78,877 research outputs found
Which hadronic decay modes are good for searching: double or something else?
It has been controversial whether can be discovered in Tevatron Run
2 through the decay followed by . We clear this controversy by an explicit calculation which
predicts to be of order . It is
concluded that observing eta_b through this decay mode in Tevatron Run 2 is
rather unrealistic. The eta_b may be observed in the forthcoming LHC
experiments through the 4-lepton channel, if the background events can be
significantly reduced by imposing some kinematical cuts. By some rough but
plausible considerations, we find that the analogous decay processes eta_b to
VV, D^*\bar{D}^* also have very suppressed branching ratios, nevertheless it
may be worth looking for \eta_b at LHC and Super B factory through the decay
modes \eta_b \to K_S K^{\pm}\pi^{\mp}, D^*\bar{D}.Comment: v2; 28 pages, 2 figures. References added, presentation improved.
Discussion on possible nonperturbative mechanism for eta_b->VV added,
analysis for eta_b->VP updated by incoprating the U-spin violation effec
Designing a Robotic Platform for Investigating Swarm Robotics
This paper documents the design and subsequent construction of a low-cost, flexible robotic platform for swarm robotics research, and the selection of appropriate swarm algorithms for the implementation of a swarm focused predominantly on target location. The design described herein is intended to allow for the construction of robots large enough to meaningfully interact with their environment while maintaining a low per-robot cost of materials and a low assembly time. The design process is separated into three stages: mechanical design, electrical design, and software design. All major design components are described in detail under the appropriate design section. The BOM for a single robot is also included, along with relevant testing information
Influence of cross-sectional shape on flow patterns in an open-channel confluence
The state-of-the-art hydrodynamic knowledge on schematized open-channel confluences is largely based on laboratory experiments in channels with a rectangular cross-section. Since in practice man-made canals often have a nonrectangular cross-section, the question can be raised to which extent the knowledge on open-channel confluences still holds for confluences of that type of canals. Therefore, this paper examines the influence of three cross-sectional shapes on the flow patterns in an asymmetric 90° open-channel confluence with fixed concordant bed and subcritical flows throughout. Large-eddy simulations are performed for a rectangular, a chamfered rectangular and a trapezoidal section. The simulations for the non-rectangular sections show that the location of both the mixing layer between the incoming flows and the shear layer between the separation zone and the contracted section are altered in comparison to the rectangular section case. Also the evolution of the separation zone is found to be different. It is demonstrated that the distribution of incoming momentum and the shape of the confluence corners are primary causes of the observed deviations
Semi-automated detection of surface degradation on bridges based on a level set method
Due to the effect of climate factors, natural phenomena and human usage, buildings and infrastructures are subject of progressive degradation. The deterioration of these structures has to be monitored in order to avoid hazards for human beings and for the natural environment in their neighborhood. Hence, on the one hand, monitoring such infrastructures is of primarily importance. On the other hand, unfortunately, nowadays this monitoring effort is mostly done by expert and skilled personnel, which follow the overall data acquisition, analysis and result reporting process, making the whole monitoring procedure quite expensive for the public (and private, as well) agencies. This paper proposes the use of a partially user-assisted procedure in order to reduce the monitoring cost and to make the obtained result less subjective as well. The developed method relies on the use of images acquired with standard cameras by even inexperienced personnel. The deterioration on the infrastructure surface is detected by image segmentation based on a level sets method. The results of the semi-automated analysis procedure are remapped on a 3D model of the infrastructure obtained by means of a terrestrial laser scanning acquisition. The proposed method has been successfully tested on a portion of a road bridge in Perarolo di Cadore (BL), Italy
3D Model Assisted Image Segmentation
The problem of segmenting a given image into coherent regions is important in Computer Vision and many industrial applications require segmenting a known object into its components. Examples include identifying individual parts of a component for proces
Bounds and Prospects for Stable Multiply Charged Particles at the LHC
Colored and colorless particles that are stable on collider scales and carry
exotic electric charges, so-called multiply-charged heavy stable particles
(MCHSPs), exist in extensions of the Standard Model, and can include the top
partner(s) in solutions of the hierarchy problem. To obtain bounds on
color-triplets and color-singlets of charges up to |Q|=8, we recast searches
for signatures of two production channels: the "open" channel - where the
particles are pair-produced above threshold, and are detectable in dedicated
LHC searches for stable multiply charged leptons, and the "closed" channel -
where a particle-antiparticle pair is produced as a bound state, detectable in
searches for a diphoton resonance. We recast the open lepton searches by
incorporating the relevant strong-interaction effects for color-triplets. In
both open and closed production, we provide a careful assessment of
photon-induced processes using the accurate LUXqed PDF, resulting in
substantially weaker bounds than previously claimed in the literature for the
colorless case. Our bounds for colored MCHSPs are shown for the first time, as
the LHC experiments have not searched for them directly. Generally, we obtain
nearly charge-independent lower mass limits of around 970 GeV (color-triplet
scalar), 1200 GeV (color-triplet fermion), and 880 - 900 GeV (color-singlet
fermion) from open production, and strongly charge-dependent limits from closed
production. In all cases there is a crossover between dominance by open and
closed searches at some charge. We provide prospective bounds for TeV LHC searches at integrated luminosities of 39.5 fb, 100
fb, and 300 fb. Moreover, we show that a joint observation in
the open and the closed channels allows to determine the mass, spin, color, and
electric charge of the particle
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