The chiral phase transition for lattice QCD with 2 color-sextet quarks

Kogut, J. B.; Sinclair, D. K.

doi:10.1103/PhysRevD.92.054508

Title: The chiral phase transition for lattice QCD with 2 color-sextet quarks

Abstract

QCD with 2 flavors of massless color-sextet quarks is studied as a possible walking-Technicolor candidate. We simulate the lattice version of this model at finite temperatures near to the chiral-symmetry restoration transition, to determine whether it is indeed a walking theory (QCD-like with a running coupling which evolves slowly over an appreciable range of length scales) or if it has an infrared fixed point, making it a conformal field theory. The lattice spacing at this transition is decreased towards zero by increasing the number N_t of lattice sites in the temporal direction. Our simulations are performed at N_t = 4,6,8,12, on lattices with spatial extent much larger than the temporal extent. A range of small fermion masses is chosen to make predictions for the chiral (zero mass) limit. We find that the bare lattice coupling does decrease as the lattice spacing is decreased. However, it decreases more slowly than would be predicted by asymptotic freedom. We discuss whether this means that the coupling is approaching a finite value as lattice N_t is increased—the conformal option, or if the apparent disagreement with the scaling predicted by asymptotic freedom is because the lattice coupling is a poor expansion parameter, and the theorymore »« less

Authors:

Kogut, J. B. ^[1]; Sinclair, D. K. ^[2]

Dept. of Energy, Washington, D.C. (United States). Div. of High Energy Physics; Univ. of Maryland, College Park, MD (United States). Dept. of Physics, TQHN
Argonne National Lab. (ANL), Argonne, IL (United States). HEP Div.

Publication Date:: Mon Sep 21 00:00:00 EDT 2015

Research Org.:: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)

Sponsoring Org.:: USDOE

OSTI Identifier:: 1542094

Alternate Identifier(s):: OSTI ID: 1222366

Grant/Contract Number:: AC02-06CH11357; AC02-05CH11231; TG-MCA99S015

Resource Type:: Accepted Manuscript

Journal Name:: Physical Review. D, Particles, Fields, Gravitation and Cosmology

Additional Journal Information:: Journal Volume: 92; Journal Issue: 5; Journal ID: ISSN 1550-7998

Publisher:: American Physical Society (APS)

Country of Publication:: United States

Language:: English

Subject:: 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats


                    Kogut, J. B., and Sinclair, D. K. The chiral phase transition for lattice QCD with 2 color-sextet quarks.  United States: N. p., 2015. 
Web.  doi:10.1103/PhysRevD.92.054508.

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                    Kogut, J. B., & Sinclair, D. K. The chiral phase transition for lattice QCD with 2 color-sextet quarks.  United States.  https://doi.org/10.1103/PhysRevD.92.054508

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                    Kogut, J. B., and Sinclair, D. K. Mon .  
"The chiral phase transition for lattice QCD with 2 color-sextet quarks".  United States.  https://doi.org/10.1103/PhysRevD.92.054508.  https://www.osti.gov/servlets/purl/1542094.

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@article{osti_1542094,

  title        = {The chiral phase transition for lattice QCD with 2 color-sextet quarks},

  author       = {Kogut, J. B. and Sinclair, D. K.},

  abstractNote = {QCD with 2 flavors of massless color-sextet quarks is studied as a possible walking-Technicolor candidate. We simulate the lattice version of this model at finite temperatures near to the chiral-symmetry restoration transition, to determine whether it is indeed a walking theory (QCD-like with a running coupling which evolves slowly over an appreciable range of length scales) or if it has an infrared fixed point, making it a conformal field theory. The lattice spacing at this transition is decreased towards zero by increasing the number Nt of lattice sites in the temporal direction. Our simulations are performed at Nt = 4,6,8,12, on lattices with spatial extent much larger than the temporal extent. A range of small fermion masses is chosen to make predictions for the chiral (zero mass) limit. We find that the bare lattice coupling does decrease as the lattice spacing is decreased. However, it decreases more slowly than would be predicted by asymptotic freedom. We discuss whether this means that the coupling is approaching a finite value as lattice Nt is increased—the conformal option, or if the apparent disagreement with the scaling predicted by asymptotic freedom is because the lattice coupling is a poor expansion parameter, and the theory walks. Currently, evidence favors QCD with 2 color-sextet quarks being a conformal field theory. Other potential sources of disagreement with the walking hypothesis are also discussed. In conclusion, we also report an estimate of the position of the deconfinement transition for Nt = 12, needed for choosing parameters for zero-temperature simulations.},

  doi          = {10.1103/PhysRevD.92.054508},

  journal      = {Physical Review. D, Particles, Fields, Gravitation and Cosmology},

  number       = 5,

  volume       = 92,

  place        = {United States},

  year         = {Mon Sep 21 00:00:00 EDT 2015},

  month        = {Mon Sep 21 00:00:00 EDT 2015}

}

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Works referencing / citing this record:

SU(3) sextet model with Wilson fermions
journal, August 2017

Hansen, Martin; Drach, Vincent; Pica, Claudio
Physical Review D, Vol. 96, Issue 3
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Low-energy effective action for pions and a dilatonic meson
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Strong dynamics, composite Higgs and the conformal window
text, January 2016

Nogradi, Daniel; Patella, Agostino
arXiv
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We continue our lattice simulations of QCD with 2 flavors of color-sextet quarks as a model for conformal or walking technicolor. A 2-loop perturbative calculation of the {beta} function which describes the evolution of this theory's running coupling constant predicts that it has a second zero at a finite coupling. This nontrivial zero would be an infrared stable fixed point, in which case the theory with massless quarks would be a conformal field theory. However, if the interaction between quarks and antiquarks becomes strong enough that a chiral condensate forms before this IR fixed point is reached, the theory ismore »« less
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Title: The chiral phase transition for lattice QCD with 2 color-sextet quarks

Abstract

Citation Formats

Scale-Invariant Hypercolor Model and a Dilaton journal, March 1986

Can the nearly conformal sextet gauge model hide the Higgs impostor? journal, December 2012

Chiral symmetry breaking with octet and sextet quarks journal, September 1984

Dynamics of spontaneous symmetry breaking in the Weinberg-Salam theory journal, November 1979

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Perturbative corrections for staggered fermion bilinears journal, May 1993

Thermodynamics of lattice QCD with 2 sextet quarks on N t = 8 lattices journal, October 2011

Zero of the discrete beta function in SU(3) lattice gauge theory with color sextet fermions journal, August 2008

Thermodynamics of lattice QCD with 2 flavors of color-sextet quarks: A model of walking/conformal technicolor journal, June 2010

Running coupling and mass anomalous dimension of SU(3) gauge theory with two flavors of symmetric-representation fermions journal, September 2010

The bulk transition of QCD with twelve flavors and the role of improvement journal, March 2013

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Chiral Hierarchies and Flavor-Changing Neutral Currents in Hypercolor journal, August 1986

Conformal window of SU ( N ) gauge theories with fermions in higher dimensional representations journal, April 2007

Novel phase in SU(3) lattice gauge theory with 12 light fermions journal, May 2012

Accelerating staggered-fermion dynamics with the rational hybrid Monte Carlo algorithm journal, January 2007

Raising the sideways scale journal, September 1981

Critical point and scale setting in SU(3) plasma: An update journal, May 2015

Phase structure of SU(3) gauge theory with two flavors of symmetric-representation fermions journal, February 2009

Chiral properties of SU(3) sextet fermions journal, November 2009

On tadpole improvement for staggered fermions journal, March 1999

Mass anomalous dimension in sextet QCD journal, April 2013

Implications of dynamical symmetry breaking: An addendum journal, February 1979

Viability of lattice perturbation theory journal, September 1993

Hierarchic chiral condensate journal, April 1986

SU(3) sextet model with Wilson fermions journal, August 2017

Low-energy effective action for pions and a dilatonic meson text, January 2016

Strong dynamics, composite Higgs and the conformal window text, January 2016

Scale-Invariant Hypercolor Model and a Dilaton
journal, March 1986

Can the nearly conformal sextet gauge model hide the Higgs impostor?
journal, December 2012

Chiral symmetry breaking with octet and sextet quarks
journal, September 1984

Dynamics of spontaneous symmetry breaking in the Weinberg-Salam theory
journal, November 1979

Evidence for a conformal phase in $SU (N)$ gauge theories
journal, October 2010

Finite-size scaling tests for SU(3) lattice gauge theory with color sextet fermions
journal, December 2009

Near the sill of the conformal window: Gauge theories with fermions in two-index representations
journal, September 2013

Perturbative corrections for staggered fermion bilinears
journal, May 1993

Thermodynamics of lattice QCD with 2 sextet quarks on $N_{t} = 8$ lattices
journal, October 2011

Zero of the discrete beta function in SU(3) lattice gauge theory with color sextet fermions
journal, August 2008

Thermodynamics of lattice QCD with 2 flavors of color-sextet quarks: A model of walking/conformal technicolor
journal, June 2010

Running coupling and mass anomalous dimension of SU(3) gauge theory with two flavors of symmetric-representation fermions
journal, September 2010

The bulk transition of QCD with twelve flavors and the role of improvement
journal, March 2013

The physics of eight flavours
journal, December 2008

Chiral Hierarchies and Flavor-Changing Neutral Currents in Hypercolor
journal, August 1986

Conformal window of $SU (N)$ gauge theories with fermions in higher dimensional representations
journal, April 2007

Novel phase in SU(3) lattice gauge theory with 12 light fermions
journal, May 2012

Accelerating staggered-fermion dynamics with the rational hybrid Monte Carlo algorithm
journal, January 2007

Raising the sideways scale
journal, September 1981

Critical point and scale setting in SU(3) plasma: An update
journal, May 2015

Phase structure of SU(3) gauge theory with two flavors of symmetric-representation fermions
journal, February 2009

Chiral properties of SU(3) sextet fermions
journal, November 2009

On tadpole improvement for staggered fermions
journal, March 1999

Mass anomalous dimension in sextet QCD
journal, April 2013

Implications of dynamical symmetry breaking: An addendum
journal, February 1979

Viability of lattice perturbation theory
journal, September 1993

Hierarchic chiral condensate
journal, April 1986

SU(3) sextet model with Wilson fermions
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text, January 2016

Strong dynamics, composite Higgs and the conformal window
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