Publications (5)0 Total impact
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ABSTRACT: I will review results obtained recently within the Hamilton approach to QCD
in Coulomb gauge. The focus will be on finite-temperature Yang--Mills theory
and chiral symmetry breaking in QCD.
11/2011;
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ABSTRACT: Spontaneous breaking of chiral symmetry is investigated in the Hamiltonian
approach to QCD in Coulomb gauge. The quark wave functional is determined by
the variational principle using an ansatz which goes beyond the commonly used
BCS-type of wave functionals and includes the coupling of the quarks to the
transversal spatial gluons. Using the lattice gluon propagator as input it is
shown that the low energy chiral properties of the quarks, like the quark
condensate and the constituent quark mass, are substantially increased by the
coupling of the quarks to the spatial gluons. Our results compare favourably
with the phenomenological values.
07/2011;
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ABSTRACT: In a recent article Hasenfratz and von Allmen have suggested a fixed point action for two flavors of Weyl fermions on the lattice with gauge group SU(2). The block-spin transformation they use maps the chiral and vector symmetries of the underlying vector theory onto two equations of the Ginsparg-Wilson (GW) type. We show that an overlap Dirac operator can be constructed which solves both GW equations simultaneously. We discuss the properties of this overlap operator and its projection onto lattice Weyl fermions which seems to be free of artefacts, in particular the projection operators are independent of the gauge field.
03/2008;
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ABSTRACT: We study whether applying lattice projectors on a vector-like Ginsparg-Wilson Dirac operator is the only way to construct left-handed lattice fermions. Using RG transformations we derive an equation for the generating functional on the lattice, obtained by blocking from the continuum. We analyze how symmetries of the continuum theory manifest themselves in this lattice generating functional and how anomalies emerge. The formalism is applied to left-handed continuum fermions and we derive two equations that characterize the corresponding lattice symmetries. To analyze possible solutions, we directly block a parameterized action for free continuum fermions to obtain the corresponding lattice action. Subsequently we study parameter values where the continuum action corresponds to left-handed fermions.
11/2007;
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ABSTRACT: In a recent article Hasenfratz and von Allmen have suggested a fixed point action for two flavors of Weyl fermions on the lattice with gauge group SU(2). The block-spin transformation they use maps the chiral and vector symmetries of the underlying vector theory onto two equations of the Ginsparg–Wilson (GW) type. We show that an overlap Dirac operator can be constructed which solves both GW equations simultaneously. We discuss the properties of this overlap operator and its projection onto lattice Weyl fermions which seems to be free of artefacts, in particular the projection operators are independent of the gauge field.
Nuclear Physics B.
