23,586 research outputs found
Strange-Beauty Meson Production at Colliders
The production rates and transverse momentum distributions of the
strange-beauty mesons and at colliders are calculated
assuming fragmentation is the dominant process. Results are given for the
Tevatron in the large transverse momentum region, where fragmentation is
expected to be most important.Comment: Minor changes in the discussion section. Also available at
http://www.ph.utexas.edu/~cheung/paper.htm
Higgs Descendants
We define a Higgs descendant to be a particle beyond the standard
model whose mass arises predominantly from the vacuum expectation value of the
Higgs boson. Higgs descendants arise naturally from new physics whose intrinsic
mass scale is unrelated to the electroweak scale. The coupling of to the
Higgs boson is fixed by the mass and spin of , yielding a highly
predictive setup in which there may be substantial modifications to the
properties of the Higgs boson. For example, if the decay of the Higgs boson to
is kinematically allowed, then this branching ratio is largely
determined. Depending on the stability of , Higgs decays may result in a
variety of possible visible or invisible final states. Alternatively, loops of
may affect Higgs boson production or its decays to standard model
particles. If is stable dark matter, then the mandatory coupling between
and the Higgs boson gives a lower bound on the direct detection cross
section as a function of the mass. We also present a number of explicit
models which are examples of Higgs descendants. Finally, we comment on Higgs
descendants in the context of the excesses near 125 GeV recently observed at
ATLAS and CMS.Comment: 9 pages, 7 figures; version to appear in Phys. Rev. D; v3 typos
correcte
Long decoding runs for Galileo's convolutional codes
Decoding results are described for long decoding runs of Galileo's convolutional codes. A 1 k-bit/sec hardware Viterbi decoder is used for the (15, 1/4) convolutional code, and a software Viterbi decoder is used for the (7, 1/2) convolutional code. The output data of these long runs are stored in data files using a data compression format which can reduce file size by a factor of 100 to 1 typically. These data files can be used to replicate the long, time-consuming runs exactly and are useful to anyone who wants to analyze the burst statistics of the Viterbi decoders. The 1 k-bit/sec hardware Viterbi decoder was developed in order to demonstrate the correctness of certain algorithmic concepts for decoding Galileo's experimental (15, 1/4) code, and for the long-constraint-length codes in general. The hardware decoder can be used both to search for good codes and to measure accurately the performance of known codes
Further results on finite-state codes
A general construction for finite-state (FS) codes is applied to some well-known block codes. Subcodes of the (24,12) Golay code are used to generate two optimal FS codes with d sub free = 12 and 16. A partition of the (16,8) Nordstrom-Robinson code yields a d sub free = 10 FS code. Simulation results are shown and decoding algorithms are briefly discussed
Bony metastases from breast cancer: a study of foetal antigen 2 as a blood tumour marker.
Background : Foetal antigen 2 (FA-2), first isolated in the amniotic fluid, was shown to be the circulating form of the aminopropeptide of the alpha 1 chain of procollagen type I. Serum concentrations of FA-2 appeared to be elevated in a number of disorders of bone metabolism. This paper is the first report of its role as a marker of bone metabolism in metastatic breast cancer.
Methods: Serum FA-2 concentrations were measured by radioimmunoassay in 153 women with different stages of breast cancer and in 34 normal controls.
Results: Serum FA-2 was significantly elevated in women with bony metastases (p < 0.015). Its levels were not significantly different among women with non-bony metastases, with non-metastatic disease, as well as among normal controls.
Conclusions: FA-2 is a promising blood marker of bone metabolism. Further studies to delineate its role in the diagnosis and management of bony metastases from breast cancer are required
Free vibration of a three-layered sandwich beam using the dynamic stiffness method and experiment
In this paper, an accurate dynamic stiffness model for a three-layered sandwich
beam of unequal thicknesses is developed and subsequently used to investigate
its free vibration characteristics. Each layer of the beam is idealised by the
Timoshenko beam theory and the combined system is reduced to a tenth-order
system using symbolic computation. An exact dynamic stiffness matrix is then
developed by relating amplitudes of harmonically varying loads to those of the
responses. The resulting dynamic stiffness matrix is used with particular
reference to the Wittrick-Williams algorithm to carry out the free vibration
analysis of a few illustrative examples. The accuracy of the theory is confirmed
both by published literature and by experiment. The paper closes with some
concluding remarks. (c) 2007 Elsevier Ltd. All rights reserved
The effects of machining process variables and tooling characterisation on the surface generation: modelling, simulation and application promise
The paper presents a novel approach for modelling and simulation of the surface generation in the machining process. The approach, by integrating dynamic cutting force model, regenerative vibration model, machining system response model and tool profile model, models the complex surface generation process. Matlab Simulink is used to interactively perform the simulation in a user-friendly, effective and efficient manner. The effects of machining variables and tooling characteristics on the surface generation are investigated through simulations. CNC turning trials have been carried out to evaluate and validate the approach and simulations presented. The proposed approach contributes to comprehensive and better understanding of the machining system, and is promising for industrial applications with particular reference to the optimisation of the machining process based on the product/component surface functionality requirements
Large Extra Dimensions at Linear Colliders
In this talk, I first present the motivation for theories wherein extra
spacetime dimensions can be compactified to have large magnitudes. In
particular, I discuss the Arkani-Hamed, Dimopoulos, Dvali (ADD) scenario. I
present the constraints that have been derived on these models from current
experiments and the expectations from future colliders. I concentrate
particularly on the possibilities of probing these extra dimensions at future
linear colliders.Comment: Talk given at the Third International Workshop on Electron-Electron
Interactions at TeV Energies (e- e- 99), Santa Cruz, California, 10-12 Dec
1999. 7 pages, LaTeX, style files attache
Group velocity of discrete-time quantum walks
We show that certain types of quantum walks can be modeled as waves that propagate in a medium with phase and group velocities that are explicitly calculable. Since the group and phase velocities indicate how fast wave packets can propagate causally, we propose the use of these wave velocities in our definition for the hitting time of quantum walks. Our definition of hitting time has the advantage that it requires neither the specification of a walker's initial condition nor of an arrival probability threshold. We give full details for the case of quantum walks on the Cayley graphs of Abelian groups. This includes the special cases of quantum walks on the line and on hypercubes
- âŠ