scholarly journals Anomalies and symmetric mass generation for Kähler-Dirac fermions

2021 ◽  
Vol 104 (9) ◽  
Author(s):  
Nouman Butt ◽  
Simon Catterall ◽  
Arnab Pradhan ◽  
Goksu Can Toga
Keyword(s):  
Dirac Fermions ◽  
Mass Generation

NATURAL HIERARCHICAL FLAVOR MIXING

1992 ◽  
Vol 07 (13) ◽  
pp. 1175-1184 ◽  
Author(s):  
E. H. LEMKE
Keyword(s):  
Predictive Power ◽  
Mass Matrix ◽  
Dirac Fermions ◽  
Mass Generation ◽  
Mixing Angles ◽  
Gap Equation ◽  
Lower Upper ◽  
Flavor Mixing ◽  
Radiative Mechanism

We consider standard fermion doublets and Dirac fermions within the framework of a radiative mechanism of mass generation. The mass matrix represents a solution of a multi-gap equation. Taking such a solution, we compute the mass matrix of the upper (lower) members of the doublets with respect to the basis where the lower (upper) members have a mass matrix that is flavor-diagonal. If this form lies in the vicinity of its diagonalized mass matrix, the mixing will be called "natural." Naturalness relations between the products of mixing angles and ratios of flavor masses result. They are of substantial predictive power in both the case of the quarks and the leptons.

Gross–Neveu–Yukawa and Gross–Neveu models

2021 ◽  
pp. 489-506
Author(s):  
Jean Zinn-Justin
Keyword(s):  
Phase Transition ◽  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Particle Physics ◽  
Continuous Phase ◽  
Two Dimensions ◽  
Fermion Mass ◽  
Dirac Fermions ◽  
Mass Generation ◽  
Four Dimensions

In this chapter, a model is considered that can be defined in continuous dimensions, the Gross– Neveu–Yukawa (GNY) model, which involves N Dirac fermions and one scalar field. The model has a continuous U(N) symmetry, and a discrete symmetry, which prevents the addition of a fermion mass term to the action. For a specific value of a coefficient of the action, the model undergoes a continuous phase transition. The broken phase illustrates a mechanism of spontaneous symmetry breaking, leading to spontaneous fermion mass generation like in the Standard Model (SM) of particle physics. In four dimensions, the GNY can be considered as a toy model to represent the interactions between the top quark and the Higgs boson, the heaviest particles of the SM of fundamental interactions, when the gauge fields are omitted. The model is renormalizable in four dimensions and its renormalization group (RG) properties can be studied in d = 4 and d = 4 − ϵ dimensions. A model of self-interacting fermions with the same symmetries and fermion content, the Gross–Neveu (GN) model, has been widely studied. In perturbation theory, for d > 2, it describes only a phase with massless fermions but, in d = 2 + ϵ dimensions, the RG indicates that, at a critical value of the coupling constant, the model experiences a phase transition. In two dimensions, it is renormalizable and exhibits the phenomenon of asymptotic freedom. The massless phase becomes infrared unstable and there is strong evidence that the spectrum corresponds to spontaneous symmetry breaking and fermion mass generation.

scholarly journals Real and imaginary mass generation in the presence of external fields and axions

2003 ◽  
Vol 2003 (09) ◽  
pp. 044-044
Author(s):  
Eduardo I Guendelman ◽  
Stefano Ansoldi ◽  
Euro Spallucci
Keyword(s):  
External Fields ◽  
Mass Generation

scholarly journals Xenon-1T excess as a possible signal of a sub-GeV hidden sector dark matter

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Amin Aboubrahim ◽  
Michael Klasen ◽  
Pran Nath
Keyword(s):  
Dark Matter ◽  
Particle Physics ◽  
Small Mass ◽  
Big Bang ◽  
Mass Splitting ◽  
Recoil Energy ◽  
Dirac Fermions ◽  
Dark Sector ◽  
Dark Photon ◽  
Physics Model

Abstract We present a particle physics model to explain the observed enhancement in the Xenon-1T data at an electron recoil energy of 2.5 keV. The model is based on a U(1) extension of the Standard Model where the dark sector consists of two essentially mass degenerate Dirac fermions in the sub-GeV region with a small mass splitting interacting with a dark photon. The dark photon is unstable and decays before the big bang nucleosynthesis, which leads to the dark matter constituted of two essentially mass degenerate Dirac fermions. The Xenon-1T excess is computed via the inelastic exothermic scattering of the heavier dark fermion from a bound electron in xenon to the lighter dark fermion producing the observed excess events in the recoil electron energy. The model can be tested with further data from Xenon-1T and in future experiments such as SuperCDMS.

scholarly journals High-frequency rectifiers based on type-II Dirac fermions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Libo Zhang ◽  
Zhiqingzi Chen ◽  
Kaixuan Zhang ◽  
Lin Wang ◽  
Huang Xu ◽  
...  
Keyword(s):  
High Frequency ◽  
Dynamic Range ◽  
High Sensitivity ◽  
High Dynamic Range ◽  
Anisotropy Ratio ◽  
Dirac Fermions ◽  
Topological States ◽  
Topological Semimetals ◽  
Polarized Surface ◽  
Symmetry Protected

AbstractThe advent of topological semimetals enables the exploitation of symmetry-protected topological phenomena and quantized transport. Here, we present homogeneous rectifiers, converting high-frequency electromagnetic energy into direct current, based on low-energy Dirac fermions of topological semimetal-NiTe2, with state-of-the-art efficiency already in the first implementation. Explicitly, these devices display room-temperature photosensitivity as high as 251 mA W−1 at 0.3 THz in an unbiased mode, with a photocurrent anisotropy ratio of 22, originating from the interplay between the spin-polarized surface and bulk states. Device performances in terms of broadband operation, high dynamic range, as well as their high sensitivity, validate the immense potential and unique advantages associated to the control of nonequilibrium gapless topological states via built-in electric field, electromagnetic polarization and symmetry breaking in topological semimetals. These findings pave the way for the exploitation of topological phase of matter for high-frequency operations in polarization-sensitive sensing, communications and imaging.

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