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  2. Pair production - Wikipedia

    en.wikipedia.org/wiki/Pair_production

    Pair production often refers specifically to a photon creating an electron–positron pair near a nucleus. As energy must be conserved, for pair production to occur, the incoming energy of the photon must be above a threshold of at least the total rest mass energy of the two particles created. (As the electron is the lightest, hence, lowest ...

  3. Non-canonical base pairing - Wikipedia

    en.wikipedia.org/wiki/Non-canonical_base_pairing

    In the A-U Hoogsteen base pair, the adenine is rotated 180° about the glycosidic bond, resulting in an alternative hydrogen bonding scheme which has one hydrogen bond in common with the Watson-Crick base pair (adenine N6 and thymine N4), while the other hydrogen bond, instead of occurring between adenine N1 and thymine N3 as in the Watson ...

  4. Dual system - Wikipedia

    en.wikipedia.org/wiki/Dual_system

    In mathematics, a dual system, dual pair or a duality over a field is a triple (,,) consisting of two vector spaces, and , over and a non-degenerate bilinear map:.. In mathematics, duality is the study of dual systems and is important in functional analysis.

  5. Supersymmetry - Wikipedia

    en.wikipedia.org/wiki/Supersymmetry

    Supersymmetry is a theoretical framework in physics that suggests the existence of a symmetry between particles with integer spin and particles with half-integer spin ().It proposes that for every known particle, there exists a partner particle with different spin properties. [1]

  6. Nuclear structure - Wikipedia

    en.wikipedia.org/wiki/Nuclear_structure

    The most common extension to mean field theory is the nuclear pairing. Nuclei with an even number of nucleons are systematically more bound than those with an odd one. This implies that each nucleon binds with another one to form a pair, consequently the system cannot be described as independent particles subjected to a common mean field.

  7. Exchange interaction - Wikipedia

    en.wikipedia.org/wiki/Exchange_interaction

    In chemistry and physics, the exchange interaction is a quantum mechanical constraint on the states of indistinguishable particles.While sometimes called an exchange force, or, in the case of fermions, Pauli repulsion, its consequences cannot always be predicted based on classical ideas of force. [1]

  8. Lagrangian mechanics - Wikipedia

    en.wikipedia.org/wiki/Lagrangian_mechanics

    In physics, Lagrangian mechanics is a formulation of classical mechanics founded on the stationary-action principle (also known as the principle of least action). It was introduced by the Italian-French mathematician and astronomer Joseph-Louis Lagrange in his presentation to the Turin Academy of Science in 1760 [ 1 ] culminating in his 1788 ...

  9. Cross section (physics) - Wikipedia

    en.wikipedia.org/wiki/Cross_section_(physics)

    The scattering of X-rays can also be described in terms of scattering cross sections, in which case the square ångström is a convenient unit: 1 Å 2 = 10 −20 m 2 = 10 000 pm 2 = 10 8 b. The sum of the scattering, photoelectric, and pair-production cross-sections (in barns) is charted as the "atomic attenuation coefficient" (narrow-beam), in ...