Loop quantum gravity induced modifications to particle dynamics

The construction of effective Hamiltonians arising from Loop Quantum Gravity and incorporating Planck scale corrections to the dynamics of photons and spin 1/2 particles is summarized. The imposition of strict bounds upon some parameters of the model using already existing experimental data is also reviewed.Comment: 9 pages, 0 figures, talk presented at the X Mexican School of Particles and Fields, latex, aipproc style 6x

Flat space modified particle dynamics induced by Loop Quantum Gravity

Starting from an heuristic approach to the semiclassical limit in loop quantum gravity, the construction of effective Hamiltonians describing Planck length corrections to the propagation of photons and spin 1/2 fermions, leading to modified energy-momentum relations, is summarized. Assuming the existence of a privileged reference frame, we also review the determination of stringent bounds upon the parameters labelling such corrections, based upon already existing experimental data, which are found to be from five to nine orders of magnitude below the expected values.Comment: 10 pages, no figures, ws-procs 975x65.cls, extended version of the talk given at the Tenth Marcel Grossmann Meeting, Rio de Janeiro, July 20-26, 200

Loop Quantum Gravity induced corrections to fermion dynamics in flat space

A summary of recent work related to the calculation of loop quantum gravity induced corrections to standard particle (photons and spin 1/2 fermions) dynamics in flat space is presented. Stringent bounds upon the parameters characterizing the corrections in the fermionic sector, arising from already known clock-comparison experiments, are reviewed.Comment: 6 pages, no figures, ws-procs9x6.tex, Talk presented at the Third International Symposium on Quantum Theory and Symmetries, U. of Cincinnati, September 10-14, 200

Slowly rotating Kerr black hole as a solution of Einstein-Cartan gravity extended by a Chern-Simons term

We consider the nondynamical Chern-Simons (CS) modification to General Relativity (GR) in the framework of the Einstein-Cartan formulation, as providing a way to incorporate a slowly rotating Kerr black hole in the space of solutions. Our proposal lies on considering the CS term as a source of torsion and on an iterative procedure to look for vacuum solutions of the system, by expanding the tetrad, the connection and the embedding parameter, in powers of a dimensionless small parameter $\beta$ which codifies the CS coupling. Starting from a torsionless zeroth-order vacuum solution we derive the second-order differential equation for the $\mathcal{O}(\beta)$ corrections to the metric, for an arbitrary embedding parameter. Furthermore we can show that the slowly rotating Kerr metric is an $\mathcal{O}(\beta)$ solution of the system either in the canonical or the axial embeddings.Comment: "Presented at the Fifth Meeting on CPT and Lorentz Symmetry, Bloomington, Indiana, June 28-July 2, 2010

Renovation proposal for Fenway Park

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2009.Includes bibliographical references (leaf 39).As the oldest stadium in baseball history, the existing structure of Fenway Park presents problems such as limiting seating capacity and obstructed views, caused by the columns supporting the second level. Opened in 1912, this stadium is considered one of today's most historical sporting venues. In 2005, the Red Sox ownership announced that the stadium would remain as the home of the Red Sox for years to come. Consequently, considerable investments were made into the stadium to increase seating capacity and to retrofit the structure. This thesis explores the aforementioned main problems, the seating capacity and the obstructed view, and proposes a new design for the seating deck. Two options are explored: one scheme is a stiff structure with concentric bracing and the second scheme is a flexible structure that implements a Tuned Mass Damper to mitigate the vibrations of the cantilevered deck. A design proposal is presented with standard steel sections. It is concluded that the second option is not feasible because it does not comply with the deflection criterion.by Luis Pedro Aldana Urrutia.M.Eng

An extended solution space for Chern-Simons gravity: the slowly rotating Kerr black hole

In the Einstein-Cartan formulation, an iterative procedure to find solutions in non-dynamical Chern-Simons (CS) gravity in vacuum is proposed. The iterations, in powers of a small parameter $\beta$ which codifies the CS coupling, start from an arbitrary torsionless solution of Einstein equations. With Schwarzschild as the zeroth-order choice, we derive a second-order differential equation for the $\mathcal{O}(\beta)$ corrections to the metric, for an arbitrary zeroth-order embedding parameter. In particular, the slowly rotating Kerr metric is an $\mathcal{O}(\beta)$ solution in either the canonical or the axial embeddings.Comment: 5 pages, PRD accepte