16212373
Noncommutative vector bundles over fuzzy ℂℙN and their covariant derivatives
We generalise the construction of fuzzy N in a manner that allows us to access all noncommutative equivariant complex vector bundles over this space. We give a simplified construction of polarization tensors on S2 that generalizes to complex projective space, identify Laplacians and natural noncommutative covariant derivative operators that map between the modules that describe noncommuative sections. In the process we find a natural generalization of the Schwinger-Jordan construction to su(n) and identify composite oscillators that obey a Heisenberg algebra on an appropriate Fock space.
13877381
A universal Dirac operator and noncommutative spin bundles over fuzzy complex projective spaces
We present a universal Dirac operator for noncommutative spin and spinc bundles over fuzzy complex projective spaces. We give an explicit construction of these bundles, which are described in terms of finite dimensional matrices, calculate the spectrum and explicitly exhibit the Dirac eigenspinors. To our knowledge the spinc spectrum for n with n ≥ 3 is new.
119683797
Noncommutative Spherically Symmetric Space
We examine some noncommutative spherically symmetric spaces in three space dimensions. A generalization of Snyder’s noncommutative (Euclidean) space allows the inclusion of the generator of dilations into the defining algebra of the coordinate and rotation operators. We then construct a spherically symmetric noncommutative Laplacian on this space having the correct limiting spectrum. This is presented via a creation and annihilation operator realization of the algebra, which may lend itself to a truncation of the Hilbert space.
119293158
Noncommuting coordinates and magnetic monopoles
The appearance of noncommuting spatial coordinates is studied in quantum systems containing a magnetic monopole and under the influence of a radial potential. We derive expressions for the commutators of the coordinates that have been restricted to the lowest energy level. Quantum corrections are found to previous results by Frenkel and Pereira based on quantizing the Dirac brackets of the classical theory. For two different potentials, the modified harmonic oscillator potential and the modified Coulomb potential, we also calculate the commutators for a projection to a fixed energy level.
121936592
Signature splitting and quasiparticle alignment in the yrast band of Ta-165
Excited states in Ta-165 were populated in the Nd-142(Al-27,4n)Ta-165 and Pr-141(Si-28,4n)Ta-165 reactions and investigated using the AFRODITE array. The yrast rotational decay sequence up to spin 53/2(-) is identified and assigned to the [514]9/2(-) configuration. The nuclear shape is investigated using total Routhian surface calculations. The experimental results are discussed in relation to existing data in the neighboring Ta isotopes and results from cranked shell model calculations. Unexpectedly large signature splitting, for a high-Omega configuration, is observed in the yrast band. Further discrepancies are observed between theoretical and experimental values for the band crossing frequency and signature splitting of the B(M1)/B(E2) ratios. The possibility that these discrepancies are a consequence of a large deviation from an axially symmetric nuclear shape is investigated.
119979477
Possible chirality in the doubly-odd Tl-198 nucleus: Residual interaction at play
A candidate for chiral bands was found in Tl-198 for the first time in a mass region of oblate (or nonaxial with gamma >= 30 degrees) deformed nuclei. Two bands show very similar quasiparticle alignments, moments of inertia, and B(M1)/B(E2) ratios. They have a relative excitation energy of about 500 keV and different patterns of energy staggering. Calculations using the two-quasiparticle-plus-triaxial-rotor model with residual proton-neutron interaction included show that a triaxial deformation with gamma similar to 44 degrees agrees very well with all the experimental observations. Furthennore, considerable energy staggering for both partner bands was calculated for this pi h(9/2) circle times vi(13/2)(-1) configuration at gamma - 30 degrees, suggesting that chiral bands may have substantial energy staggering. (Less)
121631668
A high energy-resolution zero degree facility for (p,p′) and (p,t) reactions
Medium-energy hadronic scattering and reactions at zero degrees are very selective to excitations with low angular momentum transfer. Only a few facilities exist worldwide where high energy-resolution measurements of this nature can be performed. The K600 Zero-Degree Facility at iThemba LABS, South Africa, was recently successfully developed. Measurements were performed for inelastic proton scattering at an incident energy of 200 MeV for targets ranging from 27Al to 208Pb. Excitation energy-resolution of 50 keV (FWHM) was achieved. A reasonable background subtraction procedure allows for the extraction of excitation energy spectra with low background. Measurements of the (p,t) reaction at 100 MeV benefit from a large difference in magnetic rigidity between the reaction products and primary particles, resulting in almost background-free spectra with excitation energy-resolution of 32 keV (FWHM).
118470901
Signature inversion in the yrast band of Ta-164
Excited states in Ta-164 were populated in the Nd-142(Al-27,5n)Ta-164 reaction and investigated using the AFRODITE spectrometer Arran. The yrast rotational decay sequence Lip to spin 21(-) is identified for the first time and assigned to the pi[514]9/2(-) x nu[660]1/2(+) configuration. A less intense. excited hand is also identified. Low-spin signature inversion is observed in the yrast band, and is compared with the extended total Routhian surface calculations. It is likely that quadrupole pairing plays a role in generating the anomalous signature splitting, but an additional mechanism apart front the assumed mean field and quadrupole pairing interaction may be required to account for the experimental data.
122046656
Close near-degeneracy in a pair of four-quasiparticle bands in Tl-194
A pair of rotational bands associated with the pi h(9/2) circle times nu i(13/2)(-1) configuration at lower spins and with the pi h(9/2) circle times nu i(13/2)(-3) configuration at higher spins is found in Tl-194. The two 4-quasiparticle bands show exceptionally close near-degeneracy in the excitation energies. Furthermore close similarity is also found in their alignments and B(M1)/B(E2) reduced transition probability ratios. Such close near-degeneracy probably indicates chiral geometry in the angular momentum space. (c) 2013 Elsevier B.V. All rights reserved.