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The electric ($\alpha_\pi$) and magnetic ($\beta_\pi$) Compton polarizabilities of both the charged and the neutral pion are of fundamental interest in the low-energy sector of quantum chromodynamics (QCD). Pion polarizabilities affect the…

High Energy Physics - Phenomenology · Physics 2019-06-26 Murray Moinester , Stefan Scherer

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 subject of nucleon polarizabilities in real, virtual, and doubly virtual Compton scattering is discussed with respect to what is known and how such quantities can be extracted from data.

High Energy Physics - Phenomenology · Physics 2017-08-23 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…

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

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

Virtual Compton scattering in the $\Delta$-resonance region is considered in the case of a target nucleus. The discussion involves generalized polarizabilities and is developed for zero-spin nuclei, focusing on the new information coming…

Nuclear Theory · Physics 2009-10-30 B. Pasquini , S. Boffi

We investigate the spin-independent part of the virtual Compton scattering (VCS) amplitude off the nucleon within the framework of chiral perturbation theory. We perform a consistent calculation to third order in external momenta according…

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

We present a calculation of the virtual Compton scattering amplitude for the pseudoscalar meson octet in the framework of chiral perturbation theory at ${\cal O}(p^4)$. We calculate the electromagnetic generalized polarizabilities and…

High Energy Physics - Phenomenology · Physics 2009-10-31 T. Fuchs , B. Pasquini , C. Unkmeir , S. Scherer

We discuss the low-energy behavior of the spin-averaged amplitude of virtual Compton scattering (VCS) off a nucleon. Based on gauge invariance, Lorentz invariance and the discrete symmetries, it is shown that to first order in the frequency…

Nuclear Theory · Physics 2008-11-26 D. Drechsel , G. Knoechlein , A. Metz , S. Scherer

As guideline for forthcoming experiments, we present predictions from Chiral Effective Field Theory for polarized cross sections in low energy Compton scattering for photon energies below 170 MeV, both on the proton and on the neutron.…

Nuclear Theory · Physics 2009-11-10 Robert P. Hildebrandt , Harald W. Griesshammer , Thomas R. Hemmert

We are studying the electron scattering process e p to e' p' gamma in order to obtain information on the genuine virtual Compton scattering (VCS) process gamma^* N to gamma N. In addition to the two kinematical variables of real Compton…

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

We discuss low-energy virtual Compton scattering off the proton within the framework of a nonrelativistic constituent quark model. A simple interpretation of the spin-averaged generalized polarizabilities is given in terms of the induced…

Nuclear Theory · Physics 2017-08-23 B. Pasquini , S. Scherer , D. Drechsel

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 extract the next-to-next-to-leading order results for spin-flip generalized polarizabilities (GPs) of the nucleon from the spin-dependent amplitudes for virtual Compton scattering (VCS) at ${\cal O}(p^4)$ in heavy baryon chiral…

High Energy Physics - Phenomenology · Physics 2014-11-17 Chung-Wen Kao , Barbara Pasquini , Marc Vanderhaeghen

I discuss recent results regarding the influence of pion-nucleon and and nucleon-resonance physics on the (spin-) polarizabilities of the nucleon as measured in (polarized) Compton scattering.

Nuclear Theory · Physics 2011-04-15 Thomas R. Hemmert

We compute the Compton scattering off the nucleons in the framework of manifestly covariant baryon chiral perturbation theory (B$\chi$PT). The results for observables differ substantially from the corresponding calculations in heavy-baryon…

Nuclear Theory · Physics 2009-05-26 V. Lensky , V. Pascalutsa

We calculate the $N^*$ contributions to the generalized polarizabilities of the proton in virtual Compton scattering. The following nucleon excitations are included: $N^*(1535)$, $N^*(1650)$, $N^*(1520)$, $N^*(1700)$, $\Delta(1232)$,…

Nuclear Theory · Physics 2015-06-26 G. Q. Liu , A. W. Thomas , P. A. M. Guichon

We study deeply virtual Compton scattering on a virtual pion that is emitted by a proton. Using a range of models for the generalized parton distributions of the pion, we evaluate the cross section, as well as the beam spin and beam charge…

High Energy Physics - Phenomenology · Physics 2008-12-18 Daniela Amrath , Markus Diehl , Jean-Philippe Lansberg

The nucleon generalized polarizabilities (GPs), probed in virtual Compton scattering (VCS), describe the spatial distribution of the polarization density in a nucleon. They are accessed experimentally via the process of electron-proton…

High Energy Physics - Phenomenology · Physics 2017-02-23 Vadim Lensky , Vladimir Pascalutsa , Marc Vanderhaeghen

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