3,448 research outputs found

    Forbidden Channels and SIMP Dark Matter

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    In this review, we focus on dark matter production from thermal freeze-out with forbidden channels and SIMP processes. We show that forbidden channels can be dominant to produce dark matter depending on the dark photon and / or dark Higgs mass compared to SIMP.Comment: 5 pages, Prepared for the proceedings of the 13th International Conference on Gravitation, 3-7 July 201

    On thermal production of self-interacting dark matter

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    We consider thermal production mechanisms of self-interacting dark matter in models with gauged Z3Z_3 symmetry. A complex scalar dark matter is stabilized by the Z3Z_3, that is the remnant of a local dark U(1)dU(1)_d. Light dark matter with large self-interaction can be produced from thermal freeze-out in the presence of SM-annihilation, SIMP and/or forbidden channels. We show that dark photon and/or dark Higgs should be relatively light for unitarity and then assist the thermal freeze-out. We identify the constraints on the parameter space of dark matter self-interaction and mass in cases that one or some of the channels are important in determining the relic density.Comment: 26 pages, 11 figures, Version to appear in Journal of High Energy Physic

    Unitary inflaton as decaying dark matter

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    We consider the inflation model of a singlet scalar field (sigma field) with both quadratic and linear non-minimal couplings where unitarity is ensured up to the Planck scale. We assume that a Z2Z_2 symmetry for the sigma field is respected by the scalar potential in Jordan frame but it is broken explicitly by the linear non-minimal coupling due to quantum gravity. We discuss the impacts of the linear non-minimal coupling on various dynamics from inflation to low energy, such as a sizable tensor-to-scalar ratio, a novel reheating process with quartic potential dominance, and suppressed physical parameters in the low energy, etc. In particular, the linear non-minimal coupling leads to the linear couplings of the sigma field to the Standard Model through the trace of the energy-momentum tensor in Einstein frame. Thus, regarding the sigma field as a decaying dark matter, we consider the non-thermal production mechanisms for dark matter from the decays of Higgs and inflaton condensate and show the parameter space that is compatible with the correct relic density and cosmological constraints.Comment: 36 pages, 7 figures, v2: minor corrections made and references added, v3: discussion on preheating added, accepted for Journal of High Energy Physics, v4: Lyman-alpha bound included and inflationary predictions refined for perturbative reheatin

    A minimal flavored U(1)′U(1)' for BB-meson anomalies

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    We consider an anomaly-free U(1)′U(1)' model with favorable couplings to heavy flavors in the Standard Model(SM), as motivated by BB-meson anomalies at LHCb. Taking the U(1)′U(1)' charge to be Q′=y(Lμ−Lτ)+x(B3−L3)Q'=y(L_\mu-L_\tau)+ x(B_3-L_3), we can explain the BB-meson anomalies without invoking extra charged fermions or flavor violation beyond the SM. We show that there is a viable parameter space with a small xx that is compatible with other meson decays, tau lepton and neutrino experiments as well as the LHC dimuon searches. We briefly discuss the prospects of discovering the Z′Z' gauge boson at the LHC in the proposed model.Comment: 20 pages, 4 figures, v2: references and discussion on electroweak precision test added, v3: Version to appear in Physical Review

    Erratum: Dirichlet Forms and Dirichlet Operators for Infinite Particle Systems: Essential Self-adjointness

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    We reprove the essential self-adjointness of the Dirichlet operators of Dirchlet forms for infinite particle systems with superstable and sub-exponentially decreasing interactions.Comment: This is an erratum to the work appeared in J. Math. Phys. 39(12), 6509-6536 (1998

    Prevalence of sarcopenia and sarcopenic obesity in Korean adults: The Korean Sarcopenic Obesity Study (KSOS)

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    *Context:* Sarcopenic obesity (SO), a combination of excess weight and reduced muscle mass and/or strength, is suggested to be associated with an increased risk of adverse health outcomes. 
*Objectives:* To examine the prevalence and characteristics of Sarcopenic and SO defined by using different indices such as Appendicular Skeletal muscle Mass (ASM)/height^2^ and Skeletal Muscle Index (SMI (%): skeletal muscle mass (kg)/weight (kg) × 100) for Korean adults. 
*Methods:* 591 participants were recruited from the Korean Sarcopenic Obesity Study (KSOS) which is an ongoing prospective observational cohort study. Analysis was conducted in 526 participants (328 women, 198 men) who had complete data on body composition using Dual X-ray absorptiometry and computed tomography. 
*Results:* The prevalence of sarcopenia and SO increases with aging. Using two or more standard deviations (SD) of ASM/height^2^ below reference values from young, healthy adults as a definition of sarcopenia, the prevalence of sarcopenia and SO was 6.3% and 1.3% in men and 4.1% and 1.7% in women over 60 years of age. However, using two or more SD of SMI, the prevalence of sarcopenia and SO was 5.1% and 5.1% respectively in men and 14.2% and 12.5% respectively in women. As defined by SMI, subjects with SO had 3 times the risk of metabolic syndrome (OR = 3.03, 95% confidence interval (CI) = 1.26-7.26) and subjects with non-sarcopenic obesity had approximately 2 times the risk of metabolic syndrome (OR = 1.89, 95% CI = 1.18-3.02) compared with normal subjects. 
*Conclusion:* Obese subjects with relative sarcopenia were associated with a greater likelihood for metabolic syndrome. As Koreans were more obese and aging, the prevalence of SO and its impact on health outcomes are estimated to be rapidly grow. Further research is requested to establish the definition, cause and consequences of SO.
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    Analysis on city tour routes in relation to urban spatial structure and pedestrian movement

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    Gwangju has a plan for Urban Regeneration in an old urban center where it has witnessed the decrease of population and economic vitality, Gwangju tries to draw more tourists to the old urban center by introducing a large-scale cultural project. The Asia Culture Complex (ACC) scheduled to be completed in 2014 is the biggest cultural facility in Asia. It is supposed to bring many changes in urban spatial structure and to attract more tourists. This study, utilizing Space Syntax modeling, analyzes the spatial structure of the old urban center in Gwangju and predicts the changes in urban structure after the ACC will begin operated. It finally attempts to suggest tourist trails in the old urban center and analyze their property in relation to urban tourism.Peer Reviewe
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