28 research outputs found
The Generalized Counting Rule and Oscillatory Scaling
We have studied the energy dependence of the elastic scattering data and
the pion-photoproduction data at 90 c.m. angle in light of the new
generalized counting rule derived for exclusive processes. We show that by
including the helicity flipping amplitudes (with energy dependence given by the
generalized counting rule) and their interference with the Landshoff amplitude,
we are able to reproduce the energy dependence of all cross-section and
spin-correlation (A) data available above the resonance region. The
pion-photoproduction data can also be described by this approach, but in this
case data with much finer energy spacing is needed to confirm the oscillations
about the scaling behavior.Comment: 5 pages, 4 figs, submitted to PRC rapid com
New invariants for entangled states
We propose new algebraic invariants that distinguish and classify entangled
states. Considering qubits as well as higher spin systems, we obtained complete
entanglement classifications for cases that were either unsolved or only
conjectured in the literature.Comment: published versio
Higher order Josephson effects
Gaussian linking of superconducting loops containing Josephson junctions with
enclosed magnetic fields give rise to interference shifts in the phase that
modulates the current carried through the loop, proportional to the magnitude
of the enclosed flux. We generalize these results to higher order linking of a
superconducting loop with several magnetic solenoids, and show there may be
interference shifts proportional to the product of two or more fluxes.Comment: 8 pages, 2 figure
Quantum harmonic oscillator with superoscillating initial datum
In this paper we study the evolution of superoscillating initial data for the
quantum driven harmonic oscillator. Our main result shows that
superoscillations are amplified by the harmonic potential and that the analytic
solution develops a singularity in finite time. We also show that for a large
class of solutions of the Schr\"odinger equation, superoscillating behavior at
any given time implies superoscillating behavior at any other time.Comment: 12 page
SLOCC determinant invariants of order 2^{n/2} for even n qubits
In this paper, we study SLOCC determinant invariants of order 2^{n/2} for any
even n qubits which satisfy the SLOCC determinant equations. The determinant
invariants can be constructed by a simple method and the set of all these
determinant invariants is complete with respect to permutations of qubits.
SLOCC entanglement classification can be achieved via the vanishing or not of
the determinant invariants. We exemplify the method for several even number of
qubits, with an emphasis on six qubits.Comment: J. Phys. A: Math. Theor. 45 (2012) 07530
The Proton Electromagnetic Form Factor and Quark Orbital Angular Momentum
We analyze the proton electromagnetic form factor ratio
as a function of momentum transfer
within perturbative QCD. We find that the prediction for at large
momentum transfer depends on the exclusive quark wave functions, which are
unknown. For a wide range of wave functions we find that $ QF_2/F_1 \sim\
const$ at large momentum transfer, in agreement with recent JLAB data.Comment: 8 pages, 2 figures. To appear in Proceedings of the Workshop QCD
2002, IIT Kanpur, 18-22 November (2002
Non-chaotic dynamics in general-relativistic and scalar-tensor cosmology
In the context of scalar-tensor models of dark energy and inflation, the
dynamics of vacuum scalar-tensor cosmology are analysed without specifying the
coupling function or the scalar field potential. A conformal transformation to
the Einstein frame is used and the dynamics of general relativity with a
minimally coupled scalar field are derived for a generic potential. It is shown
that the dynamics are non-chaotic, thus settling an existing debate.Comment: 20 pages, LaTeX, to appear in Class. Quantum Gra
An algebraic classification of entangled states
We provide a classification of entangled states that uses new discrete
entanglement invariants. The invariants are defined by algebraic properties of
linear maps associated with the states. We prove a theorem on a correspondence
between the invariants and sets of equivalent classes of entangled states. The
new method works for an arbitrary finite number of finite-dimensional state
subspaces. As an application of the method, we considered a large selection of
cases of three subspaces of various dimensions. We also obtain an entanglement
classification of four qubits, where we find 27 fundamental sets of classes.Comment: published versio
Radio Detection of High Energy Particles: Coherence Versus Multiple Scales
Radio Cherenkov emission underlines detection of high energy particles via a
signal growing like the particle-energy-squared. Cosmic ray-induced
electromagnetic showers are a primary application. While many studies have
treated the phenomenon approximately, none have attempted to incorporate all
the physical scales involved in problems with time- or spatially- evolving
charges. We find it is possible to decompose the calculated fields into the
product of a form factor, characterizing a moving charge distribution,
multiplying a general integral which depends on the charge evolution. In
circumstances of interest for cosmic ray physics, the resulting expressions can
be evaluated explicitely in terms of a few parameters obtainable from shower
codes. The classic issues of Frauhofer and Fresnel zones play a crucial role in
the coherence.Comment: 25 pages, 10 figure
On Energy Conditions and Stability in Effective Loop Quantum Cosmology
In isotropic loop quantum cosmology, non-perturbatively modified dynamics of
a minimally coupled scalar field violates weak, strong and dominant energy
conditions when they are stated in terms of equation of state parameter. The
violation of strong energy condition helps to have non-singular evolution by
evading singularity theorems thus leading to a generic inflationary phase.
However, the violation of weak and dominant energy conditions raises concern,
as in general relativity these conditions ensure causality of the system and
stability of vacuum via Hawking-Ellis conservation theorem. It is shown here
that the non-perturbatively modified kinetic term contributes negative pressure
but positive energy density. This crucial feature leads to violation of energy
conditions but ensures positivity of energy density, as scalar matter
Hamiltonian remains bounded from below. It is also shown that the modified
dynamics restricts group velocity for inhomogeneous modes to remain sub-luminal
thus ensuring causal propagation across spatial distances.Comment: 29 pages, revtex4; few clarifications, references added, to appear in
CQ