The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
Subir Ghosh - One of the best experts on this subject based on the ideXlab platform.
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Duality between Dirac Fermions in curved spacetime and optical solitons in non-linear Schrodinger model: magic of $$1+1$$1+1-dimensional bosonization
The European Physical Journal C, 2019Co-Authors: Subir GhoshAbstract:Bosonization in curved spacetime maps massive Thirring model (self-interacting Dirac Fermions) to a generalized Sine–Gordon model, both living in $$1+1$$ 1 + 1 -dimensional curved spacetime. Applying this duality we have shown that the Thirring model Fermion, in non-relativistic limit, gets identified with the soliton of non-linear Scrodinger model with Kerr form of non-linearity. We discuss one particular optical soliton in the latter model and relate it with the Thirring model Fermion.
Madhab Neupane - One of the best experts on this subject based on the ideXlab platform.
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discovery of a weyl Fermion semimetal and topological fermi arcs
Science, 2015Co-Authors: Ilya Belopolski, Nasser Alidoust, Madhab Neupane, Guang Bian, Chenglong Zhang, Raman Sankar, Guoqing Chang, Zhujun Yuan, Chicheng LeeAbstract:A Weyl semimetal is a new state of matter that hosts Weyl Fermions as emergent quasiparticles and admits a topological classification that protects Fermi arc surface states on the boundary of a bulk sample. This unusual electronic structure has deep analogies with particle physics and leads to unique topological properties. We report the experimental discovery of a Weyl semimetal, tantalum arsenide (TaAs). Using photoemission spectroscopy, we directly observe Fermi arcs on the surface, as well as the Weyl Fermion cones and Weyl nodes in the bulk of TaAs single crystals. We find that Fermi arcs terminate on the Weyl Fermion nodes, consistent with their topological character. Our work opens the field for the experimental study of Weyl Fermions in physics and materials science.
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a weyl Fermion semimetal with surface fermi arcs in the transition metal monopnictide taas class
Nature Communications, 2015Co-Authors: Shinming Huang, Ilya Belopolski, Nasser Alidoust, Madhab Neupane, Guang Bian, Guoqing Chang, Chicheng Lee, B WangAbstract:Weyl Fermions are massless chiral Fermions that play an important role in quantum field theory but have never been observed as fundamental particles. A Weyl semimetal is an unusual crystal that hosts Weyl Fermions as quasiparticle excitations and features Fermi arcs on its surface. Such a semimetal not only provides a condensed matter realization of the anomalies in quantum field theories but also demonstrates the topological classification beyond the gapped topological insulators. Here, we identify a topological Weyl semimetal state in the transition metal monopnictide materials class. Our first-principles calculations on TaAs reveal its bulk Weyl Fermion cones and surface Fermi arcs. Our results show that in the TaAs-type materials the Weyl semimetal state does not depend on fine-tuning of chemical composition or magnetic order, which opens the door for the experimental realization of Weyl semimetals and Fermi arc surface states in real materials. Proposals for the realization of Weyl semimetals, topologically non-trivial materials which host Weyl Fermion quasiparticles, have faced demanding experimental requirements. Here, the authors predict such a state in stoichiometric TaAs, arising due to the breaking of inversion symmetry.
George Kirczenow - One of the best experts on this subject based on the ideXlab platform.
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Composite Fermions in the quantum Hall effect
Reports on Progress in Physics, 1997Co-Authors: B L Johnson, George KirczenowAbstract:The quantum Hall effect and associated quantum transport phenomena in low-dimensional systems have been the focus of much attention for more than a decade. Recent theoretical development of interesting quasiparticles - `composite Fermions' - has led to significant advances in understanding and predicting the behaviour of two-dimensional electron systems under high transverse magnetic fields. Composite Fermions may be viewed as Fermions carrying attached (fictitious) magnetic flux. Here we review models of the integer and fractional quantum Hall effects, including the development of a unified picture of the integer and fractional effects based upon composite Fermions. The composite Fermion picture predicts remarkable new physics: the formation of a Fermi surface at high magnetic fields, and anomalous ballistic transport, thermopower, and surface acoustic wave behaviour. The specific theoretical predictions of the model, as well as the body of experimental evidence for these phenomena are reviewed. We also review recent edge-state models for magnetotransport in low-dimensional devices based on the composite Fermion picture. These models explain the fractional quantum Hall effect and transport phenomena in nanoscale devices in a unified framework that also includes edge state models of the integer quantum Hall effect. The features of the composite Fermion edge-state model are compared and contrasted with those of other recent edge-state models of the fractional quantum Hall effect.
Fidel A. Schaposnik - One of the best experts on this subject based on the ideXlab platform.
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the ζ function answer to parity violation in three dimensional gauge theories
International Journal of Modern Physics A, 1996Co-Authors: R Gamboa E Saravi, G. L. Rossini, Fidel A. SchaposnikAbstract: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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Parity violation in the three dimensional Thirring model
Physics Letters B, 1994Co-Authors: G. L. Rossini, Fidel A. SchaposnikAbstract:Abstract We discuss parity violation in the 3-dimensional ( N flavour) Thirring model. We find that the ground state Fermion current in a background gauge field does not possess a well defined parity transformation. We also investigate the connection between parity violation and Fermion mass generation, proving that radiative corrections force the Fermions to be massive.
Dam Thanh Son - One of the best experts on this subject based on the ideXlab platform.
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is the composite Fermion a dirac particle
Physical Review X, 2015Co-Authors: Dam Thanh SonAbstract:Quantum phenomena include the fractional quantum Hall effect, whose quasiparticle is the composite Fermion. Theorists show that composite Fermions possess different quantum numbers than the electrons or holes they were derived from.
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Is the composite Fermion a dirac particle?
Physical Review X, 2015Co-Authors: Dam Thanh SonAbstract:We propose a particle-hole symmetric theory of the Fermi-liquid ground state of a half-filled Landau level. This theory should be applicable for a Dirac Fermion in the magnetic field at charge neutrality, as well as for the $\nu=\frac12$ quantum Hall ground state of nonrelativistic Fermions in the limit of negligible inter-Landau-level mixing. We argue that when particle-hole symmetry is exact, the composite Fermion is a massless Dirac Fermion, characterized by a Berry phase of $\pi$ around the Fermi circle. We write down a tentative effective field theory of such a Fermion and discuss the discrete symmetries, in particular, $\mathcal C\mathcal P$. The Dirac composite Fermions interact through a gauge, but non-Chern-Simons, interaction. The particle-hole conjugate pair of Jain-sequence states at filling factors $\frac n{2n+1}$ and $\frac{n+1}{2n+1}$, which in the conventional composite Fermion picture corresponds to integer quantum Hall states with different filling factors, $n$ and $n+1$, is now mapped to the same half-integer filling factor $n+\frac12$ of the Dirac composite Fermion. The Pfaffian and anti-Pfaffian states are interpreted as $d$-wave Bardeen-Cooper-Schrieffer paired states of the Dirac Fermion with orbital angular momentum of opposite signs, while $s$-wave pairing would give rise to a particle-hole symmetric non-Abelian gapped phase. When particle-hole symmetry is not exact, the Dirac Fermion has a $\mathcal C\mathcal P$-breaking mass. The conventional Fermionic Chern-Simons theory is shown to emerge in the nonrelativistic limit of the massive theory.
