skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Ideal walking dynamics via a gauged NJL model

Authors:
; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1372723
Grant/Contract Number:
FG02-05ER41368
Resource Type:
Journal Article: Published Article
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 96; Journal Issue: 1; Related Information: CHORUS Timestamp: 2017-07-25 22:11:29; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society
Country of Publication:
United States
Language:
English

Citation Formats

Rantaharju, Jarno, Pica, Claudio, and Sannino, Francesco. Ideal walking dynamics via a gauged NJL model. United States: N. p., 2017. Web. doi:10.1103/PhysRevD.96.014512.
Rantaharju, Jarno, Pica, Claudio, & Sannino, Francesco. Ideal walking dynamics via a gauged NJL model. United States. doi:10.1103/PhysRevD.96.014512.
Rantaharju, Jarno, Pica, Claudio, and Sannino, Francesco. 2017. "Ideal walking dynamics via a gauged NJL model". United States. doi:10.1103/PhysRevD.96.014512.
@article{osti_1372723,
title = {Ideal walking dynamics via a gauged NJL model},
author = {Rantaharju, Jarno and Pica, Claudio and Sannino, Francesco},
abstractNote = {},
doi = {10.1103/PhysRevD.96.014512},
journal = {Physical Review D},
number = 1,
volume = 96,
place = {United States},
year = 2017,
month = 7
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1103/PhysRevD.96.014512

Save / Share:
  • We investigate the effects of four-fermion interactions on the phase diagram of strongly interacting theories for any representation as function of the number of colors and flavors. We show that the conformal window, for any representation, shrinks with respect to the case in which the four-fermion interactions are neglected. The anomalous dimension of the mass increases beyond the unity value at the lower boundary of the new conformal window. We plot the new phase diagram which can be used, together with the information about the anomalous dimension, to propose ideal models of walking technicolor. We discover that when the extendedmore » technicolor sector, responsible for giving masses to the standard model fermions, is sufficiently strongly coupled the technicolor theory, in isolation, must have an infrared fixed point for the full model to be phenomenologically viable. Using the new phase diagram we show that the simplest one family and minimal walking technicolor models are the archetypes of models of dynamical electroweak symmetry breaking. Our predictions can be verified via first principle lattice simulations.« less
  • We study the gauge sector of minimal walking technicolor, which is an SU(2) gauge theory with n{sub f}=2 flavors of Wilson fermions in the adjoint representation. Numerical simulations are performed on lattices N{sub t}xN{sub s}{sup 3}, with N{sub s} ranging from 8 to 16 and N{sub t}=2N{sub s}, at fixed {beta}=2.25, and varying the fermion bare mass m{sub 0}, so that our numerical results cover the full range of fermion masses from the quenched region to the chiral limit. We present results for the string tension and the glueball spectrum. A comparison of mesonic and gluonic observables leads to themore » conclusion that the infrared dynamics is given by an SU(2) pure Yang-Mills theory with a typical energy scale for the spectrum sliding to zero with the fermion mass. The typical mesonic mass scale is proportional to and much larger than this gluonic scale. Our findings are compatible with a scenario in which the massless theory is conformal in the infrared. An analysis of the scaling of the string tension with the fermion mass toward the massless limit allows us to extract the chiral condensate anomalous dimension {gamma}{sub *}, which is found to be {gamma}{sub *}=0.22{+-}0.06.« less
  • Applying the perturbative QCD method, we study the decay {ital B}{sub {ital c}}{r_arrow}{ital D}{sub {ital s}}{sup {asterisk}}{gamma} in the standard model (SM) and multiscale walking technicolor model (MWTCM). In the SM, we find that the contribution of weak annihilation is more important than that of the electromagnetic penguin diagram. The presence of pseudo Goldstone bosons in the MWTCM leads to a large enhancement in the rate of {ital B}{sub {ital c}}{r_arrow}{ital D}{sub {ital s}}{sup {asterisk}}{gamma}, but this model is in conflict with the branching ratio of {ital Z}{r_arrow}{ital b{bar b}}({ital R}{sub {ital b}}) and the CLEO data on the branchingmore » ratio {ital B}({ital b}{r_arrow}{ital s}{gamma}). If top-color is further introduced, the calculated results in the top-color-assisted MWTCM can be suppressed and be in agreement with the CLEO data for a certain range of parameters. {copyright}{ital 1996 The American Physical Society.}« less
  • QCD with two flavors of massless color-sextet quarks is considered as a model for conformal/walking technicolor. If this theory possesses 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 twomore » flavors of staggered quarks at finite temperatures on lattices of temporal extent N{sub 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{sup 2} for each of these transitions increases significantly from N{sub t} = 4 and N{sub t} = 6 as expected for the finite-temperature transitions of an asymptotically free theory. This suggests a walking rather than a conformal behavior, 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.« less
  • QCD with two flavors of massless color-sextet quarks is considered as a model for conformal/walking technicolor. If this theory possesses 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 twomore » flavors of staggered quarks at finite temperatures on lattices of temporal extent N{sub 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{sup 2} for each of these transitions increases significantly from N{sub t}=4 and N{sub t}=6 as expected for the finite-temperature transitions of an asymptotically free theory. This suggests a walking rather than a conformal behavior, 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.« less