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We derive the scattering amplitude for Goldstone bosons of chiral symmetry off the pseudoscalar charmed mesons up to leading one-loop order in a covariant chiral effective field theory, using the so-called extended-on-mass-shell…

High Energy Physics - Phenomenology · Physics 2015-11-09 De-Liang Yao , Meng-Lin Du , Feng-Kun Guo , Ulf-G. Meißner

We analyze meson-baryon scattering lengths in the framework of covariant baryon chiral perturbation theory at leading one-loop order. We compute the complete set of matching relations between the dimension-two low-energy constants in the…

High Energy Physics - Phenomenology · Physics 2009-11-10 Maxim Mai , Peter C. Bruns , Bastian Kubis , Ulf-G. Meißner

We discuss the virtual Compton scattering amplitude $\gamma^\ast+\pi\to \gamma+\pi$ which enters the reaction $\pi^-+e^-\to\pi^-+e^-+\gamma$. The low-energy scattering amplitude is divided into a model-independent part, involving only the…

High Energy Physics - Phenomenology · Physics 2007-05-23 S. Scherer

We match the known chiral perturbation theory representation of the pi pi scattering amplitude to two loops with a phenomenological description that relies on the Roy equations. On this basis, the corrections to Weinberg's low energy…

High Energy Physics - Phenomenology · Physics 2011-05-05 G. Colangelo , J. Gasser , H. Leutwyler

Within the framework of chiral effective field theory, perturbative calculation for $NN$ scattering is carried out in partial waves with orbital angular momentum $L \geqslant 1$. The primary goal is to identify the lowest angular momenta at…

Nuclear Theory · Physics 2019-02-26 Shaowei Wu , Bingwei Long

We consider pion-nucleon scattering in heavy-baryon chiral perturbation theory to third order. All electromagnetic corrections appearing to this order are included. We thus have a consistent description of strong and electromagnetic…

High Energy Physics - Phenomenology · Physics 2009-11-07 Nadia Fettes , Ulf-G. Meißner

In this report we describe the analysis status of electron-pion inelastic scattering $\pi e \to \pi' e' \gamma$ and $\pi e \to \pi' e' \pi^0$ reaction data, measured in inverse pion-electron scattering at 590 GeV/c at FNAL. The data give…

High Energy Physics - Experiment · Physics 2007-05-23 Murray A. Moinester , Aharon Ocherashvili , Victor Steiner

This work implements the combined BChPT and 1/Nc expansions for pion-nucleon elastic scattering. The effective theory is based on the baryon sector dynamical spin-flavor SU(4) symmetry emergent in the large Nc limit, whose breaking is…

High Energy Physics - Phenomenology · Physics 2025-06-12 D. Jayakodige , J. L. Goity

We apply optimized perturbation theory to the quark-meson model at finite temperature T and quark chemical potential mu. The effective potential is calculated to one loop both in the chiral limit and at the physical point and used to study…

High Energy Physics - Phenomenology · Physics 2011-02-15 Jens O. Andersen , Rashid Khan , Lars T. Kyllingstad

We evaluate the amplitude for $\gamma \gamma \rightarrow \pi^0 \pi^0$ to two loops in chiral perturbation theory. The three new counterterms which enter at this order in the low-energy expansion are estimated with resonance saturation. We…

High Energy Physics - Phenomenology · Physics 2011-07-19 S. Bellucci , J. Gasser , M. E. Sainio

We study microscopic processes responsible for chirality flips in the thermal bath of Quantum Chromodynamics at finite temperature and zero baryon chemical potential. We focus on the temperature range where the crossover from chirally…

High Energy Physics - Phenomenology · Physics 2016-09-21 M. Ruggieri , G. X. Peng , M. Chernodub

Dispersive approaches provide model independent description of meson-meson scattering. We first review here the use of dispersion relations to obtain a model independent unitarization of Chiral Perturbation Theory amplitudes, that establish…

High Energy Physics - Phenomenology · Physics 2008-11-26 J. R. Pelaez

We report on a novel scheme based on the chiral Lagrangian. It is used to analyze pion-nucleon scattering, pion photoproduction, and nucleon Compton scattering. Subthreshold partial-wave amplitudes are calculated in chiral perturbation…

High Energy Physics - Phenomenology · Physics 2015-05-20 A. M. Gasparyan , M. F. M. Lutz

The physics of pions within a finite volume is explored using lattice regularized chiral perturbation theory. This regularization scheme permits a straightforward computational approach to be used in place of analytical continuum…

High Energy Physics - Lattice · Physics 2009-11-10 B. Borasoy , R. Lewis

We evaluate the pion mass in finite volume to two loops within Chiral Perturbation Theory. The results are compared with a recently proposed extension of the asymptotic formula of Luscher. We find that contributions, which were neglected in…

High Energy Physics - Lattice · Physics 2009-11-11 Gilberto Colangelo , Christoph Haefeli

Pion-nucleon scattering, pion photoproduction, and nucleon Compton scattering are analyzed within a scheme based on the chiral Lagrangian. Partial-wave amplitudes are obtained by an analytic extrapolation of subthreshold reaction amplitudes…

High Energy Physics - Phenomenology · Physics 2011-02-11 A. M. Gasparyan , M. F. M. Lutz

In recent years, detailed studies of three-pion systems have become possible in lattice QCD. This has in turn led to interest in 3-to-3 scattering of pions in the chiral perturbation theory framework. In addition to being an interesting…

High Energy Physics - Phenomenology · Physics 2023-10-12 Jorge Baeza-Ballesteros , Johan Bijnens , Tomáš Husek , Fernando Romero-López , Stephen R. Sharpe , Mattias Sjö

The Compton scattering on a charged pion and the process \gamma\gamma \to \pi^0\pi^0 are studied using the dispersion relations. Unknown parameters of the S-wave \pi\pi interaction, represented as a board Breit-Wignar resonance, and a sum…

Nuclear Theory · Physics 2011-07-19 L. V. Fil'kov , V. L. Kashevarov

We report on our recent progress in the generation of resonant behavior in unitarized meson-meson scattering amplitudes obtained from Chiral Perturbation Theory. These amplitudes provide simultaneously a remarkable description of the…

High Energy Physics - Phenomenology · Physics 2009-11-10 J. R. Pelaez , A. Gomez Nicola

We present a determination of the pion-nucleon sigma-term based on a novel analysis of the $\pi N$ scattering amplitude in Lorentz covariant baryon chiral perturbation theory renormalized in the extended-on-mass-shell scheme. This…

High Energy Physics - Phenomenology · Physics 2015-06-03 J. Martin Camalich , J. M. Alarcon , J. A. Oller