UC Davis Particle Physics Seminars

We present a study of the invariant mass distribution of jet pairs produced in association with a W boson using data collected with the CDF detector which correspond to an integrated luminosity of 4.3 fb^-1. The observed distribution has an excess in the 120-160 GeV mass range which is not described by current theoretical predictions within the statistical and systematic uncertainties. In particular we will discuss the properties and the significance of this excess.

In the causal set approach to quantum gravity the spacetime continuum arises as an approximation to a fundamentally discrete substructure, the causal set, which is a locally finite partially ordered set. The causal set paradigm was elucidated in a classic paper by Bombelli, Lee, Meyer and Sorkin in 1987. While early kinematical results already showed promise, the program received a substantial impetus about a decade ago with the work of Rideout and Sorkin on a classical stochastic growth dynamics for causal sets. Considerable progress has been made ever since in our understanding of causal set theory while leaving undisturbed the basic paradigm. Recent highlights include a causal set expression for the Einstein-Hilbert action and the construction of a scalar field Feynman propagator on a fixed causal set.

Sachindeo Vaidya argues that an accelerating frame may be defined (i.e. as a sequence of instantaneous Lorentz transformations) in noncommutative Moyal spacetime.

Joe Polchinski discusses the idea that physics must be holographic and that the fundamental variables are nonlocal and locality is emergent; this is a complete change from previous experience, and we have much to understand.

Hal Haggard presents on computing the Bohr-Sommerfeld volume spectrum of a tetrahedron and showing that it reproduces the quantization of a grain of space found in loop gravity.

Yasunori Nomura presents a framework in which well-defined predictions are obtained in an eternally inflating multiverse, based on the principles of quantum mechanics.

Guido D'Amico presents the consequences of imposing an approximate Galilean symmetry on the Effective Theory of Inflation, the theory of small perturbations around the inflationary background.

Zacharia Chacko discusses the spectrum of gamma ray signals that arise from dark matter annihilation in the universe.

Vikram Rentala proposes a new model-independent method for spin measurements which takes advantage of quantum interference among helicity states.

Erich Poppitz discusses the Eguchi-Kawai reduction in the strong-coupling domain of gauge theories via the gravity dual of N=4 super-Yang-Mills on R^3xS^1.