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In this work the elastic scattering of two nucleons is calculated in chiral effective field theory at next-to-leading order taking into account the coupled N$\Delta$-, $\Delta$N- and $\Delta\Delta$-channels. To solve the coupled channel…

Nuclear Theory · Physics 2020-08-28 Susanne Strohmeier , Norbert Kaiser

An effective field theory is used to give a model-independent description of Compton scattering at energies comparable to the pion mass. The amplitudes for scattering on the proton and the deuteron, calculated to fourth order in small…

Nuclear Theory · Physics 2008-11-26 S. R. Beane , M. Malheiro , J. A. McGovern , D. R. Phillips , U. van Kolck

We derive the long-range components of the nucleon-nucleon (NN) two-pion-exchange potential with an intermediate Roper resonance. Leading-order interactions in heavy-baryon chiral perturbation theory are considered. NN phase shifts with…

Nuclear Theory · Physics 2026-03-02 Yang Xiao , Li-Sheng Geng , U. van Kolck

We study pion--nucleon scattering with a chiral lagrangian of pions, nucleons, and $\Delta$-isobars. The scattering amplitude is evaluated to one-loop $Q^3$ order, where $Q$ is a generic small momentum, using a new approach which is…

High Energy Physics - Phenomenology · Physics 2008-11-26 Paul J. Ellis , Hua-Bin Tang

Power counting is a systematic strategy for organizing collider observables and their associated theoretical calculations. In this paper, we use power counting to characterize a class of jet substructure observables called energy flow…

High Energy Physics - Phenomenology · Physics 2022-09-21 Pedro Cal , Jesse Thaler , Wouter J. Waalewijn

Chiral expansions of the two-pion exchange components of both two- and three-nucleon forces are reviewed and a discussion is made of the predicted pattern of hierarchies. The strength of the scalar-isoscalar central potential is found to be…

Nuclear Theory · Physics 2008-11-26 M. R. Robilotta

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 2017-08-23 M. Malheiro , S. R. Beane , D. R. Phillips , U. van Kolck

We study the scattering of a particle from a bound pair in an effective field theory using a distorted-wave renormalisation group method to find the power-counting for the three-body force terms. We find that three-body terms appear at…

Nuclear Theory · Physics 2007-05-23 T. Barford , M. C. Birse

The leading-particle effect and the factorization property of the scattering amplitude in the impact parameter space are used to study semiclassical production of pions in the central region. The mechanism is related to the isospin-uniform…

High Energy Physics - Phenomenology · Physics 2011-04-15 M. Martinis , V. Mikuta-Martinis , J. Črnugelj

Different modern phase shift equivalent NN potentials are tested by evaluating the partial wave decomposition of the kinetic and potential energy of the deuteron. Significant differences are found, which are traced back to the matrix…

Nuclear Theory · Physics 2009-10-30 A. Polls , H. Müther , R. Machleidt , M. Hjorth-Jensen

Pion-nucleus bremsstrahlung offers a possibility of measuring the structure functions of pion-Compton scattering from a study of the small-momentum-transfer region where the bremsstrahlung reaction is dominated by the single-photon-exchange…

Nuclear Theory · Physics 2013-01-01 Göran Fäldt , Ulla Tengblad

Extensive dynamical $N/D$ calculations are made in the study of $S_{11}$ channel low energy $\pi$N scatterings, based on various phenomenological model inputs of left cuts at tree level. The subtleties of the singular behavior of the…

Nuclear Theory · Physics 2022-04-25 Qu-Zhi Li , Yao Ma , Wen-Qi Niu , Yu-Fei Wang , Han-Qing Zheng

The first three coefficients of the Taylor's series expansion of the vector pion form factor as a function of the momentum transfer are evaluated using experimental data on the pion form factor and the P-wave pi pi phase shifts. The real…

High Energy Physics - Phenomenology · Physics 2007-05-23 Tran N. Truong

The binding energy of nuclear matter including exchange and pionic effects is calculated in a quark-meson coupling model with massive constituent quarks. As in the case with elementary nucleons in QHD, exchange effects are repulsive.…

Nuclear Theory · Physics 2009-10-31 M. E. Bracco , G. Krein , M. Nielsen

We develop a systematic chiral perturbation expansion for the calculation of meson-exchange currents in nuclei and apply the formalism to nuclear axial currents. We summarize the principal results of such a calculation to one loop order on…

High Energy Physics - Phenomenology · Physics 2007-05-23 Tae-Sun Park , Dong-Pil Min , Mannque Rho

The effect of perturbative QCD interactions on the high energy scattering of electroweak vector bosons, when the exchanged channel has pion quantum numbers, is considered. The chiral anomaly is shown to appear in the couplings of particular…

High Energy Physics - Phenomenology · Physics 2009-11-10 Alan R. White

We point out that the $\Delta\pi$ component of the nucleon wave function is vital to the interpretation of the recent H1 data for leading baryon production. While the $n/p$ ratio is equal to two with the $N\pi$ component alone, the…

High Energy Physics - Phenomenology · Physics 2010-02-17 A. W. Thomas , C. Boros

We use power-counting arguments as an organizing principle to apply chiral perturbation theory, including an explicit $\Delta$, to the $p p \rightarrow p p \pi^0$ reaction near threshold. There are two lowest-order leading mechanisms…

Nuclear Theory · Physics 2008-11-26 T. D. Cohen , J. L. Friar , G. A. Miller , U. van Kolck

We calculate the contribution to the nuclear energy density functional which arises from iterated pion-photon exchange between nucleons. In heavy nuclei, this novel charge symmetry breaking interaction leads to an additional binding of each…

Nuclear Theory · Physics 2009-11-10 N. Kaiser

The invariant amplitudes for pion electroproduction on the nucleon are evaluated by dispersion relations at constant t with MAID as input for the imaginary parts of these amplitudes. In the threshold region these amplitudes are confronted…

High Energy Physics - Phenomenology · Physics 2008-11-26 B. Pasquini , D. Drechsel , L. Tiator