Wang, Sen. Heriot-Watt University; Reino UnidoFil: Petillot, Yvan. Heriot-Watt University; Reino UnidoFil: Acosta, Gerardo Gabriel. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires. - Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires; Argentin
Decay of Unstable D-branes with Electric Field
Using the techniques of two dimensional conformal field theory we construct
time dependent classical solutions in open string theory describing the decay
of an unstable D-brane in the presence of background electric field, and
explicitly evaluate the time dependence of the energy momentum tensor and the
fundamental string charge density associated with this solution. The final
decay product can be interpreted as a combination of stretched fundamental
strings and tachyon matter.Comment: 35 pages, LaTe
Improved Feature Distillation via Projector Ensemble
In knowledge distillation, previous feature distillation methods mainly focus
on the design of loss functions and the selection of the distilled layers,
while the effect of the feature projector between the student and the teacher
remains under-explored. In this paper, we first discuss a plausible mechanism
of the projector with empirical evidence and then propose a new feature
distillation method based on a projector ensemble for further performance
improvement. We observe that the student network benefits from a projector even
if the feature dimensions of the student and the teacher are the same. Training
a student backbone without a projector can be considered as a multi-task
learning process, namely achieving discriminative feature extraction for
classification and feature matching between the student and the teacher for
distillation at the same time. We hypothesize and empirically verify that
without a projector, the student network tends to overfit the teacher's feature
distributions despite having different architecture and weights initialization.
This leads to degradation on the quality of the student's deep features that
are eventually used in classification. Adding a projector, on the other hand,
disentangles the two learning tasks and helps the student network to focus
better on the main feature extraction task while still being able to utilize
teacher features as a guidance through the projector. Motivated by the positive
effect of the projector in feature distillation, we propose an ensemble of
projectors to further improve the quality of student features. Experimental
results on different datasets with a series of teacher-student pairs illustrate
the effectiveness of the proposed method
RADIATE: A Radar Dataset for Automotive Perception in Bad Weather
Datasets for autonomous cars are essential for the development and
benchmarking of perception systems. However, most existing datasets are
captured with camera and LiDAR sensors in good weather conditions. In this
paper, we present the RAdar Dataset In Adverse weaThEr (RADIATE), aiming to
facilitate research on object detection, tracking and scene understanding using
radar sensing for safe autonomous driving. RADIATE includes 3 hours of
annotated radar images with more than 200K labelled road actors in total, on
average about 4.6 instances per radar image. It covers 8 different categories
of actors in a variety of weather conditions (e.g., sun, night, rain, fog and
snow) and driving scenarios (e.g., parked, urban, motorway and suburban),
representing different levels of challenge. To the best of our knowledge, this
is the first public radar dataset which provides high-resolution radar images
on public roads with a large amount of road actors labelled. The data collected
in adverse weather, e.g., fog and snowfall, is unique. Some baseline results of
radar based object detection and recognition are given to show that the use of
radar data is promising for automotive applications in bad weather, where
vision and LiDAR can fail. RADIATE also has stereo images, 32-channel LiDAR and
GPS data, directed at other applications such as sensor fusion, localisation
and mapping. The public dataset can be accessed at
http://pro.hw.ac.uk/radiate/.Comment: Accepted at IEEE International Conference on Robotics and Automation
2021 (ICRA 2021
New holographic scalar field models of dark energy in non-flat universe
Motivated by the work of Granda and Oliveros [L.N. Granda, A. Oliveros, Phys.
Lett. B {\bf 671}, 199 (2009)], we generalize their work to the non-flat case.
We study the correspondence between the quintessence, tachyon, K-essence and
dilaton scalar field models with the new holographic dark energy model in the
non-flat FRW universe. We reconstruct the potentials and the dynamics for these
scalar field models, which describe accelerated expansion of the universe. In
the limiting case of a flat universe, i.e. , all results given in [L.N.
Granda, A. Oliveros, Phys. Lett. B {\bf 671}, 199 (2009)] are obtained.Comment: 11 page
BPS States, Refined Indices, and Quiver Invariants
For D=4 BPS state construction, counting, and wall-crossing thereof, quiver
quantum mechanics offers two alternative approaches, the Coulomb phase and the
Higgs phase, which sometimes produce inequivalent counting. The authors have
proposed, in arXiv:1205.6511, two conjectures on the precise relationship
between the two, with some supporting evidences. Higgs phase ground states are
naturally divided into the Intrinsic Higgs sector, which is insensitive to
wall-crossings and thus an invariant of quiver, plus a pulled-back ambient
cohomology, conjectured to be an one-to-one image of Coulomb phase ground
states. In this note, we show that these conjectures hold for all cyclic
quivers with Abelian nodes, and further explore angular momentum and R-charge
content of individual states. Along the way, we clarify how the protected spin
character of BPS states should be computed in the Higgs phase, and further
determine the entire Hodge structure of the Higgs phase cohomology. This shows
that, while the Coulomb phase states are classified by angular momentum, the
Intrinsic Higgs states are classified by R-symmetry.Comment: 51 pages, 5 figure
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