Dynamics of strong and radiative decays of Ds-mesons in the hadrogenesis conjecture

The positive parity scalar D$_{s0}^*$(2317) and axial-vector D$_{s1}^*$(2460) charmed strange mesons are generated by coupled-channel dynamics through the s-wave scattering of Goldstone bosons off the pseudoscalar and vector D(D$_s$)-meson ground states. The specific masses of these states are obtained as a consequence of the attraction arising from the Weinberg-Tomozawa interaction in the chiral Lagrangian. Chiral corrections to order Q$_\chi^2$ are calculated and found to be small. The D$_{s0}^*$(2317) and D$_{s1}^*$(2460) mesons decay either strongly into the isospin-violating $\pi^0$D$_s$ and $\pi^0$D$_s^*$ channels or electromagnetically. We show that the $\pi^0$-$\eta$ and (K$^0$D$^+$-K$^+$D$^0$) mixings act constructively to generate strong widths of the order of 140 keV and emphasize the sensitivity of this value to the $KD$ component of the states. The one-loop contribution to the radiative decay amplitudes of scalar and axial-vector states is calculated using the electromagnetic Lagrangian to chiral order Q$_\chi^2$. We show the importance of taking into account processes involving light vector mesons explicitly in the dynamics of electromagnetic decays. The radiative width are sensitive to both $\eta D_s$ and $KD$ components, hence providing information complementary to the strong widths on the positive parity $D_s$-meson structure.Comment: 4 pages, Invited Contribution to QNP09, Beijing, September 21-26, 200

Dynamics of strong and radiative decays of Ds mesons

The positive parity scalar D$_{s0}^*$(2317) and axial-vector D$_{s1}^*$(2460) charmed strange mesons are generated by coupled-channel dynamics through the s-wave scattering of Goldstone bosons off the pseudoscalar and vector D(D$_s$)-meson ground states. The attraction leading to the specific masses of these states reflects the chiral symmetry breaking scale which characterizes the Weinberg-Tomozawa interaction in the chiral Lagrangian. Chiral corrections to order Q$_\chi^2$ are calculated and found to be small. The D$_{s0}^*$(2317) and D$_{s1}^*$(2460) mesons decay either strongly into the isospin-violating $\pi^0$D$_s$ and $\pi^0$D$_s^*$ channels or electromagnetically. We show that the $\pi^0$-$\eta$ and (K$^0$D$^+$-K$^+$D$^0$) mixings act constructively to generate strong widths of the order of 140 keV. The one-loop contribution to the radiative decay amplitudes of scalar and axial-vector states is calculated using the electromagnetic Lagrangian to chiral order Q$_\chi^2$. We show the importance of taking into account processes involving light vector mesons explicitly in the dynamics of electromagnetic decays to obtain a satisfactory description of the available data.Comment: Contribution to the Meson 2008 Conference, June 6-10, Cracow, Polan

The nature and evolution of Ultraluminous Infrared Galaxies: A mid-infrared spectroscopic survey

We report the first results of a low resolution mid-infrared spectroscopic survey of an unbiased, far-infrared selected sample of 60 ultraluminous infrared galaxies, using ISOPHOT-S on board ISO. We use the ratio of the 7.7um `PAH' emission feature to the local continuum as a discriminator between starburst and AGN activity. About 80% of all the ULIRGs are found to be predominantly powered by star formation but the fraction of AGN powered objects increases with luminosity. Observed ratios of the PAH features in ULIRGs differ slightly from those in lower luminosity starbursts. This can be plausibly explained by the higher extinction and/or different physical conditions in the interstellar medium of ULIRGs. The PAH feature-to-continuum ratio is anticorrelated with the ratio of feature-free 5.9um continuum to the IRAS 60um continuum, confirming suggestions that strong mid-IR continuum is a prime AGN signature. The location of starburst-dominated ULIRGs in such a diagram is consistent with previous ISO-SWS spectroscopy which implies significant extinction even in the mid-infrared. We have searched for indications that ULIRGs which are advanced mergers might be more AGN-like, as postulated by the classical evolutionary scenario. No such trend has been found amongst those objects for which near infrared images are available to assess their likely merger status.Comment: aastex, 4 eps figures. Revised version, accepted by ApJ (Letters

The Demographic Dimensions of Divorce: The Case of Finland

Any demographic event such as birth, death, marriage, and divorce may be registered and studied with respect to various demographic dimensions; these are most prominently age and time but also duration of marriage, time since last birth, etc. Fertility, mortality, and nuptiality are all considered to depend primarily on age. Divorce has traditionally been studied with respect to marital duration. This paper uses a multi-dimensional perspective to study the phenomenon of divorce. It is made possible by the availability of a unique data set from the Finnish Population Register that provides cross-classified information on several demographic dimensions of divorce. The study yields intriguing results that give a quite different picture than conventional one- and two-dimensional perspectives

The low fertility trap hypothesis: Forces that may lead to further postponement and fewer births in Europe

This paper starts from the assessment that there is no good theory in the social sciences that would tell us whether fertility in low-fertility countries is likely to recover in the future, stay around its current level or continue to fall. This question is key to the discussion whether or not governments should take action aimed at influencing the fertility rate. To enhance the scholarly discussion in this field, the paper introduces a clearly defined hypothesis which describes plausible self-reinforcing mechanisms that would result, if unchecked, in a continued decrease of the number of births in the countries affected. This hypothesis has three components: a demographic one based on the negative population growth momentum, i.e., the fact that fewer potential mothers in the future will result in fewer births; a sociological one based on the assumption that ideal family size for the younger cohorts is declining as a consequence of the lower actual fertility they see in previous cohorts; and an economic one based on the first part of Easterlin\u2019s (1980) relative income hypothesis, namely, that fertility results from the combination of aspirations and expected income, and assuming that aspirations of young adults are on an increasing trajectory while the expected income for the younger cohorts declines, partly as a consequence of population ageing induced by low fertility. All three factors would work towards a downward spiral in births in the future. If there is reason to assume that such mechanisms will indeed be at work, then this should strengthen the motivation of governments to take immediate action (possibly through policies addressing the tempo effect) in order to still escape from the expected trap

Future Population and Human Capital in Heterogeneous India

Within the next decade India is expected to surpass China as the world’s most populous country due to still higher fertility and a younger population. Around 2025 each country will be home to around 1.5 billion people. India is demographically very heterogeneous with some rural illiterate populations still having more than four children on average while educated urban women have fewer than 1.5 children and with great differences between states. We show that the population outlook greatly depends on the degree to which this heterogeneity is explicitly incorporated into the population projection model used. The conventional projection model, considering only the age and sex structures of the population at the national level, results in a lower projected population than the same model applied at the level of states because over time the high-fertility states gain more weight, thus applying the higher rates to more people. The opposite outcome results from an explicit consideration of education differentials because over time the proportion of more educated women with lower fertility increases, thus leading to lower predicted growth than in the conventional model. To comprehensively address this issue, we develop a five-dimensional model of India’s population by state, rural/urban place of residence, age, sex, and level of education and show the impacts of different degrees of aggregation. We also provide human capital scenarios for all Indian states that suggest that India will rapidly catch up with other more developed countries in Asia if the recent pace of education expansion is maintained