3,787 research outputs found
Eta meson rescattering effects in the p + 6Li --> eta + 7Be reaction near threshold
The p + 6Li --> eta + 7Be reaction has been investigated with an emphasis on
the eta meson and 7Be interaction in the final state. Considering the 6Li and
7Be nuclei to be alpha-d and alpha-3He clusters respectively, the reaction is
modelled to proceed via the p + d [alpha] --> 3He [\alpha] + eta reaction with
the alpha remaining a spectator. The eta meson interacts with 7Be via multiple
scatterings on the 3He and alpha clusters inside 7Be. The individual eta-3He
and eta-alpha scatterings are evaluated using few body equations for the eta-3N
and eta-4N systems with a coupled channel eta-N interaction as an input.
Calculations including four low-lying states of 7Be lead to a double hump
structure in the total cross section corresponding to the and angular momentum states. The humps
arise due to the off-shell rescattering of the eta meson on the 7Be nucleus in
the final state.Comment: New results and references adde
The Use of the Scattering Phase Shift in Resonance Physics
The scattering phase shift encodes a good amount of physical information
which can be used to study resonances from scattering data. Among others, it
can be used to calculate the continuum density of states and the collision time
in a resonant process. Whereas the first information can be employed to examine
the evolution of unstable states directly from scattering data, the second one
serves as a tool to detect resonances and their properties. We demonstrate both
methods concentrating in the latter case on 'exotic' resonances in pi-pi and
pi-K scattering.Comment: Talk given at the International Workshop PENTAQUARK04, July 20-23 at
Spring-8, Japan (new references added
Resonances and adiabatic invariance in classical and quantum scattering theory
We discover that the energy-integral of time-delay is an adiabatic invariant
in quantum scattering theory and corresponds classically to the phase space
volume. The integral thus found provides a quantization condition for
resonances, explaining a series of results recently found in non-relativistic
and relativistic regimes. Further, a connection between statistical quantities
like quantal resonance-width and classical friction has been established with a
classically deterministic quantity, the stability exponent of an adiabatically
perturbed periodic orbit. This relation can be employed to estimate the rate of
energy dissipation in finite quantum systems.Comment: 8 page
Faraday's law in the presence of magnetic monopoles
We show that if we consider the full statement of Faraday's law for a closed
physical circuit, the standard Maxwell's equations in the presence of electric
and magnetic charges have to include in their integral form a mixed term of the
form where is the magnetic charge density
and the perpendicular component of the velocity
of the electric charge.Comment: 9 page
Pentaquark Resonances from Collision Times
Having successfully explored the existing relations between the S-matrix and
collision times in scattering reactions to study the conventional baryon and
meson resonances, the method is now extended to the exotic sector. To be
specific, the collision time in various partial waves of K+ N elastic
scattering is evaluated using phase shifts extracted from the K+ N --> K+ N
data as well as from model dependent T-matrix solutions. We find several
pentaquark resonances including some low-lying ones around 1.5 to 1.6 GeV in
the P_01, P_03 and D_03 partial waves of K+ N elastic scattering.Comment: Talk given at the International Workshop PENTAQUARK04, July 20-23 at
Spring-8, Japa
Deuteron properties from muonic atom spectroscopy
Leading order () finite size corrections in muonic deuterium are
evaluated within a few body formalism for the system in muonic
deuterium and found to be sensitive to the input of the deuteron wave function.
We show that this sensitivity, taken along with the precise deuteron charge
radius determined from muonic atom spectroscopy can be used to determine the
elusive deuteron D-state probability, , for a given model of the
nucleon-nucleon (NN) potential. The radius calculated with a of 4.3\% in
the chiral NN models and about 5.7\% in the high precision NN potentials is
favoured most by the data.Comment: 14 pages, 2 figure
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