4,382 research outputs found
About a peculiar U(1): Z' discovery limit, muon anomalous magnetic moment and electron electric dipole moment
The model (Lagrangian) with a peculiar extra U(1)is clearly presented. The
assigned extra U(1) gauge charges give a strong constraint to build
Lagrangians. The Z' discovery limits are estimated and predicted at the
Tevatron and the LHC. The new contributions of the muon anomalous magnetic
moment are investigated at one and two loops, and we predict that the deviation
from the standard model may be explained. The electron electric dipole moment
could also be generated because of the explicit CP violation effect in the
Higgs sector, and a sizable contribution is expected for a moderately sized CP
phase(argument of the CP-odd Higgs).Comment: 16 pages, 6 figure
Non-monotonic temperature dependent transport in graphene grown by Chemical Vapor Deposition
Temperature-dependent resistivity of graphene grown by chemical vapor
deposition (CVD) is investigated. We observe in low mobility CVD graphene
device a strong insulating behavior at low temperatures and a metallic behavior
at high temperatures manifesting a non-monotonic in the temperature dependent
resistivity.This feature is strongly affected by carrier density modulation. To
understand this anomalous temperature dependence, we introduce thermal
activation of charge carriers in electron-hole puddles induced by randomly
distributed charged impurities. Observed temperature evolution of resistivity
is then understood from the competition among thermal activation of charge
carriers, temperature-dependent screening and phonon scattering effects. Our
results imply that the transport property of transferred CVD-grown graphene is
strongly influenced by the details of the environmentComment: 7 pages, 3 figure
Z_3 Strings and their Interactions
We construct Z_3 vortex solutions in a model in which SU(3) is spontaneously
broken to Z_3. The model is truncated to one in which there are only two
dimensionless free parameters and the interaction of vortices within this
restricted set of models is studied numerically. We find that there is a curve
in the two dimensional space of parameters for which the energy of two
asymptotically separated vortices equals the energy of the vortices at
vanishing separation. This suggests that the inter-vortex potential for Z_3
strings might be flat for these couplings, much like the case of U(1) strings
in the Bogomolnyi limit. However, we argue that the intervortex potential is
attractive at short distances and repulsive at large separations leading to the
possibility of unstable bound states of Z_3 vortices.Comment: 8 pages; mainly corrected typos in table
Atomic Layer Deposition of Ni Thin Films and Application to Area-Selective Deposition
Ni thin films were deposited by atomic layer deposition (ALD) using bis(dimethylamino-2-methyl-2-butoxo)nickel [Ni(dmamb)(2)] as a precursor and NH3 gas as a reactant. The growth characteristics and film properties of ALD Ni were investigated. Low-resistivity films were deposited on Si and SiO2 substrates, producing high-purity Ni films with a small amount of oxygen and negligible amounts of nitrogen and carbon. Additionally, ALD Ni showed excellent conformality in nanoscale via holes. Utilizing this conformality, Ni/Si core/shell nanowires with uniform diameters were fabricated. By combining ALD Ni with octadecyltrichlorosilane (OTS) self-assembled monolayer as a blocking layer, area-selective ALD was conducted for selective deposition of Ni films. When performed on the prepatterned OTS substrate, the Ni films were selectively coated only on OTS-free regions, building up Ni line patterns with 3 mu m width. Electrical measurement results showed that all of the Ni lines were electrically isolated, also indicating the selective Ni deposition. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3504196] All rights reserved.ope
1s-intraexcitonic dynamics in monolayer MoS2 probed by ultrafast mid-infrared spectroscopy
The 1s exciton-the ground state of a bound electron-hole pair-is central to understanding the photoresponse of monolayer transition metal dichalcogenides. Above the 1s exciton, recent visible and near-infrared investigations have revealed that the excited excitons are much richer, exhibiting a series of Rydberg-like states. A natural question is then how the internal excitonic transitions are interrelated on photoexcitation. Accessing these intraexcitonic transitions, however, demands a fundamentally different experimental tool capable of probing optical transitions from 1s 'bright' to np 'dark' states. Here we employ ultrafast midinfrared spectroscopy to explore the 1s intraexcitonic transitions in monolayer MoS2. We observed twofold 1s-3p intraexcitonic transitions within the A and B excitons and 1s-2p transition between the A and B excitons. Our results revealed that it takes about 0.7 ps for the 1s A exciton to reach quasi-equilibrium; a characteristic time that is associated with a rapid population transfer from the 1s B exciton, providing rich characteristics of many-body exciton dynamics in two-dimensional materials.112412Ysciescopu
Raman-scattered O VI Features in the Symbiotic Nova RR Telescopii
RR Tel is an interacting binary system in which a hot white dwarf (WD) accretes matter from a Mira-type variable star via gravitational capture of its stellar wind. This symbiotic nova shows intense Raman-scattered O VI 1032 and 1038 features at 6825 ˚A and 7082 ˚A. We present high-resolution optical spectra of RR Tel taken in 2016 and 2017 with the Magellan Inamori Kyocera Echelle (MIKE) spectrograph at Magellan-Clay telescope, Chile. We aim to study the stellar wind accretion in RR Tel from the profile analysis of Raman O VI features. With an asymmetric O VI disk model, we derive a representative Keplerian speed of > 35 km s−1 , and the corresponding scale < 0.8 au. The best-fit for the Raman profiles is obtained with a mass loss rate of the Mira M˙ ∼ 2 × 10−6 M yr−1 and a wind terminal velocity v∞ ∼ 20 km s−1 . We compare the MIKE data with an archival spectrum taken in 2003 with the Fibre-fed Extended Range Optical Spectrograph (FEROS) at the MPG/ESO 2.2 m telescope. It allows us to highlight the profile variation of the Raman O VI features, indicative of a change in the density distribution of the O VI disk in the last two decades. We also report the detection of O VI recombination lines at 3811 ˚A and 3834 ˚A, which are blended with other emission lines. Our profile decomposition suggests that the recombination of O VII takes place nearer to the WD than the O VI 1032 and 1038 emission region.Fil: Heo, J. E.. Observatorio Gemini; Chile. Universidad de La Serena; Chile. Sejong University; Corea del SurFil: Lee, H. W.. Universidad de Sejong; Corea del SurFil: Angeloni, R.. Universidad de La Serena; ChileFil: Palma, Tali. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Departamento de Astrofísica Estelar; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Di Mille, F.. Observatorio Las Campanas; Chil
Freshwater Ecosystems: From Models to Applications
Freshwater ecosystems—lakes and streams—are being endangered by agricultural, urban, and industrial pollution; hydraulic engineering; and overexploitation, which threaten their capacity to provide important services (recreation and supply of food and clean water, among others). Ecological modeling may be employed to estimate impacts and analyze mitigation strategies. Toy models are easy to construct, but applying them to real-world problems is often challenging. Here, we show in two case studies how the connection from model to application can be made. The first study analyzes whether and how the impact of climatic change on a mostly recreational fishery in an Alpine lake can be mitigated, while the second looks at restoring biodiversity after cleaning up pollution in a Korean river system, using aquatic insects, which play an essential functional role in aquatic food-webs and are very sensitive to water quality, as indicators of ecosystem health. These studies highlight the ability of process-based eco-evolutionary models to generate testable hypotheses and contribute solutions to real-world problems
Changes in inorganic aerosol compositions over the Yellow Sea area from impact of Chinese emissions mitigation
Substantial mitigation of air pollutants emissions has been performed since 2013 around Beijing, and changes in the atmospheric characteristics have been expected over the downstream area of Beijing. In this study, both WRF-Chem simulation and on-site measurements were utilized for the Baengnyeong (island) supersite, one of the representative regional background sites located in the Yellow Sea, the entrance area of the long-range transport process in Korea. The changes in the chemical compositions of inorganic aerosols were examined for spring-time during the Chinese emission mitigation period from 2014 to 2016.
The measured ratio of ionic species to PM2.5 at the Baengnyeong supersite showed changes in aerosol inorganic chemical compositions from sulfate in 2014 to nitrate in 2015–2016. The modeling results also showed that nitrate was low in 2014 and significantly increased in 2015 and 2016, and the acidic aerosol condition had also changed toward a more neutralized status in both the simulation and the observations. The WRF-Chem modeling study further indicated that the sulfur was not neutralized in 2014. However, in 2015 and 2016, SO2 was more sufficiently neutralized as sulfur emissions were substantially reduced in China, while at the same time nitrate had begun to increase in such a ‘SO2–poor’ condition in Beijing area in China, and thus approaching more enhanced neutralization over the Yellow Sea area. The causes of the higher nitrate based on the modeled characteristics of the ammonia-sulfate-nitrate aerosol formation in response to the SO2 emissions reduction in China are also discussed in this paper
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