Open Access. Powered by Scholars. Published by Universities.®

Physics Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 30 of 102

Full-Text Articles in Physics

Graviton-Photon Scattering, N.E.J. Bjerrum-Bohr, Barry R. Holstein, Ludovic Planté, Pierre Vanhove Mar 2015

Graviton-Photon Scattering, N.E.J. Bjerrum-Bohr, Barry R. Holstein, Ludovic Planté, Pierre Vanhove

Barry R Holstein

We use the feature that the gravitational Compton scattering amplitude factorizes in terms of Abelian QED amplitudes to evaluate various gravitational Compton processes. We examine both the QED and gravitational Compton scattering from a massive spin-1 system by the use of helicity amplitude methods. In the case of gravitational Compton scattering we show how the massless limit can be used to evaluate the cross section for graviton-photon scattering and discuss the difference between photon interactions and the zero mass spin-1 limit. We show that the forward scattering cross section for graviton photoproduction has a very peculiar behavior, differing from the ...


Bending Of Light In Quantum Gravity, N.E.J. Bjerrum-Bohr, John F. Donoghue, Barry R. Holstein, Ludovic Planté, Pierre Vanhove Feb 2015

Bending Of Light In Quantum Gravity, N.E.J. Bjerrum-Bohr, John F. Donoghue, Barry R. Holstein, Ludovic Planté, Pierre Vanhove

Barry R Holstein

We consider the scattering of lightlike matter in the presence of a heavy scalar object (such as the Sun or a Schwarzschild black hole). By treating general relativity as an effective field theory we directly compute the nonanalytic components of the one-loop gravitational amplitude for the scattering of massless scalars or photons from an external massive scalar field. These results allow a semiclassical computation of the bending angle for light rays grazing the Sun, including long-range ℏ contributions. We discuss implications of this computation, in particular the violation of some classical formulations of the equivalence principle.


Generalized Polarizabilities And The Chiral Structure Of The Nucleon, Thomas R. Hemmert, Barry R. Holstein, Germar Knöchlein, Stefan Scherer Feb 2011

Generalized Polarizabilities And The Chiral Structure Of The Nucleon, Thomas R. Hemmert, Barry R. Holstein, Germar Knöchlein, Stefan Scherer

Barry R Holstein

No abstract provided.


Electric-Dipole Moments Of Nuclei, Jf Donoghue, Br Holstein, Mj Musolf Feb 2011

Electric-Dipole Moments Of Nuclei, Jf Donoghue, Br Holstein, Mj Musolf

Barry R Holstein

Recent calculations by Sushkov, Flambaum and Khriplovich have suggested that the existence of the possibility of kaon exchange within nuclei allows nuclear electric dipole moments within the standard model to be enhanced substantially over those of nucleons. This suggestion is analysed carefully and it is found that the constraints of chiral symmetry, which were not correctly included in the earlier calculation, reduce this prediction substantially.


The Lifetime Of A Deeply Bound H Dibaryon And The Cygnus-X-3 Events, Jf Donoghue, Eugene Golowich, Br Holstein Feb 2011

The Lifetime Of A Deeply Bound H Dibaryon And The Cygnus-X-3 Events, Jf Donoghue, Eugene Golowich, Br Holstein

Barry R Holstein

The explanation of the Cygnus X-3 events which involves a strange-quark star emitting the doubly strange H dibaryon requires the H to have a lifetime of greater than ten years. We calculate the ΔS=2 H→ NN for an H bound below ΛN threshold, and find τHless, approximate6 days.


Quantum-Mechanics In Curved Space, Jf Donoghue, Br Holstein Feb 2011

Quantum-Mechanics In Curved Space, Jf Donoghue, Br Holstein

Barry R Holstein

The quantum mechanical wave equation for a particle in a Schwarzschild metric is derived using general relativity in the linearized approximation. The significance of the various terms in the effective Hamiltonian is discussed and shown to be associated with the post‐Newtonian terms for the corresponding classical motion.


Anions And Anomalies, M Bawin, Sa Coon, Br Holstein Feb 2011

Anions And Anomalies, M Bawin, Sa Coon, Br Holstein

Barry R Holstein

We analyze the recent claim that experimental measurements of binding energies of dipole-bound anions can be understood in terms of a quantum mechanical anomaly. The discrepancy between the experimental critical dipole moments and that predicted by the anisotropic inverse square potential of a static dipole precludes such an explanation. As has long been known, in the physical problem one must include rotational structure so that the long distance behavior changes from 1/r2 to 1/r4. In a simple model this can be shown to lead to a modification of the critical dipole moment of 20% or so, bringing it ...


Strong Bounds On Weak Couplings, Jf Donoghue, Br Holstein Feb 2011

Strong Bounds On Weak Couplings, Jf Donoghue, Br Holstein

Barry R Holstein

Analysis of nonleptonic ΔS = 1 weak decays strongly restricts the possible size of right-handed weak couplings. Limits thus obtained are competitive with those obtained via other means.


Delta(1232) And The Polarizabilities Of The Nucleon, Tr Hemmert, Br Holstein, J Kambor Feb 2011

Delta(1232) And The Polarizabilities Of The Nucleon, Tr Hemmert, Br Holstein, J Kambor

Barry R Holstein

Previous calculations of the polarizabilities of the nucleon within the framework of heavy baryon chiral perturbation theory have included the contribution of the Δ(1232) only in its effects on various contact terms or have been performed in chiral SU(3) where systematic errors are difficult to control. Herein, we perform a corresponding calculation in chiral SU(2) wherein Δ(1232) is treated as an explicit degree of freedom and the expansion is taken to third order in soft momenta, the pion mass, and the quantity MΔ-MN, collectively denoted ε. We present the results of a systematic O(ε3) calculation ...


Higgs-Boson-Exchange Models Of Cp Violation And K-]2pi, Jf Donoghue, Js Hagelin, Br Holstein Feb 2011

Higgs-Boson-Exchange Models Of Cp Violation And K-]2pi, Jf Donoghue, Js Hagelin, Br Holstein

Barry R Holstein

Work by Deshpande and Sanda, which appears to invalidate Higgs-boson-exchange models of CP noninvariance, is buttressed by (i) use of the MIT bag model to calculate matrix elements, (ii) use of experimental rather than calculated numbers for the K→2π decay amplitude and the KL-KS mass difference, and (iii) inclusion of possible t-quark effects. We conclude that, barring accidental cancellations, such Higgs-boson-exchange models are incompatible with experiment.


Evidence For Su(3) Breaking In Cabibbo-Type Fits Of Semi-Leptonic Hyperon Decay, Jf Donoghue, Br Holstein Feb 2011

Evidence For Su(3) Breaking In Cabibbo-Type Fits Of Semi-Leptonic Hyperon Decay, Jf Donoghue, Br Holstein

Barry R Holstein

We analyze recent precision experiments involving semileptonic hyperon decay and demonstrate that there exists definite evidence for SU(3) breaking. The type of breaking observed is a difference in the D/(F+D) ratios in the ΔS=0 and ΔS=1 sectors, which is at variance with the simplest quark-model expectations. We comment on the relevance of symmetry breaking to the determination of weak mixing angles.


Photon-Photon Scattering, Pion Polarizability, And Chiral-Symmetry, Jf Donoghue, Br Holstein Feb 2011

Photon-Photon Scattering, Pion Polarizability, And Chiral-Symmetry, Jf Donoghue, Br Holstein

Barry R Holstein

Recent attempts to detect the pion polarizability via analysis of γγ→ππ measurements are examined. The connection between calculations based on dispersion relations and on chiral perturbation theory is established by matching the low-energy chiral amplitude with that given by a full dispersive treatment. Using the values for the polarizability required by chiral symmetry, predicted and experimental cross sections are shown to be in agreement.


Chiral Loops In Pi-0,Eta-0-]Gamma-Gamma And Eta-Eta' Mixing, Jf Donoghue, Br Holstein, Ycr Lin Feb 2011

Chiral Loops In Pi-0,Eta-0-]Gamma-Gamma And Eta-Eta' Mixing, Jf Donoghue, Br Holstein, Ycr Lin

Barry R Holstein

We compute the one-loop corrections to the Wess-Zumino Lagrangean governing π0, η8→γγ. The SU(3) relation between the two decay rates receives modifications of order mK2lnmK2, as does the Gell-Mann-Okubo mass formula. A consistent picture of η-η′ mixing emerges from both the two-photon widths and the mass matrix, however with a mixing angle θ≈-20° instead of the usual θ≈-10°.


Hadronic Parity Violation: Past, Present, And Future, Br Holstein Feb 2011

Hadronic Parity Violation: Past, Present, And Future, Br Holstein

Barry R Holstein

The history of hadronic parity violation is reviewed, from its beginning in 1957 to the present time. The current state of the subject is shown to be confused and a program to resolve this dilemma, including theoretical calculations using effective theoretic methods together with new low energy experiments in low A systems, is proposed.


Temperature Measured By A Uniformly Accelerated Observer, Jf Donoghue, Br Holstein Feb 2011

Temperature Measured By A Uniformly Accelerated Observer, Jf Donoghue, Br Holstein

Barry R Holstein

By use of elementary quantum‐mechanical arguments we demonstrate how an observer with uniform acceleration a perceives himself as immersed in a heat bath of temperature kT=aℏ/2πc.


Wavefunction Renormalization And Nuclear Parity Nonconservation, Jf Donoghue, Br Holstein Feb 2011

Wavefunction Renormalization And Nuclear Parity Nonconservation, Jf Donoghue, Br Holstein

Barry R Holstein

It is argued that a recent calculation, which envisions a major role for a parity violating wave function renormalization term, predicts effects in a variety of low energy weak processes which are in contradiction to experiment. It is also shown that the physics of such renormalization terms are already included in previous work.


Long Distance Effects And Strangeness In The Nucleon, John Donoghue, Barry Holstein, Tobias Huber, Andreas Ross Feb 2011

Long Distance Effects And Strangeness In The Nucleon, John Donoghue, Barry Holstein, Tobias Huber, Andreas Ross

Barry R Holstein

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 low-energy 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 ...


Measurement Of The Weak Neutral Current Via Nuclear Parity Violation, Jf Donoghue, Br Holstein Feb 2011

Measurement Of The Weak Neutral Current Via Nuclear Parity Violation, Jf Donoghue, Br Holstein

Barry R Holstein

Present low-energy experiments which detect parity violation in nuclei are analyzed, and a consistent set of weak couplings is extracted. Using symmetries and the quark model, it is shown that a parity-violating weak-neutral-current contribution is required by the data, and we extract values sin2θW=0.0±0.4 or ρ=1.1±0.2, consistent with other determinations. The error quoted is statistical only, and does not include a possibly sizable theoretical uncertainty. On the other hand, if we assume the world-average values for ρ and θW, we can obtain from the data (with minimal quark-model assumptions) the matrix element ...


Dispersion-Relations And The Nucleon Polarizability, Br Holstein, Am Nathan Feb 2011

Dispersion-Relations And The Nucleon Polarizability, Br Holstein, Am Nathan

Barry R Holstein

Recent experimental results on the proton and neutron polarizabilities are examined from the point of view of backward dispersion relations. Results are found to be in reasonable agreement with the measured values. A rigorous relationship between the nucleon and pion polarizabilities is derived and shown to be in excellent agreement with several models.


Compton Scattering And The Spin Structure Of The Nucleon At Low Energies, Tr Hemmert, Br Holstein, J Kambor, G Knochlein Feb 2011

Compton Scattering And The Spin Structure Of The Nucleon At Low Energies, Tr Hemmert, Br Holstein, J Kambor, G Knochlein

Barry R Holstein

We analyze polarized Compton scattering which provides information on the spin-structure of the nucleon. For scattering processes with photon energies up to 100 MeV the spin-structure dependence can be encoded into four independent parameters—the so-called spin-polarizabilities γi, i=1,…,4, of the nucleon, which we calculate within the framework of the “small scale expansion” in SU(2) baryon chiral perturbation theory. Specific application is made to “forward” and “backward” spin-polarizabilities.


Derivation Of The Weak Quark-Model Interaction Between Nucleons, Br Holstein Feb 2011

Derivation Of The Weak Quark-Model Interaction Between Nucleons, Br Holstein

Barry R Holstein

No abstract provided.


Analysis Of Delta-S=1 Non-Leptonic Weak Decays And The Delta-I=1-2 Rule, Jf Donoghue, Eugene Golowich, Wa Ponce, Br Holstein Feb 2011

Analysis Of Delta-S=1 Non-Leptonic Weak Decays And The Delta-I=1-2 Rule, Jf Donoghue, Eugene Golowich, Wa Ponce, Br Holstein

Barry R Holstein

Current-algebra and quark-model methods are used to investigate hyperon and kaon transition amplitudes for various contributions to the weak nonleptonic Hamiltonian of the Weinberg-Salam model. Substantial enhancements are found for matrix elements of certain operators which are induced by quantum-chromodynamic radiative corrections and contain right-handed currents. These operators improve the agreement with experiment in most cases, although problems remain in P-wave hyperon amplitudes. In this approach, the ΔI=1/2 rule is understandable in both kaons and baryons under plausible assumptions.


Quark-Model Calculation Of The Weak Electric Coupling In Semi-Leptonic Baryon Decay, Jf Donoghue, Br Holstein Feb 2011

Quark-Model Calculation Of The Weak Electric Coupling In Semi-Leptonic Baryon Decay, Jf Donoghue, Br Holstein

Barry R Holstein

The weak electric form factor g2 is calculated in the nonrelativistic quark model (NRQM) and the MIT bag model for weak ΔS=1 semileptonic transitions. The bag-model result is g2/g1=0.30 with the NRQM result roughly twice this. Other weak transition form factors are tabulated, including expected SU(3)-breaking effects.


Resonances In Radiative Hyperon Decays, B Borasoy, Br Holstein Feb 2011

Resonances In Radiative Hyperon Decays, B Borasoy, Br Holstein

Barry R Holstein

The importance of resonances for the radiative hyperon decays is examined in the framework of chiral perturbation theory. Low lying baryon resonances are included into the effective theory and tree contributions to these decays are calculated. We find significant contributions to both the parity-conserving and parity-violating decay amplitudes and a large negative value for the asymmetry parameter in polarized Σ+→pγ is found, in agreement with the experimental result αγpΣ+=-0.76±0.08.


Effective Interactions Are Effective Interactions, Br Holstein Feb 2011

Effective Interactions Are Effective Interactions, Br Holstein

Barry R Holstein

In recent years it has been realized that effective interactions—those valid over a limited range of energy-momentum—are often preferable even when more complete theories are available. We shall here present examples of such methods over a range of physical applications—from classical and quantum mechanics, to quantum gravity.


A Brief Introduction To Chiral Perturbation Theory, Br Holstein Feb 2011

A Brief Introduction To Chiral Perturbation Theory, Br Holstein

Barry R Holstein

A brief introduction to the subject of chiral perturbation theory (Xpt) is presented, including a discussion of effective field theory and applications of Xpt in the arena of purely mesonic interactions as well as in the πN sector.


A Derivative Of The Gerasimov-Drell-Hearn Sum Rule, V Pascalutsa, Br Holstein, M Vanderhaeghen Feb 2011

A Derivative Of The Gerasimov-Drell-Hearn Sum Rule, V Pascalutsa, Br Holstein, M Vanderhaeghen

Barry R Holstein

We derive a sum rule which establishes a linear relation between a particle's anomalous magnetic moment and a quantity connected to the photoabsorption cross section. This quantity cannot be measured directly. However, it can be computed within a given theory. As an example, we demonstrate validity of the sum rule in QED at tree level—the renowned Schwinger's correction to the anomalous magnetic moment is readily reproduced. In the case of the strong interactions, we also consider the calculation of the nucleon magnetic moment within chiral theories.


Direct Quark-Model Calculation Of Weak Nonleptonic Matrix-Elements, Jf Donoghue, Br Holstein Feb 2011

Direct Quark-Model Calculation Of Weak Nonleptonic Matrix-Elements, Jf Donoghue, Br Holstein

Barry R Holstein

It is shown how wave-packet techniques developed by Donoghue and Johnson may be utilized to calculate parity-violating nonleptonic hyperon decay amplitudes directly—without the use of current algebra and PCAC (partial conservation of axial-vector current).


The Principle Of Equivalence At Finite Temperature, Jf Donoghue, Br Holstein, Rw Robinett Feb 2011

The Principle Of Equivalence At Finite Temperature, Jf Donoghue, Br Holstein, Rw Robinett

Barry R Holstein

We demonstrate that the equivalence principle is violated by radiative corrections to the gravitational and inertial masses at finite temperature. We argue that this result can be attributed to the Lorentz noninvariance of the finite temperature vacuum.


The Van Der Waals Interaction, Br Holstein Feb 2011

The Van Der Waals Interaction, Br Holstein

Barry R Holstein

The interaction between two neutral but polarizable systems at separation R, usually called the van der Waals force, is discussed from different points of view. The change in character from 1/R6 to 1/R7 due to retardation is explained.