pion 音标拼音: [p'ɑɪ
, ɑn]
n . ｋ介子
ｋ介子
pion n 1 :
a meson involved in holding the nucleus together ;
produced as the result of high -
energy particle collision [
synonym :
{
pion }, {
pi -
meson }]
Meson \
Mes "
on \,
n . [
NL .,
fr .
Gr .
me `
son middle ,
neut .
of me `
sos ,
a .,
middle .]
1 . (
Anat .)
The mesial plane dividing the body of an animal into similar right and left halves .
The line in which it meets the dorsal surface has been called the dorsimeson ,
and the corresponding ventral edge the ventrimeson . --
B .
G .
Wilder .
[
1913 Webster ]
2 . (
Physics )
An elementary particle made up of two quarks ;
a hadron having a baryon number of zero ;
any hadron other than a baryon .
Mesons are bosons with integral values of spin ,
having a mass intermediate between those of the electron and a nucleon ;
they may have positive or negative charges ,
or may be neutral .
Mesons are of three types :
the {
pion } ([
pi ]-
meson ), {
kaon } (
K -
mesons ),
and {[
eta ]-
mesons }.
[
PJC ]
{
mu meson } (
Physics )
the former name for the {
muon },
a particle which is not a true meson [
2 ].
The term is no longer used in technical literature ,
except historically .
[
PJC ]
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