arXiv subjects

Roxanne P. Springer

Publications and source records attributed to Roxanne P. Springer.

28 records · Page 2Linked to original sources

arXiv1999

The Anapole Form Factor of the Deuteron

We find the leading order result for the anapole form factor of the deuteron using effective field theory. The momentum dependence of the anapole form factor is different from that of the matrix element of the strange currents in the deuteron, which may provide a way for disentangling these two competing effects when analyzing parity violating electron-deuteron scattering experiments. We give closed form expressions for both the form factor and integrals often encountered in the NN effective field theory.

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arXiv1999

Parity Violation in Effective Field Theory and the Deuteron Anapole Moment

Effective field theory, including pions, provides a consistent and systematic description of nucleon-nucleon strong interactions up to center-of-mass momentum of order 300 MeV per nucleon. We describe the inclusion of hadronic parity violation into this effective field theory and find an analytic form for the deuteron anapole moment at leading order in the expansion.

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arXiv1998

Gamma-Deuteron Compton Scattering in Effective Field Theory

The differential cross section for gamma-deuteron Compton scattering is computed to next-to-leading order (NLO) in an effective field theory that describes nucleon-nucleon interactions below the pion production threshold. Contributions at NLO include the nucleon isoscalar electric polarizability from its 1/m_pi behavior in the chiral limit. The parameter free prediction of the gamma-deuteron differential cross section at NLO is in good agreement with data.

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arXiv1998

Weak Nonleptonic Omega Decay in Chiral Perturbation Theory

We calculate the weak nonleptonic decay of the Omega^- baryon to octet final states in heavy baryon chiral perturbation theory (HBChPT). We include the one-loop leading logarithmic effects and show that this improves the universality of the HBChPT constants.

hep-ph↗

arXiv1998

An Effective Field Theory Calculation of the Parity Violating Asymmetry in n+p -> d+gamma

Weak interactions are expected to induce a parity violating pion-nucleon coupling, h_{πNN}^{(1)}. This coupling should be measurable in a proposed experiment to study the parity violating asymmetry A_γin the process \vec n + p \to d+γ. We compute the leading dependence of A_γon the coupling h_{πNN}^{(1)} using recently developed effective field theory techniques and find an asymmetry of A_γ= +0.17 h_{πNN}^{(1)} at leading order. This asymmetry has the opposite sign to that given by Desplanques, Donoghue and Holstein.

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arXiv1998

The Polarizability of the Deuteron

The scalar and tensor polarizabilities of the deuteron are calculated using the recently developed effective field theory that describes nucleon-nucleon interactions. Leading and next-to-leading order contributions in the perturbative expansion predict a scalar electric polarizability of 0.595 fm^3. The tensor electric polarizability receives contributions starting at next-to-leading order from the exchange of a single potential pion and is found to be -0.062 fm^3. We compute the leading contributions to the scalar and tensor magnetic polarizabilities, finding 0.067 fm^3 and 0.195 fm^3, respectively.

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arXiv1997

$NNK$ and $ΛΛK$ Amplitudes in Chiral Perturbation Theory

We explore the S-wave and P-wave amplitudes for $NNK$ and $ΛΛK$ interactions using chiral perturbation theory to ${\cal O}(m_s\log m_s)$. In contrast to the large corrections found in P-wave amplitudes in the nonleptonic decay of octet baryons, the $NNK$ amplitudes receive only small corrections to their tree-level values. The uncertainty in the $ΛΛK$ amplitudes is found to be large.

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arXiv1997

The Weak $ΛΛK^0$ Interaction

We calculate the leading contribution to the weak $ΛΛK$ coupling in heavy baryon chiral perturbation theory, including the SU(3) breaking terms arising at one-loop. This coupling gives the leading one-boson exchange amplitude for the process $ΛΛ\toΛn$ and is an important component in understanding the decay of $ΛΛ$-hypernuclei. We find the S-wave and P-wave amplitudes to be stable under one-loop corrections, but the associated errors become large. We discuss the theoretical errors and potential effects of higher order terms.

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arXiv1996

Effective Lagrangians and Parity-Conserving Time-Reversal Violation at Low Energies

Using effective Lagrangians, we argue that any time-reversal-violating but parity-conserving effects are too small to be observed in flavor-conserving nuclear processes without dramatic improvement in experimental accuracy. In the process we discuss other arguments that have appeared in the literature.

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arXiv1993

Probing Hadronic Structure with The Decay $Δ\rightarrow Nl^+l^-$

We compute the branching ratio for $Δ\rightarrow Ne^+e^-$ and $Δ\rightarrow Nμ^+μ^-$ in chiral perturbation theory and find that both decays should be observable at CEBAF. With sufficiently low thresholds on the $e^+e^-$ invariant mass a branching ratio of $\sim 10^{-5}$ may be observed for $Δ\rightarrow Ne^+e^-$. For the $Δ\rightarrow Nμ^+μ^-$ decay mode we predict a branching ratio of $3\times 10^{-7}$. The dependence of the M1 and E2 amplitudes on the momentum transfer will provide a useful test of chiral perturbation theory which predicts $\sim 20\%$ variation over the allowed kinematic range.

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