9,680 research outputs found
H^+ -> W^+ l_i^- l_j^+$ decay in the two Higgs doublet model
We study the lepton flavor violating H^+ -> W^+ l_i^- l_j^+ and the lepton
flavor conserving $H^+ -> W^+ l_i^- l_i^+ (l_i=\tau, l_j=\mu) decays in the
general 2HDM, so called model III. We estimate the decay width \Gamma for LFV
(LFC) at the order of the magnitude of (10^{-11}-10^{-5}) GeV
((10^{-9}-10^{-4}) GeV), for 200 GeV\leq m_{H^\pm}\leq 400
GeV, and the intermediate values of the coupling
\bar{\xi}^{E}_{N,\tau \mu}\sim 5 GeV (\bar{\xi}^{E}_{N,\tau
\tau}\sim 30 GeV). We observe that the experimental result of the process
under consideration can give comprehensive information about the physics beyond
the standard model and the existing free parameters.Comment: 8 pages, 7 Figure
The impact of a large object with Jupiter in July 2009
On 2009 July 19, we observed a single, large impact on Jupiter at a
planetocentric latitude of 55^{\circ}S. This and the Shoemaker-Levy 9 (SL9)
impacts on Jupiter in 1994 are the only planetary-scale impacts ever observed.
The 2009 impact had an entry trajectory opposite and with a lower incidence
angle than that of SL9. Comparison of the initial aerosol cloud debris
properties, spanning 4,800 km east-west and 2,500 km north-south, with those
produced by the SL9 fragments, and dynamical calculations of pre-impact orbit,
indicate that the impactor was most probably an icy body with a size of 0.5-1
km. The collision rate of events of this magnitude may be five to ten times
more frequent than previously thought. The search for unpredicted impacts, such
as the current one, could be best performed in 890-nm and K (2.03-2.36 {\mu}m)
filters in strong gaseous absorption, where the high-altitude aerosols are more
reflective than Jupiter's primary cloud.Comment: 15 pages, 5 figure
Intrinsic decoherence and classical-quantum correspondence in two coupled delta-kicked rotors
We show that classical-quantum correspondence of center of mass motion in two
coupled delta-kicked rotors can be obtained from intrinsic decoherence of the
system itself which occurs due to the entanglement of the center of mass motion
to the internal degree of freedom without coupling to external environment
Optical Light Curve of the Type Ia Supernova 1998bu in M96 and the Supernova Calibration of the Hubble Constant
We present the UBVRI light curves of the Type Ia supernova SN 1998bu which
appeared in the nearby galaxy M96 (NGC 3368). M96 is a spiral galaxy in the Leo
I group which has a Cepheid-based distance. Our photometry allows us to
calculate the absolute magnitude and reddening of this supernova. These data,
when combined with measurements of the four other well-observed supernovae with
Cepheid based distances, allow us to calculate the Hubble constant with respect
to the Hubble flow defined by the distant Calan/Tololo Type Ia sample. We find
a Hubble constant of 64.0 +/- 2.2(internal) +/- 3.5(external) km/s/Mpc,
consistent with most previous estimates based on Type Ia supernovae. We note
that the two well-observed Type Ia supernovae in Fornax, if placed at the
Cepheid distance to the possible Fornax spiral NGC 1365, are apparently too
faint with respect to the Calan/Tololo sample calibrated with the five Type Ia
supernovae with Cepheid distances to the host galaxies.Comment: AAS LaTeX, 20 pages, 4 figures, 6 tables, accepted for publication in
the Astronomical Journal. Figure 1 (finding chart) not include
Quantum Pair Creation of Soliton Domain Walls
A large body of experimental evidence suggests that the decay of the false
vacuum, accompanied by quantum pair creation of soliton domain walls, can occur
in a variety of condensed matter systems. Examples include nucleation of charge
soliton pairs in density waves [eg. J. H. Miller, Jr. et al., Phys. Rev. Lett.
84, 1555 (2000)] and flux soliton pairs in long Josephon junctions. Recently,
Dias and Lemos [J. Math. Phys. 42, 3292 (2001)] have argued that the mass
of the soliton should be interpreted as a line density and a surface density,
respectively, for (2+1)-D and (3+1)-D systems in the expression for the pair
production rate. As the transverse dimensions are increased and the total mass
(energy) becomes large, thermal activation becomes suppressed, so quantum
processes can dominate even at relatively high temperatures. This paper will
discuss both experimental evidence and theoretical arguments for the existence
of high-temperature collective quantum phenomena
Area-angle variables for general relativity
We introduce a modified Regge calculus for general relativity on a
triangulated four dimensional Riemannian manifold where the fundamental
variables are areas and a certain class of angles. These variables satisfy
constraints which are local in the triangulation. We expect the formulation to
have applications to classical discrete gravity and non-perturbative approaches
to quantum gravity.Comment: 7 pages, 1 figure. v2 small changes to match published versio
NuSTAR reveals the hidden nature of SS433
SS433 is the only Galactic binary system known to accrete at highly
super-critical rates, analogous to tidal disruption events, and needed to
explain the mass of some high redshift quasars. Probing the inner regions of
SS433 in the X-rays is crucial to understanding this system, and super-critical
accretion in general, but has not yet been possible due to obscuration. NuSTAR
observed SS433 in the hard X-ray band across multiple phases of its
super-orbital precession period. Spectral-timing tools have allowed us to
confirm that the hard X-ray emission from the inner regions is scattered
towards us by the walls of the wind-cone. By comparing to numerical models, we
determine an intrinsic X-ray luminosity of >= 3x10^37 erg/s and that, if viewed
face on, the apparent luminosity would be > 1x10^39 erg/s, confirming its
long-suspected nature as an ultraluminous X-ray source (ULX). A lag due to
absorption by Fe XXV/XXVI in outflowing material travelling at least 0.14-0.29c
matches absorption lines seen in ULXs and - in future - will allow us to map a
super-critical outflow for the first time.Comment: 24 pages, 8 figures, submitted for publicatio
Creative and Stylistic Devices Employed by Children During a Storybook Narrative Task: A Cross-Cultural Study
Purpose: The purpose of this study was to analyze the effects of culture on the creative and stylistic features children employ when producing narratives based on wordless picture books.
Method: Participants included 60 first- and second-grade African American, Latino American, and Caucasian children. A subset of narratives based on wordless picture books collected as part of a larger study was coded and analyzed for the following creative and stylistic conventions: organizational style (topic centered, linear, cyclical), dialogue (direct, indirect), reference to character relationships (nature, naming, conduct), embellishment (fantasy, suspense, conflict), and paralinguistic devices (expressive sounds, exclamatory utterances).
Results: Many similarities and differences between ethnic groups were found. No significant differences were found between ethnic groups in organizational style or use of paralinguistic devices. African American children included more fantasy in their stories, Latino children named their characters more often, and Caucasian children made more references to the nature of character relationships.
Conclusion: Even within the context of a highly structured narrative task based on wordless picture books, culture influences children’s production of narratives. Enhanced understanding of narrative structure, creativity, and style is necessary to provide ecologically valid narrative assessment and intervention for children from diverse cultural backgrounds
Evaluation of turbulent dissipation rate retrievals from Doppler Cloud Radar
Turbulent dissipation rate retrievals from cloud radar Doppler velocity measurements are evaluated using independent, in situ observations in Arctic stratocumulus clouds. In situ validation data sets of dissipation rate are derived using sonic anemometer measurements from a tethered balloon and high frequency pressure variation observations from a research aircraft, both flown in proximity to stationary, ground-based radars. Modest biases are found among the data sets in particularly low- or high-turbulence regimes, but in general the radar-retrieved values correspond well with the in situ measurements. Root mean square differences are typically a factor of 4-6 relative to any given magnitude of dissipation rate. These differences are no larger than those found when comparing dissipation rates computed from tetheredballoon and meteorological tower-mounted sonic anemometer measurements made at spatial distances of a few hundred meters. Temporal lag analyses suggest that approximately half of the observed differences are due to spatial sampling considerations, such that the anticipated radar-based retrieval uncertainty is on the order of a factor of 2-3. Moreover, radar retrievals are clearly able to capture the vertical dissipation rate structure observed by the in situ sensors, while offering substantially more information on the time variability of turbulence profiles. Together these evaluations indicate that radar-based retrievals can, at a minimum, be used to determine the vertical structure of turbulence in Arctic stratocumulus clouds
- …