scholarly journals The two-loop axial anomaly in N = 1 supersymmetric Yang-Mills theory

1982 ◽  
Vol 109 (6) ◽  
pp. 449-452 ◽  
Author(s):  
D.R.T. Jones ◽  
J.P. Leveille
Keyword(s):  
Author(s):  
Michael Kachelriess

The axial anomaly is derived both from the non-invariance of the path-integral measure under UA(1) transformations and calculations of specific triangle diagrams. It is demonstrated that the anomalous terms are cancelled in the electroweak sector of the standard model, if the electric charge of all fermions adds up to zero. The CP-odd term F̃μν‎Fμν‎ introduced by the axial anomaly is a gauge-invariant renormalisable interaction which is also generated by instanton transitions between Yang–Mills vacua with different winding numbers. The Peceei–Quinn symmetry is discussed as a possible explanation why this term does not contribute to the QCD action.


Universe ◽  
2021 ◽  
Vol 7 (6) ◽  
pp. 198
Author(s):  
Janning Meinert ◽  
Ralf Hofmann

Motivated by the SU(2)CMB modification of the cosmological model ΛCDM, we consider isolated fuzzy-dark-matter lumps, made of ultralight axion particles whose masses arise due to distinct SU(2) Yang–Mills scales and the Planck mass MP. In contrast to SU(2)CMB, these Yang–Mills theories are in confining phases (zero temperature) throughout most of the Universe’s history and associate with the three lepton flavours of the Standard Model of particle physics. As the Universe expands, axionic fuzzy dark matter comprises a three-component fluid which undergoes certain depercolation transitions when dark energy (a global axion condensate) is converted into dark matter. We extract the lightest axion mass ma,e=0.675×10−23eV from well motivated model fits to observed rotation curves in low-surface-brightness galaxies (SPARC catalogue). Since the virial mass of an isolated lump solely depends on MP and the associated Yang–Mills scale the properties of an e-lump predict those of μ- and τ-lumps. As a result, a typical e-lump virial mass ∼6.3×1010M⊙ suggests that massive compact objects in galactic centers such as Sagittarius A* in the Milky Way are (merged) μ- and τ-lumps. In addition, τ-lumps may constitute globular clusters. SU(2)CMB is always thermalised, and its axion condensate never has depercolated. If the axial anomaly indeed would link leptons with dark matter and the CMB with dark energy then this would demystify the dark Universe through a firmly established feature of particle physics.


2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Kazem Bitaghsir Fadafan ◽  
Andy O’Bannon ◽  
Ronnie Rodgers ◽  
Matthew Russell

Abstract We construct a top-down holographic model of Weyl semimetal states using (3 + 1)-dimensional $$ \mathcal{N} $$ N = 4 supersymmetric SU(Nc) Yang-Mills theory, at large Nc and strong coupling, coupled to a number Nf ≪ Nc of $$ \mathcal{N} $$ N = 2 hypermultiplets with mass m. A U(1) subgroup of the R-symmetry acts on the hypermultiplet fermions as an axial symmetry. In the presence of a constant external axial gauge field in a spatial direction, b, we find the defining characteristic of a Weyl semi-metal: a quantum phase transition as m/b increases, from a topological state with non-zero anomalous Hall conductivity to a trivial insulator. The transition is first order. Remarkably, the anomalous Hall conductivity is independent of the hypermultiplet mass, taking the value dictated by the axial anomaly. At non-zero temperature the transition remains first order, and the anomalous Hall conductivity acquires non-trivial dependence on the hypermultiplet mass and temperature.


2021 ◽  
Vol 127 (9) ◽  
Author(s):  
Nirmalendu Acharyya ◽  
Mahul Pandey ◽  
Sachindeo Vaidya

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