Particle decay Definition and 68 Threads

I would like to know if this thought makes any sence or if i'm missing something Heisenberg principle states that: ΔxΔρ ≥ ħ/2 ⇒ Δρ ≥ ħ /2Δx If we consider a scenario where we increase the precision of our measurement of position, we have Δx ⇒ 0 the principle implies: Δρ ≥ ħ/2Δx → Δρ ⇒ ∞...

I was wondering whether the decay of neutrons and protons (if they happen to be able to decay, as it is predicted by some GUTs) could be avoided in some cases. Let's begin with neutrons: In principle neutrons have a very short time when they are isolated (around 10 minutes) and they suffer...

Everywhere I look, I see the claim that J/psi decays to "g g g" about 64% of the time, and to "gamma -----> hadrons" about 13% of the time. My question is, exactly how does one distinguish between (1) J/psi -----> g g g ------> hadrons, and (2) J/psi -----> gamma ------> hadrons? If you...

1) We know in case of beta decay if there is excess of protons or neutrons in the nucleus beta decay take place. Force involved - weak interaction Reason involved - to stabilize, to obtain proton neuton 1:1 ratio in the nucleus. E. g., Beta minus - Carbon 14 transforms into Nitrogen 14 2) Case...

I've been trying for a very long time to show that the following integral: $$ I_D=2{\displaystyle \int} \, {\displaystyle \prod_{i=1}^3} d \Pi_i \, (2\pi )^4\delta^4(p_H-p_L-p_R) |{\cal M}({e_L}^c e_R \leftrightarrow h^*)|^2 f_{L}^0f_{R}^0(1+f_{H}^0). $$ can be reduced to one dimension: $$ I_D...

Attempt at solution: By conservation of momentum: $$P = (M,0,0,0) = p_1 + p_2 = (E_1 + E_2, 0, 0,0)$$ thus $$ M = E_1 + E_2 = 2k^2 + m_1^2 + m_2^2$$ Now $$E_1^2 - E_2^2 = m_1^2 - m_2^2 = (m_1 + m_2)(m_1-m_2)$$ $$ = M(m_1-m_2) = (2k^2+m_1^2+m_2^2)(m_1-m_2)$$ Isolating k: $$ k =...

Homework Statement I have a mother particle at rest, which decays to a daughter particle. The daughter has mass m, momentum p and energy E and is at an angle θ1. Now I have to assume that the daughter is emitted at an angle θ2, and the mother is moving along the x-axis with velocity βc. I need...

Homework Statement A Sigma^+ decays at rest into a neutron and a pion^+ meson, i.e. according to the reaction $$\Sigma \rightarrow n + \pi$$ The n and π masses are assumed known. The kinetic energy of the π + is measured to be 92 MeV. Determine the momentum of the pion. Homework Equations...

Hello! I wanted to ask why does the neutral Σ decay almost always to one γ(or two) and a neutral Λ. Why can't it decay to anything else? Thanks!

I believe that conservation laws, like for energy and momentum, are obeyed during the particle decay process, e.g. the total energy of the new output particles is equal to the energy of the one input particle. But is that relationship subject to quantum fuzziness? Suppose we, somehow, prepare...

Hi, I'm undergraduate researcher and my professor is interested in the answer to this question. He's kind of left me in the dark on why this is important to us, but that is another matter. We want hadrons that are produced at LHC conditions and decay before reaching the detector. So far all...

Homework Statement An Fe nucleus (A=57) decays from an excited stated to the ground state by emitting a gamma ray. The energy of the photon is 14.4 KeV when the nucleus is held fixed. If the nucleus is free to recoil then the energy of the photon emitted will be? Homework Equations ## E =...

Homework Statement A free neutron is unstable and decays into proton electron and an anti neutrino. The rest masses of these particles are ##m_n = 939.6 MeV, m_p = 938.3 MeV m_e = 0.51 MeV ##and ##m_{\nu} = 0 ## so that the change in the total rest mass in the decay is 0.79 MeV. If in a...

Homework Statement [/B] A particle detector shows tracks produced by two particles X and Y that were created by the decay of a lambda particle at O. Which of the following is a correct statement about energy at the decay? The energy of X must be greater than that of Y. The combined energy...

Given that an unstable particle has a constant probability of decaying per unit time, why is it said that its chance of surviving falls exponentially?

This question was asked in an competitive exam in India. The relevant equations are momentum conservation in the classical sense and the 4 momentum conservation. My attempt: Classical momentum conservation would seem inaccurate since the kinetic energies are high. However, a straightforward...

Homework Statement A certain elementary particle lives only a time [T][/0] = 5 sec (proper time) before disintegrating. What velocity must the particle have if it is to reach the Earth from the Sun before disintegrating? Distance between the Earth and Sun is 1.5x10^11 meters.[/B]Homework...

Homework Statement Unstable particles cannot live very long. Their mean life time t is defined by N(t) = N0e−t/τ , i.e., after a time of t, the number of particles left is N0/e. (For muons, τ=2.2µs.) Due to time dilation and length contraction, unstable particles can still travel far if their...

Homework Statement Unstable particles cannot live very long. Their mean life time t is defined by N(t) = N0e−t/τ , i.e., after a time of t, the number of particles left is N0/e. (For muons, τ=2.2µs.) Due to time dilation and length contraction, unstable particles can still travel far if their...

Maybe my question is a bit more philosophical than scientific. In the macroscopic world entropy means that things become more chaotic and less orderly as they decay. It seems to me somewhat paradoxical that in the quantum world lower generation particles "decay" into the first generation...

Homework Statement Stopped pions provide a useful mono-energetic source of neutrinos. For a pion at rest, calculate the energy of the neutrino in the decay $$\pi^+\rightarrow \mu^++\nu_{\mu}$$ You do not need to consider the subsequent decay of the ##\mu^+## and you can assume that the...

Hi guys. This is my first post here. Here it goes. I'm attending an introductory course on particle physics. By now, I'm supposed to know how to find out if a given reaction, say νμ+p→μ++n (for example) is possible or not. Unfortunately, the rules by which a reaction must abide are still foggy...

Hello everyone, I've been wondering for a while how is it possible to determine which decays are possible from a particle or, given a decay be sure that the given decay is possible and hence draw a Feynman diagram of it. I know I have to take into account conservation charge, energy...

For instancr like neutron decaying into proton electron and antineutrino. I read it in a book that says that according to Fermi, each of these particles are vibrations in different quantum fields and that each field exerted a tiny influence on the others. Because of quantum mechanics, we can't...

A particle with mass M a rest decays into two particles a and b. I know that Ea + Eb = Mc2, from conservation of energy. But I'm pretty confused about signs in the conservation of momentum equation, and I've actually seen two versions! pa + pb = 0, so pa = - pb. But I've also seen pa = pb! I...

I was recently reading an article that attempted to explain how the results of the Cronin-Fitch experiment illustrated CP violation. (http://hyperphysics.phy-astr.gsu.edu/hbase/particles/cronin.html) However, it wasn't very well explained. Could someone please explain this to me?

I'm new to quantum physics, and this might be a stupid question. What is the difference between Photons and the Higgs Boson? I know that neither of them interact with the Higgs field. And that when CERN found the Higgs Boson, it decayed into other particles INCLUDING photons. So what's the...

What reasons prevent the decay $\omega \rightarrow \pi^0 \pi^0 \pi^0$ from happening?

Homework Statement [/B] (a) Explain lepton universality. (b) Explain why decay mode is forbidden and find hadronic branching ratios. (c) Find the lifetime of tau lepton. (d) What tau decay mode would be suitable? (e) Find the precision. (f) How do you improve the results? (g) Why is it much...

Why is the decay ##\tau^{-} \rightarrow \mu^+ + \mu^- + \mu^-## not allowed? Charge, lepton number are conserved. I have a feeling it is something really basic. I'm thinking in weak interactions you only go from a ##l^- \rightarrow \nu_{l}## and not 'hop' from one muon to another non-neutrino muon.

Homework Statement A pion at rest (mπ = 273me) decays into a muon (mμ = 207me) and an antineutrino (mn ≈ 0). Find (a) the kinetic energy of the muon and (b) the energy of the antineutrino in electron volts. Homework Equations K = (γ-1)mc2 E = γmc2 ER = mc2 E2 = p2c2 + (mc2)2 I didn't...

Homework Statement a) Particle A decays at rest into two photons. Calculate, in terms of the rest mass of A, the energy and momentum of each photon. b) In a different reference frame, particle A is initially in motion such that its kinetic energy is equal to its rest energy. Find the momentum...

Hello. I was taught that a charge which changes its velocity must radiate (at least, in classical electrodynamics). Let's consider a charged particle which decays into another charged particle (and, maybe, others neutral particles; but not photons). In this case, can we find electromagnetic...

Homework Statement A Higgs boson has mass 125 GeV/c2, decaying into a pair of Z bosons, mass 91 GeV/c2. In the lab frame, one of the Z bosons is at rest. Determine the kinetic energy for the other Z boson in this laboratory frame. Homework Equations E = γmc2 γ=1/√(1-β2) The Attempt at a...

Hi all, I think that the off shell decay dosn't decrease the decay cross section, I mean if a particle X decays into a jet pair has mass for example Mjj ~ 130 GeV, being X has mass M ~ 130 GeV so decay in resonance or on shell into jj or being MX even much greater ~ 2000 GeV , this...

In the process of particle decay (eg carbon-14 ---> nitrogen-14), is there any relations with radioactivity? Is it reversible? ( up quark + 2 x down quark + W positive boson = down quark + 2 x up quark + electron, so that carbon-14 turns to nitrogen-14. Is it possible that down quark + 2 x up...

Homework Statement A K_0 particle has a mass of 497.7 MeV/c^2. It decays into a -∏ and +∏, each having a mass of 139.6 MeV/c^2. Following the decay of the K_0, one of the pions is at rest in the laboratory. Determine the kinetic energy of the other pion after the decay and of the K_0 prior to...

Physics Particle Decay Question (Cons. of Momentum??) Homework Statement An isotope of Polonium 210Po with mass 3.49x10^-25 kg can decay into an alpha-particle(He Nucleus) with mass of 6.64x10^-27 kg and an isotope of lead 206Pb with a mass of 3.42x10^-25. If the polonium decays at rest. and...

Homework Statement An accelerator produces a beam of Un that travels to a detector located 100m away. The particles travel with a velocity of .866c, so in the laboratory frame it takes the particles .385*10^-6 seconds to get to the detector. By the time the particles get to the detector, half...

Homework Statement Calculate following decay rate \frac{\Gamma(D_{0} \rightarrow K^{-} \pi^{+})}{\Gamma(D_{0} \rightarrow \pi^{+} \pi^{-})} Use the (Cabibbo–Kobayashi–Maskawa) CKM-matrix. Homework Equations The Attempt at a Solution D^{0} = |cu\rangle , D^{+} = |cd\rangle ...

Homework Statement A particle X with rest mass mx is traveling with speed vx = 0.8c along the x-axis in the lab frame. (a) Write down the four-vector momentum of the particle in the lab frame in terms of vx and mx. The particle decays to two particles, A and B, each with mass mx/4...

I'm not a physics person (did not take it in high school), but I was wondering why the speed of light is the constant (in relativity) and not the half life of an electron or positron. The name of a good introductory book to physics would be good too. Thanks in advance.

why is that particles such as the tau muon have a short lifespan and why is it that particles decay into other partcles? furthermore, what are the process that occur in particle decay?

Ive searched in vain for a listing of what particles with which interactions decay into which particles. This is a subject I know very little on so any starting direction would be greatly appreciated

Particle can decay through many channels with probabilities p_i, where in each channel its decay time is different \tau_i. It always decays through one of the channels. Particle decays according to exponential law where probability to decay in time t is...

Ive read that elementary particles can decay. I am trying to understand how this can be with a particle that has no composition. So i have two questions: If elementary particle A decays into particles B and C, then why can't we say that A is composed of B and C? If an elementary particle can...

Hello everybody, I'm assigned to do particle physics home, which I don't really understant because I'm a freshman and I have choosen it as a free subject. Obviously, that was a mistake. I have been reading a book, but I'm not sure if I understand everything. Homework Statement A particle of...

If a particle decays via A →B + C, and A had some initial non-zero momentum, is it possible for either B or C to be stationary? I can't seem to find a restriction on this from energy conservation or momentum conservation. From energy conservation, the stationary particle B still contributes...

Hi everyone, I find the following table from WolframAlpha concerning the probability of various decay modes of the pion \pi^{+}. My question is: Are these probabilities calculated, or are they numbers from numerous experiments? Thanks,

What drives particle decay? Is it an elementary, irreducible observation or can we model it based on a set of observable variables? Do all particle decay modes involve the weak force? Does one even need the intervention of a given force to have particle decay? Does string theory explain...