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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Introduction
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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Publication RELIABLE PREDICTIONS IN EXCLUSIVE RARE B-DECAYS(1991) BURDMAN, G; Donoghue, JFWe discuss the relations between form factors for B→K*γ and B→varrhoeν which follow from static heavy quark symmetry methods plus SU(3). We discuss carefully the hard perturbative QCD corrections which could invalidate these results and find that the dominant perturbative corrections are ones which respect the static symmetry predictions, and in addition that the perturbative corrections are small compared to soft contributions. We show that there is a special kinematic point in B→varrhoeν that involves the same combination of form factors as in B→K*γ, thus allowing a prediction of the ratio of rates which is largely free from hadronic uncertainties.Publication 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 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 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 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 KAON DECAYS AND A DETERMINATION OF THE SCALE OF CHIRAL SYMMETRY(1984) Donoghue, JF; Golowich, Eugene; Holstein, BRUsing effective chiral Lagrangians, we consider the occurrence of quadratic terms in the ΔI=1/2 K→3π matrix element. The inclusion of higher-derivative Lagrangians leads to a significant improvement over the usual current-algebra analysis. This allows an extraction directly from experimental data of Λχ, a measure of the scale of chiral symmetry. We give an operational definition of the chiral scale, and find Λχ≈1 GeV. The issue of uncertainty in the phenomenological determination of the B parameter is clarified.Publication KL-]PI-0E+E- AS A PROBE OF CP VIOLATION(1987) Donoghue, JF; Holstein, BR; VALENCIA, GWe point out that the decay mode KL→π0e+e- is predominantly CP violating in the standard model and is expected to occur with a branching ratio of several parts in 1012. The decay should be sensitive to direct ΔS=1 CP violation. Analysis of the Dalitz plot may enable the CP-violating nature of the process to be confirmed.Publication GRAVITATIONAL COUPLING AT FINITE TEMPERATURE(1986) Donoghue, JF; Holstein, BR; ROBINETT, RWWe discuss a thermodynamic identity which helps explain why 〈H〉≠〈T00〉 at finite temperature. In addition we complete the discussion of the gravitational force by including the gravitational variation of the temperature. Gradients in the temperature induce extra forces not accounted for by the usual coupling to the energy-momentum tensor.Publication Fine tunings and quark masses: Phenomenology of multiple domain theories(1999) Donoghue, JohnThis talk describes some of the consequences for particle phenomenology of the hypothesis that the physical parameters may vary in different domains of the universe.Publication DISPERSIVE CONTRIBUTIONS TO K0-KBAR0 MIXING AND CP VIOLATION(1984) Donoghue, JF; Holstein, BRWe consider the role of dispersive contributions in the analysis of the KL-KS system. These long-distance pieces can be present in both the real and imaginary parts of the mixing element M12. We provide an estimate of one such effect in Im M12, the η′ pole, which turns out to be potentially significant. These terms can substantially modify phenomenological studies, as we demonstrate for several cases. Improved experimental bounds on ε′/ε can provide a strong limit on dispersive effects in Im M12, and may in the near future remove the uncertainties caused by these contributions.