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  2. Dirac cone - Wikipedia

    en.wikipedia.org/wiki/Dirac_cone

    In k-space, this shows up as a hypercone, which have doubly degenerate bands which also meet at Dirac points. [11] Dirac semimetals contain both time reversal and spatial inversion symmetry; when one of these is broken, the Dirac points are split into two constituent Weyl points, and the material becomes a Weyl semimetal.

  3. Electronic properties of graphene - Wikipedia

    en.wikipedia.org/wiki/Electronic_properties_of...

    The two bands touch at the zone corners (the K point in the Brillouin zone), where there is a zero density of states but no band gap. The graphene sheet thus displays a semimetallic (or zero-gap semiconductor) character. Two of the six Dirac points are independent, while the rest are equivalent by symmetry.

  4. Graphene - Wikipedia

    en.wikipedia.org/wiki/Graphene

    The Dirac points are six locations in momentum space on the edge of the Brillouin zone, divided into two non-equivalent sets of three points. These sets are labeled K and K'. These sets give graphene a valley degeneracy of =. In contrast, for traditional semiconductors, the primary point of interest is generally Γ, where momentum is zero. [60]

  5. Light-cone coordinates - Wikipedia

    en.wikipedia.org/wiki/Light-cone_coordinates

    The spatial coordinate of a point on the string is conveniently described by a parameter which runs from to . Time is appropriately described by a parameter σ 0 {\displaystyle \sigma _{0}} . Associating each point on the string in a D-dimensional spacetime with coordinates x 0 , x {\displaystyle x_{0},x} and transverse coordinates x i , i = 2

  6. Dirac matter - Wikipedia

    en.wikipedia.org/wiki/Dirac_matter

    The term Dirac matter refers to a class of condensed matter systems which can be effectively described by the Dirac equation.Even though the Dirac equation itself was formulated for fermions, the quasi-particles present within Dirac matter can be of any statistics.

  7. Dirac structure - Wikipedia

    en.wikipedia.org/wiki/Dirac_structure

    In mathematics a Dirac structure is a geometric structure generalizing both symplectic structures and Poisson structures, and having several applications to mechanics. It is based on the notion of the Dirac bracket constraint introduced by Paul Dirac and was first introduced by Ted Courant and Alan Weinstein .

  8. Interaction picture - Wikipedia

    en.wikipedia.org/wiki/Interaction_picture

    This approach is called the 'differential' and 'field' approach by Schwinger, as opposed to the 'integral' and 'particle' approach of the Feynman diagrams. [ 12 ] [ 13 ] The core idea is that if the interaction has a small coupling constant (i.e. in the case of electromagnetism of the order of the fine structure constant) successive ...

  9. Gamma matrices - Wikipedia

    en.wikipedia.org/wiki/Gamma_matrices

    The defining property for the gamma matrices to generate a Clifford algebra is the anticommutation relation {,} = + = ,where the curly brackets {,} represent the anticommutator, is the Minkowski metric with signature (+ − − −), and is the 4 × 4 identity matrix.