A search for massive neutral bosons in orthopositronium decay

We have searched for an exotic decay of orthopositronium into a single photon and a short-lived neutral boson in the hitherto unexplored mass region above 900 ${\rm keV}/{\it c}^{2}$, by noting that this decay is one of few remaining candidates which could explain the discrepancy of the orthopositronium decay-rate. A high-resolution measurement of the associated photon energy spectrum was carried out with a germanium detector to search for a sharp peak from this two-body decay. Our negative result provides the upper-limits of\mbox{ }$2.0 \times 10^{-4}$ on the branching ratio of such a decay in the mass region from 847 to 1013 ${\rm keV}/{\it c}^{2}$, and excludes the possibility of this decay mode explaining the discrepancy in the orthopositronium decay-rate.Comment: a LaTeX file (text 7 pages) and a uuencoded gz-compressed PostScript file (text 7 pages + figures 4 pages

Composite Skyrme Model with Vector Mesons

We study the composite Skyrme model, proposed by Cheung and G\"{u}rsey, introducing vector mesons in a chiral Lagrangian. We calculate the static properties of baryons and compare with results obtained from models without vector mesons.Comment: LaTeX, 9 pages, 3 figures, to be published in Phys. Rev.

First test of O(α2)O(\alpha ^{2}) correction of the orthopositronium decay rate

Positronium is an ideal system for the research of the bound state QED. New precise measurement of orthopositronium decay rate has been performed with an accuracy of 150 ppm. This result is consistent with the last three results and also the 2nd order correction. The result combined with the last three is 7.0401$\pm0.0007\mu \mathrm{sec}^{-1}$ (100 ppm), which is consistent with the 2nd order correction and differs from the 1st order calculation by 2.6$\sigma$ It is the first test to validate the 2nd order correction.Comment: will be submitted to Phys. Lett.

How System Errors Affect Aircrew Resource Management (CRM)

System errors, both mechanical and human in nature, can have a grave effect on aircrew judgement in flight. The effects of these errors can be massively compounded during emergency situations. Crew Resource Management (CRM) is an important process aircrews can utilize to minimize risks and enhance assessments. The employment of this technique can be validated by aviation mishaps over the last three decades and how system errors increased the probability of the incident occurring. Suggestions can be made to further prevent similar accidents from occurring in the future utilizing historical aeronautical records. This paper outlines an approach by which systems errors can be recognized and prevented using CRM. It is the hope of the authors that employing such an approach will drastically decrease the incidence rate and severity of aviation mishaps due to systems errors. 2015 The Authors

Class of exact solutions of the Skyrme and the Faddeev model

Class of exact solutions of the Skyrme and the Faddeev model are presented. In contrast to previously found solutions, they are produced by the interplay of the two terms in the Lagrangians of the models. They are not solitonic but of wave character. With an appropriate choice of field variables, the field equations of the two models are written in exactly the same form. The solutions supply us with examples of the superposition of two plane waves in nonlinear field theories.Comment: 14 pages, Revtex,Some minor correction

Accurate Mg/Ca, Sr/Ca, and Ba/Ca ratio measurements in carbonates by SIMS and NanoSIMS and an assessment of heterogeneity in common calcium carbonate standards

As archives of past climate variability, the micron and sub-micron scales of element:calcium (Me/Ca) variability in both biogenic and inorganic carbonates contain important geochemical information. Ideally working at smaller and smaller scales leads to higher temporal resolution of past changes, but more often it has revealed the strong overprint of other processes on the climate signal. Therefore, the role of SIMS and NanoSIMS techniques in studying paleoenvironmental proxies continues to increase. We evaluate the accuracy and precision of the CAMECA ims 7F-GEO and NanoSIMS-50L ion probes for measurements of Sr/Ca, Mg/Ca, and Ba/Ca ratios in carbonate minerals. Nine carbonate reference materials were examined for their ^(88)Sr/^(42)Ca, ^(24)Mg/^(42)Ca, and ^(138)Ba/^(42)Ca ratios using a primary O^− beam with spot sizes of 20–40 μm (SIMS) and 0.8–2 μm (NanoSIMS). To assess accuracy, seven of these standards were analyzed for Sr/Ca and Mg/Ca with ID-ICP-MS. Variability in the elemental ratios arising from drift and changes in the tuning of the ims 7F-GEO over a nine month period is smaller than the chemical heterogeneity of the most frequently analyzed standards (OKA and Blue-CC). Across a whole crystal, Blue-CC is more homogeneous (1σ of 2.39% and 1.60% for Sr/Ca and Mg/Ca respectively) than OKA, but in the bulk matrix of OKA there is even less variability (1σ of 0.85% and 0.83% respectively). We find that carbonate samples can be accurately normalized to carbonate standards with significantly different absolute Me/Ca ratios. NanoSIMS intensity ratios follow counting statistics better than ± 1% (2σ) at any one spot, but conversion to Me/Ca ratios increases the uncertainty. Two factors give rise to this limitation. First, the spatial heterogeneity of nominally homogeneous standards can lead to accuracy offsets that are as large as the ranges quoted above. Second, the NanoSIMS generates higher instrumental mass fractionation relative to SIMS. The combination of three different analytical techniques demonstrates that Blue-CC and homogeneous calcite zones in OKA are promising reference materials for precise analyses. Accuracy is crucially dependent on making independent measurements on exactly the same crystal of standard used in the SIMS and NanoSIMS machines

Charmed Strange Pentaquarks in the Large NcN_c Limit

The properties of pentaquarks containing a heavy anti-quark and strange quarks are studied in the bound state picture. In the flavor SU(3) limit, there are many pentaquark states with the same binding energy. When the SU(3) symmetry breaking effects are included, however, three states become particularly stable due to a ``Gell-Mann--Okubo mechanism''. They are the $\bar Qsuud$ and $\bar Qsudd$ states discussed by Lipkin, and a a previously unstudied $\bar Qssud$ state. These states will have $J^P={1\over2}^+$ and their masses are estimated. These states, if exist, may be seen in experiments in the near future.Comment: 12 pages in REVTeX, no figure

Slow relaxation of conductance of amorphous hopping insulators

We discuss memory effects in the conductance of hopping insulators due to slow rearrangements of structural defects leading to formation of polarons close to the electron hopping states. An abrupt change in the gate voltage and corresponding shift of the chemical potential change populations of the hopping sites, which then slowly relax due to rearrangements of structural defects. As a result, the density of hopping states becomes time dependent on a scale relevant to rearrangement of the structural defects leading to the excess time dependent conductivity.Comment: 6 pages, 1 figur

Baryons with Two Heavy Quarks as Solitons

Using the chiral soliton model and heavy quark symmetry we study baryons containing two heavy quarks. If there exists a stable (under strong interactions) meson consisting of two heavy quarks and two light ones, then we find that there always exists a state of this meson bound to a chiral soliton and to a chiral anti-soliton, corresponding to a two heavy quark baryon and a baryon containing two heavy anti-quarks and five light quarks, or a ``heptaquark".Comment: 7 pages and 2 postscript figures appended, LaTex, UCI-TR 94-3

Two Skyrmion Dynamics with Omega Mesons

We present our first results of numerical simulations of two skyrmion dynamics using an $\omega$-meson stabilized effective Lagrangian. We consider skyrmion-skyrmion scattering with a fixed initial velocity of $\beta=0.5$, for various impact parameters and groomings. The physical picture that emerges is surprisingly rich, while consistent with previous results and general conservation laws. We find meson radiation, skyrmion scattering out of the scattering plane, orbiting and capture to bound states.Comment: 19 pages, 22 figure