scholarly journals A First-Quantized Model for Unparticles and Gauge Theories around Conformal Window

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 471
Author(s):  
Nicolas Boulanger ◽  
Fabien Buisseret ◽  
Guillaume Lhost
Keyword(s):  
Bound States ◽  
Gauge Theories ◽  
Mass Operator ◽  
Conformal Symmetry ◽  
Mass Term ◽  
String Tension ◽  
Coupling Constant ◽  
Scalar Particles ◽  
Conformally Invariant ◽  
Invariant Potential

We first quantize an action proposed by Casalbuoni and Gomis in 2014 that describes two massless relativistic scalar particles interacting via a conformally invariant potential. The spectrum is a continuum of massive states that may be interpreted as unparticles. We then obtain in a similar way the mass operator for a deformed action in which two terms are introduced that break the conformal symmetry: a mass term and an extra position-dependent coupling constant. A simple Ansatz for the latter leads to a mass operator with linear confinement in terms of an effective string tension σ. The quantized model is confining when σ≠0 and its mass spectrum shows Regge trajectories. We propose a tensionless limit in which highly excited confined states reduce to (gapped) unparticles. Moreover, the low-lying confined bound states become massless in the latter limit as a sign of conformal symmetry restoration and the ratio between their masses and σ stays constant. The originality of our approach is that it applies to both confining and conformal phases via an effective interacting model.

scholarly journals Higgs potential from Wick rotation in conformal BSM

2019 ◽  
Vol 34 (31) ◽  
pp. 1950257
Author(s):  
Ichiro Oda
Keyword(s):  
Standard Model ◽  
Conformal Symmetry ◽  
Planck Scale ◽  
Mass Term ◽  
Conformal Factor ◽  
Higgs Potential ◽  
Wick Rotation ◽  
Potential Term ◽  
Conformally Invariant ◽  
Invariant Potential

It is well known that in order to make the path integral of general relativity converge, one has to perform the Wick rotation over the conformal factor in addition to the more familiar Wick rotation of the time axis to pass to the spacetime with Euclidean signature. In this paper, we will apply this technique to a scalar field in the conformally invariant scalar–tensor gravity with a conformally invariant beyond-standard-model (BSM). It is then shown that a potential term in the conformally invariant potential, which corresponds to the Higgs mass term in the Higgs potential of the Standard Model (SM), can have a negative coefficient. The change of sign of the potential term naturally induces spontaneous symmetry breakdown of the electroweak gauge symmetry after symmetry breaking of conformal symmetry (local scale symmetry) via the Coleman–Weinberg mechanism around the Planck scale. This study might shed light on the fact that the existence of a stable vacuum in quantum gravity is relevant to that in the SM.

scholarly journals Confinement and Pseudoscalar Glueball Spectrum in the 2 + 1D QCD-Like Theory from the Non-Susy D2 Brane

2022 ◽  
Vol 258 ◽  
pp. 10004
Author(s):  
Adrita Chakraborty
Keyword(s):  
Bound States ◽  
String Tension ◽  
Energy Scale ◽  
Coupling Constant ◽  
Running Coupling ◽  
Monotonically Increasing Function ◽  
Glueball Spectrum ◽  
Holographic Approach ◽  
Increasing Function ◽  
Lattice Approach

We study two important properties of 2+1D QCD, namely confinement and Pseudoscalar glueball spectrum, using holographic approach. The confined state of the bounded quark-antiquark pair occurs in the self-coupling dominated nonperturbative regime, where the free gluons form the bound states, known as glueballs. The gauge theory corresponding to low energy decoupled geometry of isotropic non-supersymmetric D2 brane, which is again similar to the 2+1D YM theory, has been taken into account but in this case the coupling constant is found to vary with the energy scale. At BPS limit, this theory reduces to supersymmetric YM theory. We have considered NG action of a test string and calculate the potential of such confined state located on the boundary. The QCD flux tube tension for large quark-antiquark separation is observed to be a monotonically increasing function of running coupling. The mass spectrum of Pseudoscalar glueball is evaluated numerically from the fluctuations of the axion in the gravity theory using WKB approximation. This produces the mass to be related to the string tension and the levels of the first three energy states. The various results that we obtained quite match with those previously studied through the lattice approach.

scholarly journals TOPOLOGICAL INSULATOR AND THE DIRAC EQUATION

SPIN ◽  
2011 ◽  
Vol 01 (01) ◽  
pp. 33-44 ◽  
Author(s):  
SHUN-QING SHEN ◽  
WEN-YU SHAN ◽  
HAI-ZHOU LU
Keyword(s):  
Dirac Equation ◽  
Topological Insulator ◽  
Bound States ◽  
Topological Insulators ◽  
Mass Term ◽  
Point Of View ◽  
Quadratic Term ◽  
General Description ◽  
Dirac Equations ◽  
Topological Quantum

We present a general description of topological insulators from the point of view of Dirac equations. The Z2 index for the Dirac equation is always zero, and thus the Dirac equation is topologically trivial. After the quadratic term in momentum is introduced to correct the mass term m or the band gap of the Dirac equation, i.e., m → m − Bp2, the Z2 index is modified as 1 for mB > 0 and 0 for mB < 0. For a fixed B there exists a topological quantum phase transition from a topologically trivial system to a nontrivial system when the sign of mass m changes. A series of solutions near the boundary in the modified Dirac equation is obtained, which is characteristic of topological insulator. From the solutions of the bound states and the Z2 index we establish a relation between the Dirac equation and topological insulators.

scholarly journals Conformal Symmetry in Field Theory and in Quantum Gravity

Universe ◽  
2018 ◽  
Vol 4 (11) ◽  
pp. 125 ◽  
Author(s):  
Lesław Rachwał
Keyword(s):  
Field Theory ◽  
Scattering Amplitudes ◽  
Effective Action ◽  
Conformal Symmetry ◽  
Gravitational Theory ◽  
Fine Tuning ◽  
Conformal Anomaly ◽  
Conformal Theory ◽  
Conformally Invariant ◽  
Non Local

Conformal symmetry always played an important role in field theory (both quantum and classical) and in gravity. We present construction of quantum conformal gravity and discuss its features regarding scattering amplitudes and quantum effective action. First, the long and complicated story of UV-divergences is recalled. With the development of UV-finite higher derivative (or non-local) gravitational theory, all problems with infinities and spacetime singularities might be completely solved. Moreover, the non-local quantum conformal theory reveals itself to be ghost-free, so the unitarity of the theory should be safe. After the construction of UV-finite theory, we focused on making it manifestly conformally invariant using the dilaton trick. We also argue that in this class of theories conformal anomaly can be taken to vanish by fine-tuning the couplings. As applications of this theory, the constraints of the conformal symmetry on the form of the effective action and on the scattering amplitudes are shown. We also remark about the preservation of the unitarity bound for scattering. Finally, the old model of conformal supergravity by Fradkin and Tseytlin is briefly presented.

ISSUES OF SYMMETRIES IN THE GROSS-NEVEU MODEL

1989 ◽  
Vol 04 (11) ◽  
pp. 2827-2835 ◽  
Author(s):  
E. MORENO ◽  
F.A. SCHAPOSNIK
Keyword(s):  
Path Integral ◽  
Integral Approach ◽  
Coupling Constant ◽  
Invariant Model ◽  
Path Integral Approach ◽  
Conformally Invariant ◽  
Gross Neveu Model

We study the chiral Gross-Neveu model using a path integral approach. After showing how U (1) massless excitations decouple we investigate the SU (N) sector of the theory. One then finds that for certain values of the coupling constant, the original (vector SU (N)) symmetry is enlarged to a chiral SU (N), giving rise to a conformally invariant model.

scholarly journals Spontaneous Symmetry Breaking in 5D Conformally Invariant Gravity

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Taeyoon Moon ◽  
Phillial Oh
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Conformal Symmetry ◽  
Brane World ◽  
Spontaneous Breaking ◽  
Warp Factor ◽  
Translational Symmetry ◽  
Tensor Perturbation ◽  
Conformally Invariant ◽  
Conformal Quantum Mechanics

We explore the possibility of the spontaneous symmetry breaking in 5D conformally invariant gravity, whose action consists of a scalar field nonminimally coupled to the curvature with its potential. Performing dimensional reduction via ADM decomposition, we find that the model allows an exact solution giving rise to the 4D Minkowski vacuum. Exploiting the conformal invariance with Gaussian warp factor, we show that it also admits a solution which implements the spontaneous breaking of conformal symmetry. We investigate its stability by performing the tensor perturbation and find the resulting system is described by the conformal quantum mechanics. Possible applications to the spontaneous symmetry breaking of time-translational symmetry along the dynamical fifth direction and the brane-world scenario are discussed.

scholarly journals THE ζ FUNCTION ANSWER TO PARITY VIOLATION IN THREE-DIMENSIONAL GAUGE THEORIES

1996 ◽  
Vol 11 (15) ◽  
pp. 2643-2660 ◽  
Author(s):  
R.E. GAMBOA SARAVÍ ◽  
G.L. ROSSINI ◽  
F.A. SCHAPOSNIK
Keyword(s):  
Gauge Field ◽  
Parity Violation ◽  
Gauge Theories ◽  
Three Dimensional ◽  
Mass Term ◽  
Three Dimensions ◽  
Fermion Mass ◽  
Chern Simons ◽  
Fermion Current ◽  
Arbitrary Gauge

We study parity violation in (2+1)-dimensional gauge theories coupled to massive fermions. Using the ζ function regularization approach we evaluate the ground state fermion current in an arbitrary gauge field background, showing that it gets two different contributions which violate parity invariance and induce a Chern–Simons term in the gauge field effective action. One is related to the well-known classical parity breaking produced by a fermion mass term in three dimensions; the other, already present for massless fermions, is related to peculiarities of gauge-invariant regularization in odd-dimensional spaces.

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