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Compton scattering on light nuclei ($A=2,3$) has emerged as an effective avenue to search for signatures of neutron polarizabilities, both spin--independent and spin--dependent ones. In this discussion I will focus on the theoretical aspect…

Nuclear Theory · Physics 2015-05-14 Deepshikha Shukla

We discuss the application of an effective field theory (EFT) which incorporates the chiral symmetry of QCD to Compton scattering from the proton and deuteron. We describe the chiral EFT analysis of the proton Compton scattering database…

Nuclear Theory · Physics 2015-06-11 Daniel R. Phillips , Judith A. McGovern , Harald W. Griesshammer

A brief review of Compton scattering off the deuteron in Chiral Effective Field Theory, including gauge invariance and the correct Thomson limit. We model-independently determine the iso-scalar, spin-independent dipole polarisabilities of…

Nuclear Theory · Physics 2017-08-23 Harald W. Griesshammer

We consider two-nucleon scattering close to threshold. Partial-wave amplitudes are obtained by an analytic extrapolation of subthreshold reaction amplitudes calculated in a relativistic formulation of chiral perturbation theory. The…

Nuclear Theory · Physics 2015-06-12 A. M. Gasparyan , M. F. M. Lutz , E. Epelbaum

Compton scattering on the deuteron is studied in the framework of baryon chiral perturbation theory to third order in small momenta, for photon energies of order the pion mass. The scattering amplitude is a sum of one- and two-nucleon…

Nuclear Theory · Physics 2009-04-17 S. R. Beane , M. Malheiro , D. R. Phillips , U. van Kolck

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…

Nuclear Theory · Physics 2009-10-30 Thomas R. Hemmert , Barry R. Holstein , Joachim Kambor , Germar Knoechlein

We present a calculation of the virtual Compton scattering amplitude for $\gamma^\ast+\pi\to \gamma+\pi$ in the framework of chiral perturbation theory at ${\cal O}(p^4)$. We explicitly derive expressions for generalized electromagnetic…

High Energy Physics - Phenomenology · Physics 2009-10-31 C. Unkmeir , S. Scherer , A. I. L'vov , D. Drechsel

We reexamine the low-energy expansion of polarized Compton scattering off the proton and show that the leading non-Born contribution to the beam asymmetry of low-energy Compton scattering is given by the magnetic polarizability alone, the…

Nuclear Theory · Physics 2014-05-07 Nadiia Krupina

Interpreting measurements requires a physical theory, but the theory's accuracy may vary across the experimental domain. To optimize experimental design, and so to ensure that the substantial resources necessary for modern experiments are…

We present calculations of differential cross sections for Compton scattering from the proton, using amplitudes calculated to fourth order in heavy baryon chiral perturbation theory. We compare with available data up to 200 MeV. We find…

Nuclear Theory · Physics 2014-11-18 Judith A. McGovern

As a guideline for future experiments to extract the four (leading) spin polarizabilities of the nucleon, we have constructed the forward amplitude for polarized Compton scattering by dispersion integrals. These integrals have been…

High Energy Physics - Phenomenology · Physics 2010-05-28 B. Pasquini , P. Pedroni , D. Drechsel

Below pion threshold virtual Compton scattering off the nucleon gives access to the generalized electromagnetic polarizabilities. Different theoretical results for the generalized polarizabilities have been compared. In particular, the…

High Energy Physics - Phenomenology · Physics 2007-05-23 A. Metz , B. Pasquini , D. Drechsel

In recent years, real and virtual Compton scattering off the nucleon have attracted considerable interest from both the experimental and theoretical sides. Real Compton scattering gives access to the so-called electromagnetic…

Nuclear Theory · Physics 2009-11-10 Stefan Scherer

The general structure of the cross section of $\gamma N$ scattering with polarized photon and/or nucleon in initial and/or final state is systematically described and exposed through invariant amplitudes. A low-energy expansion of the cross…

High Energy Physics - Phenomenology · Physics 2009-09-25 D. Babusci , G. Giordano , A. I. L'vov , G. Matone , A. M. Nathan

Virtual Compton scattering off nucleons and pions at low energies is discussed. Predictions for the generalized polarizabilities of the nucleon are presented within the framework of heavy-baryon chiral perturbation theory and the linear…

High Energy Physics - Phenomenology · Physics 2011-04-15 S. Scherer

A forward dispersion calculation is implemented for the spin polarizabilities $\gamma_1, ... ,\gamma_4$ of the proton and the neutron. These polarizabilities are related to the spin structure of the nucleon at low energies and are…

Nuclear Theory · Physics 2009-10-30 D. Drechsel , G. Krein , O. Hanstein

We present a fit of the spin-independent electromagnetic polarisabilities of the proton to low-energy Compton scattering data in the framework of covariant baryon chiral effective field theory. Using the Baldin sum rule to constrain their…

Nuclear Theory · Physics 2014-03-19 Vadim Lensky , Judith A. McGovern

Compton scattering offers in principle an intriguing new window on nucleon structure. Existing experiments and future programs are discussed and the state of theoretical understanding of such measurements is explored.

High Energy Physics - Phenomenology · Physics 2009-10-30 Barry R. Holstein

We review theoretical progress and prospects for determining the nucleon's static dipole polarisabilities from Compton scattering on few-nucleon targets, including new values; see Refs. [1-5] for details and a more thorough bibliography.

Nuclear Theory · Physics 2016-12-12 Harald W. Griesshammer , Judith A. McGovern , Daniel R. Phillips

We evaluate the forward Compton scattering off the proton, based on Kramers-Kronig kind of relations which express the Compton amplitudes in terms of integrals of total photoabsorption cross sections. We obtain two distinct fits to the…

Nuclear Theory · Physics 2015-10-28 Oleksii Gryniuk , Franziska Hagelstein , Vladimir Pascalutsa