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We compare eigenvalue correlations of the Dirac operator with a chemical potential obtained from lattice simulations of quenched QCD with analytic predictions obtained from chiral effective theories in the zero-momentum limit. By comparing…

High Energy Physics - Lattice · Physics 2008-11-26 James C. Osborn , Tilo Wettig

We compare the eigenvalue spectra of the Dirac operator from a simulation with two mass degenerate dynamical chirally improved fermions with Random Matrix Theory. Comparisons with distribution of k-th eigenvalues (k=1,2) in fixed…

High Energy Physics - Lattice · Physics 2008-11-26 C. B. Lang , Pushan Majumdar , Wolfgang Ortner

Eigenvalues and eigenfunctions of the QCD Dirac operator are studied for an instanton liquid partition function. We find that for energy differences $\delta E$ below an energy scale $E_c$, identified as the Thouless energy, the eigenvalue…

High Energy Physics - Phenomenology · Physics 2009-10-31 J. C. Osborn , J. J. M. Verbaarschot

We investigate the spectral properties of the Wilson Dirac operator in quenched QCD in the microscopic regime. We distinguish the topological sectors using the index as determined by the Wilson flow method. Consequently, the distributions…

High Energy Physics - Lattice · Physics 2012-01-04 Albert Deuzeman , Urs Wenger , Jair Wuilloud

Eigenvalues and eigenfunctions of the QCD Dirac operator are studied for gauge field configurations given by a liquid of instantons. We find that for energy differences $\delta E$ below an energy scale $E_c$ the eigenvalue correlations are…

High Energy Physics - Phenomenology · Physics 2009-10-31 J. C. Osborn , J. J. M. Verbaarschot

We discuss the eigenvalue distribution of the overlap Dirac operator in quenched QCD on lattices of size 8^{4}, 10^{4} and 12^{4} at \beta = 5.85 and \beta = 6. We distinguish the topological sectors and study the distributions of the…

High Energy Physics - Lattice · Physics 2009-11-10 W. Bietenholz , K. Jansen , S. Shcheredin

We analyze the eigenvalue statistics of the staggered Dirac operator above $T_{c}$ in QCD with 2+1 flavors of dynamical quarks. We use physical quark masses in our simulations. We compare the eigenvalue statistics from several parts of the…

High Energy Physics - Lattice · Physics 2011-11-16 Tamás G. Kovács , Ferenc Pittler

In this lecture we discuss correlations of the QCD Dirac eigenvalues. We find that below a scale of $E_c\sim \Lambda/L^2$ they are given by chiral Random Matrix Theory. This follows from analytical arguments based on partially quenched…

High Energy Physics - Theory · Physics 2007-05-23 J. J. M. Verbaarschot

We propose a new method to obtain the K -> pi pi amplitude from K -> pi which allows one to fully account for the effects of final state interactions. The method is based on a set of dispersion relations for the K -> pi pi amplitude in…

High Energy Physics - Phenomenology · Physics 2007-05-23 M. Buchler

We present simulation results for lattice QCD with light pions. For the quark fields we apply chirally symmetric lattice Dirac operators, in particular the overlap hypercube operator, along with the standard overlap operator for comparison.…

High Energy Physics - Lattice · Physics 2007-05-23 W. Bietenholz , S. Shcheredin

In the epsilon-regime of QCD the main features of the spectrum of the low-lying eigenvalues of the (euclidean) Dirac operator are expected to be described by a certain universality class of random matrix models. In particular, the latter…

High Energy Physics - Lattice · Physics 2009-11-10 Leonardo Giusti , Martin Lüscher , Peter Weisz , Hartmut Wittig

We analyze how individual eigenvalues of the QCD Dirac operator at nonzero quark chemical potential are distributed in the complex plane. Exact and approximate analytical results for both quenched and unquenched distributions are derived…

High Energy Physics - Lattice · Physics 2008-11-26 G. Akemann , J. Bloch , L. Shifrin , T. Wettig

Motivated by the statistical fluctuation of Dirac spectrum of QCD-like theories subjected to (pseudo)reality-violating perturbations and in the epsilon-regime, we compute the smallest eigenvalue distribution and the level spacing…

High Energy Physics - Lattice · Physics 2013-12-18 Shinsuke M. Nishigaki

In quantum chromodynamics (QCD) at nonzero chemical potential, the eigenvalues of the Dirac operator are scattered in the complex plane. Can the fluctuation properties of the Dirac spectrum be described by universal predictions of…

High Energy Physics - Lattice · Physics 2009-10-31 H. Markum , R. Pullirsch , T. Wettig

We propose a new method to obtain the K -> pi pi amplitude from K -> pi which allows one to fully account for the effects of final state interactions. The method is based on a set of dispersion relations for the K -> pi pi amplitude in…

High Energy Physics - Phenomenology · Physics 2009-11-07 M. Buechler , G. Colangelo , J. Kambor , F. Orellana

The application of Random Matrix Theory to the Dirac operator of QCD yields predictions for the probability distributions of the lowest eigenvalues. We measured Dirac operator spectra using massless overlap fermions in quenched QCD at…

High Energy Physics - Lattice · Physics 2009-11-10 S. Shcheredin , W. Bietenholz , T. Chiarappa , K. Jansen , K. -I. Nagai

We determine the volume and mass dependence of scalar and pseudoscalar two-point functions in N_f-flavour QCD, in the presence of an isospin chemical potential and at fixed gauge-field topology. We obtain these results at second order in…

High Energy Physics - Lattice · Physics 2008-12-25 G. Akemann , F. Basile , L. Lellouch

We discuss a new Random Matrix Model for QCD with a chemical potential that is based on the symmetries of the Dirac operator and can be solved exactly for all eigenvalue correlations for any number of flavors. In the microscopic limit of…

High Energy Physics - Lattice · Physics 2009-11-10 James C. Osborn

In this talk, I first motivate the use of Chiral Perturbation Theory in the context of Lattice QCD. In particular, I explain how partially quenched QCD, which has, in general, unequal valence- and sea-quark masses, can be used to obtain…

High Energy Physics - Phenomenology · Physics 2017-08-23 Maarten Golterman

The low lying spectrum of QCD in the delta-regime is calculated here in chiral perturbation theory up to NNL order. The spectrum has a simple form in terms of the pion decay constant F and a combination of the low energy constants Lambda1…

High Energy Physics - Theory · Physics 2010-03-25 P. Hasenfratz