Donoghue, John
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Distinguished Professor, Department of Physics, College of Natural Sciences
Last Name
Donoghue
First Name
John
Discipline
Physics
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I am a professor of physics at the University of Massachusetts at Amherst.
My research area is theoretical particle physics.
My research area is theoretical particle physics.
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172 results
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Publication Metadata only ELECTROMAGNETIC EFFECTS IN PSI'-]J-PSI+PI-O AND QUARK MASSES(1985) Donoghue, JF; TUAN, SFWe investigate the contribution of electromagnetism to the decay ψ′ → J/ψ + π0, and find it to be small compared to the effect of quark masses, calculated via the axial anomaly. The decay rate is then a reliable measure of quark masses, and we extract (md−mu)/ms = 0.033±0.005.Publication Open Access On the Marriage of Chiral Perturbation Theory and Dispersion Relations(1995) Donoghue, JohnI describe the methodology for the use of dispersion relations in connection with chiral perturbation theory. The conditions for matching the two formalisms are given at $O(E^2)$ and $O(E^4)$. The two have several complementary features, as well as some limitations, and these are described by the use of examples, which include chiral sum rules related to the Weinberg sum rules, form factors, and a more complicated reaction, $\gamma \gamma \rightarrow \pi \pi$.Publication Metadata only ELECTROMAGNETIC DECAY OF GLUEBALLS(1984) Donoghue, JFThe magnetic dipole radiative decay of a JPC=0-+ glueball is considered within the MIT bag model. The resultant width, due to gluonic coupling to quarks, is sizable. In addition to η-η′-glueball mixing, other contributions are found to be significant. We comment that, for magnetic dipole transitions, the radiative widths of glueballs can be expected to be larger than those of radially excited QQ̅ mesons, due to wave-function-orthogonality effects in the latter case.Publication Open Access GENERAL-RELATIVITY AS AN EFFECTIVE-FIELD THEORY - THE LEADING QUANTUM CORRECTIONS(1994) Donoghue, JFI 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 propagation 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 necessary consequences of quantum gravity. The methodology is illustrated by a calculation of the leading quantum corrections to the gravitational interaction of two heavy masses.Publication Metadata only IS D0-]PHI-KBAR0 REALLY A CLEAR SIGNAL FOR THE ANNIHILATION DIAGRAM(1986) Donoghue, JFIt is shown that rescattering effects required by unitarity can produce the reaction D0→φK¯0, even when the ‘‘W-exchange’’ or ‘‘annihilation’’ diagram is not present. This is addressed both in a general context and a specific model. In the latter, it is the mode D0→K*η which plays the major role in generating the φK final state, as the K*η state is produced using the uū component of the η, and scatters, K*η→Kφ by quark exchange, utilizing the ss¯ component of the η. .AEPublication Metadata only GLUON MASS IN THE BAG MODEL(1984) Donoghue, JFBernard has proposed a measure of the effective gluon "mass" in terms of the screening of the linear potential for adjoint sources, and has extracted an estimate of mE=500-800 MeV from a lattice Monte Carlo calculation. The same quantity is calculated in the bag model, with the result mE=740±100 MeV. This arises as an effect of confinement, even though the gluons themselves are massless. The model illustrates several interesting features of this measure of "mass", and these are discussed.Publication Open Access SU(3) baryon chiral perturbation theory and long distance regularization(1999) Donoghue, JF; Holstein, BR; Borasoy, BThe use of SU(3) chiral perturbation theory in the analysis of low energy meson-baryon interactions is discussed. It is emphasized that short distance effects, arising from propagation of Goldstone bosons over distances smaller than a typical hadronic size, are modeldependent and can lead to a lack of convergence in the SU(3) chiral expansion if they are included in loop diagrams. In this paper we demonstrate how to remove such effects in a chirally consistent fashion by use of a cutoff and demonstrate that such removal ameliorates problems which have arisen in previous calculations due to large loop effects.Publication Open Access Comments on the Minimal Vectorial Standard Model(2009-01) Anber, Mohamed M.; Aydemir, Ufuk; Donoghue, John; Pais, PreemaWe explore the available parameter space of the minimal vectorial Standard Model. In this theory, the gauge currents are initially vectorial but the Higgs sector produces chiral mass eigenstates, leading to a set of heavy right-handed mirror particles. We describe the phenomenology of the residual parameter space and suggest that the model will be readily tested at the LHC.Publication Metadata only The chiral limit K -> pi pi matrix elements of the electroweak penguin operators Q(7,8)(2003-01) Maltman, K; Cirigliano, V; Donoghue, JF; Golowich, EugeneThe SU(3) chiral limit K → ππ matrix elements of the electroweak penguin operators, Q7,8, are determined using hadronic τ decay data, and dispersive and finite energy sum rules.Publication Open Access Random values of the physical parameters(2001-01) Donoghue, JFI briefly describe two motivations, two mechanisms and two possible tests of the hypothesis that the physical parameters of the ground state of a theory can vary in different rerions of the universe.