12,120 research outputs found
Comment on "New Methods for Old Coulomb Few-Body Problems"
In this Comment on the above mentioned paper by F. E. Harris, A. M. Frolov,
and V. H. Smith, we briefly review our contributions to development of new
methods for solution of the Coulomb four-body problem. We show that our
research group, headed by Prof. T. K. Rebane, had a priority in using the fully
correlated exponential basis for variational calculations of four-body systems.
We also draw attention to the fact that our group subsequently implemented a
more advanced method, which uses highly efficient exponential-trigonometric
basis functions for solution of the same problem.Comment: Accepted by the International Journal of Quantum Chemistr
Positron annihilation in the MuPs system
The life-time of the four-body atomic system MuPs ( or
muonium-positronium) against positron annihilation has been evaluated as . Various annihilation
rates for MuPs are determined to a good numerical accuracy, e.g., 2.446485 ,
6.62798 , 3.61680 , 6.32973 . The
hyperfine structure splitting for the ground state in the MuPs system has also
been evaluated as = 23.078
Stability and hyperfine structure of the four- and five-body muon-atomic clusters and
Based on the results of accurate variational calculations we demonstrate
stability of the five-body negatively charged ions . Each of these five-body ions contains two electrons , one
negatively charged muon and two nuclei of the hydrogen isotopes . The bound state properties of these five-body ions, including
their hyperfine structure, are briefly discussed. We also investigate the
hyperfine structure of the ground states of the four-body muonic quasi-atoms
. In particular, we determine the hyperfine
structure splittings for the ground state of the four-body muonic quasi-atoms:
and
Stationary strings near a higher-dimensional rotating black hole
We study stationary string configurations in a space-time of a
higher-dimensional rotating black hole. We demonstrate that the Nambu-Goto
equations for a stationary string in the 5D Myers-Perry metric allow a
separation of variables. We present these equations in the first-order form and
study their properties. We prove that the only stationary string configuration
which crosses the infinite red-shift surface and remains regular there is a
principal Killing string. A worldsheet of such a string is generated by a
principal null geodesic and a timelike at infinity Killing vector field. We
obtain principal Killing string solutions in the Myers-Perry metrics with an
arbitrary number of dimensions. It is shown that due to the interaction of a
string with a rotating black hole there is an angular momentum transfer from
the black hole to the string. We calculate the rate of this transfer in a
spacetime with an arbitrary number of dimensions. This effect slows down the
rotation of the black hole. We discuss possible final stationary configurations
of a rotating black hole interacting with a string.Comment: 13 pages, contains additianal material at the end of Section 8, also
small misprints are correcte
Planckian space is an exact solution of the semiclassical Einstein equations
The product space configuration (with and being
radiuses of the components) carrying the electric charge is demonstrated to
be an exact solution of the semiclassical Einstein equations in presence of the
Maxwell field. If the logarithmic UV divergences are absent in the
four-dimensional theory the solution we find is identical to the classical
Bertotti-Robinson space () with no quantum corrections added. In
general, the analysis involves the quadratic curvature coupling
appearing in the effective action. The solutions we find are of the following
types: i) (for arbitrary ) charged configuration which is quantum
deformation of the Bertotti-Robinson space; ii) () Q=0
configuration with and being of the Planck order; iii)
() configuration ( and are of the Planck
order) not connected analytically to the Bertotti-Robinson space. The
interpretation of the solutions obtained and an indication on the internal
structure of the Schwarzschild black hole are discussed.Comment: 14 pages, latex, 1 figure; v2: a note on S2*S2 type solutions adde
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