15,583 research outputs found

    Is it possible to Measure the Weak Phase of a Penguin Diagram?

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    The b→db\to d penguin amplitude receives contributions from internal uu, cc and tt-quarks. We show that it is impossible to measure the weak phase of any of these penguin contributions without theoretical input. However, a single assumption involving the hadronic parameters makes it possible to obtain the weak phase and test for the presence of new physics in the b→db\to d flavour-changing neutral current.Comment: 4 pages, latex, no figures, talk given by R. Sinha at the 3rd International Conference on B Physics and CP Violation, Taipei, Taiwan, December 3-7, 1999, to appear in the Proceeding

    Probing New Physics via an Angular Analysis of B --> V1 V2 decays

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    We show that an angular analysis of B --> V1 V2 decays yields numerous tests for new physics in the decay amplitudes. Unlike direct CP asymmetries, many of these new-physics observables are nonzero even if the strong phase differences vanish. For certain observables, neither time-dependent measurements nor tagging is necessary. Should a signal for new physics be found, one can place a lower limit on the size of the new-physics parameters, as well as on their effect on the measurement of the phase of B0--Bbar0 mixing.Comment: 9 pages, plain latex, no figures. Title modified slightly. Paragraph added about viability of method. Conclusions unchanged. To be published in Europhysics Letter

    A new sound mode in liquid Helium 4?

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    This letter is based on the hypothesis of a small entropy content of the superfluid fraction of liquid helium. We show that such a superfluid entropy gives rise to a new sound mode in a ring-shaped superleak. This mode is named sixth sound. We propose an experiment by which its sound velocity and thereby the superfluid entropy can be measured. A negative experiment would yield a new upper limit for the superfluid entropy.Comment: 9 pages, latex, published in Phys. Lett. A 187 (1994) 8

    The “Demand Side” of Transnational Bribery and Corruption: Why Leveling the Playing Field on the Supply Side Isn’t Enough

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    The domestic and international legal framework for combating bribery and corruption (“ABC laws”), including both private and public corrupt practices that are transnational (cross border) in character, has dramatically expanded over the last twenty years. Despite these developments, major gaps remain. This Article examines one of the largest systemic gaps: the absence of effective tools to control the demand side of transnational bribery and corruption—the corrupt solicitation of a benefit—especially when it involves a public official

    Electrodynamics of superconductors

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    An alternate set of equations to describe the electrodynamics of superconductors at a macroscopic level is proposed. These equations resemble equations originally proposed by the London brothers but later discarded by them. Unlike the conventional London equations the alternate equations are relativistically covariant, and they can be understood as arising from the 'rigidity' of the superfluid wave function in a relativistically covariant microscopic theory. They predict that an internal 'spontaneous' electric field exists in superconductors, and that externally applied electric fields, both longitudinal and transverse, are screened over a London penetration length, as magnetic fields are. The associated longitudinal dielectric function predicts a much steeper plasmon dispersion relation than the conventional theory, and a blue shift of the minimum plasmon frequency for small samples. It is argued that the conventional London equations lead to difficulties that are removed in the present theory, and that the proposed equations do not contradict any known experimental facts. Experimental tests are discussed.Comment: Small changes following referee's and editor's comments; to be published in Phys.Rev.

    Precession during merger 1: Strong polarization changes are observationally accessible features of strong-field gravity during binary black hole merger

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    The short gravitational wave signal from the merger of compact binaries encodes a surprising amount of information about the strong-field dynamics of merger into frequencies accessible to ground-based interferometers. In this paper we describe a previously-unknown "precession" of the peak emission direction with time, both before and after the merger, about the total angular momentum direction. We demonstrate the gravitational wave polarization encodes the orientation of this direction to the line of sight. We argue the effects of polarization can be estimated nonparametrically, directly from the gravitational wave signal as seen along one line of sight, as a slowly-varying feature on top of a rapidly-varying carrier. After merger, our results can be interpreted as a coherent excitation of quasinormal modes of different angular orders, a superposition which naturally "precesses" and modulates the line-of-sight amplitude. Recent analytic calculations have arrived at a similar geometric interpretation. We suspect the line-of-sight polarization content will be a convenient observable with which to define new high-precision tests of general relativity using gravitational waves. Additionally, as the nonlinear merger process seeds the initial coherent perturbation, we speculate the amplitude of this effect provides a new probe of the strong-field dynamics during merger. To demonstrate the ubiquity of the effects we describe, we summarize the post-merger evolution of 104 generic precessing binary mergers. Finally, we provide estimates for the detectable impacts of precession on the waveforms from high-mass sources. These expressions may identify new precessing binary parameters whose waveforms are dissimilar from the existing sample.Comment: 11 figures; v2 includes response to referee suggestion
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