Thermodynamics of lattice QCD with 2 flavours of colour-sextet quarks: A model of walking/conformal Technicolor

Abstract

QCD with two flavours of massless colour-sextet quarks is considered as a model for conformal/walking Technicolor. If this theory possess an infrared fixed point, as indicated by 2-loop perturbation theory, it is a conformal(unparticle) field theory. If, on the other hand, a chiral condensate forms on the weak-coupling side of this would-be fixed point, the theory remains confining. The only difference between such a theory and regular QCD is that there is a range of momentum scales over which the coupling constant runs very slowly (walks). In this first analysis, we simulate the lattice version of QCD with two flavours of staggered quarks at finite temperatures on lattices of temporal extent $N_t=4$ and 6. The deconfinement and chiral-symmetry restoration couplings give us a measure of the scales associated with confinement and chiral-symmetry breaking. We find that, in contrast to what is seen with fundamental quarks, these transition couplings are very different. $\beta =6/g^2$ for each of these transitions increases significantly from $N_t=4$ and $N_t=6$ as expected for the finite temperature transitions of an asymptotically-free theory. This suggests a walking rather than a conformal behaviour, in contrast to what is observed with Wilson quarks. In contrast to what is found for fundamental quarks, the deconfined phase exhibits states in which the Polyakov loop is oriented in the directions of all three cube roots of unity. At very weak coupling the states with complex Polyakov loops undergo a transition to a state with a real, negative Polyakov loop.

21 pages, 9 figures, Revtex with postscript figures. One extra reference was added; text is unchanged. Corrected typographical error

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• Fundamental Composite Electroweak Dynamics: Status at the LHC
• Running coupling and mass anomalous dimension of SU(3) gauge theory with two flavors of symmetric-representation fermions
• Mesonic spectroscopy of Minimal Walking Technicolor
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• Electroweak interactions and dark baryons in the sextet BSM model with a composite Higgs particle
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• Study of the conformal hyperscaling relation through the Schwinger-Dyson equation
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• QCD-like technicolor on the lattice
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• Sextet Model with Wilson Fermions
• The SU(3) Sextet Model with Wilson Fermions
• Deconfinement vs. chiral symmetry and higher representation matter
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• Technicolor and Beyond: Unification in Theory Space
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• Thermodynamics of lattice QCD with 3 flavours of colour-sextet quarks II: N_t=6 and N_t=8
• Anomalous Dimensions at an Infrared Fixed Point in an SU($N_c$) Gauge Theory with Fermions in the Fundamental and Antisymmetric Tensor Representations
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