Role of deformation in the nonmesonic decay of light hypernuclei

We discuss the nonmesonic decay of deformed p-shell hypernuclei. The Nilsson model with angular momentum projection is employed in order to take into account the deformation effects. The nonmesonic decay rate and the intrinsic $\Lambda$ asymmetry parameter decrease as a function of the deformation parameter, while the ratio of the neutron- to proton-induced decay rates increases. We find that the deformation effects change these observables by about 10 % for $^9_{\Lambda}$Be from the spherical limit.Comment: RevTex, 17 pages, 3 ps figure

Recent results on the nonmesonic weak decay of hypernuclei within a one-meson-exchange model

We update our previous results for the nonmesonic decay of $^{12}_\Lambda$C and $^5_\Lambda$He. We pay special attention to the role played by Final State Intreractions on the decay observables. We follow a One-Meson-Exchange model which includes the exchange of the $\pi, \rho, K, K^*, \eta$ and $\omega$ mesons. We also present recent predictions for different observables concerning the decay of the doubly strange $^6_{\Lambda \Lambda}$He hypernucleus.Comment: 4 pages. Contribution to the Mesons and Light Nuclei'01 Conference, Prague, 2-6 July 200

Lowest Order Effective Field Theory for the weak ΛN\Lambda N interaction

The $|\Delta S|=1$ $\Lambda N$ interaction, responsible for the decay of hypernuclei, is studied by means of an Effective Field Theory where the long range physics is described by pion and kaon exchange mechanisms, and its short range counterpart is obtained from the most general non-derivative local four-fermion interaction. We show that, including the Lowest Order Parity Conserving contact terms, allows us to reproduce the total decay rates for $^5_\Lambda {\rm He}$, $^{11}_\Lambda {\rm B}$ and $^{12}_\Lambda {\rm C}$ with a reasonable value of ${\hat \chi^2}$, while in order to get a prediction for the Parity Violating (PV) asymmetry compatible with experiments, we have to include the Lowest Order PV contact pieces.Comment: 3 pages, no figures. Contribution to the 17th International IUPAP Conference on Few-body Problems in Physics, June 5-10, 2003 Durham, North Carolina, USA. Uses espcrc1.st

The role of unions in an endogenous growth model with human capital

In this paper we study the relationship between unions and growth in a two-sector overlapping generations model with altruism and human capital. This relationship depends on the interaction between the technology in the sector that produces human capital, the degree of unionization of the economy and the operativeness of the bequest motive.endogenous growth, unions, altruism, human capital

Dynamical meson-baryon resonances with chiral Lagrangians

The s-wave meson-baryon interaction is studied using the lowest-order chiral Lagrangian in a unitary coupled-channels Bethe-Salpeter equation. In the strangeness $S=-1$ sector the low-energy $K^- p$ dynamics leads to the dynamical generation of the $\Lambda(1405)$ as a ${\bar K}N$ state, along with a good description of the $K^- p$ scattering observables. At higher energies, the $\Lambda(1670)$ is also found to be generated dynamically as a $K \Xi$ quasibound state for the first time. For strangeness S=0, it is the $S_{11}(1535)$ resonance that emerges from the coupled-channels equations, leading to a satisfactory description of meson-baryon scattering observables in the energy region around the $S_{11}(1535)$. We speculate on the possible dynamical generation of $\Xi$ resonances within the chiral $S=-2$ sector as ${\bar K} \Lambda$ or ${\bar K} \Sigma$ quasibound states.Comment: 8 pages, 5 figures, Talk given at NSTAR2001, Workshop on the Physics of Excited Nucleons, Mainz (Germany), March 7-10, to be published in World Scientifi

A Study of Kindergarten 2 Students’ English Phonics Achievement and Their Perceptions towards the Use of English Phonics Online Games at St. Mark’s International School, Thailand

This study aimed to compare the Kindergarten 2 students’ achievement in English Phonics before and after the use of English Phonics online games and to find out their perceptions towards such games. Eleven Kindergarten 2 students of St. Mark’s International School in the academic year 2015-2016 participated in the two-month study. This research used a mixed method design. A one-group pretest-posttest experiment was conducted to determine if there was a significant difference in the students’ English Phonics achievement before and after using English Phonics online games. In addition, an interview on how the students’ perceived the use of English Phonics online games was done. Analyses showed that Kindergarten 2 students’ English Phonics achievement was very good before the use of online games, and it increased to excellent after the use of online games. Paired Samples t-test revealed that there was a significant difference between the pre- and post-tests scores of Kindergarten 2 students before and after using English Phonics online games at the level of 0.05. The interview results revealed that: 1) all Kindergarten 2 students had positive perceptions towards the use of online games in English Phonics; 2) the students had positive perceptions towards the use of English phonics online games because the games helped them learn how to spell and read and featured animations, colorful and attractive common objects, and interactive/hands-on and game/challenge components. Based on the findings, the use of online games in English Phonics is recommended in teaching and learning English Phonics, especially for young learners. Further relevant studies are also recommended

Building On Science: My Career (So Far) in Cell Research

Growing up, I always wanted to become a medical doctor. Like many young students pursuing medicine, I entered my undergraduate degree in the biological sciences. The science courses were a struggle for me to get through and I found myself even more interested in my option courses such as psychology or even economics. Nevertheless, I finished my biological sciences degree. I did apply to medicine but did not get in, so I decided to get a master’s degree in order to improve my curriculum vitae in hopes of eventually getting into medicine

Violation of the Δ\DeltaI=1/2 rule in the nonmesonic weak decay of Λ\Lambda hypernuclei

Violations of the $\Delta$I=1/2 rule are investigated in the nonmesonic weak hypernuclear decay using a weak $\Lambda$N$\to$NN transition potential based on meson exchange. While the weak $\Delta$I=3/2 matrix elements of baryons with pseudoscalar mesons are known to be very small, the same matrix elements of baryons with vector mesons, evaluated in the factorization approximation, are found to be significant. Within the uncertainties of the factorization approximation we find that the total rate increases by at most 6% lying within the error bars of the more recent experimental result. The neutron- to proton-induced rate, on the other hand, can change by up to a factor of two, while the asymmetry parameter is strongly affected as well.Comment: 17 pages. Paper related to a contribution presented at the International Conference on Hypernuclear and Strange Particle Physics (HYP97). Submitted to Phys. Lett.