Daniel R. Phillips

Effective theory of theΔ(1232)resonance in Compton scattering off the nucleon

We formulate a new power-counting scheme for a chiral effective field theory of nucleons, pions, and Deltas. This extends chiral perturbation theory into the Delta-resonance region. We calculate nucleon Compton scattering up to next-to-leading order in this theory. The resultant description of existing

Extra dimensions, SN1987a, and nucleon-nucleon scattering data

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Precision calculation of the π−d scattering length and its impact on threshold πN scattering

p cross section data is very good for photon energies up to about 300 MeV. We also find reasonable numbers for the spin-independent polarizabilities

Precision calculation of threshold π−d scattering, πN scattering lengths, and the GMO sum rule

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Improving the convergence of NN effective field theory

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Nonperturbative regularization and renormalization: Simple examples from nonrelativistic quantum mechanics

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How short is too short? Constraining zero-range interactions in nucleon-nucleon scattering

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The S-wave pion–nucleon scattering lengths from pionic atoms using effective field theory

Abstract One of the strongest constraints on the existence of large, compact, “gravity-only” dimensions comes from SN1987a. If the rate of energy loss into these putative extra dimensions is too high, then the neutrino pulse from the supernova will differ from that actually seen. The dominant mechanism for the production of Kaluza–Klein gravitons and dilatons in the supernova is via gravistrahlung and dilastrahlung from the nucleon–nucleon system. In this paper we compute the rates for these processes in a model-independent way using low-energy theorems which relate the emissivities to the measured nucleon–nucleon cross section. This is possible because for soft gravitons and dilatons the leading contribution to the energy-loss rate is from graphs in which the gravitational radiation is produced from external nucleon legs. Previous calculations neglected these mechanisms. We re-evaluate the bounds on toroidally-compactified “gravity-only” dimensions, and find that consistency with the observed SN1987a neutrino signal requires that if there are two such dimensions then their radius must be less than 1 micron.

Neutrino and axion emissivities of neutron stars from nucleon–nucleon scattering data

We present a calculation of the pi^- d scattering length with an accuracy of a few percent using chiral perturbation theory. For the first time isospin-violating corrections are included consistently. Using data on pionic deuterium and pionic hydrogen atoms, we extract the isoscalar and isovector pion-nucleon scattering lengths and obtain a^+=(7.6 +/- 3.1) x 10^{-3} mpi^{-1} and a^-=(86.1 +/- 0.9) x 10^{-3} mpi^{-1}. Via the Goldberger-Miyazawa-Oehme sum rule, this leads to a charged-pion-nucleon coupling constant g_c^2/4 pi = 13.69 +/- 0.20.

Compton scattering from the proton in an effective field theory with explicit Delta degrees of freedom

Abstract We use chiral perturbation theory (ChPT) to calculate the π − d scattering length with an accuracy of a few percent, including isospin-violating corrections in both the two- and three-body sectors. In particular, we provide the technical details of a recent letter (Baru et al., 2011) [1] , where we used data on pionic deuterium and pionic hydrogen atoms to extract the isoscalar and isovector pion–nucleon scattering lengths a + and a − . We study isospin-breaking contributions to the three-body part of a π − d due to mass differences, isospin violation in the πN scattering lengths, and virtual photons. This last class of effects is ostensibly infrared enhanced due to the smallness of the deuteron binding energy. However, we show that the leading virtual-photon effects that might undergo such enhancement cancel, and hence the standard ChPT counting provides a reliable estimate of isospin violation in a π − d due to virtual photons. Finally, we discuss the validity of the Goldberger–Miyazawa–Oehme sum rule in the presence of isospin violation, and use it to determine the charged-pion–nucleon coupling constant.