330 research outputs found
Interaction of the Particle with the String in Pole-Dipole Approximation
Within the framework of generalized Papapetrou method, we derive the
effective equations of motion for a string with two particles attached to its
ends, along with appropriate boundary conditions. The equations of motion are
the usual Nambu-Goto-like equations, while boundary conditions turn out to be
equations of motion for the particles at the string ends. The form of those
equations is discussed, and they are explicitly solved for a particular case of
a straight-line string rotating around its center. From this solution we obtain
the correction terms to the law describing Regge trajectories,
due to nonzero angular momenta of the particles.Comment: Proceedings of the BW2007 conference, 5 page
Classical Spinning Branes in Curved Backgrounds
The dynamics of a classical branelike object in a curved background is
derived from the covariant stress-energy conservation of the brane matter. The
world sheet equations and boundary conditions are obtained in the pole-dipole
approximation, where nontrivial brane thickness gives rise to its intrinsic
angular momentum. It is shown that intrinsic angular momentum couples to both,
the background curvature and the brane orbital degrees of freedom. The whole
procedure is manifestly covariant with respect to spacetime diffeomorphisms and
world sheet reparametrizations. In addition, two extra gauge symmetries are
discovered and utilized. The examples of the point particle and the string in 4
spacetime dimensions are analyzed in more detail. A particular attention is
paid to the Nambu-Goto string with massive spinning particles attached to its
ends
Epitaxial growth by monolayer restricted galvanic displacement
The development of a new method for epitaxial growth of metals in solution by galvanic displacement of layers pre-deposited by underpotential deposition (UPD) was discussed and experimentally illustrated throughout the lecture. Cyclic voltammetry (CV) and scanning tunneling microscopy (STM) are employed to carry out and monitor a āquasi-perfectā, two-dimensional growth of Ag on Au(111), Cu on Ag(111), and Cu on Au(111) by repetitive galvanic displacement of underpotentially deposited monolayers. A comparative study emphasizes the displacement stoichiometry as an efficient tool for thickness control during the deposition process and as a key parameter that affects the deposit morphology. The excellent quality of layers deposited by monolayer-restricted galvanic displacement is manifested by a steady UPD voltammetry and ascertained by a flat and uniform surface morphology maintained during the entire growth process
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