Related papers: Are Pions Perturbative in Effective Field Theory?
The main elements and methods of chiral perturbation theory, the effective field theory of the Standard Model below the scale of spontaneous chiral symmetry breaking, are summarized. Applications to the interactions of mesons and baryons at…
I propose a prescription for separating the high- and low-energy contributions in effective field theories. This prescription allows a relativistic treatment of matter fields in chiral perturbation theory while the power counting remains…
In these lectures we give a brief introduction to perturbative and non-perturbative string theory. The outline is the following: 1. Introduction to perturbative string theory 1.1 From point particle to extended objects 1.2 Free closed and…
Physics beyond the standard model can affect top-quark physics indirectly. We describe the effective field theory approach to describing such physics, and contrast it with the vertex-function approach that has been pursued previously. We…
Weak interactions in two-nucleon system at low energies are explored in the framework of effective field theory. We review our recent calculations of parity-violating observables in radiative neutron capture on a proton at threshold where…
The pion structure function is investigated in a simple model, where pion and constituent quark fields are coupled through the simplest pseudoscalar coupling. The imaginary part of the forward gamma* pi-> gamma* pi scattering amplitude is…
In a low energy effective theory, the fields of heavy particles with mass $m$ and total momentum $p$ depend on both a velocity $v$ and a residual momentum $k$ such that $p =mv +k$. However, there is some arbitrariness in such a description…
We study the simplest terms that need to be included in active field theories to couple them to external potentials. To do so, we consider active Brownian particles and implement a systematic perturbative expansion in the particle…
The pion-baryon triangle diagram is inspected for a special kinematic region where the squared momentum transfer $t$ is close to $4m_\pi^2$: $|t - 4m_\pi^2| \lesssim m_\pi^4/m_N^2$. Instead of arguing on the ground of anomalous threshold,…
We derive the leading contribution to the four-nucleon force within the framework of chiral effective field theory. It is governed by the exchange of pions and the lowest-order nucleon-nucleon contact interaction and includes effects due to…
Chiral perturbation theory, the low energy effective theory of the strong interactions for the light pseudoscalar degrees of freedom, is based on effective Lagrangian techniques and is an expansion in the powers of the external momenta and…
The origin of the breakdown scale in an effective field theory treatment of nuclear forces is investigated. Different organizational schemes used in the nonperturbative calculation of nucleon-nucleon scattering seem to break down for…
One of the major problems in developing new physics scenarios is that very often the parameters can be adjusted such that in perturbation theory almost all experimental low-energy results can be accommodated. It is therefore desirable to…
We investigate the modification of the pion self-energy at finite temperature due to its interaction with a low-density, isospin-symmetric nuclear medium embedded in a constant magnetic background. To one loop, for fixed temperature and…
Recent developments of perturbation theory at finite temperature based on effective field theory methods are reviewed. These methods allow the contributions from the different scales to be separated and the perturbative series to be…
We investigate the role of the pion in Covariant Density Functional Theory. Starting from conventional Relativistic Mean Field (RMF) theory with a non-linear coupling of the $\sigma$-meson and without exchange terms we add pions with a…
An introduction to methods of effective field theory is given. Examples are presented, including Rayleigh scattering from nonrelativistic quantum mechnics, chiral perturbation theory/QCD as well as electromagnetic and weak interactions of…
In this review we present the recent advances for calculations of the reactions $NN\to NN\pi$ using chiral effective field theory. Discussed are the next-to-next-to leading order loop contributions with nucleon and Delta-isobar for near…
The uncoupled $P$-wave channels of nucleon-nucleon scattering are studied in an effective field theory (EFT) including a perturbative dibaryon field and perturbative pions. Good agreement between EFT results and the Nijmegen partial wave…
We derive a novel chiral power counting scheme for in-medium chiral perturbation theory with explicit nucleonic and pionic degrees of freedom coupled to external sources. It allows for a systematic expansion taking into account local as…