C parity

In physics, C parity or charge parity is a multiplicative quantum number of some particles that describes its behavior under a symmetry operation of charge conjugation (see Csymmetry).
Charge conjugation changes the sign of all quantic charges (i.e., additive quantum numbers):
 electrical charge
 baryon number and lepton number
 flavor charges: strangeness, charm, bottomness (formerly `beauty'), topness (formerly `truth')
 Isospin 3rdcomponent
On the contrary, does not affect:
As a result, a particle is substituted by its antiparticle.
For the eigenstates of charge conjugation
and is called the C parity or charge parity.
The above implies that and have exactly the same quantum charges, so only truly neutral systems —those where all quantum charges and magnetic moment are 0— are eigenstates of charge parity, that is, the photon and particleantiparticle bound states: neutral pion, η, positronium... The neutron is not an eigenstate because it has a magnetic moment, and so does not have an associated C parity.
For a system of free particles, the C parity is the product of C parities for each particle.
In a pair of bound bosons there is an additional component due to the orbital angular momentum. For example, in a bound state of two pions, π^{+} π^{−} with an orbital angular momentum L, exchanging π^{+} and π^{−} inverts the relative position vector, which is identical to a parity operation. Under this operation, the angular part of the spatial wave function contributes a phase factor of (−1)^{L}, where L is the angular momentum quantum number associated with L.
 .
With a twofermion system, two extra factors appear: one comes from the spin part of the wave function, and the second from the exchange of a fermion by its antifermion.
Bound states can be described with the spectroscopic notation ^{2S+1}L_{J} (see term symbol) , where S is the total spin quantum number, L the total orbital momentum quantum number and J the total angular momentum quantum number. Example: the positronium is a bound state electronpositron similar to an hydrogen atom. The parapositronium and ortopositronium correspond to the states ^{1}S_{0} and ^{3}S_{1}.
 With S = 0 spins are antiparallel, and with S = 1 they are parallel. This gives a multiplicity (2S+1) of 1 or 3, respectively
 The total orbital angular momentum quantum number is L = 0 (S, in spectroscopic notation)
 Total angular momentum quantum number is J = 0, 1
 C parity η_{C} = (−1)^{L + S} = +1, −1, respectively. Since charge parity is preserved, annihilation of these states in photons (η_{C}(γ) = −1) must be:

^{1}S_{0} → γ + γ ^{3}S_{1} → γ + γ + γ η_{C}: +1 = (−1) × (−1) −1 = (−1) × (−1) × (−1)
References
External links
See also
C, P and T Symmetries CP symmetry · CPT symmetryCategories:
Wikimedia Foundation. 2010.
Look at other dictionaries:
Parity — is a concept of equality of status or functional equivalence. It has several different specific definitions.* Parity (physics), the name of the symmetry of interactions under spatial inversion * Parity (mathematics) indicates whether a number is… … Wikipedia
Parity game — Parity Games are (possibly) infinite games played on a graph by two players, 0 and 1. In such games, game positions are assigned priorities, i.e. natural numbers.A play in a parity game is a maximal sequence of nodes following the transition… … Wikipedia
Parity file — Parity files are files that are created to accompany data files, and are used to preserve data integrity and assist in data recovery. They are useful when data files are transmitted or stored on less than perfect mediums such as newsgroup… … Wikipedia
Parity — Par i*ty, n. [L. paritas, fr. par, paris, equal: cf. F. parit[ e]. See {Pair}, {Peer} an equal.] 1. The quality or condition of being equal or equivalent; a like state or degree; equality; equivalence; close correspondence; analogy; as, parity of … The Collaborative International Dictionary of English
Parity Boot — ist ein Bootsektor Virus, das Ende der 1980er und Anfang der 90er Jahre weite Verbreitung fand.[1] Noch 1996 war es in Deutschland mit bis zu 36% lange Zeit das am weitesten verbreitete Virus. Verbreitung erlangte das Virus unter anderem über… … Deutsch Wikipedia
parity check — par i*ty check , n. (Computers) The act or process of testing whether a byte or other data structure has an even or odd number of bits set to the value of 1; it is used primarily to detect errors in data, especially in memory banks or in data… … The Collaborative International Dictionary of English
Parity of esteem — is a phrase used in political philosophy to explain a theory to overcome inter communal conflict. Promoters of the theory argue that parity of esteem offers a language for negotiation of a post conflict equilibrium. This negotiation begins with… … Wikipedia
parity bit — par i*ty bit , n. (Computers) The bit within a data structure which is assigned a value of 1 or 0 so as to make the parity[7] of the data structure odd or even. Data structures may or may not have parity bits, dpending on whether the system does… … The Collaborative International Dictionary of English
parity — I noun alikeness, analogy, approximation, balance, close correspondence, coequality, comparability, comparison, correlation, correspondence, equability, equality, equation, equilibrium, equipoise, equivalence, equivalency, identical value,… … Law dictionary
Parity (sports) — Parity in sports is defined as attempting to make an equal playing field for all participants, specifically with regard to financial issues. When parity in a sports league is achieved, all participating teams enjoy roughly equivalent levels of… … Wikipedia
parity index — parity index, U.S. the average prices paid by farmers for goods and services in a particular year, expressed in terms of the equivalent prices during the base period used. The parity index is used to establish the parity ratio … Useful english dictionary