811 research outputs found
Deeply Virtual Pseudoscalar Meson Production with CLAS
Deeply virtual meson scattering cross sections and asymmetries for the pi^0
and eta exclusive electroproduction in a very wide kinematic range of Q^2, t
and x_B have been measured with CLAS (JLab). Initial analysis is already
showing remarkable results. These data will help us to better understand the
transition from soft to hard mechanisms.Comment: Prepared for XII Workshop on High Energy Spin Physics DSPIN-07,
Dubna, September 3-7, 200
Intermediate coherent-phase(PB) states of radiation fields and their nonclassical properties
Intermediate states interpolating coherent states and Pegg-Barnett phase
states are investigated using the ladder operator approach. These states reduce
to coherent and Pegg-Barnett phase states in two different limits. Statistical
and squeezing properties are studied in detail.Comment: 9 pages, 3 EPS figures, use epsf.sty. Accepted for publication in
Phys.Lett.
Theory Support for the Excited Baryon Program at the Jlab 12 GeV Upgrade
This document outlines major directions in theoretical support for the
measurement of nucleon resonance transition form factors at the JLab 12 GeV
upgrade with the CLAS12 detector. Using single and double meson production,
prominent resonances in the mass range up to 2 GeV will be studied in the range
of photon virtuality up to 12 GeV where quark degrees of freedom are
expected to dominate. High level theoretical analysis of these data will open
up opportunities to understand how the interactions of dressed quarks create
the ground and excited nucleon states and how these interactions emerge from
QCD. The paper reviews the current status and the prospects of QCD based model
approaches that relate phenomenological information on transition form factors
to the non-perturbative strong interaction mechanisms, that are responsible for
resonance formation.Comment: 52 pages, 19 figures, White Paper of the Electromagnetic N-N*
Transition Form Factor Workshop at Jefferson Lab, October 13-15, 2008,
Newport News, VA, US
States interpolating between number and coherent states and their interaction with atomic systems
Using the eigenvalue definition of binomial states we construct new
intermediate number-coherent states which reduce to number and coherent states
in two different limits. We reveal the connection of these intermediate states
with photon-added coherent states and investigate their non-classical
properties and quasi-probability distributions in detail. It is of interest to
note that these new states, which interpolate between coherent states and
number states, neither of which exhibit squeezing, are nevertheless squeezed
states. A scheme to produce these states is proposed. We also study the
interaction of these states with atomic systems in the framework of the
two-photon Jaynes-Cummings model, and describe the response of the atomic
system as it varies between the pure Rabi oscillation and the collapse-revival
mode and investigate field observables such as photon number distribution,
entropy and the Q-function.Comment: 26 pages, 29 EPS figures, Latex, Accepted for publication in J.Phys.
Coherent and squeezed states of quantum Heisenberg algebras
Starting from deformed quantum Heisenberg Lie algebras some realizations are
given in terms of the usual creation and annihilation operators of the standard
harmonic oscillator. Then the associated algebra eigenstates are computed and
give rise to new classes of deformed coherent and squeezed states. They are
parametrized by deformed algebra parameters and suitable redefinitions of them
as paragrassmann numbers. Some properties of these deformed states also are
analyzed.Comment: 32 pages, 3 figure
Interpolating Coherent States for Heisenberg-Weyl and Single-Photon SU(1,1) Algebras
New quantal states which interpolate between the coherent states of the
Heisenberg_Weyl and SU(1,1) algebras are introduced. The interpolating states
are obtained as the coherent states of a closed and symmetric algebra which
interpolates between the two algebras. The overcompleteness of the
interpolating coherent states is established. Differential operator
representations in suitable spaces of entire functions are given for the
generators of the algebra. A nonsymmetric set of operators to realize the
Heisenberg-Weyl algebra is provided and the relevant coherent states are
studied.Comment: 13 pages nd 5 ps figure
Perspectives for a mixed two-qubit system with binomial quantum states
The problem of the relationship between entanglement and two-qubit systems in
which it is embedded is central to the quantum information theory. This paper
suggests that the concurrence hierarchy as an entanglement measure provides an
alternative view of how to think about this problem. We consider mixed states
of two qubits and obtain an exact solution of the time-dependent master
equation that describes the evolution of two two-level qubits (or atoms) within
a perfect cavity for the case of multiphoton transition. We consider the
situation for which the field may start from a binomial state. Employing this
solution, the significant features of the entanglement when a second qubit is
weakly coupled to the field and becomes entangled with the first qubit, is
investigated. We also describe the response of the atomic system as it varies
between the Rabi oscillations and the collapse-revival mode and investigate the
atomic inversion and the Q-function. We identify and numerically demonstrate
the region of parameters where significantly large entanglement can be
obtained. Most interestingly, it is shown that features of the entanglement is
influenced significantly when the multi-photon process is involved. Finally, we
obtain illustrative examples of some novel aspects of this system and show how
the off-resonant case can sensitize entanglement to the role of initial state
setting.Comment: 18 pages, 9 figure
Approach to Perturbative Results in the N-Delta Transition
We show that constraints from perturbative QCD calculations play a role in
the nucleon to Delta(1232) electromagnetic transition even at moderate momentum
transfer scales. The pQCD constraints, tied to real photoproduction data and
unseparated resonance response functions, lead to explicit forms for the
helicity amplitudes wherein the E2/M1 ratio remains small at moderately large
momentum transfer.Comment: 4 pages, 2 figures, ReVTe
Squeezed States of the Generalized Minimum Uncertainty State for the Caldirola-Kanai Hamiltonian
We show that the ground state of the well-known pseudo-stationary states for
the Caldirola-Kanai Hamiltonian is a generalized minimum uncertainty state,
which has the minimum allowed uncertainty , where is a constant depending on the damping
factor and natural frequency. The most general symmetric Gaussian states are
obtained as the one-parameter squeezed states of the pseudo-stationary ground
state. It is further shown that the coherent states of the pseudo-stationary
ground state constitute another class of the generalized minimum uncertainty
states.Comment: RevTex4, 9 pages, no fingure; to be published in Journal of Physics
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