The Low-Energy Theorem of Pion Photoproduction in Soliton Models of the Nucleon

We derive an analytic expression for the Kroll-Ruderman amplitude up to the order 1/N_C for general Skyrme-type models of the nucleon. Due to the degeneracy of intermediate N- and Delta-states we find deviations from the standard low-energy theorem for the photoproduction of neutral pions.Comment: 17 pages, LATEX, SI-93-TP3S

Electric Quadrupole Moments of the Decuplet and the Strangeness Content of the Proton

In the SU3 Skyrme model the electric quadrupole moments of $\frac{3}{2}^+$ baryons show a strong sensitivity with respect to flavor distortions in baryon wavefunctions. SU3 symmetric wavefunctions lead to quadrupole moments proportional to the charge of the baryon whereas for strongly broken flavor symmetry a proportionality to baryonic isospin emerges. Since the flavor distortions in the wavefunctions also determine the strangeness content of the proton the Skyrme model provides a link between both quantities.Comment: 6 pages, LATEX, (1 LATEX-figure), hardcopy : preprint# SI-94-TP3S

Hyperons as collective excitations of chiral solitons

According to the large $N_C$ limit of QCD baryons are considered as soliton solutions in effective mesons theories. While the classical solitons dwell in the isospin subgroup of flavor SU(3) hyperon states are generated by canonical quantization of the collective coordinates which describe the flavor orientation of the soliton. The resulting Hamiltonian is diagonalized exactly allowing one to discuss the dependence of various baryon properties on flavor symmetry breaking. In particular axial charges, baryon magnetic moments and radiative decay widths are considered.Comment: 3 pages, uses col2.sty (included), Talk presented at the III Int. Conf. on Hyperons, Charm and Beauty Hadrons, Genova, June--July 199

SU(3) Symmetry Breaking and Octet Baryon Polarizabilities

Static polarizabilities of the low--lying $1/2^+$ baryons are studied within the collective coordinate approach to the three flavor generalization of the Skyrme model; in particular, magnetic polarizabilities are considered. Predicted polarizabilities, which result from different treatments of the strange degrees of freedom in this model, are critically compared. Their deviations from the flavor symmetric formulations are discussed.Comment: 11 pages, LaTeX, 4 tables, no figures, final version to be published in Phys. Lett.

Effective Lagrangian with vector mesons : Linear response theory

The soliton breathing mode is investigated in the framework of linear response theory within a Skyrme model vector meson stabilized. The effective Lagrangian considered includes the $\rho$ (introduced following the standard prescription of nonlinear chiral symmetry) and the $\omega$ mesons. The monopole response function is found to have a pronounced peak which is identified to the $P11$ (Roper) resonance. The results are compared to those obtained within the local approximation.Comment: 8 pages of plain Latex and 2 figures (available from the author), preprint LPN 93-12 and IPNO/TH 93-4

Meson photoproduction at threshold in three flavor soliton models

In Skyrme-type models, the leading term of the low-energy photoproduction amplitude is identical to the standard expression and independent of the number of flavors considered, but subleading terms are not.Comment: 8 pages, LaTeX, no figure

3D Perception Based Lifelong Navigation of Service Robots in Dynamic Environments

Lifelong navigation of mobile robots is to ability to reliably operate over extended periods of time in dynamically changing environments. Historically, computational capacity and sensor capability have been the constraining factors to the richness of the internal representation of the environment that a mobile robot could use for navigation tasks. With affordable contemporary sensing technology available that provides rich 3D information of the environment and increased computational power, we can increasingly make use of more semantic environmental information in navigation related tasks.A navigation system has many subsystems that must operate in real time competing for computation resources in such as the perception, localization, and path planning systems. The main thesis proposed in this work is that we can utilize 3D information from the environment in our systems to increase navigational robustness without making trade-offs in any of the real time subsystems. To support these claims, this dissertation presents robust, real world 3D perception based navigation systems in the domains of indoor doorway detection and traversal, sidewalk-level outdoor navigation in urban environments, and global localization in large scale indoor warehouse environments.The discussion of these systems includes methods of 3D point cloud based object detection to find respective objects of semantic interest for the given navigation tasks as well as the use of 3D information in the navigational systems for purposes such as localization and dynamic obstacle avoidance. Experimental results for each of these applications demonstrate the effectiveness of the techniques for robust long term autonomous operation

Double-Dipole Excitations in 40Ca

The double-dipole strength distribution in $^{40}$Ca is calculated microscopically within a model space of 1p1h - and 2p2h excitations. Anharmonic effects in the centroid energies of the $0^+$- and $2^+$ components are found to be small, in agreement with experimental observation. Firm conclusions about the spreading width cannot be drawn, as yet, due to computational limitations in the number of 2p2h states.Comment: 8 pages of LaTeX, two figures available at ftp://rsm1.physcis.uiuc.edu/pub/figs

Loosely bound hyperons in the SU(3) Skyrme model

Hyperon pairs bound in deuteron like states are obtained within the SU(3) Skyrme model in agreement with general expectations from boson exchange models. The central binding from the flavor symmetry breaking terms increases with the strangeness contents of the interacting baryons whereas the kinetic non-linear $\sigma$-model term fixes the spin and isospin of the bound pair. We give a complete account of the interactions of octet baryons within the product approximation to baryon number $B=2$ configurations.Comment: 35 pages REVTEX including 2 figs, with 3 further figs available on request from [email protected] or from [email protected] SI-94-TP3S2; STPHY-Th/94-

Quantum Corrections to Baryon Properties in Chiral Soliton Models

We present a procedure to calculate 1-loop graphs in the soliton sector of chiral Lagrangians and use it to calculate quantum corrections to certain baryon observables in Skyrme-type models. Results generally show an improvement over the values obtained in tree approximation except for the case of the axial coupling g_A.Comment: Chapters on magnetic polarizabilities and e.m. properties of Delta isobar added, 90 pages, Latex, 9 Postscript figure