1,207 research outputs found

    Precise bounds on the Higgs boson mass

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    We study the renormalization group evolution of the Higgs quartic coupling λH\lambda_{H} and the Higgs mass mHm_{H} in the Standard Model. The one loop equation for λH\lambda_{H} is non linear and it is of the Riccati type which we numerically and analytically solve in the energy range [mt,EGU][m_{t},E_{GU}] where mtm_{t} is the mass of the top quark and EGU=1014E_{GU}=10^{14} GeV. We find that depending on the value of λH(mt)\lambda_{H}(m_{t}) the solution for λH(E)\lambda_{H}(E) may have singularities or zeros and become negative in the former energy range so the ultra violet cut off of the standard model should be below the energy where the zero or singularity of λH\lambda_{H} occurs. We find that for 0.369λH(mt)0.6130.369\leq\lambda_{H}(m_{t})\leq0.613 the Standard Model is valid in the whole range [mt,EGU][m_{t},E_{GU}]. We consider two cases of the Higgs mass relation to the parameters of the standard model: (a) the effective potential method and (b) the tree level mass relations. The limits for λH(mt)\lambda_{H}(m_{t}) correspond to the following Higgs mass relation 150mH193150\leq m_{H}\lessapprox 193 GeV. We also plot the dependence of the ultra violet cut off on the value of the Higgs mass. We analyze the evolution of the vacuum expectation value of the Higgs field and show that it depends on the value of the Higgs mass. The pattern of the energy behavior of the VEV is different for the cases (a) and (b). The behavior of λH(E)\lambda_{H}(E), mH(E)m_{H}(E) and v(E)v(E) indicates the existence of a phase transition in the standard model. For the effective potential this phase transition occurs at the mass range mH180m_{H}\approx 180 GeV and for the tree level mass relations at mH168m_{H}\approx 168 GeV.Comment: 14 pages, 7 figures. Expanded the discussion of the Higgs mass relation between the parameters of the Standard Model. Included the method of the Higgs effective potentia

    Quark mixings as a test of a new symmetry of quark Yukawa couplings

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    Based on the hierarchy exhibited by quarks masses at low energies, we assume that Yukawa couplings of up and down quarks are related by YuYd2Y_u\propto Y_d^2 at grand unification scales. This ansatz gives rise to a symmetrical CKM matrix at the grand unification (GU) scale. Using three specific models as illustrative examples for the evolution down to low energies, we obtain the entries and asymmetries of the CKM matrix which are in very good agreement with their measured values. This indicates that the small asymmetry of the CKM matrix at low energies may be the effect of the renormalization group evolution only.Comment: LaTeX file, 10 pages including 1 tabl

    From cradle to grave: tracking socioeconomic inequalities in mortality in a cohort of 11 868 men and women born in Uppsala, Sweden, 1915-1929.

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    BACKGROUND: Ample evidence has shown that early-life social conditions are associated with mortality later in life. However, little attention has been given to the strength of these effects across specific age intervals from birth to old age. In this paper, we study the effect of the family's socioeconomic position and mother's marital status at birth on all-cause mortality at different age intervals in a Swedish cohort of 11 868 individuals followed across their lifespan. METHODS: Using the Uppsala Birth Cohort Multigenerational Study, we fitted Cox regression models to estimate age-varying HRs of all-cause mortality according to mother's marital status and family's socioeconomic position. RESULTS: Mother's marital status and family's socioeconomic position at birth were associated with higher mortality rates throughout life (HR 1.18 (95% CI 1.12 to 1.26) for unmarried mothers; 1.19 (95% CI 1.12 to 1.25) for low socioeconomic position). While the effect of family's socioeconomic position showed little variation across different age groups, the effect of marital status was stronger for infant mortality (HR 1.47 (95% CI 1.23 to 1.76); p=0.04 for heterogeneity). The results remained robust when early life and adult mediator variables were included. CONCLUSIONS: Family's socioeconomic position and mother's marital status involve different dimensions of social stratification with independent effects on mortality throughout life. Our findings support the importance of improving early-life conditions in order to enhance healthy ageing

    Relationship between moonlight and nightly activity patterns of the ocelot (Leopardus pardalis) and some of its prey species in Formosa, Northern Argentina

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    The moon can profoundly influence the activity patterns of animals. If predators are more successful under bright moonlight, prey species are likely to respond by shifting their own activity patterns (predator-avoidance hypothesis). However, the assumption that prey will necessarily avoid full-moon nights does not take into account that moonlight also allows prey to more easily detect predators, and to forage more efficiently. Thus, nightly activity patterns could depend on night vision capabilities (visual-acuity hypothesis). To consider the possible influences of moonlight and to distinguish between these hypotheses, we used camera-trapping records of a predator, the ocelot (Leopardus pardalis), and several of its night-active prey to compare activity patterns under different moonlight conditions. The ocelots' activity patterns were not strongly related to moonlight, but showed a slight tendency for higher activity during brighter nights. Tapeti rabbits (Sylvilagus brasiliensis) and brocket deer (Mazama americana) showed a clear preference for brighter nights. White-eared opossums (Didelphis albiventris) also showed a trend to be less active in new moon light. In contrast, smaller grey four-eyed opossums (Philander opossum) and the poor eye-sight nine-banded armadillo (Dasypus novemcinctus) showed similar activity patterns across all moon phases. Since activity patterns of most prey species were not shifted away from the activity of the ocelot, the differences between species are probably linked to their night vision capabilities, and emphasise the need for more information on the visual system of these taxa. Their activity patterns seem to be less strongly linked to avoidance of predation than previously thought, suggesting that foraging and predator detection benefits may play a more important role than usually acknowledged.The cameras were partly funded by a National Geographic Society/Waitt grant to MH (grant number NGS 1072-78) and partly by quality-related funding through the Research Excellence Framework to the Biological Sciences Research Group of the University of Derby. The long-term camera-trap monitoring was in part made possible through grants to EFD and the Owl Monkey Project from the L.S.B. Leakey Foundation, National Geographic Society and the National Science Foundation of the USA (NSF-BCS-0621020, 0837921 (REU), 0924352 (REU), 1026991 (REU), 1219368 (RAPID) and 1232349 (2012)

    Kerr nonlinearities and nonclassical states with superconducting qubits and nanomechanical resonators

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    We propose the use of a superconducting charge qubit capacitively coupled to two resonant nanomechanical resonators to generate Yurke-Stoler states, i.e. quantum superpositions of pairs of distinguishable coherent states 180^\circ out of phase with each other. This is achieved by effectively implementing Kerr nonlinearities induced through application of a strong external driving field in one of the resonators. A simple study of the effect of dissipation on our scheme is also presented, and lower bounds of fidelity and purity of the generated state are calculated. Our procedure to implement a Kerr nonlinearity in this system may be used for high precision measurements in nanomechanical resonators.Comment: 5 pages, 2 figures, fixed typo

    Influencia del tipo de bloque de arcilla aligerada en la transmitancia térmica equivalente de diferentes tipos de fachadas en edificios

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    This paper compares the equivalent thermal transmittances of different façades built using commercial clay bricks with three different thicknesses and façades made using the same method but with ceramic bricks with optimized rhomboidal interior geometry. Equivalent thermal transmittances of 0.300 W/m2·K were recorded for the rhomboidal brick with a thickness of 0.290 m and a façade with thermo-acoustic insulation and a large format brick on the interior, but the final thickness of the façade was 0.445 m. For ventilated façades made of the proposed rhomboidal brick with thicknesses of 0.290 and 0.240 m an 8–9% improvement was found, with values of 0.312 W/m2·K and 0.339 W/m2·K, respectively. It can be concluded that in view of the small difference in thermal terms, the best option is to use a brick 0.240 m thick, as the overall thickness of the façade will not then exceed 0.300 m.En el presente trabajo se comparan las transmitancias térmicas equivalentes de diferentes fachadas ejecutadas con bloques comerciales de tres espesores 0,290 m, 0,240 m y 0,190 m, con el mismo montaje pero con un bloque cerámico optimizado con geometría interior romboidal. Se ha obtenido una transmitancia térmica equivalente de 0,300 W/m2·K para el ladrillo con geometría romboidal de 0,290 m de espesor y pared con aislamiento termoacústico y gran formato en el interior, con un espesor total de fachada de 0,445 m. Para fachadas ventiladas con el ladrillo romboidal propuesto con espesores de 0,290 y 0,240 m, se obtiene una mejora de un 8%–9%, con valores de 0,312 W/m2·K y 0,339 W/m2·K, respectivamente. Podemos concluir que, dada la pequeña diferencia en términos térmicos, la mejor opción es el uso de ladrillos de 0,240 m de espesor, siempre y cuando el espesor total de fachada no exceda los 0,300 m
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