Nuclear and Neutron Matter Calculations with Different Model Spaces

In this work we investigate the so-called model-space Brueckner-Hartree-Fock (MBHF) approach for nuclear matter as well as for neutron matter and the extension of this which includes the particle-particle and hole-hole (PPHH) diagrams. A central ingredient in the model-space approach for nuclear matter is the boundary momentum $k_M$ beyond which the single-particle potential energy is set equal to zero. This is also the boundary of the model space within which the PPHH diagrams are calculated. It has been rather uncertain which value should be used for $k_M$. We have carried out model-space nuclear matter and neutron matter calculations with and without PPHH diagrams for various choices of $k_M$ and using several modern nucleon-nucleon potentials. Our results exhibit a saturation region where the nuclear and neutron matter matter energies are quite stable as $k_M$ varies. The location of this region may serve to determine an "optimum" choice for $k_M$. However, we find that the strength of the tensor force has a significant influence on binding energy variation with $k_M$. The implications for nuclear and neutron matter calculations are discussed.Comment: 24 pages, Elsevier LaTeX style, 17 figs include

Low momentum nucleon-nucleon potential and shell model effective interactions

A low momentum nucleon-nucleon (NN) potential V-low-k is derived from meson exhange potentials by integrating out the model dependent high momentum modes of V_NN. The smooth and approximately unique V-low-k is used as input for shell model calculations instead of the usual Brueckner G matrix. Such an approach eliminates the nuclear mass dependence of the input interaction one finds in the G matrix approach, allowing the same input interaction to be used in different nuclear regions. Shell model calculations of 18O, 134Te and 135I using the same input V-low-k have been performed. For cut-off momentum Lambda in the vicinity of 2 fm-1, our calculated low-lying spectra for these nuclei are in good agreement with experiments, and are weakly dependent on Lambda.Comment: 5 pages, 5 figure

Probing neutrino mass hierarchies and ϕ13\phi_{13} with supernova neutrinos

We investigate the feasibility of probing the neutrino mass hierarchy and the mixing angle $\phi_{13}$ with the neutrino burst from a future supernova. An inverse power-law density $\rho \sim r^{n}$ with varying $n$ is adopted in the analysis as the density profile of a typical core-collapse supernova. The survival probabilities of $\nu_{e}$ and $\bar{\nu}_{e}$ are shown to reduce to two-dimensional functions of $n$ and $\phi_{13}$. It is found that in the $n-\sin^{2} \phi_{13}$ parameter space, the 3D plots of the probability functions exhibit highly non-trivial structures that are sensitive to the mass hierarchy, the mixing angle $\phi_{13}$, and the value of $n$. The conditions that lead to observable differences in the 3D plots are established. With the uncertainty of $n$ considered, a qualitative analysis of the Earth matter effect is also included.Comment: 16 pages, 3 figures. Ref [11] added, and some typos correcte

A manned exobiology laboratory based on the Moon

Establishment of an exobiology laboratory on the Moon would provide a unique opportunity for exploration of extraterrestrial materials on a long-term, ongoing basis, for elucidation of exobiological processes and chemical evolution. A major function of the lunar exobiology laboratory would be to examine samples collected from other planets (e.g., Mars) for the presence of extant or extinct life. By establishing a laboratory on the Moon, preliminary analyses could be conducted away from Earth, thus establishing that extraterrestrial materials are benign before their return to Earth for more extensive investigations. The Moon-based exobiology laboratory would have three major components for study of samples returned from other planets: (1) the search for extant life - this component would focus on the detection and identification of life forms using biological, physical, and chemical methods; (2) the search for extinct life - this component would concentrate on identification of extinct life using micropaleontological physical and chemical means; and (3) the search and evidence of chemical evolution - this component would be devoted to the detection and identification of molecules revealing prebiotic chemical evolution

Antikaons in nuclei and dense nuclear matter

We present recent progress on the properties of antikaons in nuclei and dense nuclear matter as obtained from two {\bar K}N interaction models: one based on the lowest-order meson-baryon chiral lagrangian and the other derived from a meson-exchange picture.Comment: 10 pages, 6 figures. Contribution to the proceedings of HYP200

Realistic Shell-Model Calculations for Proton-Rich N=50 Isotones

The structure of the N=50 isotones 98Cd, 97Ag, and 96Pd is studied in terms of shell model employing a realistic effective interaction derived from the Bonn-A nucleon-nucleon potential. The single-hole energies are fixed by resorting to an analysis of the low-energy spectra of the isotones with A>= 91. Comparison shows that our results are in very satisfactory agreement with the available experimental data. This supports confidence in the predictions of our calculationsComment: 8 pages, 3 figures, to be published on Journal of Physics

Solar Neutrinos with Three Flavor Mixings

The recent 71Ga solar neutrino observation is combined with the 37Cl and Kamiokande-II observations in an analysis for neutrino masses and mixings. The allowed parameter region is found for matter enhanced mixings among all three neutrino flavors. Distortions of the solar neutrino spectrum unique to three flavors are possible and may be observed in continuing and next generation experiments.Comment: August 1992 (Revised) PURD-TH-92-

An extension of Wiener integration with the use of operator theory

With the use of tensor product of Hilbert space, and a diagonalization procedure from operator theory, we derive an approximation formula for a general class of stochastic integrals. Further we establish a generalized Fourier expansion for these stochastic integrals. In our extension, we circumvent some of the limitations of the more widely used stochastic integral due to Wiener and Ito, i.e., stochastic integration with respect to Brownian motion. Finally we discuss the connection between the two approaches, as well as a priori estimates and applications.Comment: 13 page

Vertical Heating Structures Associated with the MJO as Characterized by TRMM Estimates, ECMWF Reanalyses, and Forecasts: A Case Study during 1998/99 Winter

The Madden–Julian oscillation (MJO) is a fundamental mode of the tropical atmosphere variability that exerts significant influence on global climate and weather systems. Current global circulation models, unfortunately, are incapable of robustly representing this form of variability. Meanwhile, a well-accepted and comprehensive theory for the MJO is still elusive. To help address this challenge, recent emphasis has been placed on characterizing the vertical structures of the MJO. In this study, the authors analyze vertical heating structures by utilizing recently updated heating estimates based on the Tropical Rainfall Measuring Mission (TRMM) from two different latent heating estimates and one radiative heating estimate. Heating structures from two different versions of the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalyses/forecasts are also examined. Because of the limited period of available datasets at the time of this study, the authors focus on the winter season from October 1998 to March 1999. The results suggest that diabatic heating associated with the MJO convection in the ECMWF outputs exhibits much stronger amplitude and deeper structures than that in the TRMM estimates over the equatorial eastern Indian Ocean and western Pacific. Further analysis illustrates that this difference might be due to stronger convective and weaker stratiform components in the ECMWF estimates relative to the TRMM estimates, with the latter suggesting a comparable contribution by the stratiform and convective counterparts in contributing to the total rain rate. Based on the TRMM estimates, it is also illustrated that the stratiform fraction of total rain rate varies with the evolution of the MJO. Stratiform rain ratio over the Indian Ocean is found to be 5% above (below) average for the disturbed (suppressed) phase of the MJO. The results are discussed with respect to whether these heating estimates provide enough convergent information to have implications on theories of the MJO and whether they can help validate global weather and climate models