48,289 research outputs found
Ab initio approach to s-shell hypernuclei 3H_Lambda, 4H_Lambda, 4He_Lambda and 5He_Lambda with a Lambda N-Sigma N interaction
Variational calculations for s-shell hypernuclei are performed by explicitly
including degrees of freedom. Four sets of YN interactions (SC97d(S),
SC97e(S), SC97f(S) and SC89(S)) are used. The bound-state solution of
He is obtained and a large energy expectation value of the tensor
transition part is found. The internal energy of the
He subsystem is strongly affected by the presence of a particle
with the strong tensor transition potential.Comment: Phys. Rev. Lett. 89, 142504 (2002
Absorption cross section in de Sitter space
We study the wave equation for a minimally coupled massive scalar in
three-dimensional de Sitter space. We compute the absorption cross section to
investigate its cosmological horizon in the southern diamond. Although the
absorption cross section is not defined exactly, we can be determined it from
the fact that the low-energy -wave absorption cross section for a
massless scalar is given by the area of the cosmological horizon. On the other
hand, the low-temperature limit of -mode absorption cross section is
useful for extracting information surrounding the cosmological horizon. Finally
we mention a computation of the absorption cross section on the CFT-side using
the dS/CFT correspondence.Comment: 13 pages, version to appear in MPL
Modified Reconstruction of Standard Model in Non-Commutative Differential Geometry
Sogami recently proposed the new idea to express Higgs particle as a kind of
gauge particle by prescribing the generalized covariant derivative with gauge
and Higgs fields operating on quark and lepton fields. The field strengths for
both the gauge and Higgs fields are defined by the commutators of the covariant
derivative by which he could obtain the Yang-Mills Higgs Lagrangian in the
standard model. Inspired by Sogami's work, we present a modification of our
previous scheme to formulate the spontaneously broken gauge theory in
non-commutative geometry on the discrete space; Minkowski space multiplied by
two points space by introducing the generation mixing matrix in operation of
the generalized derivative on the more fundamental fields a_i(x,y) which
compose the gauge and Higgs fields. The standard model is reconstructed
according to the modified scheme, which does not yields not only any special
relations between the particle masses but also the special restriction on the
Higgs potential.Comment: 21 page
Full-Coupled Channel Approach to Doubly Strange -Shell Hypernuclei
We describe {\it ab initio} calculations of doubly strange, , -shell
hypernuclei (H, H,
He and He) as a first attempt to
explore the few-body problem of the {\it full}-coupled channel scheme for these
systems. The wave function includes , ,
and channels. Minnesota , D2 , and
simulated potentials based on the Nijmegen hard-core model, are used.
Bound state solutions of these systems are obtained. We find that a set of
phenomenological interactions among the octet baryons in and
-2 sectors, which is consistent with all of the available experimental binding
energies of and -2 -shell (hyper-)nuclei, can predict a particle
stable bound state of H.
For H and He,
and potentials enhance the net
coupling, and a large probability is obtained even for a weaker
potential.Comment: 4 pages, 1 figur
Positron scattering and annihilation from the hydrogen molecule at zero energy
The confined variational method is used to generate a basis of correlated
gaussians to describe the interaction region wave function for positron
scattering from the H molecule. The scattering length was
while the zero energy of 15.7 is compatible with
experimental values. The variation of the scattering length and
with inter-nuclear distance was surprisingly rapid due to virtual state
formation at
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