Pion Definition and 120 Threads

  1. C

    Calculate the momentum of a 249 MeV pion

    Homework Statement The question is from "Advanced Physics" by Adams and Allday. It is from section 9 "The Physics of Particles", "Practice Exam Questions". It is question 10. The level of this study is between school and University. I am uncertain about the answer to part c, ii (3rd...
  2. C

    Calculating lifetime of a moving pion

    Homework Statement What is the speed of a pion if its average lifetime is measured to be 4.91E-8s? At rest, its average lifetime is 2.60E-6s. What is the particle's lifetime at rest? Homework Equations \Delta t = \Delta t0 / \sqrt{1-(v2/c2} The Attempt at a Solution I don't...
  3. Y

    Negative Pion Decay: Muon & Antimuon Neutrino

    Hello! I was just wondering something... Why is it that a negative pion always decays into a muon and antimuon neutrino? Why not an electron and antielectron neutrino? (and the same for a positive pion) Any answers would be grately appreciated :-) Samantha
  4. D

    Why do \pi\^{\pm} have different charges than \pi\^{0}?

    How is it that \pi\^{\pm} have charges \pm e and \pi\^{0} has a charge of 0? The \pi\^{+} has one up quark and an anti-down quark, which doesn't add up to zero (same deal goes for \pi\^{-}, and the \pi\^{0} has a linear combination that doesn't seem to add up to zero. Where have I gone wrong?
  5. B

    Calculating Pion Halflife: Gamma, Time Dilation, and Particle Decay

    Problem: A group of 'pi' mesons (pions) is observed traveling at speed 0.8c in a particle physics laboratory. (a) What is the factor 'gamma' for the pions? (b) If the pions' proper half-life is 1.8x10^-8 s, what is their half-life as observed in the lab frame? (c) If there were initially...
  6. P

    Why Does the Vector Current Contribute to Pion Decay?

    I have studied that the hadronic matrix element of pion decay (Pi+->mu+ anti muon neutrino) is given as <0|ubar gamma[mu](1-gamma[5])d|pion>. The vector current does not seem to contribute, because it cannot connect a state of unnatural parity to hadronic vacuum. Only the axial and...
  7. I

    The different lifetimes of W boson and Pion?

    The positive W boson decays to a anti-muon and a muon neutrino, it should be a weak interaction. And the positive Pion can decays to a anti-muon and a muon neutrino, too. But the lifetimes of them are totally different, so why? I know the positive Pion is composed of two quarks, but could you...
  8. I

    Can a neutral pion decay to a neutrino and an anti-neutrino?

    Is it allowed? such as a electron neutrino and an electron anti-neutrino. And why? Now, I am confused... Thanks.
  9. J

    Chiral anomaly, pion to photon decay

    Hello, I understand that the non-zero (or non-small) rate for \pi^0 \rightarrow \gamma\gamma was historically a big motivation for the non-conservation of the axial current. I've been trying to work on problem IV.7.2 (p. 252) in Zee which asks to show that this amplitude vanishes if \partial_\mu...
  10. L

    Relativity: Pion decay can someone check my answers please

    Hello! I have to hand in this coursework tomorrow and I just wanted to check I had done it correctly so if someone could have a look I'd be really grateful... It's quite long... Homework Statement A negatively charged pion \pi^{-} has mass m=140MeV/c^{2} and lifetime 2.6 x 10^{-8}s. a)...
  11. L

    Pion Reaction: Learn About e⁻+n→e⁻+p⁺+π⁻

    Hello. I've been having a hard time finding information about the following reaction: e^{-}+n\rightarrowe^{-}+p^{+}+\pi^{-} I hope you could give me some information about it. I'm interested in energies for the incident e^{-} above 200MeV. I think it has to do something with...
  12. E

    Understand Eta Particle Decay into 3 Pions

    1. The statement, all variables and given/known data I am studying the decay of the \eta-particle. Povh et Al, 'Particles and nuclei' say that a decay into 3 pions is not possible via the strong interaction. "For reasons of symmetry 3 pions (isospin equals 1) can not couple to zero isospin."...
  13. N

    What Causes the Short Lifetime of Neutral Pions in Strong Interactions?

    Hi all, I'm having trouble understanding the short lifetime on the neutral pion. I understand that in the residual strong interaction between nucleons, the range of the virtual pion is limited by Heisenberg's uncertainty relation for energy, which thus limits its lifetime. I don't...
  14. I

    Composition of Neutral Pion: uubar, ddbar, or Linear Combination?

    How is it possible to have a pion that is made up of a linear combination of quarks? I mean, what are the physical constituents of the neutral pion? is it uubar or ddbar? Or does the linear combination mean that there is a 50 50 chance of a neutral pion being a made of uubar and ddbar?
  15. A

    How is Muon Speed Derived from Pion Decay Using Special Relativity?

    I'm not sure whether this should go in this forum or the Advanced forum, but here goes. Homework Statement Given: A pion+ decays into muon+ and neutrino, \pi^+ \rightarrow \mu^+ + \nu neutrino mass approaches zero, and the pion is initially at rest. Problem statement: Use...
  16. K

    Pion and Nucleon Masses: The Role of Electromagnetic Self-Energy Explained

    I have one stupid question: Is it true that the difference of proton and nucleon mass is due to the electromagnetic self-energy of the proton? The same question about pi^0 and pi^- mass difference.
  17. P

    Parity Violation in Pion Decay Explained

    Consider this decay: Pion+ -> muon+ + neutrino It says that one can check the longitudinal polarization of the muon+ and this would confirm that the parity is not conserved. Can you explain what this means in simple terms?
  18. C

    QFT anomaly in electromagnetic, neutral Pion decays

    The electromagnetic neutral pion decay is a three-point interaction: it decays into two virtual and charged Kaons or Protons, of which one then radiates a photon and then annihalates with the other to produce a second photon. (Obviously, a neutral particle cannot radiate photons directly)...
  19. H

    Calculating Energy, Momentum & Mass for Neutral Pion Decay

    Hi first time user here. I was hoping someone could please help me with the following question: A moving neutral pion is observed to decay into 2 photons each with energy 80MeV, there being an angle 120deg between their trajectories.Calc i)The total energy of the meson ii)The momentum of...
  20. R

    Pion decay via the weak interaction

    Hi, i have a particle physics exam in 2 days and am confused on pion decay via the weak interaction, namely: pi[-] ->muon + anti-muno neutrino Thankyou Ray Veldkamp
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