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Friday, December 16, 2011


  • Mesons are particles with zero or integral spin so they are Bosons.
  • The lightest meson is pion or π-meson, with other meson masses ranging beyond proton mass.
  • All mesons are unstable and decays in various ways.


  • This particle is to transmit nuclear forces, it must interact strongly with nuclei, and therefore it should be scattered and absorbed quickly by matter through which it passes.
  • π mesons are thus hypothetical particles responsible for the nuclear forces and had properties pridicted by Yukawa.
  • Protons and neurtons can be transferred into one anotherby emitting or absorbing one of these particles.
  • There are three kinds of pions π+, π- and π0. π- is the anti particle of π+.
  • These new particles can be thought of making bonds between (n,n) , (p,p) and (n,p) or (p,n)

K mesons

  • These are heavier unstable particles and have a great variety of different decay modes.
  • THere are six different ways that K+ mesons commonly decay, in each case giving two or three less massive particles






  • Mass of K+ is 966me.
  • K- are anti particles of K+ mesons and have the same decay modes with appropriate exchange of decay products for their anti particles.
  • K0 and K 0 ¯ are anti particles.

Mesons (B=0) Bosons

Particle Symbol Mass MeV/c2 Mean life (s) spin S Y I I3
Pion π+ 140 2.6×10-8 0 0 0 1 +1
π0 135 8.7×10-17 0
π- 140 2.6×10-8 -1
Kon K+ 494 1.2×10-8 0 +1 +1 1/2 +1/2
K0 498 9×10-11
K- 494 5×10-8 -1/2
Eta η0 549 6×10-19 0 0 0 0 0

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