44,258 research outputs found
Monopoles and Knots in Skyrme Theory
We show that the Skyrme theory actually is a theory of monopoles which allows
a new type of solitons, the topological knots made of monopole-anti-monopole
pair,which is different from the well-known skyrmions. Furthermore, we derive a
generalized Skyrme action from the Yang-Mills action of QCD, which we propose
to be an effective action of QCD in the infra-red limit. We discuss the
physical implications of our results.Comment: 4 pages. Phys. Rev. Lett. in pres
Schwinger Effect in Non-parallel D1-branes: A Path Integral Approach
We study the Schwinger effect in a system of non-parallel D1-branes for the
bosonic strings using the path integral formalism. We drive the string pair
creation rate by calculating the one loop vacuum amplitude of the setup in
presence of the background electric filed defined along one of the D1-branes.
We find an angle dependent minimum value for the background field and show that
the decaying of vacuum into string pairs takes place for the field above this
value. It is shown that in limit the vacuum
becomes stable and thus no pair creation occurs
Gauge Independent Trace Anomaly for Gravitons
We show that the trace anomaly for gravitons calculated using the usual
effective action formalism depends on the choice of gauge when the background
spacetime is not a solution of the classical equation of motion, that is, when
off-shell. We then use the gauge independent Vilkovisky-DeWitt effective action
to restore gauge independence to the off-shell case. Additionally we explicitly
evaluate trace anomalies for some N-sphere background spacetimes.Comment: 19 pages, additional references and title chang
Purification through Zeno-like Measurements
A series of frequent measurements on a quantum system (Zeno-like
measurements) is shown to result in the ``purification'' of another quantum
system in interaction with the former. Even though the measurements are
performed on the former system, their effect drives the latter into a pure
state, irrespectively of its initial (mixed) state, provided certain conditions
are satisfied.Comment: REVTeX4, 4 pages, 1 figure; to be published in Phys. Rev. Lett.
(2003
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