Pion Definition and 120 Threads

Homework Statement A ##\pi^0## at rest decays into two photons, one traveling in the +z direction and the other in the –z direction. What is the angle between the photons in a reference frame moving at speed v=0.99c along the x-axis? Homework Equations The Attempt at a Solution...

Homework Statement A pion in its rest frame decays into a muon and a neutrino. Find the velocity of the muon and its mean-lifetime in the pion rest frame. (I've done this part). The muon decays into an electron and two neutrinos. If the two neutrinos happen to travel in the same direction...

If one directed a 3 GeV electron beam at a target (say carbon) would pions be produced? If so, what percentage would be produced compared to bombarding the same target with a 3 GeV proton beam? In other words, how important is it that electrons do not interact via the strong nuclear force...

In Perkins's Introduction to High Energy Physics, the author obtained the spin of neutral pions from the decay \pi^0 → 2\gamma He argued that the z-component of the total photon spin in the above decay can have the value S_z=0 or 2. If s_\pi=1, then only S_z=0 is possible, and the two-photon...

Why is there only one neutral pion? Shouldn't there be two of them with slightly different masses, one with u/u-bar quarks, and one with d/d-bar quarks? Do neutral pions "oscillate" in some way? After all, s/s-bar mesons, c/c-bar mesons, and b/b-bar mesons are all different.

Homework Statement 42. If a charged pion that decays in 10−8 second in its own rest frame is to travel 30 m in the laboratory before decaying, the pion’s speed must be most nearly (A) 0.43 × 108 m/s (B) 2.84 × 108 m/s (C) 2.90 × 108 m/s (D) 2.98 × 108 m/s (E) 3.00 × 108 m/s Homework...

Hello, I'm new and I'm Italian. I write in English with the help of google translator. I'm looking for some answers, but I have not found anything, and nor in Italian nor English. I hope to receive help in this forum. the question: The pion photoproduction is possible, when the...

I wondered if the following decay was possible: \Xi^0 \to \Lambda + \pi^0 The only mechanism I can think of is that a strange quark of the Lambda particle emits a Z and becomes a down quark followed by the Z creating a up-antiup pair. But I'm not sure whether the strange to up transition (by...

Homework Statement An unstable particle called the pion has a mean lifetime of 25ns in its own rest frame. A beam of of pions travels through the lab with a speed of 0.60c. a) what is the mean lifetime of the pions as measured in the lab frame? b) how far does a pion travel ( as measured...

I am trying to revise for PhD, going over MSc work. Could anyone help me with this question? Homework Statement A pion traveling at speed β(=v/c) decays into a muon and a neutrino, π→μ + \nu. If the neutrino emerges at 90° to the original pion direction at what angle does the muon come off...

Hi all, I was having trouble with this problem and hoping that someone could help me with it. A pion has a rest energy of 135 MeV. It decays into two gamma rays, bursts of electro magnetic radiation that travel at the speed of light. A pion moving through the laboratory at v = 0.97c decays...

Homework Statement When a beam if high-energy protons collides with protons at rest in the laboratory, pions are produced by the reaction p + p --> p + p + ∏. Compute the threshold energy of the protons in the beam for this reaction to occur. Homework Equations (mc^2)^2 = E^2 - (pc)^2...

I hope you don’t mind me asking this OPERA question here but I think it’s more of a QM question. I just watched NOVA Ghost Particle and it got me thinking. The only problem is that my brain isn’t strong enough to hold all that I’m reading about this experiment. From what I gather, the CERN...

I have read that 3 pion decay of the eta is not allowed as a strong reaction, but proceeds as an electromagnetic interaction. I do not see why it is strong forbidden.

Decay of tauon into pion and neutrino... Hello all. I have a question. One of the weak decays of a tauon(energy 20GeV) is to a charged pion(rest mass 139.6Mev/c^2) and a neutrino(take the neutrino to be massless). What condition results in the maximum energy of the pion after the...

I'm reading Zee book on quantum field theory. He wants to explain that pion is the goldstone boson arising from the spontaneous symmetry breaking of the chiral symmetry. So he start with the weak decay \pi^{-} \rightarrow \bar{\nu} + e^{-} and write this equation <0|J^{\mu}_{5}|k>=f k^{\mu}...

Which fundamental force mediates the reaction \pi^+ + D \rightarrow p + p? My initial assumption was the strong force because states only feature quarks (i.e. there are no leptons) but looking at it again I'm not 100% sure. Do I need to include colour factors? Could it be a neutral current...

Hi, I was wondering whether the decay of the Pi-0 meson in QED to an electron positron pair can occur as follows: Pi-0 -> virtual photon -> e+e- or does it have to go via Pi-0 -> two virtual photons -> e+e- (the Feynman diagram has a 'square' of virtual electrons/photons)? I have...

So the pion(+)n is made up of an up quark and a down antiquark. And somehow, it emits a W+ boson, which then turns into a muon and a muon-neutrino. From the Wiki article, "W bosons can decay to a lepton and neutrino or to an up-type quark and a down-type quark." Does this mean that the...

Hello, i'd really need some help with the following questions. 1) Neutral Pion It's quark content is written as: \pi^0=(u\overline{u}-d\overline{d})/\sqrt{2} But the u-quark have a (quite) different mass than the d-quarks. This means that the neutral pion is a superposition of states of...

Basically can a neutral pion go to two electrons and two positrons and under what interaction would it do this? I know its defiantly not the strong force, so is it weak or EM? I'm pretty sure its EM but not 100% Thanks

hi, yesterday i had a discussion with some friends about the decays of pions which produced a few questions that we couldn't resolve properly. if anyone can shed some light on this matter, or point out flaws in the reasoning below, that would be great. so starting with the decay of a neutral...

Homework Statement A pion that is moving at 0.98c, desintegrates producing two photons that form both of them the same angle with the direction of the initial pion. Find the angle and the enrgy for the photons. (Pion mass: 135 Mev/c2) Homework Equations E = K + m0c2 The Attempt at a...

Forgive my question for being so elementry, but I'm jumping a bit ahead of my curriculum... I've attached a decay process for the negative pion. I actually spliced together the initial pion decay and then the subsequent muon decay, assuming the entire process is correct. 1) the first W-...

Hi, I have a question regarding the CP operator on pion systems. 1) CP \mid \pi^0 \rangle 2) CP \mid \pi^+ \pi^- \rangle 3) CP \mid \pi^0 \pi^0 \rangle I'd like to solve this in the above ket notation and apply the operators as is on the different parts of the represented wave function...

1. The problem is based uponYukawa's original prediction for pion mass-energy. suppose the force between nucleons is due to the emission of a particle mass m from one nucleon and the absorption by another. given the range of the nuclear force is R=(1.4)\times10^{-15} use \DeltaE\Deltat...

I'm running into a dilemma: I've recently worked out the Feynman rules for Chiral perturbation theory for 2 flavors, and discovered that the term \mathcal{L}=\frac{f_\pi^2}{4} \Tr[(D_\mu U)^\dag (D^\mu U)] seems to contain the term ~ e^2 A_\mu A^\mu \pi^0 \,\pi^0 describing a direct...

Homework Statement A pi+, produced by a cosmic ray, has an energy of 280MeV in the laboratory frame S. It undergoes a decay: pi+ ---> muon+ & muon-neutrino. The muon produced continues to travel along the same direction as the pi+ and has a mean lifetime of 2.2mirco seconds in the muon's...

hi, is the following decay possible? \pi^- \rightarrow u \bar{u} + \mu^- + \bar{\nu}_\mu my idea: the quark content of \pi^- is \bar u d , the d quark could decay into an up-quark, emitting a w^- boson which decays into the muon and anti-muon-neutrino. or is there any problem? (normally...

Homework Statement A pi+ meson can undergo the following decay process: pi+ --> muon+ + muon neutrino where the rest mass of the muon neutrino can be considered as zero. Show that the energy and momentum of the muon+ in the rest frame of the pi+ are given by...

Hi, I have a question from Perkins: I'm not sure I understand the line in boldface. If s_\pi = 1 then why is S_z = 0? Thanks!

Why is it not allowed for the neutral pion to decay to three photons? The PDG states that this mode violates charge conjugation, although obviously the two photon decay is the dominant decay of this particle, and I don't see how adding another neutral particle to the decay causes a violation of...

Does anyone know what happened to them? LowlyPion was our most prolific HH until he disappeared without a trace several months ago. He'd had a fight with a mentor, but I can't believe that would have driven him off, he was too well liked. rewebster said he was dying from having had the...

Reading on pions the book glanced over this idea: Aloud: Neutral pion --> photon and photon Not aloud: Neutral pion --> photon the book says its due to energy momentum conservation? but if photons are massless how does this work? Cheers

Homework Statement A (pi)0 meson whose rest mass is 135 MeV/c2 is moving with a kinetic energy of 1 GeV. It decays in flight into two photons whose paths are along the direction of motion of the meson. Find the energies of the two photons. Homework Equations Lab Frame: The...

Show that the phase space factor \rho \propto p^2 dp/dE for the decay \pi\rightarrow \mu + \upsilon is \rho \propto \frac{({m_\pi}^2 - {m_\mu}^2)^2}{{m_\pi}^3}E_\mu where E is the total energy.I can show that p^2 = ({m_\pi}^2 - {m_\mu}^2)^2/4{m_\pi}^2 but then I get stuck, I don't know how...

decay rho-->eta + pion is forbidden.why? is it only violation of charge conjugate or its not conserve the energy & momentum.

Homework Statement we are given a neutral pion moving at 0.98c straight in the x-direction. The pions rest mass is 135MeV/c^2. two photons are emitted in opposite direction parallel to the pion's motion. I need to find the two frequencies of each photon. Homework Equations m=0...

The pion \pi+ has the same quark content as the rho\rho+, but different rest mass. Why is that? And does the same apply to the \pi- and \rho-. Will they have the same mass difference? Thanks for your help!

Homework Statement When a beam of high energy protons collides with protons at rest in the laboratory, neutral pions are produced by the reaction p + p ---> p + p + pi^o. Compute the threshold energy of the protons in the beam for this reaction to occur. Homework Equations The...

Homework Statement A neutral pion traveling along the x-axis decays into two photons, one being ejected exactly forward and the other exactly backward. The first photon has three times the energy of the second. Prove that the original pion had speed 0.5c. Homework Equations for m=0...

Pion Nucleon Scattering and a bit about group theory/ representations Hello everybody, I am going through Ryder's book about Quantum Field Theory right now. In the chapter about Pion Nucleon scattering he writes the interaction term like L_{int}=ig \bar{\psi} \gamma_5 \tau_a \psi \phi^a...

Homework Statement A neutral pion may decay into two photons. A particular pion is traveling along the x-axis when it decays into two photos, the first going directly along the +x axis, the second going directly back along the -x axis. The energy of the photons is measured and it is found that...

I wasn't sure whether this question should go in advanced or introductory physics but I decided to post here since it doesn't involve any complex maths. Homework Statement Part 1 Consider a neutral pion at rest. On the basis of conservation of energy and momentum alone, show that it is...

Homework Statement A pion traveling near the speed of light hits a nucleus and travels an average distance of 3.5fm before interacting. Estimate the time req. for the strong force to interact. Homework Equations The Attempt at a Solution So are they saying that the pion hits the...

So I know the neutral pion decays as \pi \rightarrow \gamma\gamma my question is though, what forbids this from being an electromagnetic decay? I know it is not decaying via the strong force as there are no quarks resulting from decay. However, I do not see what forbids this from decaying...

Homework Statement The neutral pion is an unstable particle that decays very quickly after its creation into two photons (“particles” of light: v = c, mo = 0). The pion has a rest-mass energy of 135 MeV. Consider a pion that has a kinetic energy of 90 MeV 1) Determine the v of this pion...

Hi, I have a question about this decay: \pi^- \rightarrow e^- \overline{\nu_e} there is a factor: 1 - \frac{v_e}{c} what are these values, v_e,c, and why this quantity is equal to: \frac{m^2_e}{m^2_\pi + m^2_e}? Thank you Ciccio

Quick question. If particles that mediate interactions are called gauge bosons, why isn't Pion considered a gauge boson. I'm pretty sure I've come across a few interactions mediated by it.

Why the decay of neutral pion to electron positon pair is forbidden?