17,109 research outputs found
Theoretical correction to the neutral meson asymmetry
Certain types of asymmetries in neutral meson physics have not been treated
properly, ignoring the difference of normalization factors with an assumption
of the equality of total decay width. Since the corrected asymmetries in
meson are different from known asymmetries by a shift in the first order of CP-
and CPT-violation parameters, experimental data should be analyzed with the
consideration of this effect as in meson physics.Comment: 7 page
Type IIP supernova light curves affected by the acceleration of red supergiant winds
We introduce the first synthetic light-curve model set of Type IIP supernovae
exploded within circumstellar media in which the acceleration of the red
supergiant winds is taken into account. Because wind acceleration makes the
wind velocities near the progenitors low, the density of the immediate vicinity
of the red supergiant supernova progenitors can be higher than that
extrapolated by using a constant terminal wind velocity. Therefore, even if the
mass-loss rate of the progenitor is relatively low, it can have a dense
circumstellar medium at the immediate stellar vicinity and the early light
curves of Type IIP supernovae are significantly affected by it. We adopt a
simple beta velocity law to formulate the wind acceleration. We provide
bolometric and multicolor light curves of Type IIP supernovae exploding within
such accelerated winds from the combinations of three progenitors, 12 - 16
Msun; five beta, 1-5; seven mass-loss rates, 1e-5 - 1e-2 Msun/yr; and four
explosion energies, 0.5e51 - 2e51 erg. All the light curve models are available
at https://goo.gl/o5phYb. When the circumstellar density is sufficiently high,
our models do not show a classical shock breakout as a consequence of the
interaction with the dense and optically-thick circumstellar media. Instead,
they show a delayed 'wind breakout', substantially affecting early light curves
of Type IIP supernovae. We find that the mass-loss rates of the progenitors
need to be 1e-3 - 1e-2 Msun/yr to explain typical rise times of 5 - 10 days in
Type IIP supernovae assuming a dense circumstellar radius of 1e15 cm.Comment: 12 pages, 9 figures, 2 tables, accepted by Monthly Notices of the
Royal Astronomical Societ
Renormalization analysis of intermittency in two coupled maps
The critical behavior for intermittency is studied in two coupled
one-dimensional (1D) maps. We find two fixed maps of an approximate
renormalization operator in the space of coupled maps. Each fixed map has a
common relavant eigenvaule associated with the scaling of the control parameter
of the uncoupled one-dimensional map. However, the relevant ``coupling
eigenvalue'' associated with coupling perturbation varies depending on the
fixed maps. These renormalization results are also confirmed for a
linearly-coupled case.Comment: 11 pages, RevTeX, 2 eps figure
New Measurements of Ge Decay: Impact on the Gallium Anomaly
A dedicated high-statistics measurement of the Ge half-life is found
to be in accurate agreement with an accepted value of 11.430.03 d,
eliminating a recently proposed route to bypass the "gallium anomaly" affecting
several neutrino experiments. Our data also severely constrain the possibility
of Ge decay to low-energy excited levels of the Ga daughter
nucleus as a solution to this puzzle. Additional unpublished measurements of
this decay are discussed. Following the incorporation of this new information,
the gallium anomaly survives with high statistical significance.Comment: 3 pages, 2 figure
Ultra-stripped Type Ic supernovae from close binary evolution
Recent discoveries of weak and fast optical transients raise the question of
their origin. We investigate the minimum ejecta mass associated with
core-collapse supernovae (SNe) of Type Ic. We show that mass transfer from a
helium star to a compact companion can produce an ultra-stripped core which
undergoes iron core collapse and leads to an extremely fast and faint SN Ic. In
this Letter, a detailed example is presented in which the pre-SN stellar mass
is barely above the Chandrasekhar limit, resulting in the ejection of only
~0.05-0.20 M_sun of material and the formation of a low-mass neutron star. We
compute synthetic light curves of this case and demonstrate that SN 2005ek
could be explained by our model. We estimate that the fraction of such
ultra-stripped to all SNe could be as high as 0.001-0.01. Finally, we argue
that the second explosion in some double neutron star systems (for example, the
double pulsar PSR J0737-3039B) was likely associated with an ultra-stripped SN
Ic.Comment: ApJ Letters, in press, 6 pages, 5 figures (emulateapj style). Very
minor changes to match printed version. Follow DOI link below for online
published versio
On the origin of microturbulence in hot stars
We present results from the first extensive study of convection zones in the
envelopes of hot massive stars, which are caused by opacity peaks associated
with iron and helium ionization. These convective regions can be located very
close to the stellar surface. Recent observations of microturbulence in massive
stars from the VLT-Flames survey are in good agreement with our predictions
concerning the occurrence and the strength of sub-surface convection in hot
stars. We argue further that convection close to the surface may trigger
clumping at the base of the stellar wind of massive stars.Comment: to appear in Comm. in Astroseismology - Proceedings of the 38th
LIAC/HELAS-ESTA/BAG, 200
Impurities, Quantum Interference and Quantum Phase Transitions in s-wave superconductors
We study the effects of quantum interference in impurity structures
consisting of two or three magnetic impurities that are located on the surface
of an s-wave superconductor. By using a self-consistent Bogoliubov-de Gennes
formalism, we show that quantum interference leads to characteristic signatures
not only in the local density of states (LDOS), but also in the spatial form of
the superconducting order parameter. We demonstrate that the signatures of
quantum interference in the LDOS are qualitatively, and to a large extent
quantitatively unaffected by the suppression of the superconducting order
parameter near impurities, which illustrates the robustness of quantum
interference phenomena. Moreover, we show that by changing the interimpurity
distance, or the impurities' scattering strength, the s-wave superconductor can
be tuned through a series of first order quantum phase transitions in which the
spin polarization of its ground state changes. In contrast to the single
impurity case, this transition is not necessarily accompanied by a -phase
shift of the order parameter, and can in certain cases even lead to its
enhancement. Our results demonstrate that the superconductor's LDOS, its spin
state, and the spatial form of the superconducting order parameter are
determined by a subtle interplay between the relative positions of the
impurities and their scattering strength
Conformal Couplings in Induced Gravity
It is found that the induced gravity with conformal couplings requires the
conformal invariance in both classical and quantum levels for consistency. This
is also true for the induced gravity with an extended conformal coupling
interacting with torsion.Comment: 10 pages, Revtex3.0, to appear in General Relativity and Gravitatio
Stochastic motion planning and applications to traffic
This paper presents a stochastic motion planning algorithm and its application to traffic navigation. The algorithm copes with the uncertainty of road traffic conditions by stochastic modeling of travel delay on road networks. The algorithm determines paths between two points that optimize a cost function of the delay probability distribution. It can be used to find paths that maximize the probability of reaching a destination within a particular travel deadline. For such problems, standard shortest-path algorithms don’t work because the optimal substructure property doesn’t hold. We evaluate our algorithm using both simulations and real-world drives, using delay data gathered from a set of taxis equipped with GPS sensors and a wireless network. Our algorithm can be integrated into on-board navigation systems as well as route-finding Web sites, providing drivers with good paths that meet their desired goals.National Science Foundation (U.S.) (grant EFRI-0710252)National Science Foundation (U.S.) (grant IIS-0426838
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