3,895 research outputs found
Sampling the Probability Distribution of Type Ia Supernova Lightcurve Parameters in Cosmological Analysis
In order to obtain robust cosmological constraints from Type Ia supernova (SN
Ia) data, we have applied Markov Chain Monte Carlo (MCMC) to SN Ia lightcurve
fitting. We develop a method for sampling the resultant probability density
distributions (pdf) of the SN Ia lightcuve parameters in the MCMC likelihood
analysis to constrain cosmological parameters, and validate it using simulated
data sets. Applying this method to the Joint Lightcurve Analysis (JLA) data set
of SNe Ia, we find that sampling the SN Ia lightcurve parameter pdf's leads to
cosmological parameters closer to that of a flat Universe with a cosmological
constant, compared to the usual practice of using only the best fit values of
the SN Ia lightcurve parameters. Our method will be useful in the use of SN Ia
data for precision cosmology.Comment: 9 pages, 6 figures, 4 tables. Revised version accepted by MNRA
Two photon couplings of the lightest isoscalars from BELLE data
Amplitude Analysis of two photon production of and ,
using S-matrix constraints and fitting all available data, including the latest
precision results from Belle, yields a single partial wave solution up to 1.4
GeV. The two photon couplings of the , and
are determined from the residues of the resonance poles.Comment: 11 pages, 3 figures, extended for detail
A new method to study the number of colors in the final-state interactions of hadrons
We match the scattering amplitudes of Chiral Perturbation
Theory with those from dispersion relations that respect analyticity and
coupled channel unitarity, as well as accurately describing experiment. Their
dependence on the number of colors () is obtained. By varying the
trajectories of the poles and residues (the couplings to ) of light
mesons, the , , and are investigated.
Our results show that the method proposed is a reliable way to study the
dependence in hadron-hadron scattering with final-state interactions.Comment: 7 pages, 3 figures, improved behaviou
The profitability of technical analysis in the Taiwan-U.S. forward foreign exchange market
Based on technical analysis and White's and Hansen's data-snooping-robust tests, we examine the efficiency of the Taiwan-U.S. forward foreign exchange market and find that, unlike the spot market, the forward market is inefficient even under a very high transaction cost, suggesting that the failure of forward rate unbiasedness documented in the literature may be due to forward market inefficiency.data snooping, forward exchange rate unbiasedness, market efficiency, profitability, reality check, technical analysis
and the structure observed around the threshold
We analyze the origin of the structure observed in the reaction for invariant masses close to the
antiproton-proton () threshold, commonly associated with the
resonance. Specifically, we explore the effect of a possible contribution from
the two-step process .
The calculation is performed in distorted-wave Born approximation which allows
an appropriate inclusion of the interaction in the transition
amplitude. The amplitude itself is generated from a corresponding
potential recently derived within chiral effective field theory. We are able to
reproduce the measured spectra for the reactions
and for invariant masses around the threshold. The structure seen in the spectrum emerges as
a threshold effect due to the opening of the channel.Comment: 9 pages, 5 figure
Re-examining the resonance in the reaction
The reaction is investigated
at energies close to the threshold with emphasis on the role played by the
resonance. The interaction in the final
system, constructed within chiral effective field theory and supplemented by a
pole diagram that represents a bare resonance, is taken into account
rigorously. The pole parameters of the are extracted and found to be
compatible with the ones of the resonance that have been established
in the reaction . The actual result for the
is MeV and MeV.
Predictions for the electromagnetic form factors in the timelike
region are presented.Comment: 11 pages, 3 figure
Efficiency in Corporate Takeovers
Corporate takeover is a very important economic activity that generates profound consequences on many classes of market participants. The great financing needs and transaction costs directly change the wealth of both shareholders and creditors. The corporate restructuring induced by the takeover results in a significant impact on the welfare of management, employees, and customers. The reshaped industrial map due to the takeover further influences the competition strategies of other firms. Moreover, the changes in the taxable revenues when the takeover happens across the industry can also affect the tax income to the government. The paramount impact on corporations and the economy highlights the importance of studying the efficiency in corporate takeovers. This dissertation contributes to the discussion on takeover efficiency by exploring three key questions
- …