181 research outputs found
Signatures of magnetic-field effects in nonsequential double ionization manifesting as backscattering for molecules versus forward scattering for atoms
For two-electron diatomic molecules, we investigate magnetic field effects in nonsequential double ionization where recollisions prevail. We do so by formulating a three-dimensional semiclassical model that fully accounts for the Coulomb singularities and for magnetic field effects during time propagation. Using this model, we identify a prominent signature of nondipole effects. Namely, we demonstrate that the recolliding electron backscatters along the direction of light propagation. Hence, this electron escapes opposite to the direction of change in momentum due to the magnetic field. This is in striking contrast to strongly driven atoms where the recolliding electron forward scatters along the direction of light propagation. We attribute these distinct signatures to the different gate that the magnetic field creates jointly with a soft recollision in molecules compared to a hard recollision in atoms. These two different gates give rise, shortly before recollision, to different momenta and positions of the recolliding electron along the direction of light propagation. As a result, we show that the Coulomb forces from the nuclei act to backscatter the recolliding electron in molecules and forward scatter it in atoms along the direction of light propagation
Conditionally optimal weights of evidence
A weight of evidence is a calibrated statistic whose values in [0, 1] indicate the degree of agreement between the data and either of two hypothesis, one being treated as the null (H 0) and the other as the alternative (H 1). A value of zero means perfect agreement with the null, whereas a value of one means perfect agreement with the alternative. The optimality we consider is minimal mean squared error (MSE) under the alternative while keeping the MSE under the null below a fixed bound. This paper studies such statistics from a conditional point of view, in particular for location and scale models. © Springer-Verlag 2005
Carbon K-shell Photo Ionization of CO: Molecular frame angular Distributions of normal and conjugate shakeup Satellites
We have measured the molecular frame angular distributions of photoelectrons
emitted from the Carbon K shell of fixed-in-space CO molecules for the case of
simultaneous excitation of the remaining molecular ion. Normal and conjugate
shake up states are observed. Photo electrons belonging to normal \Sigma
-satellite lines show an angular distribution resembling that observed for the
main photoline at the same electron energy. Surprisingly a similar shape is
found for conjugate shake up states with \Pi -symmetry. In our data we identify
shake rather than electron scattering (PEVE) as the mechanism producing the
conjugate lines. The angular distributions clearly show the presence of a
\Sigma -shape resonance for all of the satellite lines.Comment: 8 pages, 2 figure
The effect of CEO stock-based compensation on pricing of future earnings
This paper examines whether CEO stock-based compensation has an effect on the market's ability to predict future earnings. When stock-based compensation motivates managers to share their private information with shareholders, it will expedite the pricing of future earnings in current stock prices. In contrast, when equity-compensated managers attempt to temporarily manipulate the stock price to maximize their own benefit rather than that of shareholders, the market may not fully anticipate future performance. We find that a CEO's stock-based compensation strengthens the association between current returns and future earnings, indicating that more information about future earnings is reflected in current stock prices. In addition, we find that the positive effect is weaker for firms that have a high level of signed discretionary accruals or a low management forecast frequency. Overall, our study suggests that on average, equity-based compensation improves the informativeness of stock prices about future earnings, while opportunistic discretionary accruals or lowered earnings guidance hamper this improvement
Chronon corrections to the Dirac equation
The Dirac equation is not semisimple. We therefore regard it as a contraction
of a simpler decontracted theory. The decontracted theory is necessarily purely
algebraic and non-local. In one simple model the algebra is a Clifford algebra
with 6N generators. The quantum imaginary is the contraction of a
dynamical variable whose back-reaction provides the Dirac mass. The simplified
Dirac equation is exactly Lorentz invariant but its symmetry group is SO(3,3),
a decontraction of the Poincare group, and it has a slight but fundamental
non-locality beyond that of the usual Dirac equation. On operational grounds
the non-locality is ~10^{-25} sec in size and the associated mass is about the
Higgs mass.
There is a non-standard small but unique spin-orbit coupling ~1/N, whose
observation would be some evidence for the simpler theory. All the fields of
the Standard Model call for similar non-local simplification.Comment: 14 pages, no figures. Accepted to J.Math.Phy
Correlation dynamics between electrons and ions in the fragmentation of D molecules by short laser pulses
We studied the recollision dynamics between the electrons and D ions
following the tunneling ionization of D molecules in an intense short pulse
laser field. The returning electron collisionally excites the D ion to
excited electronic states from there D can dissociate or be further
ionized by the laser field, resulting in D + D or D + D,
respectively. We modeled the fragmentation dynamics and calculated the
resulting kinetic energy spectrum of D to compare with recent experiments.
Since the recollision time is locked to the tunneling ionization time which
occurs only within fraction of an optical cycle, the peaks in the D kinetic
energy spectra provides a measure of the time when the recollision occurs. This
collision dynamics forms the basis of the molecular clock where the clock can
be read with attosecond precision, as first proposed by Corkum and coworkers.
By analyzing each of the elementary processes leading to the fragmentation
quantitatively, we identified how the molecular clock is to be read from the
measured kinetic energy spectra of D and what laser parameters be used in
order to measure the clock more accurately.Comment: 13 pages with 14 figure
Investigating cooperation with robotic peers
We explored how people establish cooperation with robotic peers, by giving participants the chance to choose whether to cooperate or not with a more/less selfish robot, as well as a more or less interactive, in a more or less critical environment. We measured the participants' tendency to cooperate with the robot as well as their perception of anthropomorphism, trust and credibility through questionnaires. We found that cooperation in Human-Robot Interaction (HRI) follows the same rule of Human-Human Interaction (HHI), participants rewarded cooperation with cooperation, and punished selfishness with selfishness. We also discovered two specific robotic profiles capable of increasing cooperation, related to the payoff. A mute and non-interactive robot is preferred with a high payoff, while participants preferred a more human-behaving robot in conditions of low payoff. Taken together, these results suggest that proper cooperation in HRI is possible but is related to the complexity of the task
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