3,224 research outputs found
Completeness of scattering states of the Dirac Hamiltonian with a step potential
The completeness, together with the orthonormality, of the eigenfunctions of
the Dirac Hamiltonian with a step potential is shown explicitly. These
eigenfunctions describe the scattering process of a relativistic fermion off
the step potential and the resolution of the identity in terms of them
(completeness) is shown by explicitly summing them up, where appropriate
treatments of the momentum integrations are crucial. The result would bring
about a basis on which a field theoretical treatment for such a system can be
developed.Comment: 16 pages, 1 figure
Acceptance Corrections and Extreme-Independent Models in Relativistic Heavy Ion Collisions
Kopeliovich's suggestion [nucl-th/0306044] to perform nuclear geometry
(Glauber) calculations using different cross sections according to the
experimental configuration is quite different from the standard practice of the
last 20 years and leads to a different nuclear geometry definition for each
experiment. The standard procedure for experimentalists is to perform the
nuclear geometry calculation using the total inelastic N-N cross section, which
results in a common nuclear geometry definition for all experiments. The
incomplete acceptance of individual experiments is taken into account by
correcting the detector response for the probability of measuring zero for an
inelastic collision, which can often be determined experimentally. This clearly
separates experimental issues such as different acceptances from theoretical
issues which should apply in general to all experiments. Extreme-Independent
models are used to illustrate the conditions for which the two methods give
consistent or inconsistent results.Comment: 4 pages, 1 figure, published in Physical Review
Pressure Tuning of an Ionic Insulator into a Heavy Electron Metal: An Infrared Study of YbS
Optical conductivity [] of YbS has been measured under
pressure up to 20 GPa. Below 8 GPa, is low since YbS is an
insulator with an energy gap between fully occupied 4 state and unoccupied
conduction () band. Above 8 GPa, however, increases
dramatically, developing a Drude component due to heavy carriers and
characteristic infrared peaks. It is shown that increasing pressure has caused
an energy overlap and hybridization between the band and 4 state, thus
driving the initially ionic and insulating YbS into a correlated metal with
heavy carriers
Kondo effect in CeX (X=S, Se, Te) studied by electrical resistivity under high pressure
We have measured the electrical resistivity of cerium monochalcogenices, CeS,
CeSe, and CeTe, under high pressures up to 8 GPa. Pressure dependences of the
antiferromagnetic ordering temperature , crystal field splitting, and
the anomaly of the Kondo effect have been studied to cover the whole
region from the magnetic ordering regime at low pressure to the Fermi liquid
regime at high pressure. initially increases with increasing pressure,
and starts to decrease at high pressure as expected from the Doniach's diagram.
Simultaneously, the behavior in the resistivity is enhanced, indicating
the enhancement of the Kondo effect by pressure. It is also characteristic in
CeX that the crystal field splitting rapidly decreases at a common rate
of K/GPa. This leads to the increase in the degeneracy of the state
and further enhancement of the Kondo effect. It is shown that the pressure
dependent degeneracy of the state is a key factor to understand the
pressure dependence of , Kondo effect, magnetoresistance, and the peak
structure in the temperature dependence of resistivity.Comment: 9 pages, 5 figures, accepted for publication in J. Phys. Soc. Jp
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