scholarly journals Quantum critical point of Dirac fermion mass generation without spontaneous symmetry breaking

2016 ◽  
Vol 94 (24) ◽  
Author(s):  
Yuan-Yao He ◽  
Han-Qing Wu ◽  
Yi-Zhuang You ◽  
Cenke Xu ◽  
Zi Yang Meng ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Critical Point ◽  
Quantum Critical Point ◽  
Fermion Mass ◽  
Dirac Fermion ◽  
Mass Generation ◽  
Quantum Critical

scholarly journals ANOMALOUS FERMION MASS GENERATION AT THREE LOOPS

2013 ◽  
Vol 28 (22) ◽  
pp. 1350083 ◽  
Author(s):  
APOSTOLOS PILAFTSIS
Keyword(s):  
Gauge Theory ◽  
Quantum Gravity ◽  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Model Building ◽  
Heavy Fermions ◽  
Fermion Mass ◽  
Mass Generation ◽  
Fermion Masses ◽  
Gravity Effects

We present a novel mechanism for generating fermion masses through global anomalies at the three-loop level. In a gauge theory, global anomalies are triggered by the possible existence of scalar or pseudoscalar states and heavy fermions, whose masses may not necessarily result from spontaneous symmetry breaking. The implications of this mass-generating mechanism for model building are discussed, including the possibility of creating low-scale fermion masses by quantum gravity effects.

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 Tuning the charge density wave quantum critical point and the appearance of superconductivity in TiSe2

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Sangyun Lee ◽  
Tae Beom Park ◽  
Jihyun Kim ◽  
Soon-Gil Jung ◽  
Won Kyung Seong ◽  
...  
Keyword(s):  
Charge Density ◽  
Critical Point ◽  
Charge Density Wave ◽  
Density Wave ◽  
Quantum Critical Point ◽  
Quantum Critical

scholarly journals Lattice-shifted nematic quantum critical point in FeSe1−xSx

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
S. Chibani ◽  
D. Farina ◽  
P. Massat ◽  
M. Cazayous ◽  
A. Sacuto ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Critical Point ◽  
Degrees Of Freedom ◽  
Quantum Critical Point ◽  
Substantial Effect ◽  
Low Energy ◽  
Elastic Coupling ◽  
Superconducting Transition ◽  
Local Moments ◽  
Quantum Critical

AbstractWe report the evolution of nematic fluctuations in FeSe1−xSx single crystals as a function of Sulfur content x across the nematic quantum critical point (QCP) xc ~ 0.17 via Raman scattering. The Raman spectra in the B1g nematic channel consist of two components, but only the low energy one displays clear fingerprints of critical behavior and is attributed to itinerant carriers. Curie–Weiss analysis of the associated nematic susceptibility indicates a substantial effect of nemato-elastic coupling, which shifts the location of the nematic QCP. We argue that this lattice-induced shift likely explains the absence of any enhancement of the superconducting transition temperature at the QCP. The presence of two components in the nematic fluctuations spectrum is attributed to the dual aspect of electronic degrees of freedom in Hund’s metals, with both itinerant carriers and local moments contributing to the nematic susceptibility.

scholarly journals Tachyons and Solitons in Spontaneous Symmetry Breaking in the Frame of Field Theory

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1358
Author(s):  
Yiannis Contoyiannis ◽  
Michael P. Hanias ◽  
Pericles Papadopoulos ◽  
Stavros G. Stavrinides ◽  
Myron Kampitakis ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Critical Point ◽  
Universality Class ◽  
Lattice Simulation ◽  
Ginzburg Landau ◽  
Spin Lattice ◽  
Nuclear Collisions ◽  
Ising Spin ◽  
Relativistic Nuclear Collisions

This paper presents our study of the presence of the unstable critical point in spontaneous symmetry breaking (SSB) in the framework of Ginzburg–Landau (G-L) free energy. Through a 3D Ising spin lattice simulation, we found a zone of hysteresis where the unstable critical point continued to exist, despite the system having entered the broken symmetry phase. Within the hysteresis zone, the presence of the kink–antikink SSB solitons expands and, therefore, these can be observed. In scalar field theories, such as Higgs fields, the mass of this soliton inside the hysteresis zone could behave as a tachyon mass, namely as an imaginary quantity. Due to the fact that groups Ζ(2) and SU(2) belong to the same universality class, one expects that, in future experiments of ultra-relativistic nuclear collisions, in addition to the expected bosons condensations, structures of tachyon fields could appear.

scholarly journals Avoided ferromagnetic quantum critical point in pressurized La5Co2Ge3

2021 ◽  
Vol 103 (5) ◽  
Author(s):  
Li Xiang ◽  
Elena Gati ◽  
Sergey L. Bud'ko ◽  
Scott M. Saunders ◽  
Paul C. Canfield
Keyword(s):  
Critical Point ◽  
Quantum Critical Point ◽  
Quantum Critical

scholarly journals Multiband nodeless superconductivity near the charge-density-wave quantum critical point in ZrTe 3− x Se x

2016 ◽  
Vol 25 (7) ◽  
pp. 077403
Author(s):  
Shan Cui ◽  
Lan-Po He ◽  
Xiao-Chen Hong ◽  
Xiang-De Zhu ◽  
Cedomir Petrovic ◽  
...  
Keyword(s):  
Charge Density ◽  
Critical Point ◽  
Charge Density Wave ◽  
Density Wave ◽  
Quantum Critical Point ◽  
Quantum Critical
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