8,362 research outputs found
Scalar Quantum Field Theory with Cubic Interaction
In this paper it is shown that an i phi^3 field theory is a physically
acceptable field theory model (the spectrum is positive and the theory is
unitary). The demonstration rests on the perturbative construction of a linear
operator C, which is needed to define the Hilbert space inner product. The C
operator is a new, time-independent observable in PT-symmetric quantum field
theory.Comment: Corrected expressions in equations (20) and (21
Quantum tunneling as a classical anomaly
Classical mechanics is a singular theory in that real-energy classical
particles can never enter classically forbidden regions. However, if one
regulates classical mechanics by allowing the energy E of a particle to be
complex, the particle exhibits quantum-like behavior: Complex-energy classical
particles can travel between classically allowed regions separated by potential
barriers. When Im(E) -> 0, the classical tunneling probabilities persist.
Hence, one can interpret quantum tunneling as an anomaly. A numerical
comparison of complex classical tunneling probabilities with quantum tunneling
probabilities leads to the conjecture that as ReE increases, complex classical
tunneling probabilities approach the corresponding quantum probabilities. Thus,
this work attempts to generalize the Bohr correspondence principle from
classically allowed to classically forbidden regions.Comment: 12 pages, 7 figure
Non-perturbative calculations for the effective potential of the symmetric and non-Hermitian field theoretic model
We investigate the effective potential of the symmetric
field theory, perturbatively as well as non-perturbatively. For the
perturbative calculations, we first use normal ordering to obtain the first
order effective potential from which the predicted vacuum condensate vanishes
exponentially as in agreement with previous calculations. For the
higher orders, we employed the invariance of the bare parameters under the
change of the mass scale to fix the transformed form totally equivalent to
the original theory. The form so obtained up to is new and shows that all
the 1PI amplitudes are perurbative for both and regions. For
the intermediate region, we modified the fractal self-similar resummation
method to have a unique resummation formula for all values. This unique
formula is necessary because the effective potential is the generating
functional for all the 1PI amplitudes which can be obtained via and thus we can obtain an analytic calculation for the 1PI
amplitudes. Again, the resummed from of the effective potential is new and
interpolates the effective potential between the perturbative regions.
Moreover, the resummed effective potential agrees in spirit of previous
calculation concerning bound states.Comment: 20 page
Harmonic oscillator well with a screened Coulombic core is quasi-exactly solvable
In the quantization scheme which weakens the hermiticity of a Hamiltonian to
its mere PT invariance the superposition V(x) = x^2+ Ze^2/x of the harmonic and
Coulomb potentials is defined at the purely imaginary effective charges
(Ze^2=if) and regularized by a purely imaginary shift of x. This model is
quasi-exactly solvable: We show that at each excited, (N+1)-st
harmonic-oscillator energy E=2N+3 there exists not only the well known harmonic
oscillator bound state (at the vanishing charge f=0) but also a normalizable
(N+1)-plet of the further elementary Sturmian eigenstates \psi_n(x) at
eigencharges f=f_n > 0, n = 0, 1, ..., N. Beyond the first few smallest
multiplicities N we recommend their perturbative construction.Comment: 13 pages, Latex file, to appear in J. Phys. A: Math. Ge
HI Detection in two Dwarf S0 Galaxies in Nearby Groups: ESO384-016 and NGC 59
An \hi survey of 10 dE/dS0 galaxies in the nearby Sculptor and Centaurus A
groups was made using the Australia Telescope Compact Array (ATCA). The
observed galaxies have accurate distances derived by Jerjen et al (1998; 2000b)
using the surface brightness fluctuation technique. Their absolute magnitudes
are in the range . Only two of the ten galaxies were
detected at our detection limit ( \msol for the Centaurus
group and \msol for the Sculptor group), the two dS0
galaxies ESO384-016 in the Centaurus A Group and NGC 59 in the Sculptor Group,
with \hi masses of \msol and \msol respectively. Those two detections were confirmed using the Green
Bank Telescope. These small \hi reservoirs could fuel future generations of low
level star formation and could explain the bluer colors seen at the center of
the detected galaxies. Similarly to what is seen with the Virgo dEs, the two
objects with \hi appear to be on the outskirt of the groups.Comment: 25 pages (11 figures), accepted by A
Use of Equivalent Hermitian Hamiltonian for -Symmetric Sinusoidal Optical Lattices
We show how the band structure and beam dynamics of non-Hermitian
-symmetric sinusoidal optical lattices can be approached from the point of
view of the equivalent Hermitian problem, obtained by an analytic continuation
in the transverse spatial variable . In this latter problem the eigenvalue
equation reduces to the Mathieu equation, whose eigenfunctions and properties
have been well studied. That being the case, the beam propagation, which
parallels the time-development of the wave-function in quantum mechanics, can
be calculated using the equivalent of the method of stationary states. We also
discuss a model potential that interpolates between a sinusoidal and periodic
square well potential, showing that some of the striking properties of the
sinusoidal potential, in particular birefringence, become much less prominent
as one goes away from the sinusoidal case.Comment: 11 pages, 8 figure
On some meaningful inner product for real Klein-Gordon fields with positive semi-definite norm
A simple derivation of a meaningful, manifestly covariant inner product for
real Klein-Gordon (KG) fields with positive semi-definite norm is provided
which turns out - assuming a symmetric bilinear form - to be the real-KG-field
limit of the inner product for complex KG fields reviewed by A. Mostafazadeh
and F. Zamani in December, 2003, and February, 2006 (quant-ph/0312078,
quant-ph/0602151, quant-ph/0602161). It is explicitly shown that the positive
semi-definite norm associated with the derived inner product for real KG fields
measures the number of active positive and negative energy Fourier modes of the
real KG field on the relativistic mass shell. The very existence of an inner
product with positive semi-definite norm for the considered real, i.e. neutral,
KG fields shows that the metric operator entering the inner product does not
contain the charge-conjugation operator. This observation sheds some additional
light on the meaning of the C operator in the CPT inner product of PT-symmetric
Quantum Mechanics defined by C.M. Bender, D.C. Brody and H.F. Jones.Comment: 8 pages, no figures; correction of obvious typos and marginal
improvement of formulation
A family of complex potentials with real spectrum
We consider a two-parameter non hermitean quantum-mechanical hamiltonian that
is invariant under the combined effects of parity and time reversal
transformation. Numerical investigation shows that for some values of the
potential parameters the hamiltonian operator supports real eigenvalues and
localized eigenfunctions. In contrast with other PT symmetric models, which
require special integration paths in the complex plane, our model is integrable
along a line parallel to the real axis.Comment: Six figures and four table
A 60 pc counter-rotating core in NGC 4621
We present adaptive optics assisted OASIS integral field spectrography of the
S0 galaxy NGC 4621. Two-dimensional stellar kinematical maps (mean velocity and
dispersion) reveal the presence of a 60 pc diameter counter-rotating core
(CRC), the smallest observed to date. The OASIS data also suggests that the
kinematic center of the CRC is slightly offset from the center of the outer
isophotes. This seems to be confirmed by archival HST/STIS data. We also
present the HST/WFPC2 V-I colour map, which exhibits a central elongated red
structure, also slightly off-centered in the same direction as the kinematic
centre. We then construct an axisymmetric model of NGC 4621: the two-integral
distribution function is derived using the Multi-Gaussian Expansion and the
Hunter & Qian (1993) formalisms. Although the stellar velocities are reasonably
fitted, including the region of the counter-rotating core, significant
discrepancies between the model and the observations demonstrate the need for a
more general model (e.g. a three-integral model).Comment: 9 pages, 8 figure
- …