17,922 research outputs found
Hyperfinite-Dimensional Representations of Canonical Commutation Relation
This paper presents some methods of representing canonical commutation
relations in terms of hyperfinite-dimensional matrices, which are constructed
by nonstandard analysis. The first method uses representations of a nonstandard
extension of finite Heisenberg group, called hyperfinite Heisenberg group. The
second is based on hyperfinite-dimensional representations of so(3). Then, the
cases of infinite degree of freedom are argued in terms of the algebra of
hyperfinite parafermi oscillators, which is mathematically equivalent to a
hyperfinite-dimensional representation of so(n).Comment: 18 pages, LaTe
The nrMSSU(5) and universality of soft masses
We discuss the problem of universality of the soft, supersymmetry-breaking
terms in the minimal supersymmetric SU(5) model (MSSU(5)) completed with
flavor-dependent nonrenormalizable operators (NROs), or nrMSSU(5). These are
exploited to correct the wrong fermion spectrum and to slow down the too-fast
decay rate of the proton that the MSSU(5) model predicts. In general, the
presence of such operators in the superpotential and K\"ahler potential gives
rise to tree-level flavor- and CP-violating entries in the sfermion mass
matrices at the cutoff scale, even when the mediation of supersymmetry (SUSY)
breaking is generation and field-type independent. We identify the conditions
under which such terms can be avoided.Comment: 4 pages, LateX, to appear in the proceedings of SUSY09, Boston, MA,
USA, 5-10 June 200
Comment on "Efimov States and their Fano Resonances in a Neutron-Rich Nucleus"
By introducing a mass asymmetry in a non-Borromean three-body system, without
changing the energy relations, the virtual state pole cannot move from the
negative real axis of the complex energy plane (with nonzero width) and become
a resonance, because the analytical structure of the unitarity cuts remains the
same.Comment: To be published in PR
Radii in weakly-bound light halo nuclei
A systematic study of the root-mean-square distance between the constituents
of weakly-bound nuclei consisting of two halo neutrons and a core is performed
using a renormalized zero-range model. The radii are obtained from a universal
scaling function that depends on the mass ratio of the neutron and the core, as
well as on the nature of the subsystems, bound or virtual. Our calculations are
qualitatively consistent with recent data for the neutron-neutron
root-mean-square distance in the halo of Li and Be nuclei
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