245,533 research outputs found

    Uncertainty and UK Monetary Policy

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    This paper provides empirical evidence on the response of monetary policymakers to uncertainty. Using data for the UK since the introduction of inflation targets in October 1992, we find that the impact of inflation on interest rates is lower when inflation is more uncertain and is larger when the output gap is more uncertain. These findings are consistent with the predictions of the theoretical literature. We also find that uncertainty has reduced the volatility but has not affected the average value of interest rates and argue that monetary policy would have been less passive in the absence of uncertainty

    Testing the Opportunistic Approach to Monetary Policy

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    The Opportunistic Approach to Monetary Policy is an influential but untested model of optimal monetary policy. We provide the first tests of the model, using US data from 1983Q1-2004Q1. Our results support the Opportunistic Approach. We find that policymakers respond to the gap between inflation and an intermediate target that reflects the recent history of inflation. We find that there is no response of interest rates to inflation when inflation is within 1% of the intermediate target but a strong response when inflation is further from the intermediate target

    Do the gravitational corrections to the beta functions of the quartic and Yukawa couplings have an intrinsic physical meaning?

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    We study the beta functions of the quartic and Yukawa couplings of General Relativity and Unimodular Gravity coupled to the λϕ4\lambda\phi^4 and Yukawa theories with masses. We show that the General Relativity corrections to those beta functions as obtained from the 1PI functional by using the standard MS multiplicative renormalization scheme of Dimensional Regularization are gauge dependent and, further, that they can be removed by a non-multiplicative, though local, field redefinition. An analogous analysis is carried out when General Relativity is replaced with Unimodular Gravity. Thus we show that any claim made about the change in the asymptotic behaviour of the quartic and Yukawa couplings made by General Relativity and Unimodular Gravity lack intrinsic physical meaning.Comment: 6 pages, 7 figure

    Noncommutative GUT inspired theories and the UV finiteness of the fermionic four point functions

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    We show at one-loop and first order in the noncommutativity parameters that in any noncommutative GUT inspired theory the total contribution to the fermionic four point functions coming only from the interaction between fermions and gauge bosons, though not UV finite by power counting, is UV finite at the end of the day. We also show that this is at odds with the general case for noncommutative gauge theories --chiral or otherwise-- defined by means of Seiberg-Witten maps that are the same --barring the gauge group representation-- for left-handed spinors as for right-handed spinors. We believe that the results presented in this paper tilt the scales to the side of noncommutative GUTS and noncommutative GUT inspired versions of the Standard Model.Comment: 11 pages, 3 figures. Version 2: references fixed and completed. Version 3: Comments adde

    New Results from an old Friend: The Crab Nebula and its Pulsar

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    We summarize here the results, most of which are preliminary, of a number of recent observations of the Crab nebula system with the Chandra X-Ray Observatory. We discuss four different topics: (1) The motion on long (> 1yr) time scales of the southern jet. (2) The discovery that pulsar is not at the center of the projected ring on the sky and that the ring may well lie on the axis of symmetry but appears to be displaced at a latitude of about 5 degrees. (Note that this deprojection is by no means unique.) (3) The results and puzzling implications of the Chandra phase-resolved spectroscopy of the pulsar when compared to observations of pulse-phase variations of similar and dissimilar measures in other regions of the spectrum. (4) The search for the X-ray location of the site of the recently-discovered gamma-ray flaring. We also comment briefly on our plan to use the Chandra data we obtained for the previous project to study the nature of the low-energy flux variations recently detected at hard X-ray energies.Comment: 6 pages, 5 figures, submitted to the proceedings of the conference: "The Extreme and Variable High Energy Sky", 19-23 September 2011, Chia Laguna (Cagliari) - Ital


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    BEES. THEIR VISION, CHEMICAL SENSES, AND LANGUAGE. Karl von Frisch, the University of Munich. Revised edition. Cornell University Press, Ithaca, New York and London. 157 pages. 7.50(3.50),paperback7.50 ( 3.50), paperback 2.45