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1994

Selected Works

Selected Works

John Donoghue

Articles 1 - 2 of 2

Full-Text Articles in Physics

Chiral Sum Rules And Their Phenomenology, John Donoghue, Eugene Golwich Dec 1993

Chiral Sum Rules And Their Phenomenology, John Donoghue, Eugene Golwich

John Donoghue

We present an analysis of four sum rules, each based on chiral symmetry and containing the difference p&(s)—p&(s) of isovector vector and axial-vector spectral functions. Experimental data from ~ lepton decay and electron-positron scattering identify the spectral functions over a limited kinematic domain. We summarize the status of the existing database. However, a successful determination of the sum rules requires additional content, in the form of theoretical input. We show how chiral symmetry and the operator product expansion can be used to constrain the spectral functions, respectively, in the low energy and the high energy limits and proceed ...


General Relativity As An Effective Field Theory: The Leading Quantum Corrections, John Donoghue Dec 1993

General Relativity As An Effective Field Theory: The Leading Quantum Corrections, John Donoghue

John Donoghue

I describe the treatment of gravity as a quantum effective field theory. This allows a natural separation of the (known) low energy quantum effects from the (unknown) high energy contributions. Within this framework, gravity is a well behaved quantum field theory at ordinary energies. In studying the class of quantum corrections at low energy, the dominant effects at large distance can be isolated, as these are due to the propagaion of the massless particles (including gravitons) of the theory and are manifested in the nonlocal/nonanalytic contributions to vertex functions and propagators. These leading quantum corrections are parameter-free and represent ...