Differential Astrometry of Sub-arcsecond Scale Binaries at the Palomar Testbed Interferometer

We have used the Palomar Testbed Interferometer to perform very high precision differential astrometry on the 0.25 arcsecond separation binary star HD 171779. In 70 minutes of observation we achieve a measurement uncertainty of approximately 9 micro-arcseconds in one axis, consistent with theoretical expectations. Night-to-night repeatability over four nights is at the level of 16 micro-arcseconds. This method of very-narrow-angle astrometry may be extremely useful for searching for planets with masses as small as 0.5 Jupiter Masses around a previously neglected class of stars -- so-called ``speckle binaries.'' It will also provide measurements of stellar parameters such as masses and distances, useful for constraining stellar models at the 10^-3 level.Comment: 19 pages including 6 figures. Submitted to ApJ. Typos corrected, several parts reworded for clarificatio

Exchange Rates and Monetary Policy in Emerging Market Economies

This paper investigates the effects of exchange rate regimes and alternative monetary policy rules for an emerging market economy that is subject to a volatile external environment in the form of shocks to world interest rates and the terms of trade. In particular, we highlight the impact of financial frictions and the degree of exchange rate pass through in determining the relative performance of alternative regimes in stablizing the economy in the face of external shocks. Our results are quite sharp. When exchange rate pass-through is high, a policy of non-traded goods inflation targeting does best in stablizing the economy, and is better in welfare terms. When exchange rate pass-through is low, however, a policy of strict CPI inflation targeting is better. In all cases, a fixed exchange rate is undesirable. In addition, financial frictions have no implications for the ranking of alternative policy rules.

Charge assignments in multiple-U(1) gauge theories

We discuss the choice of gauge field basis in multiple-U(1) gauge theories. We find that there is a preferred basis, specified by the charge orthogonality condition, in which the U(1) gauge fields do not mix under one-loop renormalization group running.Comment: 7 pages, LaTe

Exchange Rates and Monetary Policy in Emerging Market Economies

This paper investigates the effects of exchange rate regimes and alternative monetary policy rules for an emerging market economy that is subject to a volatile external environment in the form of shocks to world interest rates and the terms of trade. In particular, we highlight the impact of financial frictions and the degree of exchange rate pass through in determining the relative performance of alternative regimes in stablizing the economy in the face of external shocks. Our results are quite sharp. When exchange rate pass-through is high, a policy of non-traded goods inflation targeting does best in stablizing the economy, and is better in welfare terms. When exchange rate pass-through is low, however, a policy of strict CPI inflation targeting is better. In all cases, a fixed exchange rate is undesirable. In addition, financial frictions have no implications for the ranking of alternative policy rules.

Narrow Technihadron Production at the First Muon Collider

In modern technicolor models, there exist very narrow spin-zero and spin-one neutral technihadrons---$pi^0_T$, $rho^0_T$ and $omega_T$---with masses of a few 100 GeV. The large coupling of $\pi^0_T$ to $\mu^+\mu^-$, the direct coupling of $rho^0_T$ and $omega_T$ to the photon and $Z^0$, and the superb energy resolution of the First Muon Collider may make it possible to resolve these technihadrons and produce them at extraordinarily large rates.Comment: 11 pages, latex, including 2 postscript figure

New strong sector, odd-parity processes, and the Tevatron

The color-octet isosinglet "rho" of a new strong-interaction sector is readily produced in ppbar collisions. Its odd-parity decay to an "eta" and a gluon may exceed its decay rate to dijets. At center of mass energies sufficiently greater than the colored "rho" mass, the odd-parity production of ("omega" + colored "eta") or ("rho" + colored "pion") may be comparable to ttbar production. Considering that the "omega" has a dominant odd-parity decay mode, we end up with (Z, W, or gamma) + 4 jet events with two of the jets containing b or bbar.Comment: 8 pages, uuencoded PS file, try ghostscript or direct printing rather than ghostview, PS file of paper without figure is available on WWW at http://bigmac2.physics.utoronto.ca/BHpapers.htm

Vacuum Alignment in Technicolor Theories-I. The Technifermion Sector

We have carried out numerical studies of vacuum alignment in technicolor models of electroweak and flavor symmetry breaking. The goal is to understand alignment's implications for strong and weak CP nonconservation in quark interactions. In this first part, we restrict our attention to the technifermion sector of simple models. We find several interesting phenomena, including (1) the possibility that all observable phases in the technifermions' unitary vacuum-alignment matrix are integer multiples of \pi/N' where N' \le N, the number of technifermion doublets, and (2) the possibility of exceptionally light pseudoGoldstone technipions.Comment: 19 pages, Latex with one postscript figur