相关论文: Chiral-Scale Perturbation Theory About an Infrared…

These lecture notes include the following topics. Chapter 1 deals with QCD and its global symmetries in the chiral limit, explicit symmetry breaking in terms of the quark masses, and the concept of Green functions and Ward identities…

We describe Scalar-Pseudoscalar partner degeneration at the QCD chiral transition in terms of the dominant low-energy physical states for the light quark sector. First, we obtain within model-independent one-loop Chiral Perturbation Theory…

We review dilaton chiral perturbation theory (dChPT), the effective low-energy theory for the light sector of near-conformal, confining theories. dChPT provides a systematic expansion in both the fermion mass and the distance to the…

An exposition is made of recent developments using techniques of unitary chiral perturbation theory, $U \chi P T$, which allows one to extend predictions using chiral Lagrangians to higher energies than ordinary chiral perturbation theory,…

We use three-flavor chiral perturbation theory ($\chi$PT) to calculate the pressure, light and $s$-quark condensates of QCD in the confined phase at finite temperature to ${\cal O}(p^6)$ in the low-energy expansion. We also include…

We present updated results on the chiral properties of SU(3) gauge theories with 2 and 6 massless Dirac fermions in the fundamental representation. Our focus is on the ratio $\langle \bar{\psi} \psi \rangle / F^3$, where $\langle \bar{\psi}…

Chiral symmetry and its spontaneous breaking play an important role both in the light hadron and heavy hadron systems. The chiral perturbation theory ($\chi$PT) is the low energy effective field theory of the QCD. In this work, we shall…

I discuss the recent attempts to build an effective chiral Lagrangian incorporating massive resonance states. A useful approximation scheme to organize the resonance Lagrangian is provided by the large-Nc limit of QCD. Integrating out the…

We determine the low-energy constants (LECs) $f_0$, $L_4^r$ and $L_5^r$ of SU(3) Chiral Perturbation Theory ($\chi$PT) from a lattice QCD calculation of the scalar form factors of the pion with fully controlled systematics. Lattice results…

Multi-flavour (N_f>=3) Chiral Perturbation Theory (ChPT) may exhibit instabilities due to vacuum fluctuations of sea q-bar q pairs. Keeping the fluctuations small would require a very precise fine-tuning of the low-energy constants L_4 and…

We calculate the complete $T$-matrices of pion-nucleon ($\pi N$) scattering to the third order in heavy baryon SU(3) chiral perturbation theory. The baryon mass in the chiral limit $M_0$ and the low-energy constants are determined by…

An extended $U(3)_L\bigotimes U(3)_R$ chiral effective field theory which includes pseudoscalar and vector meson nonets as dynamic variables is presented. The theory combines a hidden symmetry approach with a general procedure of including…

We discuss Partially Quenched Chiral Perturbation Theory (PQ$\chi$PT) and possible fitting strategies to Lattice QCD data at next-to-next-to-leading order (NNLO) in the mesonic sector. We also present a complete calculation of the masses of…

For a low-temperature expansion in QCD it is well-known that the Lagrangian of vacuum chiral perturbation theory can be applied. This is due to the fact that the thermal effects of the heavy modes are Boltzmann suppressed. The present work…

We study pion--nucleon scattering with a chiral lagrangian of pions, nucleons, and $\Delta$-isobars to order $Q^3$, where $Q$ is a generic small momentum. We compare the results from heavy baryon chiral perturbation theory with those from…

Our recently developed variant of variationnally optimized perturbation (OPT), in particular consistently incorporating renormalization group properties (RGOPT), is adapted to the calculation of the QCD spectral density of the Dirac…

First, the L\sigma M is nonperturbatively solved via loop-order gap equations. Then the Nambu-Goldstone theorem (NGT) is expressed in L\sigma M language. Next, the Lee null tadpole sum for this SU(2) L\sigma M theory is shown to require N_c…

In the framework of the low energy Chiral Lagrangian, the renormalization group equations for the couplings are investigated up to order p^6, both for the SU(2) as for the SU(3) cases. Infrared attractive fixed points for ratios of…

In the low energy domain, Chiral Perturbation Theory parametrizes the small chiral symmetry breaking effects, produced by the quark masses $m_u$, $m_d$ and $m_s$, in terms of order parameters of massless QCD. The latter can then, in…

We review our recent study of the pion mass dependence of the rho and sigma resonances generated from one-loop SU(2) Chiral Perturbation Theory (ChPT) with the Inverse Amplitude Method (IAM) which was modified to properly account for the…