New FOCUS results on charm mixing and CP violation

We present a summary of recent results on CP violation and mixing in the charm quark sector based on a high statistics sample collected by photoproduction experiment FOCUS (E831 at Fermilab). We have measured the difference in lifetimes for the $D^0$ decays: $D^0 \to K^-\pi^+$ and $D^0 \to K^-K^+$. This translates into a measurement of the $y_{CP}$ mixing parameter in the \d0d0 system, under the assumptions that $K^-K^+$ is an equal mixture of CP odd and CP even eigenstates, and CP violation is negligible in the neutral charm meson system. We verified the latter assumption by searching for a CP violating asymmetry in the Cabibbo suppressed decay modes $D^+ \to K^-K^+\pi^+$, $D^0 \to K^-K^+$ and $D^0 \to \pi^-\pi^+$. We show preliminary results on a measurement of the branching ratio $\Gamma(D^{*+}\to \pi^+ (K^+\pi^-))/\Gamma(D^{*+}\to \pi^+ (K^-\pi^+))$.Comment: 9 pages, 6 figures, requires espcrc2.sty. Presented by S.Bianco at CPConf2000, September 2000, Ferrara (Italy). In this revision, fixed several stylistic flaws, add two significant references, fixed a typo in Tab.

VOLUMEN 25, NÚMERO 40 (2003)

TERMOCRONOLOGÍA K-Ar EN ILLITAS: ASPECTOS METODOLÓGICOS. Mantilla Figueroa, L. C.CINÉTICA DE LA NUCLEACIÓN Y EL CRECIMIENTO DEL GRANATE EN LAS ROCAS METAPELÍTICAS DE LA FORMACIÓN SILGARÁ, REGIÓN SUROCCIDENTAL DEL MACIZO DE SANTANDER. Ríos Reyes, C., Gélvez Llanes, J., Márquez Romero, R. y Castellanos Alarcón, O.INTRODUCCIÓN A LA GEOLOGÍA DEL SECTOR VÉLEZ–BOLÍVAR–GUAVATÁ (DPTO. DE SANTANDER, COLOMBIA) Y SU IMPORTANCIA PARA LA EXPLORACIÓN DE DEPÓSITOSHIDROTERMALES. Mantilla Figueroa, L. C.; Cruz G. L. E.; Colegial G. J. D.RECOGNITION OF ANCIENT SHOREFACE DEPOSITS. FACIES, FACIES SUCESSIONS, AND ASSOCIATIONS. AN EXAMPLE FROM THE CRETACEOUS GALLUP CLASTIC WEDGE, NEW MÉXICO. Álvarez Bastos, MNUEVAS EVIDENCIAS ACERCA DE LA PRESENCIA DE UNA BANDA DE CIZALLAMIENTO EN LA SECUENCIA METAPELÍTICA DE LA FORMACIÓN SILGARÁ, SECTOR ARATOCA-PESCADERO (REGION SUROCCIDENTAL DEL MACIZO DE SANTANDER). Mantilla Figueroa, L. C.; Ríos Reyes, C. A.; Gélvez Llanes, J. R.; Márquez Romero, R. E.; Ordóñez Calderón, J. C.; Cepeda Espitia, S.LOS DELIRIOS: UN YACIMIENTO HIDROTERMAL DE ORO Y PLATA EN LA REGIÓN DE VETAS, SANTANDER (COLOMBIA). García Ramírez, C. A., Uribe Portilla, E.MINERALOGÍA, GEOQUÍMICA Y ALGUNOS ASPECTOS GENÉTICOS DE LA MINA EL DIAMANTE - NARIÑO (COLOMBIA). Molano, J.C. and Shimazaki, H.COMPARATIVE FLUID INCLUSION STUDIES OF THE SAN MARTÍN SKARN (MÉXICO) AND THE EPITHERMAL COMSTOCK LODE (USA) AND PACHUCA-REAL DEL MONTE (MÉXICO) DEPOSITS. Campos Álvarez, N. O

VOLUMEN 25, NÚMERO 40 (2003)

TERMOCRONOLOGÍA K-Ar EN ILLITAS: ASPECTOS METODOLÓGICOS. Mantilla Figueroa, L. C.CINÉTICA DE LA NUCLEACIÓN Y EL CRECIMIENTO DEL GRANATE EN LAS ROCAS METAPELÍTICAS DE LA FORMACIÓN SILGARÁ, REGIÓN SUROCCIDENTAL DEL MACIZO DE SANTANDER. Ríos Reyes, C., Gélvez Llanes, J., Márquez Romero, R. y Castellanos Alarcón, O.INTRODUCCIÓN A LA GEOLOGÍA DEL SECTOR VÉLEZ–BOLÍVAR–GUAVATÁ (DPTO. DE SANTANDER, COLOMBIA) Y SU IMPORTANCIA PARA LA EXPLORACIÓN DE DEPÓSITOSHIDROTERMALES. Mantilla Figueroa, L. C.; Cruz G. L. E.; Colegial G. J. D.RECOGNITION OF ANCIENT SHOREFACE DEPOSITS. FACIES, FACIES SUCESSIONS, AND ASSOCIATIONS. AN EXAMPLE FROM THE CRETACEOUS GALLUP CLASTIC WEDGE, NEW MÉXICO. Álvarez Bastos, MNUEVAS EVIDENCIAS ACERCA DE LA PRESENCIA DE UNA BANDA DE CIZALLAMIENTO EN LA SECUENCIA METAPELÍTICA DE LA FORMACIÓN SILGARÁ, SECTOR ARATOCA-PESCADERO (REGION SUROCCIDENTAL DEL MACIZO DE SANTANDER). Mantilla Figueroa, L. C.; Ríos Reyes, C. A.; Gélvez Llanes, J. R.; Márquez Romero, R. E.; Ordóñez Calderón, J. C.; Cepeda Espitia, S.LOS DELIRIOS: UN YACIMIENTO HIDROTERMAL DE ORO Y PLATA EN LA REGIÓN DE VETAS, SANTANDER (COLOMBIA). García Ramírez, C. A., Uribe Portilla, E.MINERALOGÍA, GEOQUÍMICA Y ALGUNOS ASPECTOS GENÉTICOS DE LA MINA EL DIAMANTE - NARIÑO (COLOMBIA). Molano, J.C. and Shimazaki, H.COMPARATIVE FLUID INCLUSION STUDIES OF THE SAN MARTÍN SKARN (MÉXICO) AND THE EPITHERMAL COMSTOCK LODE (USA) AND PACHUCA-REAL DEL MONTE (MÉXICO) DEPOSITS. Campos Álvarez, N. O

A measurement of lifetime differences in the neutral D-meson system

Using a high statistics sample of photoproduced charm particles from the FOCUS experiment at Fermilab, we compare the lifetimes of neutral D mesons decaying via D0 to K- pi+ and K- K+ to measure the lifetime differences between CP even and CP odd final states. These measurements bear on the phenomenology of D0 - D0bar mixing. If the D0 to K-pi+ is an equal mixture of CP even and CP odd eigenstates, we measure yCP = 0.0342 \pm 0.0139 \pm 0.0074

Insects as Stem Engineers: Interactions Mediated by the Twig-Girdler Oncideres albomarginata chamela Enhance Arthropod Diversity

Background: Ecosystem engineering may influence community structure and biodiversity by controlling the availability of resources and/or habitats used by other organisms. Insect herbivores may act as ecosystem engineers but there is still poor understanding of the role of these insects structuring arthropod communities. Methodology/Principal Findings: We evaluated the effect of ecosystem engineering by the stem-borer Oncideres albomarginata chamela on the arthropod community of a tropical dry forest for three consecutive years. The results showed that ecosystem engineering by O. albomarginata chamela had strong positive effects on the colonization, abundance, species richness and composition of the associated arthropod community, and it occurred mainly through the creation of a habitat with high availability of oviposition sites for secondary colonizers. These effects cascade upward to higher trophic levels. Overall, ecosystem engineering by O. albomarginata chamela was responsible for nearly 95 % of the abundance of secondary colonizers and 82 % of the species richness. Conclusions/Significance: Our results suggest that ecosystem engineering by O. albomarginata chamela is a keystone process structuring an arthropod community composed by xylovores, predators and parasitoids. This study is the first to empirically demonstrate the effect of the ecosystem engineering by stem-boring insects on important attributes o