2,155 research outputs found

    Standard-model prediction for direct CP violation in K→ππK\to\pi\pi decay

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    We report the first lattice QCD calculation of the complex kaon decay amplitude A0A_0 with physical kinematics, using a 323×6432^3\times 64 lattice volume and a single lattice spacing aa, with 1/a=1.3784(68)1/a= 1.3784(68) GeV. We find Re(A0)=4.66(1.00)(1.26)×10−7(A_0) = 4.66(1.00)(1.26) \times 10^{-7} GeV and Im(A0)=−1.90(1.23)(1.08)×10−11(A_0) = -1.90(1.23)(1.08) \times 10^{-11} GeV, where the first error is statistical and the second systematic. The first value is in approximate agreement with the experimental result: Re(A0)=3.3201(18)×10−7(A_0) = 3.3201(18) \times 10^{-7} GeV while the second can be used to compute the direct CP violating ratio Re(ε′/ε)=1.38(5.15)(4.59)×10−4(\varepsilon'/\varepsilon)=1.38(5.15)(4.59)\times 10^{-4}, which is 2.1σ2.1\sigma below the experimental value 16.6(2.3)×10−416.6(2.3)\times 10^{-4}. The real part of A0A_0 is CP conserving and serves as a test of our method while the result for Re(ε′/ε)(\varepsilon'/\varepsilon) provides a new test of the standard-model theory of CP violation, one which can be made more accurate with increasing computer capability.Comment: 9 pages, 3 figures. Updated to match published versio

    First Results From The Taiwanese-American Occultation Survey (TAOS)

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    Results from the first two years of data from the Taiwanese-American Occultation Survey (TAOS) are presented. Stars have been monitored photometrically at 4 Hz or 5 Hz to search for occultations by small (~3 km) Kuiper Belt Objects (KBOs). No statistically significant events were found, allowing us to present an upper bound to the size distribution of KBOs with diameters 0.5 km < D < 28 km.Comment: 5 pages, 5 figure, accepted in Ap

    Next to leading order spin-orbit effects in the motion of inspiralling compact binaries

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    Using effective field theory (EFT) techniques we calculate the next-to-leading order (NLO) spin-orbit contributions to the gravitational potential of inspiralling compact binaries. We use the covariant spin supplementarity condition (SSC), and explicitly prove the equivalence with previous results by Faye et al. in arXiv:gr-qc/0605139. We also show that the direct application of the Newton-Wigner SSC at the level of the action leads to the correct dynamics using a canonical (Dirac) algebra. This paper then completes the calculation of the necessary spin dynamics within the EFT formalism that will be used in a separate paper to compute the spin contributions to the energy flux and phase evolution to NLO.Comment: 25 pages, 4 figures, revtex4. v2: minor changes, refs. added. To appear in Class. Quant. Gra

    The TAOS Project: Statistical Analysis of Multi-Telescope Time Series Data

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    The Taiwanese-American Occultation Survey (TAOS) monitors fields of up to ~1000 stars at 5 Hz simultaneously with four small telescopes to detect occultation events from small (~1 km) Kuiper Belt Objects (KBOs). The survey presents a number of challenges, in particular the fact that the occultation events we are searching for are extremely rare and are typically manifested as slight flux drops for only one or two consecutive time series measurements. We have developed a statistical analysis technique to search the multi-telescope data set for simultaneous flux drops which provides a robust false positive rejection and calculation of event significance. In this paper, we describe in detail this statistical technique and its application to the TAOS data set.Comment: 15 pages, 14 figures. Submitted to PAS

    Spin induced multipole moments for the gravitational wave amplitude from binary inspirals to 2.5 Post-Newtonian order

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    Using the NRGR effective field theory formalism we calculate the remaining source multipole moments necessary to obtain the spin contributions to the gravitational wave amplitude to 2.5 Post-Newtonian (PN) order. We also reproduce the tail contribution to the waveform linear in spin at 2.5PN arising from the nonlinear interaction between the current quadrupole and the mass monopole.Comment: 17 pages, 4 figures. v2 Minor changes, to appear in JCA

    The TAOS Project: Upper Bounds on the Population of Small KBOs and Tests of Models of Formation and Evolution of the Outer Solar System

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    We have analyzed the first 3.75 years of data from TAOS, the Taiwanese American Occultation Survey. TAOS monitors bright stars to search for occultations by Kuiper Belt Objects (KBOs). This dataset comprises 5e5 star-hours of multi-telescope photometric data taken at 4 or 5 Hz. No events consistent with KBO occultations were found in this dataset. We compute the number of events expected for the Kuiper Belt formation and evolution models of Pan & Sari (2005), Kenyon & Bromley (2004), Benavidez & Campo Bagatin (2009), and Fraser (2009). A comparison with the upper limits we derive from our data constrains the parameter space of these models. This is the first detailed comparison of models of the KBO size distribution with data from an occultation survey. Our results suggest that the KBO population is comprised of objects with low internal strength and that planetary migration played a role in the shaping of the size distribution.Comment: 18 pages, 16 figures, Aj submitte

    The Taiwanese-American Occultation Survey: The Multi-Telescope Robotic Observatory

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    The Taiwanese-American Occultation Survey (TAOS) operates four fully automatic telescopes to search for occultations of stars by Kuiper Belt Objects. It is a versatile facility that is also useful for the study of initial optical GRB afterglows. This paper provides a detailed description of the TAOS multi-telescope system, control software, and high-speed imaging.Comment: 11 pages, 11 figure

    The Taiwanese-American Occultation Survey Project Stellar Variability. II. Detection of 15 Variable Stars

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    The Taiwanese-American Occultation Survey (TAOS) project has collected more than a billion photometric measurements since 2005 January. These sky survey data—covering timescales from a fraction of a second to a few hundred days—are a useful source to study stellar variability. A total of 167 star fields, mostly along the ecliptic plane, have been selected for photometric monitoring with the TAOS telescopes. This paper presents our initial analysis of a search for periodic variable stars from the time-series TAOS data on one particular TAOS field, No. 151 (R.A. = 17^(h)30^(m)6^(s).7, decl. = 27°17'30", J2000), which had been observed over 47 epochs in 2005. A total of 81 candidate variables are identified in the 3 deg^2 field, with magnitudes in the range 8 < R < 16. On the basis of the periodicity and shape of the light curves, 29 variables, 15 of which were previously unknown, are classified as RR Lyrae, Cepheid, δ Scuti, SX Phonencis, semi-regular, and eclipsing binaries
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