Related papers: Quark condensate and deviations from string-like b…
Quantum Chromodynamics on a lattice with Wilson fermions and a chirally twisted mass term for two degenerate quark flavours is considered in the framework of chiral perturbation theory. The pion masses and decay constants are calculated in…
A density wave in quark matter is discussed at finite temperature, which occurs along with the chiral condensation, and is described by a dual standing wave in scalar and pseudo-scalar condensates on the chiral circle. The mechanism is…
A large separation of scales is frequently required by theories describing physics beyond the Standard Model. In mass-split models with some massless (light) and some heavy flavors, large scale separation arises by construction if the…
The restoration of dynamical chiral symmetry for a higher number of light-quark flavors $N_f$ implies suppression of the dynamically generated quark mass. The study of various larger values of $N_f$ may have a greater impact on the internal…
The structure of the hadron spectrum is discussed in connection with the main phenomena of nonperturbative QCD: confinement and chiral symmetry breaking (CSB). For the higher part of the spectrum ($M \ge 2 GeV$) spin and chiral effects are…
Chiral symmetry breaking (ChSB) is reviewed to some extent within the quark-level-linear-sigma-model (QLL$\sigma$M) theory and standard chiral perturbation theory (ChPT). It is shown, on the basis of several examples related to the pion, as…
We compute the static-light meson spectrum with N_f = 2 flavours of sea quarks using Wilson twisted mass lattice QCD. We consider five different values for the light quark mass corresponding to 300 MeV < m_PS < 600 MeV and we present…
We show how to obtain information about the states of an effective field theory in terms of the underlying fundamental theory. In particular we analyze the spectroscopic nature of meson resonances from the meson-meson scattering amplitudes…
The interactions of $\rho$, $K^*$, $\phi$ and $\omega$ vector-mesons with low-momentum $\pi$, $K$ and $\eta$ pseudoscalar mesons are constrained by chiral symmetry. We derive a heavy vector-meson chiral Lagrangian in which the vector mesons…
QCD sum rules predict that the change of the strange quark condensate $<\bar s s>$ in hadron matter at finite baryon density causes a shift of the peak position of the di-electron spectra from $\phi$ meson decays. Due to the expansion of…
We study the low energy dynamics of pions in a gravity dual of chiral symmetry breaking. The string theory construction consists of a probe D7 brane in the Constable Myers non-supersymmetric background, which has been shown to describe…
One of the most challenging issues in QCD is the investigation of spontaneous chiral-symmetry breaking, which is characterized by the non-vanishing chiral condensate when the bare fermion mass is zero. In standard methods, one has to…
We compute pseudoscalar meson masses and decay constants using staggered quarks on lattices with three flavors of sea quarks and lattice spacings $\approx 0.12$ fm and $\approx 0.09$ fm. We fit partially quenched results to ``staggered…
We extend our previous formulation of low-energy QCD in terms of an effective lagrangian containing operators of dimensionality $d\le 6$ constructed with pseudoscalars and quark fields, describing physics below the scale of chiral symmetry…
The effective quark models are employed to describe the hadronization of QCD in the quark sector. They reveal a different structure depending on how the spontaneous chiral symmetry breaking (CSB) is implemented. When the generation of light…
The mass differences in all neutral pseudo scalar mesons and CP violations associated with the mixings are investigated in the context of the fermion- boson-type subquark model. These phenomena are unifyingly explained by the neutral scalar…
We show that vector-like quarks in the fundamental or higher-dimensional representations of QCD can generate the electro-weak scale in a phenomenologically viable way by chiral symmetry breaking condensates. The thereby generated scales are…
In our world the standard model of particle physics contains within it the fairly intractable theory called QCD. A toy version with two colours is often studied as a model confining and chiral symmetry breaking field theory. Here we…
Spontaneous chiral symmetry breaking, mesons and baryons are illustrated in the language of the Dirac theory. Various forces acting between quarks inside baryons are discussed. I explain why the naive quark models typically overestimate…
We calculate charmed meson spectra and decay constants in lattice QCD employing one-loop $O(a)$ improved heavy quark action and axial-vector currents. In quenched simulations at $a \sim 0.1$ fm with the plaquette gauge action as well as a…