Meson Definition and 115 Threads

I understand that when the quark theory was being developed that SU(3) was used to explain the mesons that were ultimately found to be composed of the up, down, and strange quarks. I also get that the SU(3) is grouped as an octet and a singlet, with the eta prime meson being the singlet. But I'm...

Hello, first post. I am trying to understand what a meson is. I have googled this and looked at both the wiki page and several intro physics presentations, but the concept is eluding me. Could someone please explain what a meson is? Thanks, sciencenoob

About the pi0 meson: I have a vague understanding of the idea of quantum super-position giving the linear combination of uubar and ddbar, even though it is very hard to picture - if possible I would like to avoid going off onto a tangent about this... My question is: am I right in saying...

The neutral phi meson decays to make two photons after around 8 x10-17 seconds Is this just straight annihilation of the quark anti quark pair? If it is this does it take this amount of time due the quark colour, as in do you need a red up and a red anti up for annihilation? Or does this...

Homework Statement Why is D*+(2010) → D+(1869)π0 allowed via the strong interaction but Ds*+(2110) → Ds+(1969)π0 forbidden. The numbers in the brackets are masses in MeV. Homework Equations The Attempt at a Solution My guess was that mass was not conserved, but if π0 is 135 MeV...

Homework Statement \frac{\Gamma\left( D^{*+} \rightarrow D^{0}\pi^{+}\right)}{\Gamma\left( D^{*+} \rightarrow D^{+}\pi^{0}\right)} = ? Homework Equations D^{*+} = |c\bar{d}\rangle D^{*0} = |c\bar{u}\rangle see also Clebsch-Gordon coefficients The Attempt at a Solution I know...

what are standards model limits on decay of K0, Do, B0 meson into a pair of neutrino and anti neutrino. I know that these highly suppressed due to involve FCNC. but if someone can tell me about theoretical limits on these reactions.

I have some questions about the matrix <0|j^{\mu}_5|\pi(p)>=if_{\pi}p^{\mu} 1.Pi is a psuedoscalar particle, but the current between vacuum and pi state is an axial one, why not a psuedoscalar one? And how do we determine the current appearing in the similar matrix like <0|j|meson>...

Does the decay of B0 meson into two muons at the 3 ppb level, imply that this test for low-energy SUSY has failed?

Can the rho(0) meson decay to a pion(0)+gamma ray? If so, which, between this decay and the decay to pion(+) + pion(-) dominates? I know decay modes will dominate as a result of the relative strength of fundamental forces involved, so what are the forces and their relative strengths in this...

Homework Statement A ∏° meson moving with a velocity v in the z direction decays into two photons. One of the photons travels in the z direction and the other travels in the minus z direction. a) If one photon has an energy that is nine times greater than the other photon, calculate the speed...

Homework Statement K mesons (“kaons”) are unstable particles composed of a quark and an antiquark. They can be produced copiously in energetic collisions between stable particles at accelerator laboratories. Soon after they are produced, kaons decay to lighter particles. One type of kaon...

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Homework Statement consider a pion decaying into 2 photons. In the rest frame of the pion, the two photons must emerge back-to-back photons are equally likely to emerge in any direction. determine the rest frame angular distribution of the emerging photons. Homework Equations ΔP=f(θ)Δθ is...

Why is there no meson made up by only up and down quarks but even under parity? Is there something that forbids its existence? The pions are all axial (pseudoscalar) mesons. As we go higher in energy, there are such "flavour-pure" mesons. Is this a consequence of the almost-unbroken isospin...

Hi all, I have a question regarding to the branching ratio of neutral D-meson decay. Give three decays: 1. D --> negative kaon + positive pion 2. D --> positive pion + negative pion 3. D --> positive kaon + negative pion The one with highest branching ratio is 1. due to its non-cross...

Homework Statement I saw here, but since the thread is closed I need to ask my question in a new thread. I have two decays: \rho^0\to \pi^+\pi^- and \rho^0\to \pi^0\pi^0. The text says that both are allowed with respect to laws of conservation of energy and impulse. Why is the second one...

Mesons are bosons, while the baryons are fermions. My question is, meson is a type of hadron that made from the interaction of quark with gluon. Quark is fermion, not boson. so why mesons are boson?

1) What is mean by fermion with half integer spin and boson with integer spin Is that fermion, 1/2,3/2... boson, 1,2,3 2) Why meson don't have q = +1, S = -1 or q = -1, S = +1 in term of quark model

Homework Statement The pion-zero meson has its mass quoted as 135.0MeV/c2. It decays into two gamma rays: ∏0 → γ + γ b) Assuming the ∏0meson to be initially at rest, calculate the energy and hence the wavelength of the two gamma rays. Homework Equations E= hc/λ The Attempt at a...

Homework Statement This one stumped me a little Two protons are heading toward each other with equal speeds. What minimum kinetic energy must each have if a ∏2 meson is to be created in the process? Homework Equations E=mc2 p+p→p+p+∏2 E=Ek-mc2 ? not sure if I got this right or even...

Does anyone know why the $$\rho^0\to\pi^0\gamma$$ decay is suppressed? I've been working on it, and so far I think it can conserve parity, charge conjugation, angular momentum, etc. But the PDG indicates that it basically never happens. Why? Thanks!

After being created in a high-energy particle particle accelerator, a pi meson at rest has an average lifetime of 2.60 x 10^-8s. Travelling at a speed very close to the speed of light, a pi meson travels a distance of 120m before decaying. How fast is it moving? Answer: 0.998c Could...

In atom spectrum, such as for hydrogen, there are states of 1s, 2s, 2p, 3s, 3p, 3d, etc. There are no 1p, 1d or 2d, 2f. Simply because n= n_r + L +1. So the maximum of L is n-1. But when I read articles talk about meson, they list meson states of 1p, 1d, 1f, etc. Such as in the article “Quark...

Hi all. I'm looking at the decay of a neutral ρ meson to two neutral π's. I think it is disallowed but I can't figure out why. The J^{P} of the ρ is 1^{-} and 0^{-} for the neutral π's. The formula P(ρ^{0})=(-1)^{L}P(π^{0})P(π^{0}) then says that the decay is allowed provided the π's are...

Could anyone please explain the sequence below taken from Mandl QFT textbook (p.53)? 1. i\hbar c\Delta^+(x-x')=[\phi^+(x),\phi^-(x')] 2. i\hbar c\Delta^+(x-x')=\langle 0|[\phi^+(x),\phi^-(x')]|0\rangle 3. i\hbar c\Delta^+(x-x')=\langle 0|\phi^+(x)\phi^-(x')|0\rangle 4. i\hbar...

Homework Statement Hi guys, I have been given the problem of drawing the feyman diagrams and finding the decay rates for the two decays: D0 \rightarrow K+ + \pi- and D0 \rightarrow K- + \pi+ D0 \rightarrow \pi- + \pi+ Homework Equations The coupling constant g = 10^-5 for the weak...

I understand that the pi+ meson is made up of an up and an anti down quark, and the opposite for the pi- meson. What I'm not really understanding is the makeup of the pi0 quark: http://img219.imageshack.us/i/piol.png/ *Sorry, couldn't get the image tags to work :(* there is 3 main points I...

Homework Statement I have a question. If meson K^{0} consists of d\bar{s} then its antiparticle \bar{K}^{0} consists of \bar{d}s ? Homework Equations The Attempt at a Solution

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Is anybody know the value of kappa meson decay constant?

nuclear diameters will a meson traverse? Approximately how many nuclear diameters (A=100) will a (pi)0 meson traverse at a speed of 0.95c before it decays? My textbook is very vague for the chapter containing this material. The only thing that is really given is that the mass is 135.0...

We know that when photon/electron/muon/proton hit another proton then many types of mesons exit the proton. Why these mesons are not confined inside the proton, and single quarks are? Thanks, and sorry if this is a stupid question... I couldn't find an answer in the literature.

¿Is it possible the decay of rho neutral meson to two pions? Homework Statement We initially have the neutral rho meson -----> pion+ + pion- ¿Is this reaction possible? ¿What are the conserved quantities?¿Which is the interaction involved in the process? Homework...

hi, my notes say that a meson is a quark anti quark pair and that all quarks are spin half fermions. fair enough. it then says that mesons are bosons with spin 0, 1 \hbar, 2 \hbar \dots this i don't get. apparently, antimatter has the same mass, opposite electric charge and also the...

Homework Statement Part A) Establish which of the following combinations of particles can exist in a state of I=1 : a) \pi^0\pi^0 b) \pi^+\pi^- c) \pi^+\pi^+ d) \Sigma^0\pi^0 e) \Lambda^0\pi^0 Part B) of the problem is: In what states of isospin may exist the following systems? f)...

Why is the composition of eta prime meson known as the singlet state? See: http://en.wikipedia.org/wiki/Eta_meson Thanks

The B+ particle and B- particle are produced by higher energy collisions between protion and anti protons. The B meson has a mass of 5.28 GeV/c^2. The proton has mass 938 MeV/c^2. Calculate the min KE of the proton neccesary for a B+ B- pair to be produced from a proton anti-proton head on...

I've been wondering ever since I read about mesons, how they can exist. Shouldn't the particle anti-particle pair annihilate? Or is there something I'm missing from my idea of the meson?

In my physics class my teacher said that a meson is made up of one quark and one anti-quark. But when, for example, an electron are that close to a positron pair annihilation occurs. Why does this not happen in a meson?

I have been learning about quarks which is really interesting, but i have become confused when it comes to mesons. I have learned the basics of annhilation, particle and anti-particle, etc, but I have learned that neutral mesons, such as the pi neutral meson are made of a quark, (e.g. up), and...

Homework Statement The Ko meson is a subatomic particle of rest mass MK = 498 MeV/c2 that decays into two charged pions, Ko \rightarrow \pipositive+ \pinegative. Both pions have the same mass, m\pi = 140 Mev/c2. A Ko at rest decays into two pions. Use conservation of energy and momentum to...

Homework Statement A k^0 meson at rest decays into a \pi^+ meson and a \pi^- meson, each having a speed 0f 0.85c. If the k^0 Meson is traveling at 0.9c decays, what is the : (i) The greatest speed that one of the \pi mesons can have (i) What is the least speed? Homework...

I am confused by eta meson and eta prime meson . I can not the difference between them .anybody can help me ? who can tell me what are they made up ? some textbook say that the neutral eta meson is considered to be a quark combination (uubar+ddbar-2*ssbar)/6^(1/2),but I am still not clear.

[SOLVED] Restmass, lifetime of a meson Homework Statement A \rho meson is a highly unstable subatomic particle with a rest mass of 776 MeV/c^2 and a mean lifetime of 4\times10^{-24}s. What is the minimum uncertainty in the meson's energy? Homework Equations We know that rest energy...

Hi I have just started an intro physics course - it has very little maths, explaining as much as possible in words. I am having trouble with understanding the relationship between colour charges and quarks and how they are formed to create hadrons. I understand that the colour charge...

Homework Statement Assume that a high-energy nucleon is emitting a pion, i.e. the process N→N+π. Is the pion real or virtual or both? Motivate your answer with a calculation or a good argument. Homework Equations Virtual particles does not obey energy (and momentum) conservation. The...

Homework Statement A proton or a neutron can sometimes "violate" conservation of energy by emitting and then re-absorbing a pi meson, which as a mass of 135 MeV/c^2. This is possible as long as the pi meson is re-absorbed within a shoart enough time \Delta T consistent with the Uncertainty...

How are meson spins worked out? I can't understand why the pion has spin 0 when it is made up of one up quark and one anti upquark, while the rho meson is made up of the same two quarks but has spin 1...

Homework Statement I'm trying to determine the predicted meson masses but am having a little trouble with working out the spins... Homework Equations m=(q\overline{q})=m_{1}+m_{2}+A\frac{S_{1} \bullet S_{2}}{m_{1}m_{2}} The Attempt at a Solution I understand that using a quark up...