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Concept
Méson vecteur
Résumé
In high energy physics, a vector meson is a meson with total spin 1 and odd parity (usually noted as JP = 1−). Vector mesons have been seen in experiments since the 1960s, and are well known for their spectroscopic pattern of masses.
The vector mesons contrast with the pseudovector mesons, which also have a total spin 1 but instead have even parity. The vector and pseudovector mesons are also dissimilar in that the spectroscopy of vector mesons tends to show nearly pure states of constituent quark flavors, whereas pseudovector mesons and scalar mesons tend to be expressed as composites of mixed states.
Since the development of the quark model by Murray Gell-Mann (and also independently by George Zweig), the vector mesons have demonstrated the spectroscopy of pure states. The fact that the I = 1 rho meson (ρ) and I = 0 omega meson (ω) have nearly equal mass centered on 770–780MeV/c2, while the phi meson (φ) has a higher mass around 1020MeV/c2, indicates that the light-quark vector mesons appear in nearly pure states, with the φ meson having a nearly 100 percent amplitude of hidden strangeness.
These nearly pure states characteristic of the vector mesons are not at all evident in the pseudoscalar meson or scalar meson multiplets, and may be only slightly realized among the tensor meson and pseudovector meson multiplets. This fact makes the vector mesons an excellent probe of the quark flavor content of other types of mesons, measured through the respective decay rates of non-vector mesons into the different types of vector mesons. Such experiments are very revealing for theorists who seek to determine the flavor content of mixed state mesons.
At higher masses, the vector mesons include charm and bottom quarks in their structure. In this realm, the radiative processes tend to stand out, with heavy tensor and scalar mesons decaying dominantly into vector mesons by photon emission. Pseudovector mesons transition by a similar process into pseudoscalar mesons.
Source officielle
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Proximité ontologique
Cours associés (4)
PHYS-471: Particle physics: the flavour frontiers
This course will present experimental aspects of flavour physics primarily in the quark sector but also in the lepton sector and their role in the development of the Standard Model of particle physics
PHYS-311: Nuclear and particle physics I
Introduction générale sur l'état des connaissances en physique des particules élémentaires: de la cinématique relativiste à l'interprétation phénoménologique des collisions à haute énergie.
PHYS-415: Particle physics I
Presentation of particle properties, their symmetries and interactions.
Introduction to quantum electrodynamics and to the Feynman rules.
Séances de cours associées (18)
Physique des particules: Fondamentaux et interactions
Couvre les bases de la physique des particules, y compris les particules élémentaires, les forces, le modèle standard et les phénomènes rares au LHC.
Symmetries et modèle Quark
Explore les symétries, le modèle de quark, la construction de méson, la symétrie de saveur SU(3), la formation de baryons et les structures de multiplets.
Quarks et Mesons : Isospin et symétrie des saveurs
Couvre les antiquarks, mésons, isospin, opérateurs d'échelle, et la symétrie de saveur dans les quarks et mésons.
Publications associées (173)
Personnes associées (43)
Unités associées (12)
Concepts associés (9)
Méson scalaire
In high energy physics, a scalar meson is a meson with total spin 0 and even parity (usually noted as JP=0+). Compare to pseudoscalar meson. The first known scalar mesons have been observed since the late 1950s, with observations of numerous light states and heavier states proliferating since the 1980s. Scalar mesons are most often observed in proton-antiproton annihilation, radiative decays of vector mesons, and meson-meson scattering.
Pseudovector meson
In high energy physics, a pseudovector meson or axial vector meson is a meson with total spin 1 and even parity (+) (usually noted as J^ P = 1^+ ). Compare to a vector meson, which has a total spin 1 and odd parity (that is, J^ P = 1^− ). The known pseudovector mesons fall into two different classes, all have even spatial parity ( P = "+" ), but they differ in another kind of parity called charge parity (C) which can be either even (+) or odd (−).
Force nucléaire
La force nucléaire, qui s'exerce entre nucléons, est responsable de la liaison des protons et des neutrons dans les noyaux atomiques. Elle peut être interprétée en termes d'échanges de mésons légers, comme les pions. Même si son existence est démontrée depuis les années 1930, les scientifiques n'ont pas réussi à établir une loi permettant de calculer sa valeur à partir de paramètres connus, contrairement aux lois de Coulomb et de Newton.