Deepshikha Shukla

Analyzing the effects of neutron polarizabilities in elastic Compton scattering off 3He

Abstract Motivated by the fact that a polarized 3He nucleus is expected to behave approximately as a polarized neutron, we examine manifestations of neutron electromagnetic polarizabilities in elastic Compton scattering from the Helium-3 nucleus. We calculate both unpolarized and double-polarization observables using chiral perturbation theory to next-to-leading order ( O ( e 2 Q ) ) at energies, ω ≲ m π , where m π is the pion mass. Our results show that the unpolarized differential cross-section can be used to measure neutron electric and magnetic polarizabilities, while two double-polarization observables are sensitive to different linear combinations of the four neutron spin polarizabilities.

Compton scattering from the proton: An analysis using the delta expansion up to N3LO

We report on a chiral effective field theory calculation of Compton scattering from the proton. Our calculation includes pions, nucleons, and the Delta(1232) as explicit degrees of freedom. It uses the “delta expansion”, and so implements the hierarchy of scales Mπ < ∆≡M∆−MN < Λχ , through a counting Mπ/∆ ∼ ∆/Λχ ∼ δ . In this expansion the power counting in the vicinity of the Delta peak changes, and resummation of the loop graphs associated with the Delta width is indicated. This is designed to extend the region of χPT applicability to momenta p∼ ∆. We have computed the nucleon Compton amplitude in the delta expansion up to N3LO— O(e2δ 4)—for photon energies ω ∼ Mπ . This is the first order at which the proton Compton scattering amplitudes receive contributions from contact operators which encode contributions to the spin-independent polarisabilities from states with energies ∼ Λχ . We fit the coefficients of these two operators to the experimental proton Compton data that has been taken in the relevant photon-energy domain, and are in a position to extract new results for αp and βp.

Elastic Compton scattering from 3He and the role of the Delta

Abstract.We report observables for elastic Compton scattering from 3He in Chiral Effective Field Theory with an explicit

Nucleon Spin Polarisabilities from Polarised Deuteron Compton Scattering

\Delta(1232)

Chiral potentials, perturbation theory and the 1S0 channel of NN scattering

Δ(1232) degree of freedom (

Universal Correlations in Pion-less EFT with the Resonating Group Model: Three, Four, and Six Nucleons

\chi

Universality in Pion-less EFT with the Resonating Group Model: Three and Four Nucleons

χ EFT) for energies between 50 and 120MeV. The

Erratum: Investigating Neutron Polarizabilities through Compton Scattering on He3 [Phys. Rev. Lett. 98, 232303 (2007)]

\gamma

Elastic Compton Scattering from 3He

γ3He amplitude is complete at N

Universal Correlations in ``Pion-less'' Effective Field Theory: 3, 4 and 6 Nucleons

^{3}