In
high energy physics
Particle physics or high energy physics is the study of fundamental particles and forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standard Model as fermions (matter particles) and ...
, a pseudovector meson or axial vector meson is a
meson
In particle physics, a meson ( or ) is a type of hadronic subatomic particle composed of an equal number of quarks and antiquarks, usually one of each, bound together by the strong interaction. Because mesons are composed of quark subparticles, ...
with
total spin 1 and even
parity (+) (usually noted as
:Compare to a
vector meson
In high energy physics, a vector meson is a meson with total spin 1 and odd parity (usually noted as ). Vector mesons have been seen in experiments since the 1960s, and are well known for their spectroscopic pattern of masses.
The vector meso ...
, which has a total spin 1 and odd parity
Charge parity (C) in addition to spatial parity (P)
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
In physics, the C parity or charge parity is a multiplicative quantum number of some particles that describes their behavior under the symmetry operation of charge conjugation.
Charge conjugation changes the sign of all quantum charges (that is, a ...
'' (C) which can be either even (+) or odd (−). The two types of pseudovector meson are:
* those with odd charge parity
* those with even charge parity
The 1 group has no intrinsic spin excitation , but do gain spin from angular momentum of the orbits of the two constituent quarks around their mutual center. The second group (1) have both intrinsic spin and with and
coupling
A coupling is a device used to connect two shafts together at their ends for the purpose of transmitting power. The primary purpose of couplings is to join two pieces of rotating equipment while permitting some degree of misalignment or end mov ...
to
Pseudovector, or axial vector, mesons in the 1 category are most readily be seen in
proton
A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...
‑
antiproton
The antiproton, , (pronounced ''p-bar'') is the antiparticle of the proton. Antiprotons are stable, but they are typically short-lived, since any collision with a proton will cause both particles to be annihilated in a burst of energy.
The exis ...
annihilation and
pion
In particle physics, a pion (or a pi meson, denoted with the Greek letter pi: ) is any of three subatomic particles: , , and . Each pion consists of a quark and an antiquark and is therefore a meson. Pions are the lightest mesons and, more gen ...
‑
nucleon
In physics and chemistry, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus. The number of nucleons in a nucleus defines the atom's mass number (nucleon number).
Until the 1960s, nucleons were ...
scattering. The mesons in the 1 category are normally seen in proton-proton and pion-nucleon scattering.
Discrepant mass estimates
The difference between the two groups gives them slightly different masses, from the
spin‑orbit coupling rule. Theoretically, the and mesons are in the 1 group, and ''should'' have heavier masses, according to the spin-orbit mass splitting. However, the measured masses of the mesons do not appear to follow the rule, as evidenced by the and mesons being ''heavier''. There are considerable uncertainties in experimental measurement of pseudovector mesons; more experimental data will be needed to confirm and accurately determine the discrepancy between theory and measurement.
The 1 multiplet of light mesons may show similar behavior to that of other vector mesons, in that the mixing of light quarks with strange quarks appears to be small for this quantum number. The 1 multiplet, on the other hand, may be affected by other factors that generally reduce meson masses. Again, further experimentation is required in order to solidify the observations.
Examples
* 1 candidates: (1170), (1235), (1380)
* 1 candidates: (1285), (1260), (1420)
*
strange
Strange may refer to:
Fiction
* Strange (comic book), a comic book limited series by Marvel Comics
* Strange (Marvel Comics), one of a pair of Marvel Comics characters known as The Strangers
* Adam Strange, a DC Comics superhero
* The title cha ...
candidates: (1270), (1400)
* heavy candidates: ,
See also
*
List of mesons
:''This list is of all known and predicted scalar, pseudoscalar and vector mesons. See list of particles for a more detailed list of particles found in particle physics.''
This article contains a list of mesons, unstable subatomic particles co ...
*
Pseudoscalar meson
In high-energy physics, a pseudoscalar meson is a meson with total spin 0 and odd parity (usually notated as
Pseudoscalar mesons are commonly seen in proton-proton scattering and proton-antiproton annihilation, and include the pion (), k ...
*
Scalar meson
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 numer ...
*
Pseudovector boson
Mesons
Subatomic particles with spin 1
Bosons
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