Related papers: Vacuum structure in QCD and Correlation functions
A study of two-dimensional QCD on a spatial circle with Majorana fermions in the adjoint representation of the gauge groups SU(2) and SU(3) has been performed. The main emphasis is put on the symmetry properties related to the homotopically…
The vacuum properties of lattice QCD with staggered quarks are investigated by an efficient simulation method. I present data for the quark condensate with flavor number $N_f=0, ~ 1, ~ 2, ~ 3, ~ 4$ and many quark masses, including the…
We investigate the vacuum structure of dense quark matter in strong magnetic fields at finite temperature and densities in a 3 flavor Nambu Jona Lasinio (NJL) model including the Kobayashi-Maskawa-t'Hooft (KMT) determinant term using a…
Topological properties of the vacuum were investigated in finite-temperature lattice QCD without and with dynamical quarks using a local operator of topological charge density and a variant of cooling. Below the deconfinement temperature…
Three complementary views on the QCD vacuum structure, all based on eigenmodes of the overlap operator, are reported in their interrelation: (i) spectral density, localization and chiral properties of the modes, (ii) the possibility of…
We use a variational procedure to study finite density QCD in an approximation in which the interaction between quarks is modelled by that induced by instantons. We find that uniform states with conventional chiral symmetry breaking have…
The vacuum of Quantum Chromodynamics is a superposition of degenerate states with different topological numbers that are connected by tunneling (the $\theta$-vacuum). The tunneling events are due to topologically non-trivial configurations…
We study the baryonic fluctuations of electric charge, baryon number and strangeness, by considering a realization of the Hadron Resonance Gas model in the light flavor sector of QCD. We elaborate on the idea that the susceptibilities can…
In this thesis the finite temperature transition between confined and deconfined matter is studied at zero and nonzero quark densities. The findings are relevant for the understanding of the evolution of the early Universe and contemporary…
I start by giving a brief overview over new developments in the area of confinement and topology. As an example for the interrelations between topological objects, instantons at finite temperature are discussed. Then I focus on new insights…
The impact of dynamical fermions on the vacuum structure of QCD is explored. Of particular interest is the topological charge correlator, $<q(x) q(0) >$, where negative values at small $x$ reveal a sign-alternating layered structure to the…
2-color QCD (quantum chromodynamics with N_c=2) at finite temperature T and chemical potential \mu is revisited in the strong coupling limit on the lattice with staggered fermions. The phase structure in the space of T, \mu, and the quark…
The non-local vacuum condensates of QCD describe the distributions of quarks and gluons in the non-perturbative QCD vacuum. Physically, this means that vacuum quarks and gluons have nonzero mean-squared momentum, called virtuality. In this…
The QCD coupling appears in the perturbative expansion of the current-current two-point (vacuum polarization) function. Any lattice calculation of vacuum polarization is plagued by several competing non-perturbative effects at small momenta…
With the use of the world-line formalism, the heavy-quark condensate in the SU(N)-QCD is evaluated for the cases when the next-to-1/r term in the quark-antiquark potential at short distances is either quadratic, or linear. In the former…
The Polyakov loop and the chiral condensate are used as order parameters to explore analytically the possible phase structure of finite temperature QCD. Nambu-Jona-Lasinio models in a background temporal gauge field are combined with a…
The variational approach to QCD in Coulomb gauge developed previously by the T\"ubingen group is improved by enlarging the space of quark trial vacuum wave functionals through a new Dirac structure in the quark-gluon coupling. Our ansatz…
In strongly magnetized backgrounds, electrically charged vector bosons can condense. When considering the rho-meson sector of QCD, this results in the existence of a superconducting state with Abrikosov vortices. As a next order effect,…
Utilizing the in-medium Lorentz decomposition of operators generating QCD condensates we derive general constraints among the latter ones by the requirement of a smooth transition from medium to vacuum. In this way we relate the vacuum…
The definition of QCD vacuum is an important issue in the description of hadronic properties. Recent researches on the vacuum condensates have resulted in the suggestion of in-hadron condensates which can be taken as a paradigm shift…