Topics on heavy baryon chiral perturbation theory in the large N_c limit

We compute nonanalytical pion-loop corrections to baryon masses in a combined expansion in chiral symmetry breaking and 1/N_c, where N_c is the number of colors. Specifically, we compute flavor-27 baryon mass splittings at leading order in chiral perturbation theory. Our results, at the physical value N_c=3, are compared with the expressions obtained in heavy baryon chiral perturbation theory with no 1/N_c expansion.Comment: 7 pages. Based on a talk given at 8th Mexican Workshop on Particles and Fields, Zacatecas, Mexico, 14-20 Nov 2001. To appear in the proceeding

Baryon semileptonic decays: the Mexican contribution

We give a detailed account of the techniques to compute radiative corrections in baryon semileptonic decays developed over the years by Mexican collaborations. We explain how the method works by obtaining an expression for the Dalitz plot of semileptonic decays of polarized baryons including radiative corrections to order ${\mathcal O}(\alpha q/\pi M_1)$, where $q$ is the four-momentum transfer and $M_1$ is the mass of the decaying baryon. From here we compute the totally integrated spin angular asymmetry coefficient of the emitted baryon and compare its value with other results.Comment: 10 pages. Prepared for the Commemorative Volume of the Divison of Particles and Fields of the Mexican Physical Societ

Student Perceptions of Service-Learning in the Community College

United States Census Bureau projections predict that Whites\u27 share of the population should decline from 75% in 1990 to 68% in 2010. Thus, mechanisms must be employed to facilitate cooperation and support among and across people from different ethnic and racial groups. This examination seeks to determine if service-learning is such a mechanism. The researcher utilized student experiences and perspectives, through a mixed qualitative/quantitative study, to determine the impact that a service-learning course had on a diverse group of students attending an urban community college. The researcher originally sought to determine whether a community college service-learning course changed students\u27 perceptions of those from different ethnicities and races and assisted in facilitating intergroup relations. However, the service-learning experience resulted in several different outcomes for the examined community college students. In particular, this examination revealed that service-learning facilitated a more active role for students in their studies and community. In this study, six broad themes emerged inductively from student interviews and an analysis of artifacts. These six themes included: bringing the book to life, career development, competing pressures and perseverance, a helping hand and a full heart-connection with service agency population, dealing with difference, and educational navigator. In turn, these six themes had twenty subthemes. In an effort to obtain a uniform. quantitative data set, the researcher received permission to administer two attitudinal surveys (pre-and post-experience) to students enrolled in two Introduction to Social Work sections (n=24). The attitudinal surveys allowed for a uniform quantitative analysis of student outcomes across six developmental domains (academic, career, personal, social, civic, and ethical development). An analysis of variance (ANOVA) was then conducted to determine if there was a significant improvement in any of the six domains as a result of the semester-long service-learning experience. The ANOVA found that out of the six domains, only the academic and career domains were significant at the .05 level. These results are encouraging and are consistent with the six themes and twenty subthemes that emerged from the qualitative data analysis. The study concludes with a discussion of the implications raised by the study, five specific recommendations for the examined institution, and directions for further study