415 research outputs found
On the Non-relativistic Limit of Linear Wave Equations for Zero and Unity Spin Particles
The non-relativistic limit of the linear wave equation for zero and unity
spin bosons of mass in the Duffin-Kemmer-Petiau representation is
investigated by means of a unitary transformation, analogous to the
Foldy-Wouthuysen canonical transformation for a relativistic electron. The
interacting case is also analyzed, by considering a power series expansion of
the transformed Hamiltonian, thus demonstrating that all features of particle
dynamics can be recovered if corrections of order are taken into
account through a recursive iteration procedure.Comment: 10 page
Zitterbewegung of Klein-Gordon particles and its simulation by classical systems
The Klein-Gordon equation is used to calculate the Zitterbewegung (ZB,
trembling motion) of spin-zero particles in absence of fields and in the
presence of an external magnetic field. Both Hamiltonian and wave formalisms
are employed to describe ZB and their results are compared. It is demonstrated
that, if one uses wave packets to represent particles, the ZB motion has a
decaying behavior. It is also shown that the trembling motion is caused by an
interference of two sub-packets composed of positive and negative energy states
which propagate with different velocities. In the presence of a magnetic field
the quantization of energy spectrum results in many interband frequencies
contributing to ZB oscillations and the motion follows a collapse-revival
pattern. In the limit of non-relativistic velocities the interband ZB
components vanish and the motion is reduced to cyclotron oscillations. The
exact dynamics of a charged Klein-Gordon particle in the presence of a magnetic
field is described on an operator level. The trembling motion of a KG particle
in absence of fields is simulated using a classical model proposed by Morse and
Feshbach -- it is shown that a variance of a Gaussian wave packet exhibits ZB
oscillations.Comment: 16 pages and 7 figure
First Order Actions: a New View
We analyse systems described by first order actions using the Hamilton-Jacobi
(HJ) formalism for singular systems. In this study we verify that generalized
brackets appear in a natural way in HJ approach, showing us the existence of a
symplectic structure in the phase spaces of this formalism
Relativistic Aharonov-Casher Phase in Spin One
The Aharonov-Casher (AC) phase is calculated in relativistic wave equations
of spin one. The AC phase has previously been calculated from the Dirac-Pauli
equation using a gauge-like technique \cite{MK1,MK2}. In the spin-one case, we
use Kemmer theory (a Dirac-like particle theory) to calculate the phase in a
similar manner. However the vector formalism, the Proca theory, is more widely
known and used. In the presence of an electromagnetic field, the two theories
are `equivalent' and may be transformed into one another. We adapt these
transformations to show that the Kemmer theory results apply to the Proca
theory. Then we calculate the Aharonov-Casher phase for spin-one particles
directly in the Proca formalism.Comment: 12 page
Dynamical electroweak symmetry breaking due to strong Yukawa interactions
We present a new mechanism for electroweak symmetry breaking (EWSB) based on
a strong Yukawa dynamics. We consider an SU(2)_L x U(1)_Y gauge invariant model
endowed with the usual Standard model fermion multiplets and with two massive
scalar doublets. We show that, unlike in the Standard model, EWSB is possible
even with vanishing vacuum expectation values of the scalars. Such EWSB is
achieved dynamically by means of the (presumably strong) Yukawa couplings and
manifests itself by the emergence of fermion and gauge boson masses and scalar
mass-splittings, which are expressed in a closed form in terms of the fermion
and scalar proper self-energies. The `would-be' Nambu--Goldstone bosons are
shown to be composites of both the fermions and the scalars. We demonstrate
that the simplest version of the model is compatible with basic experimental
constraints.Comment: 6 pages, REVTeX4, 3 eps figures; discussion of compatibility with EW
precision data added; version published in J. Phys.
Spin 1 fields in Riemann-Cartan space-times "via" Duffin-Kemmer-Petiau theory
We consider massive spin 1 fields, in Riemann-Cartan space-times, described
by Duffin-Kemmer-Petiau theory. We show that this approach induces a coupling
between the spin 1 field and the space-time torsion which breaks the usual
equivalence with the Proca theory, but that such equivalence is preserved in
the context of the Teleparallel Equivalent of General Relativity.Comment: 8 pages, no figures, revtex. Dedicated to Professor Gerhard Wilhelm
Bund on the occasion of his 70th birthday. To appear in Gen. Rel. Grav.
Equations numbering corrected. References update
Exact Solution of Photon Equation in Stationary G\"{o}del-type and G\"{o}del Space-Times
In this work the photon equation (massless Duffin-Kemmer-Petiau equation) is
written expilicitly for general type of stationary G\"{o}del space-times and is
solved exactly for G\"{o}del-type and G\"{o}del space-times. Harmonic
oscillator behaviour of the solutions is discussed and energy spectrum of
photon is obtained.Comment: 9 pages,RevTeX, no figure, revised for publicatio
Approximate solution of the Duffin-Kemmer-Petiau equation for a vector Yukawa potential with arbitrary total angular momenta
The usual approximation scheme is used to study the solution of the
Duffin-Kemmer-Petiau (DKP) equation for a vector Yukawa potential in the
framework of the parametric Nikiforov-Uvarov (NU) method. The approximate
energy eigenvalue equation and the corresponding wave function spinor
components are calculated for arbitrary total angular momentum in closed form.
Further, the approximate energy equation and wave function spinor components
are also given for case. A set of parameter values is used to obtain the
numerical values for the energy states with various values of quantum levelsComment: 17 pages; Communications in Theoretical Physics (2012). arXiv admin
note: substantial text overlap with arXiv:1205.0938, and with
arXiv:quant-ph/0410159 by other author
Pion-nucleus elastic scattering on 12C, 40Ca, 90Zr, and 208Pb at 400 and 500 MeV
Pion-nucleus elastic scattering at energies above the Delta(1232) resonance
is studied using both pi+ and pi- beams on 12C, 40Ca, 90Zr, and 208Pb. The
present data provide an opportunity to study the interaction of pions with
nuclei at energies where second-order corrections to impulse approximation
calculations should be small. The results are compared with other data sets at
similar energies, and with four different first-order impulse approximation
calculations. Significant disagreement exists between the calculations and the
data from this experiment
J/psi azimuthal anisotropy relative to the reaction plane in Pb-Pb collisions at 158 GeV per nucleon
The J/ azimuthal distribution relative to the reaction plane has been
measured by the NA50 experiment in Pb-Pb collisions at 158 GeV/nucleon. Various
physical mechanisms related to charmonium dissociation in the medium created in
the heavy ion collision are expected to introduce an anisotropy in the
azimuthal distribution of the observed J/ mesons at SPS energies. Hence,
the measurement of J/ elliptic anisotropy, quantified by the Fourier
coefficient v of the J/ azimuthal distribution relative to the
reaction plane, is an important tool to constrain theoretical models aimed at
explaining the anomalous J/ suppression observed in Pb-Pb collisions. We
present the measured J/ yields in different bins of azimuthal angle
relative to the reaction plane, as well as the resulting values of the Fourier
coefficient v as a function of the collision centrality and of the
J/ transverse momentum. The reaction plane has been estimated from the
azimuthal distribution of the neutral transverse energy detected in an
electromagnetic calorimeter. The analysis has been performed on a data sample
of about 100 000 events, distributed in five centrality or p
sub-samples. The extracted v values are significantly larger than zero
for non-central collisions and are seen to increase with p.Comment: proceedings of HP08 conference corrected a typo in one equatio
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