7,818 research outputs found
Aspects of Noncommutative Scalar/Tensor Duality
We study the noncommutative massless Kalb-Ramond gauge field coupled to a
dynamical U(1) gauge field in the adjoint representation together with a
compensating vector field. We derive the Seiberg-Witten map and obtain the
corresponding mapped action to first order in . The (emergent) gravity
structure found in other situations is not present here. The off-shell dual
scalar theory is derived and it does not coincide with the Seiberg-Witten
mapped scalar theory. Dispersion relations are also discussed. The p-form
generalization of the Seiberg-Witten map to order is also derived.Comment: 7 pages, typos corrected, a footnote removed and a sentence added in
the tex
Adventures of a tidally induced bar
Using N-body simulations, we study the properties of a bar induced in a discy dwarf galaxy as a result of tidal interaction with the Milky Way. The bar forms at the first pericentre passage and survives until the end of the evolution at 10 Gyr. Fourier decomposition of the bar reveals that only even modes are significant and preserve a hierarchy so that the bar mode is always the strongest. They show a characteristic profile with a maximum, similar to simulated bars forming in isolated galaxies and observed bars in real galaxies. We adopt the maximum of the bar mode as a measure of the bar strength and we estimate the bar length by comparing the density profiles along the bar and perpendicular to it. The bar strength and the bar length decrease with time, mainly at pericentres, as a result of tidal torques acting at those times and not to secular evolution. The pattern speed of the bar varies significantly on a time-scale of 1 Gyr and is controlled by the orientation of the tidal torque from the Milky Way. The bar is never tidally locked, but we discover a hint of a 5/2 orbital resonance between the third and fourth pericentre passage. The speed of the bar decreases in the long run so that the bar changes from initially rather fast to slow in the later stages. The boxy/peanut shape is present for some time and its occurrence is preceded by a short period of buckling instability
Updating Bounds on -Parity Violating Supersymmetry from Meson Oscillation Data
We update the bounds on -parity violating supersymmetry originating from
meson oscillations in the and systems. To this end, we
explicitly calculate all corresponding contributions from -parity violating
operators at the one-loop level, thereby completing and correcting existing
calculations. We apply our results to the derivation of bounds on -parity
violating couplings, based on up-to-date experimental measurements. In
addition, we consider the possibility of cancellations among flavor-changing
contributions of various origins, e.g. from multiple -parity violating
couplings or -parity conserving soft terms. Destructive interferences among
new-physics contributions could then open phenomenologically allowed regions,
for values of the parameters that are naively excluded when the parameters are
varied individually.Comment: 53 pages, 10 figures, 2 tables; final versio
Zero-bias conductance peak and Josephson effect in graphene-NbTiN junctions
We report electronic transport measurements of graphene contacted by NbTiN
electrodes, which at low temperature remain superconducting up to at least 11
Tesla. In devices with a single superconducting contact, we find a more than
twofold enhancement of the conductance at zero bias, which we interpret in
terms of reflectionless tunneling. In devices with two superconducting
contacts, we observe the Josephson effect, bipolar supercurrents and Fraunhofer
patterns.Comment: 6 pages, 5 figure
Elliptic flow of thermal dileptons as a probe of QCD matter
We study the variation of elliptic flow of thermal dileptons with transverse
momentum and invariant mass of the pairs for Pb+Pb collisions at
= 2.76 TeV. The dilepton productions from quark gluon plasma
(QGP) and hot hadrons have been considered including the spectral change of
light vector mesons in the thermal bath. The space time evolution has been
carried out within the frame work of 2+1 dimensional ideal hydrodynamics with
lattice+hadron resonance gas equation of state. We find that a judicious
selection of invariant mass(M) and transverse momentum (p_T) windows can be
used to extract the collective properties of quark matter, hadronic matter and
also get a distinct signature of medium effects on vector mesons. Our results
indicate a reduction of elliptic flow (v_2) for M beyond phi mass, which if
observed experimentally would give the measure of v_2 of the partonic phase.Comment: To appear in Phys. Rev. C (Rapid Comm.
Obituary: In Memory of Michael Jonathan Zigmond, Ph.D., September 1, 1941–August 28, 2023
Producción CientÃficaNo abstract availabl
Bar-Halo Friction in Galaxies II: Metastability
It is well-established that strong bars rotating in dense halos generally
slow down as they lose angular momentum to the halo through dynamical friction.
Angular momentum exchanges between the bar and halo particles take place at
resonances. While some particles gain and others lose, friction arises when
there is an excess of gainers over losers. This imbalance results from the
generally decreasing numbers of particles with increasing angular momentum, and
friction can therefore be avoided if there is no gradient in the density of
particles across the major resonances. Here we show that anomalously weak
friction can occur for this reason if the pattern speed of the bar fluctuates
upwards. After such an event, the density of resonant halo particles has a
local inflexion created by the earlier exchanges, and bar slowdown can be
delayed for a long period; we describe this as a metastable state. We show that
this behavior in purely collisionless N-body simulations is far more likely to
occur in methods with adaptive resolution. We also show that the phenomenon
could arise in nature, since bar-driven gas inflow could easily raise the bar
pattern speed enough to reach the metastable state. Finally, we demonstrate
that mild external, or internal, perturbations quickly restore the usual
frictional drag, and it is unlikely therefore that a strong bar in a galaxy
having a dense halo could rotate for a long period without friction.Comment: 13 pages, 11 figures, to appear in Ap
Survey Sarana dan Prasarana Pendidikan Jasmani Sekolah Menengah Pertama di Kecamatan Bengkayang Tahun 2013
The researcher how education facility and infrastructure corporealsecondary school levels first in kecamatam bengkayang 2013.Can also researchpurposes is to expresses a condition facility in learning education corporeal in highschool first in -kecamatan bengkayang 2013.Methods used method of surveying is usingdescriptive prosentase and technical data use observation, and documentation.Thepopulation is junior high school di-kecamatan bengkayang which totaled 8 schoolconsisting 3 land and 5 private sector.Technique the sample collection is total samplingis taken all populasi.adapun data processing obtained then examined back, classifiedaccording to golongannya.Based on analysis of data and obtained the result as follows:1) Athletic facilities and infrastructure that were in the category of good 0.00%, just25%, less than 75%. 2) facilities and infrastructure in the category of games that aregood enough, 0.00% 0.00%, less than 100%. 3). infrastructure Gymnastics of physicaleducation that were in the category of good 0.00%, quite a 37.50%, 62.5% less. 4) Totaloverall are in good category 0.00%, just 20. 83%, less 79.16%. Thus, physical educationfacilities and infrastructure in junior high se-Sub Bengkayang stated purpose within thecategory less
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