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A microscopic model for the $N\bar N\to\pi\pi$ process is presented in the meson exchange framework, which in the pseudophysical region agrees with available quasiempirical information. The scalar ($\sigma$) and vector ($\rho$) piece of…

Nuclear Theory · Physics 2009-09-25 C. Schütz , J. W. Durso , K. Holinde , B. C. Pearce , J. Speth

We present a calculation of pion photo- and electroproduction in manifestly Lorentz-invariant baryon chiral perturbation theory up to and including order $q^4$. We fix the low-energy constants by fitting experimental data in all available…

Nuclear Theory · Physics 2013-09-16 M. Hilt , B. C. Lehnhart , S. Scherer , L. Tiator

We formulate lattice theories in which chiral symmetry is realized nonlinearly on the fermion fields. In this framework the fermion mass term does not break chiral symmetry. This property allows us to use the Wilson term to remove the…

High Energy Physics - Lattice · Physics 2014-11-17 S. Chandrasekharan , M. Pepe , F. D. Steffen , U. -J. Wiese

We report about the recent results for s- and p-wave pion production in NN -> NNpi within effective field theory and discuss how the charge symmetry breaking in pn -> d pi^0 can be used to extract the strong contribution to the…

Nuclear Theory · Physics 2014-11-20 Vadim Baru

We present an exploratory study of two pion photo-- and electroproduction off the nucleon in the threshold region. To calculate the pertinent amplitudes, we make use of heavy baryon chiral perturbation theory. We show that due to finite…

Nuclear Theory · Physics 2009-10-28 V. Bernard , N. Kaiser , Ulf-G. Meißner , A. Schmidt

After a general introduction to the structure of effective field theories, the main ingredients of chiral perturbation theory are reviewed. Applications include the light quark mass ratios and pion-pion scattering to two-loop accuracy. In…

High Energy Physics - Phenomenology · Physics 2007-05-23 Gerhard Ecker

We discuss the extended on-mass-shell scheme for manifestly Lorentz-invariant baryon chiral perturbation theory. We present a calculation of pion photo- and electroproduction up to and including order $q^4$. The low-energy constants have…

Nuclear Theory · Physics 2017-02-08 M. Hilt , B. C. Lehnhart , S. Scherer , L. Tiator

The relative immunity of muons to synchrotron radiation suggests that they might be used in place of electrons as probes in fundamental high-energy physics experiments. Muons are commonly produced indirectly through pion decay by…

Accelerator Physics · Physics 2015-04-03 Diktys Stratakis , David V. Neuffer

We highlight some of the recent advances in the application of chiral effective field theory (chiral EFT) with baryons to the $\pi N$ scattering process. We recall some problems that cast doubt on the applicability of chiral EFT to $\pi N$…

High Energy Physics - Phenomenology · Physics 2015-06-18 Jose Manuel Alarcón

The process of two pion production in the electron-polarized proton scattering is investigated. In the Weizs\"acker-Williams approximation the differential spectral distributions and the spin-momentum correlations are considered. The spin…

High Energy Physics - Phenomenology · Physics 2013-04-02 A. I. Ahmadov , E. A. Kuraev , Yu. M. Bystritskiy

We calculate the complete $T$ matrices with decuplet contributions for pion-nucleon scattering to order $\mathcal{O}(\epsilon^3)$ in heavy baryon SU(3) chiral perturbation theory. The baryon mass in the chiral limit $M_0$ and the low-energy…

Nuclear Theory · Physics 2024-12-12 Jing Ou-Yang , Bo-Lin Huang

Consideration of the analytic properties of pion-induced baryon self energies leads to new functional forms for the extrapolation of light baryon masses. These functional forms reproduce the leading non-analytic behavior of chiral…

Nuclear Theory · Physics 2010-02-17 Anthony W. Thomas , Derek B. Leinweber , Kazuo Tsushima , Stewart V. Wright

A soft photon approximation is used to calculate the rates of lepton pair production through virtual bremsstrahlung from both pions and quarks. Standard assumptions about the evolution of a nuclear system under collision allow pion and…

High Energy Physics - Phenomenology · Physics 2010-01-15 K. Haglin , C. Gale , V. Emel'yanov

We discuss the electromagnetic corrections to the pion-nucleon scattering lengths generated by minimal e. m. coupling from a knowledge of the low energy expansion of the pion-nucleon elastic scattering amplitude as well as from the nucleon…

High Energy Physics - Phenomenology · Physics 2007-05-23 T. E. O. Ericson

Using results from the chiral perturbation theory for the s-wave interaction and the delta-resonance model for the p-wave interaction of pions with nucleons, we have evaluated the spectral functions of pions in asymmetric nuclear matter…

Nuclear Theory · Physics 2014-11-20 Jun Xu , Che Ming Ko , Yongseok Oh

The pion re-scattering operator for pion production, derived recently in time-ordered perturbation theory, is compared with the one following from the simple S-matrix construction. We show that this construction is equivalent to the…

Nuclear Theory · Physics 2009-11-10 V. Malafaia , J. Adam , M. T. Pena

A calculation of the pion-production operator up to next-to-next-to-leading order for s-wave pions is performed within chiral effective field theory. In the previous study [Phys. Rev. C 85, 054001 (2012)] we discussed the contribution of…

Nuclear Theory · Physics 2013-12-16 A. A. Filin , V. Baru , E. Epelbaum , C. Hanhart , H. Krebs , F. Myhrer

I discuss recent progress made in calculating electromagnetic corrections in the framework of the effective field theory of QCD. In the case of elastic pion-pion scattering, strong interaction predictions have been worked out to two loop…

High Energy Physics - Phenomenology · Physics 2009-10-30 Ulf-G. Meißner

Consideration of the analytic properties of pion-induced baryon self-energies leads to new functional forms for the extrapolation of light baryon masses. These functional forms reproduce the leading non-analytic behavior of chiral…

High Energy Physics - Lattice · Physics 2009-07-09 D. B. Leinweber , A. W. Thomas , K. Tsushima , S. V. Wright

Using a semi-classical treatment of the linear sigma model, we simulate the dynamical evolution of an initially hot cylindrical rod endowed with a longitudinal Bjorken scaling expansion (a ``Bjorken rod''). The field equation is propagated…

Nuclear Theory · Physics 2014-11-18 Troels C. Petersen , Jorgen Randrup