259 research outputs found

    Quantum Corrections to the Reissner-Nordstr\"{o}m and Kerr-Newman Metrics

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    We use effective field theory techniques to examine the quantum corrections to the gravitational metrics of charged particles, with and without spin. In momentum space the masslessness of the photon implies the presence of nonanalytic pieces q2,q2logq2\sim \sqrt{-q^2},q^2\log -q^2 etc. in the form factors of the energy-momentum tensor. We show how the former reproduces the classical non-linear terms of the Reissner-Nordstr\"{o}m and Kerr-Newman metrics while the latter can be interpreted as quantum corrections to these metrics, of order Gα/mr3G\alpha\hbar/mr^3Comment: 16 page latex file with two figure

    On the parameterization dependence of the energy momentum tensor and the metric

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    We use results by Kirilin to show that in general relativity the nonleading terms in the energy-momentum tensor of a particle depends on the parameterization of the gravitational field. While the classical metric that is calculated from this source, used to define the leading long-distance corrections to the metric, also has a parameteriztion dependence, it can be removed by a coordinate change. Thus the classical observables are parameterization independent. The quantum effects that emerge within the same calculation of the metric also depend on the parameterization and a full quantum calculation requires the inclusion of further diagrams. However, within a given parameterization the quantum effects calculated by us in a previous paper are well defined. Flaws of Kirilin's proposed alternate metric definition are described and we explain why the diagrams that we calculated are the appropriate ones.Comment: 8 pages, 2 figure

    Temperature measured by a uniformly accelerated observer

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    Non-isotropy in the CMB power spectrum in single field inflation

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    Contaldi et al. [1] have suggested that an initial period of kinetic energy domination in single field inflation may explain the lack of CMB power at large angular scales. We note that in this situation it is natural that there also be a spatial gradient in the initial value of the inflaton field, and that this can provide a spatial asymmetry in the observed CMB power spectrum, manifest at low multipoles. We investigate the nature of this asymmetry and comment on its relation to possible anomalies at low multipoles.Comment: 25 pages, 12 figures. In this revised version, we include the Integrated Sachs-Wolfe effect, which was missing from the original. This modifies some results in the low multipoles. The comparison with experiment is slightly better but the change is not statistically significan

    Dynamics of the Standard Model

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    Describing the fundamental theory of particle physics and its applications, this book provides a detailed account of the Standard Model, focusing on techniques that can produce information about real observed phenomena. It begins with a pedagogic account of the Standard Model, introducing essential techniques such as effective field theory and path integral methods. It then focuses on the use of the Standard Model in the calculation of physical properties of particles. Rigorous methods are emphasized, but other useful models are also described. The second edition has been updated to include theoretical and experimental advances, such as the discovery of the Higgs boson, our understanding of neutrinos, and the major advances in CP violation and electroweak physics. This book is valuable to graduate students and researchers in particle physics, nuclear physics and related fields. This edition, first published in 2014, has been reissued as an Open Access publication

    Classical Physics and Quantum Loops

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    The standard picture of the loop expansion associates a factor of h-bar with each loop, suggesting that the tree diagrams are to be associated with classical physics, while loop effects are quantum mechanical in nature. We discuss examples wherein classical effects arise from loop contributions and display the relationship between the classical terms and the long range effects of massless particles.Comment: 15 pages, 3 figure

    Dynamics of the Standard Model

    Get PDF
    Describing the fundamental theory of particle physics and its applications, this book provides a detailed account of the Standard Model, focusing on techniques that can produce information about real observed phenomena. It begins with a pedagogic account of the Standard Model, introducing essential techniques such as effective field theory and path integral methods. It then focuses on the use of the Standard Model in the calculation of physical properties of particles. Rigorous methods are emphasized, but other useful models are also described. The second edition has been updated to include theoretical and experimental advances, such as the discovery of the Higgs boson, our understanding of neutrinos, and the major advances in CP violation and electroweak physics. This book is valuable to graduate students and researchers in particle physics, nuclear physics and related fields. This edition, first published in 2014, has been reissued as an Open Access publication

    Dugodosežzni učinci i stranost u nukleonu

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    We discuss the calculation of the strange magnetic radius of the proton in chiral perturbation theory. In particular, we investigate the low-energy component of the loop integrals involving kaons. We separate the chiral calculation into a low-energy part and a high-energy component through use of a momentum space separation scale. This separation shows that most of the chiral calculation comes from high energies where the effective field theory treatment is not valid. The resulting lowenergy prediction is in better agreement with dispersive treatments. Finally, we briefly discuss magnetic moments and show how our techniques can help resolve an old puzzle in understanding the magnetic moments of the proton and Σ+.Raspravljamo o računanju stranog magnetskog polumjera protona u kiralnoj teoriji smetnje. Posebice, istražujemo niskoenergijsku sastavnicu kaonskih petljanih integrala. Razdvajamo kiralni račun u niskoenergijski dio i visokoenergijsku sastavnicu primjenom razdvajajuće ljestvice impulsnog prostora. To razdvajanje pokazuje da kiralni račun većim dijelom daje doprinos na visokim energijama za koje efektivna teorija polja nije dobra. Predviđanje za niske energije je u boljem skladu s disperzivnim računom. Na kraju, kratko raspravljamo magnetske momente i pokazujemo kako naše metode mogu riješiti stari problem razumijevanja magnetskih momenata protona i Σ+
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