Canada's Pioneering Experience with a Flexible Exchange Rate in the 1950s:(Hard) Lessons Learned for Monetary Policy in a Small Open Economy

This paper revisits Canada's pioneering experience with floating exchange rate over the period 1950-1962. It examines whether the floating rate was the best option for Canada in the 1950s by developing and estimating a New Keynesian small open economy model of the Canadian economy. The model is then used to conduct a counterfactual analysis of the impact of different monetary policies and exchange rate regimes. The main finding indicates that the flexible exchange rate helped reduce the volatility of key macro-economic variables. The Canadian monetary authorities, however, clearly did not understand all of the implications of conducting monetary policy under a flexible exchange rate and a high degree of capital mobility. The paper confirms that monetary policy was more volatile in the post-1957 period and Canada's macroeconomic performance suffered as a result.

Constraining Radio Emission from Magnetars

We report on radio observations of five magnetars and two magnetar candidates carried out at 1950 MHz with the Green Bank Telescope in 2006-2007. The data from these observations were searched for periodic emission and bright single pulses. Also, monitoring observations of magnetar 4U0142+61 following its 2006 X-ray bursts were obtained. No radio emission was detected was detected for any of our targets. The non-detections allow us to place luminosity upper limits (at 1950 MHz) of approximately L < 1.60 mJy kpc^2 for periodic emission and L < 7.6 Jy kpc^2 for single pulse emission. These are the most stringent limits yet for the magnetars observed. The resulting luminosity upper limits together with previous results are discussed, as is the importance of further radio observations of radio-loud and radio-quiet magnetars.Comment: 11 pages, 4 figure

Muonium-antimuonium conversion in models with heavy neutrinos

We study muonium-antimuonium conversion and mu+ e- to mu- e+ scattering within two different lepton-flavor-violating models with heavy neutrinos: model I is a typical seesaw that violates lepton number as well as flavor; model II has a neutrino mass texture where lepton number is conserved. We look for the largest possible amplitudes of these processes that are consistent with current bounds. We find that model I has very limited chance of providing an observable signal, except if a finely tuned condition in parameter space occurs. Model II, on the other hand, requires no fine tuning and could cause larger effects. However, the maximum amplitude provided by this model is still two orders of magnitude below the sensitivity of current experiments: one predicts an effective coupling G_MM up to 10^{-4}G_F for heavy neutrino masses near 10 TeV. We have also clarified some discrepancies in previous literature on this subject.Comment: 16 pages, 4 figures, reference adde

Lepton flavor violation in muonium decay and muon colliders in models with heavy neutrinos

We study the lepton-flavor-violating reaction $\mu^+ e^- \to e^+ e^-$ within two extensions of the standard model that include heavy neutrinos. The reaction is studied in the low energy limit in the form of muonium decay $M\to e^+ e^-$ and in the high energy regime of a muon collider. The two theoretical models we consider are: model I, a typical see-saw model that violates lepton flavor and number by inclusion of extra right handed neutrinos, and model II, a variant where lepton number is conserved and which includes extra right handed as well as left handed neutrinos, singlets under the gauge group. We find for muonium decay into $e^+e^-$ the extremely small result $Br(M\to e^+ e^-) < 10^{-19}$ in both scenarios. Alternatively, for $\mu^+ e^-$ collisions up to $\sqrt{s}\sim 50$ GeV we find $\sigma(\mu^+ e^- \to e^+ e^-)< 10^{-5}$ fb, while for energies above the $W^+ W^-$ threshold we find $\sigma(\mu^+ e^- \to W^+ W^-)$ up to 1 fb.Comment: 12 pages, 7 figures; new version recalculates the figures and results using the correlated bound on mu-e mixing from $B(\mu\to e\gamma)$ (Eq.34

Consistently computing the K -> pi long distance weak transition

First we extract the long-distance (LD) weak matrix element from certain data and give compatible theoretical estimates. We also link this LD scale to the single-quark-line (SQL) transition scale and then test the latter SQL scale against the decuplet weak decay amplitude ratio. Finally, we study LD decay. All of these experimental and theoretical values are in good agreement. We deduce an average value from eleven experimental determinations compared to the theoretical SQL values average.Comment: 19 pages, 9 figures minor change to the Conclusions and abstract sectio

NGC 7538 : Multiwavelength Study of Stellar Cluster Regions associated with IRS 1-3 and IRS 9 sources

We present deep and high-resolution (FWHM ~ 0.4 arcsec) near-infrared (NIR) imaging observations of the NGC 7538 IRS 1-3 region (in JHK bands), and IRS 9 region (in HK bands) using the 8.2m Subaru telescope. The NIR analysis is complemented with GMRT low-frequency observations at 325, 610, and 1280 MHz, molecular line observations of H13CO+ (J=1-0), and archival Chandra X-ray observations. Using the 'J-H/H-K' diagram, 144 Class II and 24 Class I young stellar object (YSO) candidates are identified in the IRS 1-3 region. Further analysis using 'K/H-K' diagram yields 145 and 96 red sources in the IRS 1-3 and IRS 9 regions, respectively. A total of 27 sources are found to have X-ray counterparts. The YSO mass function (MF), constructed using a theoretical mass-luminosity relation, shows peaks at substellar (~0.08-0.18 Msolar) and intermediate (~1-1.78 Msolar) mass ranges for the IRS 1-3 region. The MF can be fitted by a power law in the low mass regime with a slope of Gamma ~ 0.54-0.75, which is much shallower than the Salpeter value of 1.35. An upper limit of 10.2 is obtained for the star to brown dwarf ratio in the IRS 1-3 region. GMRT maps show a compact HII region associated with the IRS 1-3 sources, whose spectral index of 0.87+-0.11 suggests optical thickness. This compact region is resolved into three separate peaks in higher resolution 1280 MHz map, and the 'East' sub-peak coincides with the IRS 2 source. H13CO+ (J=1-0) emission reveals peaks in both IRS 1-3 and IRS 9 regions, none of which are coincident with visible nebular emission, suggesting the presence of dense cloud nearby. The virial masses are approximately of the order of 1000 Msolar and 500 Msolar for the clumps in IRS 1-3 and IRS 9 regions, respectively.Comment: 27 pages, 18 figures, 5 tables. Accepted for publication in MNRA

Can One Measure the Weak Phase of a Penguin Diagram?

The b -> d penguin amplitude receives contributions from internal u, c and t-quarks. We show that it is impossible to measure the weak phase of any of these penguin contributions without theoretical input. However, it is possible to obtain the weak phase if one makes a single assumption involving the hadronic parameters. With such an assumption, one can test for the presence of new physics in the b -> d flavour-changing neutral current by comparing the weak phase of B_d^0-{\bar B}_d^0 mixing with that of the t-quark contribution to the b -> d penguin.Comment: 20 pages, no figure