3,954 research outputs found

    The hadronic vacuum polarization contribution to aμa_{\mu} from full lattice QCD

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    We determine the contribution to the anomalous magnetic moment of the muon from the αQED2\alpha^2_{\mathrm{QED}} hadronic vacuum polarization diagram using full lattice QCD and including u/du/d quarks with physical masses for the first time. We use gluon field configurations that include uu, dd, ss and cc quarks in the sea at multiple values of the lattice spacing, multiple u/du/d masses and multiple volumes that allow us to include an analysis of finite-volume effects. We obtain a result for aμHVP,LOa_{\mu}^{\mathrm{HVP,LO}} of 667(6)(12)667(6)(12), where the first error is from the lattice calculation and the second includes systematic errors from missing QED and isospin-breaking effects and from quark-line disconnected diagrams. Our result implies a discrepancy between the experimental determination of aμa_{\mu} and the Standard Model of 3σ\sigma.Comment: 14 pages, 10 figures. Discussion of method extended with additional tests and figures added. Typographical errors correcte

    Colorado River Basin Study Comments--Colorado River Water Conservation District

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    Comments on the Colorado River Basin Study prepared by the the Western Water Policy Review Advisory Commission

    Measuring Active-Sterile Neutrino Oscillations with a Stopped Pion Neutrino Source

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    The question of the existence of light sterile neutrinos is of great interest in many areas of particle physics, astrophysics, and cosmology. Furthermore, should the MiniBooNE experiment at Fermilab confirm the LSND oscillation signal, then new measurements are required to identify the mechanism responsible for these oscillations. Possibilities include sterile neutrinos, CP or CPT violation, variable mass neutrinos, Lorentz violation, and extra dimensions. In this paper, we consider an experiment at a stopped pion neutrino source to determine if active-sterile neutrino oscillations with delta-m greater than 0.1 eV2 can account for the signal. By exploiting stopped pi+ decay to produce a monoenergetic nu_mu source, and measuring the rate of the neutral current reaction nu_x + 12C -> nu_x +12C* as a function of distance from the source, we show that a convincing test for active-sterile neutrino oscillations can be performed.Comment: 10 pages, 9 figure

    Opportunities for lattice QCD in quark and lepton flavor physics

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    This document is one of a series of whitepapers from the USQCD collaboration. Here, we discuss opportunities for lattice QCD in quark and lepton flavor physics. New data generated at Belle II, LHCb, BES III, NA62, KOTO, and Fermilab E989, combined with precise calculations of the relevant hadronic physics, may reveal what lies beyond the Standard Model. We outline a path toward improvements of the precision of existing lattice-QCD calculations and discuss groundbreaking new methods that allow lattice QCD to access new observables.Comment: USQCD whitepape

    PQChPT with Staggered Sea and Valence Ginsparg-Wilson Quarks: Vector Meson Masses

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    We consider partially quenched, mixed chiral perturbation theory with staggered sea and Ginsparg-Wilson valence quarks in order to extract a chiral-continuum extrapolation expression for the vector meson mass up to order O(a^2), at one-loop level. Based on general principles, we accomplish the task without explicitly constructing a sophisticated, heavy vector meson chiral Lagrangian.Comment: 12 pages, 1 figure, REVTe
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