5,936 research outputs found
Anomalous Scattering of Low-lying Excitations in a Spin-1 Bose-Einstein Condensate
We present the simplest theory of perfect tunneling of an excitation in a
Bose-Einstein condensate (BEC) through an impurity potential with an arbitrary
shape in the low-momentum limit. That is for the transverse spin wave in the
ferromagnetic phase of a spin-1 BEC. This mode obeys a Schr\"odinger-type
equation; yet, effects of the potential on its transmission coefficient and
on its scattering cross section vanish in that limit. The order
parameter determines , and the momentum -dependence of exhibits a
Rayleigh scattering type (). These properties are common
between two types of Nambu-Goldstone modes: this spin wave and the Bogoliubov
mode.Comment: 5 page
Spin and Orbital Angular Momentum Distribution Functions of the Nucleon
A theoretical prediction is given for the spin and orbital angular momentum
distribution functions of the nucleon within the framework of an effective
quark model of QCD, i.e. the chiral quark soliton model. An outstanding feature
of the model is that it predicts fairly small quark spin fraction of the
nucleon , which in turn dictates that the remaining
65% of the nucleon spin is carried by the orbital angular momentum of quarks
and antiquarks at the model energy scale of . This
large orbital angular momentum necessarily affects the scenario of scale
dependence of the nucleon spin contents in a drastic way.Comment: 16 pages, latex, 3 eps figures, the revised version to appear in
Physical Review
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