scholarly journals The twelve-flavor β-function and dilaton tests of the sextet scalar

2018 ◽  
Vol 175 ◽  
pp. 08015 ◽  
Author(s):  
Zoltan Fodor ◽  
Kieran Holland ◽  
Julius Kuti ◽  
Daniel Nogradi ◽  
Chik Him Wong
Keyword(s):  
Symmetry Breaking ◽  
Model Building ◽  
Chiral Symmetry Breaking ◽  
Gauge Coupling ◽  
Symmetric Tensor ◽  
Clear Trend ◽  
Light Scalar ◽  
Conformal Gauge ◽  
Β Function ◽  
Massless Fermions

We discuss near-conformal gauge theories beyond the standard model (BSM) where interesting results on the twelve-flavor β-function of massless fermions in the fundamental representation of the SU(3) color gauge group and dilaton tests of the light scalar with two massless fermions in the two-index symmetric tensor (sextet) representation can be viewed as parts of the same BSM paradigm under investigation. The clear trend in the decreasing size of β-functions at fixed renormalized gauge coupling is interpreted as a first indicator how the conformal window (CW) is approached in correlation with emergent near-conformal light scalars. BSM model building close to the CW will be influenced by differing expectations on the properties of the emergent light 0++ scalar either as a σ-particle of chiral symmetry breaking (ΧS B), or as a dilaton of scale symmetry breaking. The twelve-flavor β-function emerges as closest to the CW, perhaps near-conformal, or perhaps with an infrared fixed point (IRFP) at some unexplored strong coupling inside the CW. It is premature to speculate on dilaton properties of the twelveflavor model since the near-conformal realization remains an open question. However, it is interesting and important to investigate dilaton tests of the light sextet scalar whose β-function is closest to the CW in the symmetry breaking phase and emerges as the leading candidate for dilaton tests of the light scalar. We report results from high precision analysis of the twelve-flavor β-function [1] refuting its published IRFP [2, 3]. We present our objections to recent claims [4, 5] for non-universal behavior of staggered fermions used in our analysis. We also report our first analysis of dilaton tests of the light 0++ scalar in the sextet model and comment on related post-conference developments. The dilaton test is the main thrust of this conference contribution including presentation #405 on the nf = 12 β-function and presentation #260 on dilaton tests of the sextet model. They are both selected from the near-conformal BSM paradigm.

scholarly journals Four-Quark States from Functional Methods

2020 ◽  
Vol 61 (4) ◽  
Author(s):  
Gernot Eichmann ◽  
Christian S. Fischer ◽  
Walter Heupel ◽  
Nico Santowsky ◽  
Paul C. Wallbott
Keyword(s):  
Symmetry Breaking ◽  
Scalar Meson ◽  
Chiral Symmetry Breaking ◽  
The Other ◽  
Feature Article ◽  
Exotic Mesons ◽  
Scalar Mesons ◽  
Functional Methods ◽  
Internal Structures ◽  
Light Scalar

AbstractIn this feature article we summarise and highlight aspects of the treatment of four-quark states with functional methods. Model approaches to those exotic mesons almost inevitably have to assume certain internal structures, e.g. by grouping quarks and antiquarks into (anti-)diquark clusters or heavy-light $$q{\bar{q}}$$ q q ¯ pairs. Functional methods using Dyson–Schwinger and Bethe–Salpeter equations can be formulated without such prejudice and therefore have the potential to put these assumptions to test and discriminate between such models. So far, functional methods have been used to study the light scalar-meson sector and the heavy-light sector with a pair of charmed and a pair of light quarks in different quantum number channels. For all these states, the dominant components in terms of internal two-body clustering have been identified. It turns out that chiral symmetry breaking plays an important role for the dominant clusters in the light meson sector (in particular for the scalar mesons) and that this property is carried over to the heavy-light sector. Diquark-antidiquark components, on the other hand, turn out to be almost negligible for most states with the exception of open-charm heavy-light exotics.

scholarly journals SCHWINGER–DYSON EQUATIONS AND CHIRAL SYMMETRY BREAKING IN 2-D INDUCED GRAVITY

1995 ◽  
Vol 10 (06) ◽  
pp. 451-456 ◽  
Author(s):  
E. ELIZALDE ◽  
S. D. ODINTSOV ◽  
A. ROMEO ◽  
YU. I. SHIL'NOV
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Numerical Study ◽  
Chiral Symmetry Breaking ◽  
Ladder Approximation ◽  
Induced Gravity ◽  
Flat Background ◽  
Conformal Gauge

The Schwinger–Dyson equations in the ladder approximation for 2-D induced gravity coupled to fermions on a flat background are obtained in conformal gauge. A numerical study of these equations shows the possibility of chiral symmetry breaking in this theory.

ON CHIRAL SYMMETRY BREAKING WITH MASSLESS FERMIONS

1994 ◽  
Vol 09 (35) ◽  
pp. 3285-3291
Author(s):  
RAINER DICK
Keyword(s):  
Field Theory ◽  
Conformal Field Theory ◽  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Lorentz Group ◽  
Chiral Symmetry Breaking ◽  
General Structure ◽  
Transformation Behavior ◽  
Conformal Field ◽  
Massless Fermions

It is shown that Weyl spinors in Minkowski space are isomorphic to primary fields of half-integer conformal weights. This yields representations of fermionic two-point functions in terms of correlators of primary fields with a factorized transformation behavior under the Lorentz group. As an application we determine the general structure of the corresponding Lorentz covariant correlators by methods similar to that employed in conformal field theory to determine two- and three-point functions of primary fields. In particular, the chiral symmetry breaking terms resemble fermionic two-point functions of 2-D CFT up to a function of the product of momenta.

scholarly journals Inverse mass hierarchy of light scalar mesons driven by anomaly-induced flavor breaking

2020 ◽  
Vol 2020 (5) ◽  
Author(s):  
Yoshiki Kuroda ◽  
Masayasu Harada ◽  
Shinya Matsuzaki ◽  
Daisuke Jido
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Scalar Meson ◽  
Chiral Symmetry Breaking ◽  
Linear Sigma Model ◽  
Mass Hierarchy ◽  
Scalar Mesons ◽  
Light Scalar ◽  
Symmetry Breaking Term ◽  
Breaking Term

Abstract We propose a novel mechanism to reproduce the observed mass hierarchy for scalar mesons lighter than 1 GeV (called the inverse hierarchy), regarding them as mesons made of a quark and an anti-quark ($q\bar{q}$ mesons). The source is provided by the SU(3) flavor-symmetry breaking induced by the U(1) axial anomaly. In particular, the anomaly term including the explicit chiral symmetry breaking plays a significant role in the light scalar meson spectrum. To be concrete, we construct a linear sigma model for scalar mesons of $q\bar{q}$ type together with their pseudoscalar chiral partners, including an anomaly-induced explicit chiral symmetry-breaking term. We find that, due to the proposed mechanism, the inverse hierarchy, i.e., $m\left[ a_0 (980) \right] \simeq m\left[ f_0 (980) \right] > m \left[ K_0^\ast (700) \right] > m \left[ f_0(500) \right]$, is indeed realized. Consequently, the quark content of $f_0 (500)$ is dominated by the isoscalar $\bar uu+ \bar dd$ component, and $f_0 (980)$ by the strange quark bilinear one, $s\bar{s}$.

NEARLY CONFORMAL GAUGE THEORIES ON THE LATTICE

2010 ◽  
Vol 25 (27n28) ◽  
pp. 5162-5174 ◽  
Author(s):  
ZOLTÁN FODOR ◽  
KIERAN HOLLAND ◽  
JULIUS KUTI ◽  
DÁNIEL NÓGRÁDI ◽  
CHRIS SCHROEDER
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Gauge Theories ◽  
Matrix Theory ◽  
Chiral Symmetry Breaking ◽  
Chiral Condensate ◽  
Theoretical Understanding ◽  
Conformal Window ◽  
Running Coupling ◽  
Conformal Gauge

We present selected new results on chiral symmetry breaking in nearly conformal gauge theories with fermions in the fundamental representation of the SU (3) color gauge group. We found chiral symmetry breaking (χSB) for all flavors between Nf = 4 and Nf = 12 with most of the results discussed here for Nf = 4, 8, 12 as we approach the conformal window. To identify χSB we apply several methods which include, within the framework of chiral perturbation theory, the analysis of the Goldstone spectrum in the p -regime and the spectrum of the fermion Dirac operator with eigenvalue distributions of random matrix theory in the ϵ-regime. Chiral condensate enhancement is observed with increasing Nf when the electroweak symmetry breaking scale F is held fixed in technicolor language. Important finite-volume consistency checks from the theoretical understanding of the SU(Nf) rotator spectrum of the δ-regime are discussed. We also consider these gauge theories at Nf = 16 inside the conformal window. Our work on the running coupling is presented separately.1

scholarly journals Primordial monopoles and strings, inflation, and gravity waves

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Joydeep Chakrabortty ◽  
George Lazarides ◽  
Rinku Maji ◽  
Qaisar Shafi
Keyword(s):  
Symmetry Breaking ◽  
Gravity Waves ◽  
Cosmic Strings ◽  
Wave Spectrum ◽  
Gauge Coupling ◽  
String Tension ◽  
Magnetic Monopoles ◽  
Intermediate Scale ◽  
Tension Parameter ◽  
The Universe

Abstract We consider magnetic monopoles and strings that appear in non-supersymmetric SO(10) and E6 grand unified models paying attention to gauge coupling unification and proton decay in a variety of symmetry breaking schemes. The dimensionless string tension parameter Gμ spans the range 10−6− 10−30, where G is Newton’s constant and μ is the string tension. We show how intermediate scale monopoles with mass ∼ 1013− 1014 GeV and flux ≲ 2.8 × 10−16 cm−2s−1sr−1, and cosmic strings with Gμ ∼ 10−11− 10−10 survive inflation and are present in the universe at an observable level. We estimate the gravity wave spectrum emitted from cosmic strings taking into account inflation driven by a Coleman-Weinberg potential. The tensor-to-scalar ratio r lies between 0.06 and 0.003 depending on the details of the inflationary scenario.

scholarly journals A Possible Resolution to Troubles of SU(2) Center Vortex Detection in Smooth Lattice Configurations

Universe ◽  
2021 ◽  
Vol 7 (5) ◽  
pp. 122
Author(s):  
Rudolf Golubich ◽  
Manfried Faber
Keyword(s):  
Symmetry Breaking ◽  
Quantum Chromodynamics ◽  
Chiral Symmetry ◽  
Chiral Symmetry Breaking ◽  
Vortex Model ◽  
Center Vortex ◽  
Vortex Detection

The center vortex model of quantum-chromodynamics can explain confinement and chiral symmetry breaking. We present a possible resolution for problems of the vortex detection in smooth configurations and discuss improvements for the detection of center vortices.

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