Cosmological Implications of some Nonstandard Particle Physics Models

The standard cosmological model has been very successful in describing the evolution of the Universe from the first seconds until today. However, some challenges still remain concerning the nature of some of its components as well as observationally probing some of the periods of its expansion. In this thesis we discuss what are probably the three least known components of the Universe: neutrinos, dark matter, and dark energy. In particular, concerning the neutrino sector, we place limits on the relic neutrino asymmetries using some of the latest cosmological data, taking into account the effect of flavor oscillations. We find that the present bounds are still dominated by the limits coming from big bang nucleosynthesis, while the limits on the total neutrino mass from cosmological data are essentially independent of theta13. Moreover, we perform a forecast for Cosmic Origins Explorer, taken as an example of a future cosmic microwave background experiment, and find that it could improve the limits on the total lepton asymmetry. We also consider models of dark energy in which neutrinos interact with the scalar field supposed to be responsible for the acceleration of the Universe, usually implying a variation of the neutrino masses on cosmological time scales. We propose a parameterization for the neutrino mass variation that captures the essentials of those scenarios and allows one to constrain them in a model independent way, that is, without resorting to any particular scalar field model. Using different datasets we show that the ratio of the mass variation of the neutrino mass over the current mass is smaller than approximately 10−2 at 95% C.L., totally consistent with no mass variation. Finally, we discuss how observations of the 21-cm line of the atomic hydrogen at the early universe have the potential to probe the unexplored period between the so-called dark ages and the reionization epoch of the Universe, and how it can be used to place limits on particle physics properties, in particular constraints on the mass and self-annihilation cross-section of the dark matter particles

Cosmological lepton asymmetry with a nonzero mixing angle \theta_{13}

While the baryon asymmetry of the Universe is nowadays well measured by cosmological observations, the bounds on the lepton asymmetry in the form of neutrinos are still significantly weaker. We place limits on the relic neutrino asymmetries using some of the latest cosmological data, taking into account the effect of flavor oscillations. We present our results for two different values of the neutrino mixing angle \theta_{13}, and show that for large \theta_{13} the limits on the total neutrino asymmetry become more stringent, diluting even large initial flavor asymmetries. In particular, we find that the present bounds are still dominated by the limits coming from Big Bang Nucleosynthesis, while the limits on the total neutrino mass from cosmological data are essentially independent of \theta_{13}. Finally, we perform a forecast for COrE, taken as an example of a future CMB experiment, and find that it could improve the limits on the total lepton asymmetry approximately by up to a factor 6.6.Comment: 11 pages, 7 figures, 5 tables. v2: updated COrE specifications. v3: matches Phys. Rev. D accepted versio

Probing interactions within the dark matter sector via extra radiation contributions

The nature of dark matter is one of the most thrilling riddles for both cosmology and particle physics nowadays. While in the typical models the dark sector is composed only by weakly interacting massive particles, an arguably more natural scenario would include a whole set of gauge interactions which are invisible for the standard model but that are in contact with the dark matter. We present a method to constrain the number of massless gauge bosons and other relativistic particles that might be present in the dark sector using current and future cosmic microwave background data, and provide upper bounds on the size of the dark sector. We use the fact that the dark matter abundance depends on the strength of the interactions with both sectors, which allows one to relate the freeze-out temperature of the dark matter with the temperature of this cosmic background of dark gauge bosons. This relation can then be used to calculate how sizable is the impact of the relativistic dark sector in the number of degrees of freedom of the early Universe, providing an interesting and testable connection between cosmological data and direct/indirect detection experiments. The recent Planck data, in combination with other cosmic microwave background experiments and baryonic acoustic oscillations data, constrains the number of relativistic dark gauge bosons, when the freeze-out temperature of the dark matter is larger than the top mass, to be N<14 for the simplest scenarios, while those limits are slightly relaxed for the combination with the Hubble constant measurements to N<20. Future releases of Planck data are expected to reduce the uncertainty by approximately a factor of 3, which will reduce significantly the parameter space of allowed models

ETNOBOTÂNICA HISTÓRICA DAS PLANTAS DO MARANHÃO NO SÉCULO XVII BASEADA NA OBRA DE CRISTÓVÃO DE LISBOA

When the Portuguese settlers arrived in Brazil, they were impressed by the diversity of plants and uses known to the Indians. The general objective of the study was to verify the uses and provenances of the plants of Maranhão in century XVII through documentary analysis of the work of Cristóvão de Lisboa, and more specifically; identify the plants according to the current botanical nomenclature. The methodology of the work was based on the consultation of the facsimile edition of the work 'History of animals and trees of Maranhão'. Of the total number of plants (n = 55) extracted from the work, 87.27% (n = 48) were identified botanically at least at the family level, and, 12.73% (n = 07) were not identified. Regarding the origin of the species, 98.18% (n = 54) was composed of native species, and only 1.82% (n = 1) consisted of exotic species. The importance of food was highlighted among the uses raised (74%). The manioc (Manihot esculenta Crantz; Euphorbiaceae) and passion fruit (Passiflora spp.; Passifloraceae) were the best-known species among the Indians of the time. Finally, the total number of plants contained in the work of Cristóvão de Lisboa (n = 55) was lower than expected for Maranhão, an area of contact between the main Brazilian biomes.Keywords: Historiography of plants; documentary analysis; Flora of Maranhão.Quando os colonizadores portugueses chegaram ao Brasil, ficaram impressionados com a diversidade de plantas e de usos conhecidos pelos indígenas. O objetivo geral do estudo foi o de verificar os usos e procedências das plantas do Maranhão no século XVII mediante análise documental da obra de Cristóvão de Lisboa, e mais especificamente; identificar as plantas de acordo com a nomenclatura botânica atual. A metodologia do trabalho baseou-se na consulta da edição fac-símile da obra ‘História dos animais e árvores do Maranhão’. Da totalidade de plantas (n= 55) extraídas da obra, 87,27% (n= 48) foram identificadas botanicamente pelo menos ao nível de família, e, 12,73% (n=07) não foram identificadas. Quanto à procedência das espécies, 98,18% (n= 54) foi constituída por espécies nativas, e apenas 1,82% (n= 1) constituída por exótica.  A importância alimentícia teve grande destaque entre os usos levantados (74%). A mandioca (Manihot esculenta Crantz; Euphorbiaceae) e os maracujás (Passiflora spp.; Passifloraceae), foram as espécies mais conhecidas entre os indígenas da época. Por fim, o número total de plantas contidas na obra de Cristóvão de Lisboa (n=55), foi aquém do esperado para o Maranhão, área de contato entre os principais biomas brasileiros.Palavras-chave: Historiografia de plantas, análise documental, Flora do Maranhão

Age constraints and fine tuning in variable-mass particle models

VAMP (variable-mass particles) scenarios, in which the mass of the cold dark matter particles is a function of the scalar field responsible for the present acceleration of the Universe, have been proposed as a solution to the cosmic coincidence problem, since in the attractor regime both dark energy and dark matter scale in the same way. We find that only a narrow region in parameter space leads to models with viable values for the Hubble constant and dark energy density today. In the allowed region, the dark energy density starts to dominate around the present epoch and consequently such models cannot solve the coincidence problem. We show that the age of the Universe in this scenario is considerably higher than the age for noncoupled dark energy models, and conclude that more precise independent measurements of the age of the Universe would be useful in distinguishing between coupled and noncoupled dark energy models.Comment: 7 pages, 8 figures, matches the Phys. Rev. D published versio

Frequency, trends, and antecedents of severe maternal depression after three million U.S. births

Background: Postpartum depression carries adverse consequences for mothers and children, so widespread screening during primary care visits is recommended. However, the rates, timing, and factors associated with significant depressive episodes are incompletely understood. Methods and findings We examined the Healthcare Cost and Utilization Project (HCUP) State Inpatient, Emergency Department, and Ambulatory Surgery and Services Databases from California (2005–2011) and Florida (2005–2012). Within 203 million records, we identified 3,213,111 births and all mothers who had hospital encounters for severe depression within 40 weeks following delivery. We identified 15,806 episodes of postpartum depression after 11,103 deliveries among 10,883 unique women, and calculated an overall rate of 36.7 depression- associated hospital visits per 10,000 deliveries. Upward trends were observed in both states, with combined five-year increases of 34%. First depressive events were most common within 30 days of delivery, but continued for the entire observation period. About half (1,661/3,325) of PPD first episodes occurred within 34 days of delivery, 70% (2,329/3,325) by the end of the second month, and 87% (2,893/3,325) before four-months of the delivery. Women with private insurance were less likely to have hospital encounters for depression than women with public insurance and women with depression were much more likely to have had some kind of hospital encounter at some time during their pregnancies. Rates of depression increased with the number of prenatal hospital encounters in a “dose-dependent” fashion: the rate of depression was 17.2/10,000 for women with no prenatal hospital visits, doubling for women with at least one encounter (34.9/10,000), and increasing 7-fold to 126/10,000 for women with three or more encounters during their pregnancies. Conclusions: Our findings suggest that (1) hospital encounters for post-partum depression are increasing, (2) screening should begin very early and continue for the first year after delivery, and (3) added attention should be given to women who had hospital encounters during their pregnancies