36,076 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
Single-photon transport in a one dimentional waveguide coupling to a hybrid atom-optomechanical system
We explore theoretically the single-photon transport in a single-mode
waveguide that is coupled to a hybrid atom-optomechanical system in a strong
optomechanical coupling regime. Using a full quantum real-space approach,
transmission and reflection coefficients of the propagating single-photon in
the waveguide are ob- tained. The influences of atom-cavity detuning and the
dissipation of atom on the transport are also studied. Intriguingly, the
obtained spectral features can reveal the strong light-matter interaction in
this hybrid system.Comment: 7pages, 8figure
Multi anticipative bidirectional macroscopic traffic model considering cooperative driving strategy
Recent development of information and communication technologies (ICT) has enabled vehicles to timely communicate with others through wireless technologies, which will form future (intelligent) traffic systems (ITS) consisting of so-called connected vehicles. Cooperative driving with the connected vehicles is regarded as a promising driving pattern to significantly improve transportation efficiency and traffic safety. In the vast literature of traffic flow theory, there are continuum models considering multiple forward anticipative strategy, where the driver reacts to many leaders. Few study effort has been undertaken to include bidirectional driving strategy, where the driver reacts to both direct leader and direct follower, in the continuum traffic flow models. This paper aims to derive a continuum traffic model considering both multiple forward and backward driving strategy. It is shown that the derived model is a generalised version of a current continuum model for ITS and can improve important properties of such bidirectional (continuum) model
Mobility: a double-edged sword for HSPA networks
This paper presents an empirical study on the performance of mobile High Speed Packet Access (HSPA, a 3.5G cellular standard) networks in Hong Kong via extensive field tests. Our study, from the viewpoint of end users, covers virtually all possible mobile scenarios in urban areas, including subways, trains, off-shore ferries and city buses. We have confirmed that mobility has largely negative impacts on the performance of HSPA networks, as fast-changing wireless environment causes serious service deterioration or even interruption. Meanwhile our field experiment results have shown unexpected new findings and thereby exposed new features of the mobile HSPA networks, which contradict commonly held views. We surprisingly find out that mobility can improve fairness of bandwidth sharing among users and traffic flows. Also the triggering and final results of handoffs in mobile HSPA networks are unpredictable and often inappropriate, thus calling for fast reacting fallover mechanisms. We have conducted in-depth research to furnish detailed analysis and explanations to what we have observed. We conclude that mobility is a double-edged sword for HSPA networks. To the best of our knowledge, this is the first public report on a large scale empirical study on the performance of commercial mobile HSPA networks
Probing viscoelastic properties of a thin polymer film sheared between a beads layer and quartz crystal resonator
We report measurements of viscoelastic properties of thin polymer films of
10-100 nm at the MHz range. These thin films are confined between a quartz
crystal resonator and a millimetric bead layer, producing an increase of both
resonance frequency and dissipation of the quartz resonator. The shear modulus
and dynamic viscosity of thin films extracted from these measurements are
consistent with the bulk values of the polymer. This modified quartz resonator
provides an easily realizable and effective tool for probing the rheological
properties of thin films at ambient environment.Comment: submitted to ap
- …