5,950 research outputs found
Recent Astrophysics Results from ORELA and Possible Future Experiments at ORELA and SNS
I present some recent results from experiments at the Oak Ridge Electron
Linear Accelerator (ORELA) and discuss their impact in nuclear astrophysics. I
then describe some possible future nuclear astrophysics experiments at ORELA
and at the Spallation Neutron Source (SNS) being built in Oak Ridge. The SNS
and ORELA are complementary, world-class facilities and both will be needed for
important future experiments in nuclear astrophysics.Comment: 10 pages, 1 figure, 1 table. To be published in the proceedings of
the Workshop on Astrophysics, Symmetries, and Applied Physics at Spallation
Neutron Sources, Oak Ridge National Laboratory, March 200
Reduced neutron widths in the nuclear data ensemble: Experiment and theory do not agree
I have analyzed reduced neutron widths ({\Gamma}_{n}^0) for the subset of
1245 resonances in the nuclear data ensemble (NDE) for which they have been
reported. Random matrix theory (RMT) predicts for the Gaussian orthogonal
ensemble (GOE) that these widths should follow a \c{hi}^2 distribution having
one degree of freedom ({\nu}=1) - the Porter Thomas distribution (PTD). Careful
analysis of the {\Gamma}_{n}^2 values in the NDE rejects the validity of the
PTD with a statistical significance of at least 99.97% ({\nu}=0.801\pm0.052).
This striking disagreement with the RMT prediction is most likely due to the
inclusion of significant p-wave contamination to the supposedly pure s-wave
NDE. When an energy dependent threshold is used to remove the p-wave
contamination, the PTD is still rejected with a statistical significance of at
least 98.17% ({\nu}=1.217\pm0.092). Furthermore, examination of the primary
references for the NDE reveals that many resonances in most of the individual
data sets were selected using methods derived from RMT. Therefore, using the
full NDE data set to test RMT predictions seems highly questionable. These
results cast very serious doubt on claims that the NDE represents a striking
confirmation of RMT.Comment: Accepted for publication in Phys. Rev.
New Analysis of the Delta I = 1/2 Rule in Kaon Decays and the B_K Parameter
We present a new analysis of the Delta I = 1/2 rule in K --> pi pi decays and
the B_K parameter. We use the 1/N_c expansion within the effective chiral
lagrangian for pseudoscalar mesons and compute the hadronic matrix elements at
leading and next-to-leading order in the chiral and the 1/N_c expansions.
Numerically, our calculation reproduces the dominant Delta I = 1/2 K --> pi pi
amplitude. Our result depends only moderately on the choice of the cutoff scale
in the chiral loops. The Delta I = 3/2 amplitude emerges sufficiently
suppressed but shows a significant dependence on the cutoff. The B_K parameter
turns out to be smaller than the value previously obtained in the 1/N_c
approach. It also shows a significant dependence on the choice of the cutoff
scale. Our results indicate that corrections from higher order terms and/or
higher resonances are large for the Delta I = 3/2 K --> pi pi amplitude and the
(|Delta S| = 2) K^0 -- anti K^0 transition amplitude.Comment: 50 pages, LaTeX, 13 eps figure
Legalism in an Evangelical Church
The essay that follows developed from a remark that the author made at one of the larger intersynodical conferences. The remark was to the effect that there is much legalism rampant in our circles, that the result is stagnation and retrogression in all areas of church life, and that for this reason sincere and general repentance is necessary before we may anticipate a turn for the better. The expression legalism in our circles was not generally understood. It was intended to describe one aspect of all our activity in thought, speech, and endeavor, based on a comprehensive observation of life and in particular on a study of history
Analyzing epsilon'/epsilon in the 1/N_c Expansion
We present a recent analysis of epsilon'/epsilon in the 1/N_c expansion. We
show that the 1/N_c corrections to the matrix element of Q_6 are large and
positive, indicating a Delta I=1/2 enhancement similar to the one of Q_1 and
Q_2 which dominate the CP conserving amplitude. This enhances the CP ratio and
can bring the standard model prediction close to the measured value for central
values of the parameters.Comment: One reference corrected. 5 pages, talk presented by P.H. Soldan at
the 3. International Conference on B Physics and CP Violation, Taipei,
Taiwan, December 3 - 7, 1999. Slightly expanded version of the article
submitted to the proceeding
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