242 research outputs found
Coulomb Final State Interactions for Gaussian Wave Packets
Two-particle like-sign and unlike-sign correlations including Coulomb final
state interactions are calculated for Gaussian wave packets emitted from a
Gaussian source. We show that the width of the wave packets can be fully
absorbed into the spatial and momentum space widths of an effective emission
function for plane wave states, and that Coulomb final state interaction
effects are sensitive only to the latter, but not to the wave packet width
itself. Results from analytical and numerical calculations are compared with
recently published work by other authors.Comment: 10 pages Latex, 2 eps-figure
The role of the quantum dispersion in the Coulomb correction of Bose-Einstein correlations
The time dependent Schroedinger equation for two identical and charged pions
is solved using wavepacket states. It is shown that the expected Coulomb
distortion in the momentum correlation function is obliterated by the
dispersion of the localized states, and therefore becomes unobservable.Comment: 10 pages, LaTeX, 2 figures, 0.2 Mb postscript, submitted to Phys.
Lett.
Pseudochemotaxis in inhomogeneous active Brownian systems
We study dynamical properties of confined, self-propelled Brownian particles
in an inhomogeneous activity profile. Using Brownian dynamics simulations, we
calculate the probability to reach a fixed target and the mean first passage
time to the target of an active particle. We show that both these quantities
are strongly influenced by the inhomogeneous activity. When the activity is
distributed such that high-activity zone is located between the target and the
starting location, the target finding probability is increased and the passage
time is decreased in comparison to a uniformly active system. Moreover, for a
continuously distributed profile, the activity gradient results in a drift of
active particle up the gradient bearing resemblance to chemotaxis. Integrating
out the orientational degrees of freedom, we derive an approximate
Fokker-Planck equation and show that the theoretical predictions are in very
good agreement with the Brownian dynamics simulations.Comment: 7 pages, 5 figure
Facilitated diffusion of DNA-binding proteins
The diffusion-controlled limit of reaction times for site-specific
DNA-binding proteins is derived from first principles. We follow the generally
accepted concept that a protein propagates via two competitive modes, a
three-dimensional diffusion in space and a one-dimensional sliding along the
DNA. However, our theoretical treatment of the problem is new. The accuracy of
our analytical model is verified by numerical simulations. The results confirm
that the unspecific binding of protein to DNA, combined with sliding, is
capable to reduce the reaction times significantly.Comment: 4 pages, 2 figures Nov 22 2005 - accepted for PR
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