17,003 research outputs found
Scattering states of a particle, with position-dependent mass, in a symmetric heterojunction
The study of a particle with position-dependent effective mass (pdem), within
a double heterojunction is extended into the complex domain --- when the region
within the heterojunctions is described by a non Hermitian
symmetric potential. After obtaining the exact analytical solutions, the
reflection and transmission coefficients are calculated, and plotted as a
function of the energy. It is observed that at least two of the characteristic
features of non Hermitian symmetric systems --- viz., left / right
asymmetry and anomalous behaviour at spectral singularity, are preserved even
in the presence of pdem. The possibility of charge conservation is also
discussed.Comment: 12 pages, including 6 figures; Journal of Physics A : Math. Theor.
(2012
New Exactly Solvable Isospectral Partners for PT Symmetric Potentials
We examine in detail the possibilty of applying Darboux transformation to non
Hermitian hamiltonians. In particular we propose a simple method of
constructing exactly solvable PT symmetric potentials by applying Darboux
transformation to higher states of an exactly solvable PT symmetric potential.
It is shown that the resulting hamiltonian and the original one are pseudo
supersymmetric partners. We also discuss application of Darboux transformation
to hamiltonians with spontaneously broken PT symmetry.Comment: 11 pages, 2 figures, To be published in Journal of Physics A (2004
Extracting Weak Phase Information from B -> V_1 V_2 Decays
We describe a new method for extracting weak, CP-violating phase information,
with no hadronic uncertainties, from an angular analysis of B -> V_1 V_2
decays, where V_1 and V_2 are vector mesons. The quantity can be cleanly obtained from the study of decays such as B_d^0(t) ->
D^{*\pm} \rho^\mp, D^{*\pm} a_1^{\mp}, D^{*0} K^{*0}, etc. Similarly, one can
use B_s^0(t) -> D_s^{*\pm} K^{*\mp} to extract . There are no
penguin contributions to these decays. It is possible that will be the second function of CP phases, after , to be
measured at B-factories.Comment: 4 pages, RevTeX, no figure
SWKB Quantization Rules for Bound States in Quantum Wells
In a recent paper by Gomes and Adhikari (J.Phys B30 5987(1997)) a matrix
formulation of the Bohr-Sommerfield quantization rule has been applied to the
study of bound states in one dimension quantum wells. Here we study these
potentials in the frame work of supersymmetric WKB (SWKB) quantization
approximation and find that SWKB quantization rule is superior to the modified
Bohr-Sommerfield or WKB rules as it exactly reproduces the eigenenergies.Comment: 8 page
A q-deformed nonlinear map
A scheme of q-deformation of nonlinear maps is introduced. As a specific
example, a q-deformation procedure related to the Tsallis q-exponential
function is applied to the logistic map. Compared to the canonical logistic
map, the resulting family of q-logistic maps is shown to have a wider spectrum
of interesting behaviours, including the co-existence of attractors -- a
phenomenon rare in one dimensional maps.Comment: 17 pages, 19 figure
Three path interference using nuclear magnetic resonance: a test of the consistency of Born's rule
The Born rule is at the foundation of quantum mechanics and transforms our
classical way of understanding probabilities by predicting that interference
occurs between pairs of independent paths of a single object. One consequence
of the Born rule is that three way (or three paths) quantum interference does
not exist. In order to test the consistency of the Born rule, we examine
detection probabilities in three path intereference using an ensemble of
spin-1/2 quantum registers in liquid state nuclear magnetic resonance (LSNMR).
As a measure of the consistency, we evaluate the ratio of three way
interference to two way interference. Our experiment bounded the ratio to the
order of , and hence it is consistent with Born's rule.Comment: 11 pages, 4 figures; Improved presentation of figures 1 and 4,
changes made in section 2 to better describe the experiment, minor changes
throughout, and added several reference
Mathematical Modelling of Blood Flow through a Tapered Overlapping Stenosed Artery with Variable Viscosity
This paper presents a theoretical study of blood flow through a tapered and overlapping stenosed artery under the action of an externally applied magnetic field. The fluid (blood) medium is assumed to be porous in nature. The variable viscosity of blood depending on hematocrit (percentage volume of erythrocytes) is taken into account in order to improve resemblance to the real situation. The governing equation for laminar, incompressible and Newtonian fluid subject to the boundary conditions is solved by using a well known Frobenius method. The analytical expressions for velocity component, volumetric flow rate, wall shear stress and pressure gradient are obtained. The numerical values are extracted from these analytical expressions and are presented graphically. It is observed that the influence of hematocrit, magnetic field and the shape of artery have important impact on the velocity profile, pressure gradient and wall shear stress. Moreover, the effect of primary stenosis on the secondary one has been significantly observed
Fermi-surface induced modulation in an optimally doped YBCO superconductor
We have observed a Fermi-surface (FS) induced lattice modulation in a YBCO
superconductor with a wavevector along CuO chains, {\it i.e.} =(0,,0). The value of is twice the Fermi
wavevector () along {\bf b*} connecting nearly nested FS `ridges'.
The modulation exists only within O-vacancy-ordered islands
(characterized by = and persists well above and
below . Our results are consistent with the presence of a FS-induced
charge-density wave
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