15,974 research outputs found
Pentaquark Searches at CDF
Recently there has been revival of interest in exotic baryon spectroscopy
triggered by experimental evidence for pentaquarks containing u,d,s and
c-quarks. We report results of the searches for pentaquark states in decays to
p K0S, Xi- pi+,- and D*- p performed at CDF detector using 220 pb-1 sample of
pp= interactions at sqrt(s) of 1.96 TeV. No evidence for narrow resonances were
found in either mode.Comment: Presented at 6th International Conference on Hyperons, Charm and
Beauty Hadrons (BEACH 2004), Chicago, Illinois, 27 Jun - 3 Jul 200
Light pseudoscalar eta and H->eta eta decay in the simplest little Higgs mode
The SU(3) simplest little Higgs model in its original framework without the
so-called mu term inevitably involves a massless pseudoscalar boson eta, which
is problematic for b-physics and cosmological axion limit. With the mu term
introduced by hand, the eta boson acquires mass m_eta ~ mu, which can be
lighter than half the Higgs boson mass in a large portion of the parameter
space. In addition, the introduced mu term generates sizable coupling of
H-eta-eta. The Higgs boson can dominantly decay into a pair of eta's especially
when mH below the WW threshold. Another new decay channel of H->Z+eta can be
dominant or compatible with H -> WW for mH above the Z+eta threshold. We show
that the LEP bound on the Higgs boson mass is loosened to some extent due to
this new H->eta eta decay channel as well as the reduced coupling of H-Z-Z. The
Higgs boson mass bound falls to about 110 GeV for f=3-4 TeV. Since the eta
boson decays mainly into a bb pair, H-> eta eta -> 4b and H-> Z eta -> Z bb
open up other interesting search channels in the pursuit of the Higgs boson in
the future experiments. We discuss on these issues.Comment: major modification considering the simplest little Higgs model with
the mu ter
Quantization effects in Viterbi decoding rate 1/n convolutional codes
A Viterbi decoder's performance loss due to quantizing data from the additive white Gaussian noise (AWGN) channel is studied. An optimal quantization scheme and branch metric calculation method are presented. The uniformly quantized channel capacity C(sub u)(q) is used to determine the smallest number of quantization bits q that does not cause a significant loss. The quantizer stepsize which maximizes C(sub u)(q) almost minimizes the decoder bit error rate (BER). However, a slightly larger stepsize is better, like the value that minimizes the Bhattacharyya bound. The range and renormalization of state metrics is analyzed, in particular for K = 15 decoders such as the Big Viterbi Decoder (BVD) for the Galileo mission. These results are required to design reduced hardware complexity Viterbi decoders with a negligible quantization loss
Optimal combined word-length allocation and architectural synthesis of digital signal processing circuits
Published versio
A simplified model of the source channel of the Leksell Gamma Knife: testing multisource configurations with PENELOPE
A simplification of the source channel geometry of the Leksell Gamma
Knife, recently proposed by the authors and checked for a single
source configuration (Al-Dweri et al 2004), has been used to calculate the dose
distributions along the , and axes in a water phantom with a
diameter of 160~mm, for different configurations of the Gamma Knife including
201, 150 and 102 unplugged sources. The code PENELOPE (v. 2001) has been used
to perform the Monte Carlo simulations. In addition, the output factors for the
14, 8 and 4~mm helmets have been calculated. The results found for the dose
profiles show a qualitatively good agreement with previous ones obtained with
EGS4 and PENELOPE (v. 2000) codes and with the predictions of
GammaPlan. The output factors obtained with our model agree
within the statistical uncertainties with those calculated with the same Monte
Carlo codes and with those measured with different techniques. Owing to the
accuracy of the results obtained and to the reduction in the computational time
with respect to full geometry simulations (larger than a factor 15), this
simplified model opens the possibility to use Monte Carlo tools for planning
purposes in the Gamma Knife.Comment: 13 pages, 8 figures, 5 table
Elevated plasma homocysteine is associated with ischaemic heart disease in Hong Kong Chinese
published_or_final_versio
Research Framework for Consumer Satisfaction with Internet Shopping
Consumer satisfaction with Internet shopping has been conceptualized in a variety of ways. Studies in this area remain broad and appear relatively fragmented. In view of this, the purpose of this study is to propose a research framework that integrates both end-user computing satisfaction literature and service quality literature. This framework explicitly considers information quality, system quality, and service quality as the key dimensions of consumer satisfaction with Internet shopping. We believe the research framework and propositions serve as salient guidelines for researchers
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