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We study the finite temperature properties of an effective chiral Lagrangian which describes nuclear matter. Thermal fluctuations in both the nucleon and the meson fields are considered. The logarithmic and square root terms in the…

Nuclear Theory · Physics 2009-10-30 G. W. Carter , P. J. Ellis

We analyse elastic-pion nucleon scattering to fourth order in heavy baryon chiral perturbation theory, extending the third order study published in Nucl. Phys. A640 (1998) 199. We use various partial wave analyses to pin down the low-energy…

High Energy Physics - Phenomenology · Physics 2009-10-31 Nadia Fettes , Ulf-G. Meißner

We generalize chiral perturbation theory with spinless matter fields in the fundamental representation of ${\rm SU}(N)$ to curved spacetime in the presence of an external gravitational field. This work is motivated by recent interest in…

High Energy Physics - Phenomenology · Physics 2026-03-24 Cheng-Cheng Li , Xiong-Hui Cao , Feng-Kun Guo

We investigate isospin breaking in low-energy pion-nucleon scattering in the framework of chiral perturbation theory. This work extends the systematic analysis of [1] to the energy range above threshold. Various relations, which identically…

High Energy Physics - Phenomenology · Physics 2009-10-31 Nadia Fettes , Ulf-G. Meißner

We show that the interplay of chiral effective field theory and lattice QCD can be used in the evaluation of so-called disconnected diagrams, which appear in the study of the isoscalar and isovector channels of pion-pion scattering and have…

High Energy Physics - Lattice · Physics 2017-12-22 Neramballi Ripunjay Acharya , Feng-Kun Guo , Ulf-G. Meißner , Chien-Yeah Seng

We develop a novel approach to chiral meson-baryon dynamics incorporating unitarity constraints and explicit resonance fields. It is based on the most general structure of any pion-nucleon partial wave amplitude neglecting the unphysical…

Nuclear Theory · Physics 2009-10-31 Ulf-G. Meißner , J. A. Oller

In view of ongoing experimental activities to determine the pion polarizabilities, we have started to recalculate the available two-loop expressions in the framework of chiral perturbation theory, because they have never been checked…

High Energy Physics - Phenomenology · Physics 2008-11-26 Juerg Gasser , Mikhail A. Ivanov , Mikko E. Sainio

An effective field theory of quarks, gluons, and pions, with the number $N$ of colors treated as large, is proposed as a basis for calculations of hadronic phenomena at moderate energies. The qualitative consequences of the large $N$ limit…

High Energy Physics - Phenomenology · Physics 2010-12-28 Steven Weinberg

We study the two-pion exchange potential at next-to-next-to-leading order in chiral effective field theory. We propose a new cut-off scheme for the pion loop integrals based on spectral function regularization. We show that this method…

Nuclear Theory · Physics 2014-11-18 Evgeny Epelbaum , Walter Glöckle , Ulf-G. Meißner

The s-wave isoscalar amplitude for pion-pion scattering in a nuclear medium is evaluated using a nonperturbative unitary coupled channels method and the standard chiral Lagrangians. The method has proved successful to describe the pion-pion…

Nuclear Theory · Physics 2008-11-26 H. C. Chiang , E. Oset , M. J. Vicente Vacas

After a brief survey of effective field theories, the linear sigma model is discussed as a prototype of an effective field theory of the standard model below the chiral-symmetry-breaking scale. Although it can serve as a toy model for the…

High Energy Physics - Phenomenology · Physics 2011-04-15 G. Ecker

This work discusses reliability, possible obstacles and the future perspective of chiral extrapolation of lattice results. In the first part, chiral perturbation theory fits to lattice calculations of the nucleon mass are thoroughly…

High Energy Physics - Lattice · Physics 2007-05-23 Bernhard U. Musch

We give predictions for the partial wave amplitudes of pion photoproduction near threshold by means of dispersion relations at fixed t. The free parameters of this approach are determined by a fit to experimental data in the energy range…

Nuclear Theory · Physics 2016-09-08 O. Hanstein , D. Drechsel , L. Tiator

We present an accurate nucleon-nucleon ($NN$) potential based upon chiral effective Lagrangians. The model includes one- and two-pion exchange contributions up to chiral order three. We show that a quantitative fit of the $NN$ $D$-wave…

Nuclear Theory · Physics 2010-04-06 D. R. Entem , R. Machleidt

We present a detailed quark-model study of pion photoproduction within the effective Lagrangian approach. Cross sections and single-polarization observables are investigated for the four charge channels, $\gamma p\to \pi^+ n$, $\gamma n\to…

Nuclear Theory · Physics 2009-11-07 Q. Zhao , J. S. Al-Khalili , Z. -P. Li , R. L. Workman

Neutrino-induced pion and photon production from nucleons and nuclei are important for the interpretation of neutrino-oscillation experiments, and these processes are potential backgrounds in the MiniBooNE experiment [A. A. Aquilar-Arevalo…

Nuclear Theory · Physics 2010-11-30 Brian D. Serot , Xilin Zhang

We calculate the nucleon-nucleon scattering amplitudes in the 1S0 and 3S1-3D1 channels at next-to-next to leading order starting from a recently proposed non-relativistic chiral effective theory, which includes dibaryon fields as…

Nuclear Theory · Physics 2010-04-06 Joan Soto , Jaume Tarrus

We develop a framework for calculating nucleon-deuteron scattering using strict perturbation theory for treating subleading interactions in chiral effective field theory (ChEFT). Rather than using direct evaluations in the distorted-wave…

Nuclear Theory · Physics 2026-02-18 Lin Zuo , Wendi Chen , Dan-Yang Pang , Bingwei Long

An introduction to the basic ideas and methods of Chiral Perturbation Theory is presented. Several phenomenological applications of the effective Lagrangian technique to strong, electromagnetic and weak interactions are discussed.

High Energy Physics - Phenomenology · Physics 2010-11-01 A. Pich

In this work we interpret the Einstein-Hilbert (EH) Lagrangian of gravitation as the first term of a low-energy effective theory similar to those considered in the chiral Lagrangian approach to low-energy hadron physics or the electroweak…

High Energy Physics - Theory · Physics 2023-01-11 Rafael L. Delgado , Antonio Dobado , Domènec Espriu