8,677 research outputs found
Constants of Motion for Constrained Hamiltonian Systems: A Particle around a Charged Rotating Black Hole
We discuss constants of motion of a particle under an external field in a
curved spacetime, taking into account the Hamiltonian constraint which arises
from reparametrization invariance of the particle orbit. As the necessary and
sufficient condition for the existence of a constant of motion, we obtain a set
of equations with a hierarchical structure, which is understood as a
generalization of the Killing tensor equation. It is also a generalization of
the conventional argument in that it includes the case when the conservation
condition holds only on the constraint surface in the phase space. In that
case, it is shown that the constant of motion is associated with a conformal
Killing tensor. We apply the hierarchical equations and find constants of
motion in the case of a charged particle in an electro-magnetic field in black
hole spacetimes. We also demonstrate that gravitational and electro-magnetic
fields exist in which a charged particle has a constant of motion associated
with a conformal Killing tensor.Comment: 20 page
Reciprocal transmittances and reflectances: An elementary proof
We present an elementary proof concerning reciprocal transmittances and
reflectances. The proof is direct, simple, and valid for the diverse objects
that can be absorptive and induce diffraction and scattering, as long as the
objects respond linearly and locally to electromagnetic waves. The proof
enables students who understand the basics of classical electromagnetics to
grasp the physical basis of reciprocal optical responses. In addition, we show
an example to demonstrate reciprocal response numerically and experimentally.Comment: 6 pages, 5 figures. RevTEX4. Improved wording. Physics Educatio
Prospects of Measuring General Higgs Couplings at e^+e^- Linear Colliders
We examine how accurately the general HZV couplings, with V=Z,gamma, may be
determined by studying e^+e^- --> Hff-bar processes at future e^+e^- linear
colliders. By using the optimal-observable method, which makes use of all
available experimental information, we find out which combinations of the
various HZV coupling terms may be constrained most efficiently with high
luminosity. We also assess the benefits of measuring the tau-lepton helicities,
identifying the bottom-hadron charges, polarizing the electron beam and running
at two different collider energies. The HZZ couplings are generally found to be
well constrained, even without these options, while the HZ-gamma couplings are
not. The constraints on the latter may be significantly improved by beam
polarization.Comment: 28 pages (LaTeX), 5 figures (axodraw and eps
Thermodynamics of Squashed Kaluza-Klein Black Holes and Black Strings -- A Comparison of Reference Backgrounds --
We investigate thermodynamics constructed on different background reference
spacetimes for squashed Kaluza-Klein (SqKK) black hole and electrically charged
black string in five-dimensional Einstein-Maxwell system. Two spacetimes are
possible to be reference spacetimes giving finite gravitational classical
actions: one is four-dimensional Minkowski times a circle and the other is the
KK monopole. The boundary of the SqKK black hole can not be matched perfectly
to that of the former reference spacetime because of the difference in
topology. However, the resultant classical action coincides with that
calculated by the counterterm subtraction scheme. The boundary of the KK
monopole has the same topology with that of the SqKK black hole and can be
matched to the boundary of the black hole perfectly. The resultant action takes
different value from the result given by using the former reference spacetime.
After a brief review of thermodynamic quantities of the black hole solutions,
we calculate thermodynamic potentials relevant for several thermodynamic
environments. The most stable state is different for each environment: For
example, the KK monopole is the most stable state in isothermal environment
with fixed gravitational tension. On the other hand, when the size of the
extra-dimension is fixed, the Minkowski times a circle is the most stable. It
is shown that these two spacetimes can be reference spacetimes of the
five-dimensional black string.Comment: 28 pages; references added, typo corrected;version accepted for
publication in Class. Quantum Gra
D3/D7 holographic Gauge theory and Chemical potential
N=2 supersymmetric Yang-Mills theory with flavor hypermultiplets at finite
temperature and in the dS are studied for finite quark number density
() by a dual supergravity background with non-trivial dilaton and axion.
The quarks and its number density are introduced by embedding a probe D7
brane. We find a critical value of the chemical potential at the limit of
, and it coincides with the effective quark mass given in each theory
for . At this point, a transition of the D7 embedding configurations
occurs between their two typical ones. The phase diagrams of this transition
are shown in the plane of chemical potential versus temperature and
cosmological constant for YM theory at finite temperature and in dS
respectively. In this phase transition, the order parameter is considered as
. % and the critical value of the chemical potential This result seems to
be reasonable since both theories are in the quark deconfinement phase.Comment: 17 pages, 8 figure
Toroidal Spiral Nambu-Goto Strings around Higher-Dimensional Black Holes
We present solutions of the Nambu-Goto equation for test strings in a shape
of toroidal spiral in five-dimensional spacetimes. In particular, we show that
stationary toroidal spirals exist around the five-dimensional Myers-Perry black
holes. We also show the existence of innermost stationary toroidal spirals
around the five-dimensional black holes like geodesic particles orbiting around
four-dimensional black holes.Comment: 9 pages, 5 figure
Parametric resonance at the critical temperature in high energy heavy ion collisions
Parametric resonance in soft modes at the critical temperature () in
high energy heavy ion collisions is studied in the case when the temperature
() of the system is almost constant for a long time. By deviding the fields
into three parts, zero mode (condensate), soft modes and hard modes and
assuming that the hard modes are in thermal equilibrium, we derive the equation
of motion for soft modes at . Enhanced modes are extracted by
comparing with the Mathieu equation for the condensate oscillating along the
sigma axis at . It is found that the soft mode of fields at
about 174 MeV is enhanced.Comment: 8 pages, 1 figure Some statements and equations are modified to
clarif
Baryons with D5 Brane Vertex and k-Quarks
We study baryons in SU(N) gauge theories, according to the gauge/string
correspondence based on IIB string theory. The D5 brane, in which
fundamental strings are dissolved as a color singlet, is introduced as the
baryon vertex, and its configurations are studied. We find point- and
split-type of vertex. In the latter case, two cusps appears and they are
connected by a flux composed of dissolved fundamental strings with a definite
tension. In both cases, fundamental quarks are attached on the cusp(s) of
the vertex to cancel the surface term. In the confining phase, we find that the
quark in the baryon feel the potential increasing linearly with the distance
from the vertex. At finite temperature and in the deconfining phase, we find a
stable k-quarks "baryons", which are constructed of arbitrary number of
quarks.Comment: 20 pages, 11 figure
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