Wittgenstein on Personal Time

The most grandiose of the many philosophical problems of time is whether it is real or not. An example of a metaphysical argument to the effect that time is unreal is that of the idealist F.H. Bradley. In setting forth his case he made a distinction between 1) time as space-like and 2) time "as presented,â€? the "now.â€

Bayesian Grammar Induction for Language Modeling

We describe a corpus-based induction algorithm for probabilistic context-free grammars. The algorithm employs a greedy heuristic search within a Bayesian framework, and a post-pass using the Inside-Outside algorithm. We compare the performance of our algorithm to n-gram models and the Inside-Outside algorithm in three language modeling tasks. In two of the tasks, the training data is generated by a probabilistic context-free grammar and in both tasks our algorithm outperforms the other techniques. The third task involves naturally-occurring data, and in this task our algorithm does not perform as well as n-gram models but vastly outperforms the Inside-Outside algorithm.Comment: 8 pages, LaTeX, uses aclap.st

Evaluation of scheduling techniques for payload activity planning

Two tasks related to payload activity planning and scheduling were performed. The first task involved making a comparison of space mission activity scheduling problems with production scheduling problems. The second task consisted of a statistical analysis of the output of runs of the Experiment Scheduling Program (ESP). Details of the work which was performed on these two tasks are presented

Dynamics of satellites, asteroids, and rings

Work is reported on: (1) the shapes and the internal structures of satellites; (2) the tidal heating of Miranda; (3) the dynamics of arc-like rings; and (4) the structure of the zodiacal cloud that was revealed by the Infrared Astronomy Satellite. Significant progress was made in determining the shape and internal structure of Mimas and in understanding the dynamical evolution of Miranda's orbit

Note on recent measurements of the \psi(1S)\to\ga \eta_C(1S) and \psi(2S)\to\ga \eta_C(1S) branching ratios

Recently published measurements of the branching ratios {\cal B}(\psi(1S)\to\ga \eta_C(1S)) and {\cal B}(\psi(2S)\to\ga \eta_C(1S)) by the CLEO collaboration are examined in the context of a potential model that includes both relativistic and one-loop QCD corrections to the quark-antiquark interaction. The prediction for the width \Gamma(\psi(1S)\to\ga \eta_C(1S)) is in excellent agreement with the new data but the prediction for \Gamma(\psi(2S)\to\ga \eta_C(1S)) is too small. In an effort to understand this discrepancy, we derive an upper bound on \Gamma(\psi(2S)\to\ga \eta_C(1S)) and point out its experimental value saturates this bound.Comment: Corrected typos, addeded referenc

Recent developments in the modeling of heavy quarkonia

We examine the spectra and radiative decays of the cc-bar and bb-bar systems using a model which incorporates the complete one-loop spin-dependent perturbative QCD short distance potential, a linear confining term including (spin-dependent) relativistic corrections to order v^2/c^2, and a fully relativistic treatment of the kinetic energy. We compare the predictions of this model to experiments, including states and decays recently measured at Belle, BaBar, CLEO and CDF.Comment: 3 pages, contribution to PANIC05, Santa Fe, NM October 200

Light-Front Holography and AdS/QCD Correspondence

Light-Front Holography is a remarkable consequence of the correspondence between string theory in AdS space and conformal field theories in physical-space time. It allows string modes $\Phi(z)$ in the AdS fifth dimension to be precisely mapped to the light-front wavefunctions of hadrons in terms of a specific light-front impact variable $\zeta$ which measures the separation of the quark and gluonic constituents within the hadron. This mapping was originally obtained by matching the exact expression for electromagnetic current matrix elements in AdS space with the corresponding exact expression for the current matrix element using light-front theory in physical space-time. More recently we have shown that one obtains the identical holographic mapping using matrix elements of the energy-momentum tensor, thus providing an important consistency test and verification of holographic mapping from AdS to physical observables defined on the light-front. The resulting light-front Schrodinger equations predicted from AdS/QCD give a good representation of the observed meson and baryon spectra and give excellent phenomenological predictions for amplitudes such as electromagnetic form factors and decay constants.Comment: 14 pages. Presented at QCD Down Under II, Auckland, New Zealand, January 17-19, 200

Applications of AdS/QCD and Light-Front Holography to Baryon Physics

The correspondence between theories in anti-de Sitter space and field theories in physical space-time leads to an analytic, semiclassical model for strongly-coupled QCD which has scale invariance at short distances and color confinement at large distances. These equations, for both mesons and baryons, give a very good representation of the observed hadronic spectrum, including a zero mass pion. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons at the amplitude level. The meson and baryon wavefunctions derived from light-front holography and AdS/QCD also have remarkable phenomenological features, including predictions for the electromagnetic form factors and decay constants. The approach can be systematically improved using light-front Hamiltonian methods. Some novel features of QCD for baryon physics are also discussed.Comment: Presented by SJB at the International Conference on the Structure of Baryons, BARYONS'10, December 7-11, 2010, Osaka, Japa