Mesons Definition and 57 Threads

I only know of the Phi vector meson which is ##s\bar{s}## which has J=1, P=-. I am looking for its axial vector version (dont know by what name it should go) ie J=1, P=+. More specifically I am looking for any data associated with it eg its LCDAs, decay constant, mass. I am not sure I can see...

I am looking for some detailed information on pseudovector mesons, mainly on their masses and quark contents. Also I am unfamiliar with the naming conventions of many of these mesons like K1(1270), K1(1400), a1(1260), b1(1235), f1(1420), h1(1380). What do these numbers and letters mean and ? I...

There are 36 hadron composites composed of 2 quarks selectable from the set ##[u, d, c, s, t, b, \bar u, \bar d, \bar c, \bar s, \bar t, \bar b]## satisfying the condition of having total charge = ##[-1, 0, 1]##. However, the superposition states of pure hadrons are sometimes also listed as new...

Hello! I am reading some group theory applied to QCD and they show how by using the lightest 3 quarks in the ##l=0## state we get 9 pseudoscalar mesons and 9 vector mesons. The difference in masses between the 2 classes is explained by the existence of a spin-spin interaction, which seems like a...

Hello, I am learning about solutions of the Schrodinger equation including the term of rotational energy (i.e. L^2 /2I, in its quantized form) and I was wondering if there should be another quantum term describing vibrational states of hadrons or any other composite subatomic particle, in...

Problem Statement: Why are vector mesons more massive than pseudoscalar mesons? Not any sort of set problem, just reading but I can't find an answer or explanation Relevant Equations: * It's going to be something to do with the spin-spin interactions for J=0 and J=1. But then I don't see how...

At the suggestion of some of the members here, I am reading the book Space-Time Physics by Wheeler. The last problem in the first chapter states: "In a given sample of mesons, half will decay in 18 nanoseconds (18 x 10-9)), measured in a reference frame in which the mesons are at rest. Half of...

The (residual) strong force between nucleons can be desribed as - The exchange of a meson (from a nucleon to the other), as in picture b) - The exchange of a quark and an antiquark: in picture a) one nucleon "gives" a quark and receive an antiquark and it's the opposite for the other I do...

is the amplitude of pure leptonic decay of pseudo scalar meson(say K→ee), while is the amplitude of the semileptonic decay of K→π ee. Kindly explain why does sd replace sγ5d ee in the amplitude?

I presume they cannot as they are fundamental particles? But then a meson can decay into a lepton?

In list of Mesons like this you see charm/anti-charm, strange/anti-strange and bottom/anti-bottom. You don't see up/anti-up or down/anti-down. Instead you see up/anti-down or (up/anti-up and down/anti-down) in supposition. Why no down/anti-down meson?

Gluons are often depicted as fundamental particles in the Standard Model. But in looking at their mechanism, it seems they are not really fundamental particles in the sense that they are fundamental, indivisible, building blocks. They are mesons- a composite quark-antiquark pair, where their...

Homework Statement Neutral vector mesons with ##J^{PC} = 1^{−−}## include the ##\phi## (mφ = 1020 MeV), ##J/\psi## (mJ/ψ = 3100 MeV), and ##\Upsilon## (mΥ = 9460 MeV), with quark content ss¯, cc¯, and b ¯b respectively. The decays of these mesons go largely to hadronic final states (jets)...

Hello, guys. I have not understood what it means when one writes ##\pi^+=u\bar{d}##, for example. I though it simply meant that the ##\pi^+## meson was composed of one up-quark and one anti-down-quark. However, that doesn't explain what writing ##\pi^0=\frac{1}{\sqrt{2}}(d\bar{d}-u\bar{u})##...

Hello, I understand the fact that pi mesons are superpositions of uubar and ddbar. But what happens if a decay only produces a single type of meson? I am not sure of this, but omega baryon decaying into xi-minus and a neutral pion seems to produce ddbar mesons, is it so that only a single type...

Mesons: hadrons with integer spin, usually quark-antiquark states I came across this statement in a pdf of a powerpoint. Unfortunately the presentation is so badly formatted (missing images, content overlapping content, etc.) that it's hard to follow and I can't see if he ever describes mesons...

The decay \rho^0 \rightarrow \pi^- \pi^+ occurs with a probability of 100\%, whereas the decay \rho^0 \rightarrow \pi^0 \pi^0 does not occur in nature, due to isosphin conservation. I don't understand this. Looking at the Isospin and its third component ¦I,I_3\rangle we have in the first...

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

As far as I know a Baryon is made of three Quarks (eg uud, udd etc) and a Meson of two Quarks, a Quark/Antiquark pair. As I am not a student / scholar in Physics but very deeply interested in this field, I couldn't find any explanation, why a Meson is omly made up by a Quark/Antiquark pair. What...

So a particle has intrinsic parity ##\pm 1 ## . The parity of a system of particles is given by product of intrinsic parities and the result is: ##(-1)^l ## (1). Questions: 1) How does this result follow? and what exactly is ##l## here? so it's the orbital angular momentum, so say a particle...

Hi there, Since some time I started to study the semilptonic decay of B meson : ## B \to D \tau \nu ## that there is an excess in the value R (D) = ## \frac{ Br ( B \to D \tau \nu) } {Br (B \to D l \nu) } ## in BABAR experiment than the SM expectations- See for example arXiv:1302.7031v5- Now I...

Hi. I was reading an introductory book about particle physics and I visited the PDG for an exercise. I found this... http://pdg.lbl.gov/2014/tables/rpp2014-tab-mesons-strange.pdf On page 9, the data of K1(1270) is given. How do I figure out it's quark content? If I look at the data for K*(892)...

Hi, I have been getting a little confused; the textbook (and from what i can see on-line) are saying that Hadrons only interact through the strong interaction (along with the electromagnetic force if charged Q) and yet K Mesons decay through the weak interaction. If my understanding is correct...

Hi, I am currently going over this and got me thinking about a scanario where you have A -> BC Where A is S = 0, L=0, B is S = 1 L=0, C is S=1 L =0 (I'll use S = intrinsic spin, L = angular momentum, J = Total Angular momentum, |L-S|=< J =< L+S) Maybe such a decay doesn't exist, but I'm just...

I am not clear with the difference of heavy and light mesons; 1. what is their difference? 2. how can we treat their decay properties? 3.for instance many people describe them using the Bethe-Salpeter equation at 4-dimension or at 3-dimension. which one is the better method? To help me...

I need to know the relation of wave function and vertex function of mesons. Any one give me an explanation of them. Are they same? in some journals their expressions are the same and in other papers the wave function expresses as a function of the vertex function of meson. Which one is the...

Homework Statement 12-16 K + mesons can be photoproduced by the reaction γ + p → K+ + Λ where the initial proton is at rest in the lab. From the conservation laws, discover if it is possible for either the K+ or the Λ to be at rest in the lab, and for what photon energy (in terms of...

As the title says- what is it that makes all mesons unstable? I know some quarks are less stable than others obviously, but why is there no stable meson? What is it about any combination of quark and anti-quark that makes a particle decay nearly immediately? In a related topic- what exactly...

I'm studying the \tau \rightarrow \rho \; \nu_{\tau} decay. I'm asked to calculate the decay width, using a parameterization of the matrix element of the hadronic current. I actually find a matrix element of the form: \left<\rho |\; \bar{u} \gamma^{\mu} \left( 1-\gamma^{5} \right ) d \; |...

Why the semi-leptonic decays of mesons involving neutrinos are consider as clean signal for new Physics. As for as I think these are free from hadronic complexities (because we do not know exactly about strong interactions) and electromagnetic interference (because neutrinos do not couple to...

The pseudoscalar mesons have J^P = 0^- They form a nonet: for S = ±1, I (isospin) = 1/2 and so there are two particles for each value of strangeness. This account for 4 particles: the ground-state Kaons. For S=0, I can be 0 or 1. I=1 gives a triplet: \pi^\pm \mbox{ and } \pi^0. For...

Hello physicists, I was speaking to my friend about mesons when I realized that surely a meson would annihialate at creation due to the fact that it has a quark and anti-quark. I know it doesn't, but I'm wondering why. Clarrification on this would be great. Thanks, Joe

Homework Statement The proper mean lifetime of a \pi^{+} mesons is 26ns. (a) (i) What is the mean lifetime of \pi^{+} mesons traveling with \beta=\frac{v}{c}=0.73? (ii) What distance is traveled at this velocity during one mean lifetime? (iii) What distance would be traveled in the...

Hi, Does anyone out there know the rules for mesons when it comes to the particle/antiparticle combinations? Is it simply like an up and anti-up quark that makes up a meson or is it like up and anti-down or down and anti-up? Or can it even be other combinations of the six quarks? Also I have...

I've read that mesons consist of a quark and an antiquark. So, here's my question. Why don't the quark and the anti-quark annihilate with each other (like they ususally do)? For example, the pi(0) meson consists of the up and the anti-up quark and the eta meson consists of the down and the...

This question is mostly about how to interpret notation used in Particle Physics. At lowest order the rate of b\rightarrow s\gamma is proportional to \langle B_p|b^\dagger b|B_p\rangle where p is either u or d labels and b, b+ are creation annhilation operators. However, I am unable to...

I was wondering if there was something similar to the 8 fold way representation used on mesons for the fermions?

Homework Statement B mesons can be created through the reaction chain e+e- → \Upsilon(4S) → B+B- by colliding beams of electrons and positrons head-on at centre-of-mass energy equivalent to the mass of the \Upsilon(4S) resonance. a) If the electron beam energy is 8GeV, show that a positron...

If a Meson is a Hadron that contains a Quark and an Anti-Quark which are both Fermions then why are Mesons a type of Gauge Boson?

I'm trying to understand why the Bc meson (anti b and c) has a lifetime of 0.46 picoseconds whilst the Bs, B+ and B- have lifetimes of ~1.6 picoseconds. Is this a density of states thing? or to do with the CKM elements? Thanks for any help.

So mesons consist of two quark. I am wondering why no stable mesons exist?

Homework Statement The half life time of mesons \mu with velocity 0.95 c has been obtained experimentally as 6\times 10^{-6}s. Calculate the half life of those mesons in a system in which they are at rest. Note: It shouldn't be "half life" but something like "mean life" or something like...

Hello all. Would anybody know where I can find data on gyromagnetic ratios/magnetic moments/g-factors of mesons? I find everything about nucleons, electrons and muons, but that's about where it stops. Even the Particle Data Groups is silent about it. Or is there any reason why it is not possible...

That is, how many different states are there assuming you distinguish two particles as different if they have different quantum numbers or different masses. For example, the \Delta^-(1232),\Delta^0(1232),\Delta^+(1232),\Delta^{++}(1232) are four different states. And these are all different...

Experimentalists have measured CP violation in neutral K and B mesons. Everybody is unhappy that so far there are only 2 systems so for which these measurements are possible. (Neutral D mesons are predicted to show such a small effect that it is probably unmeasurable for a long time.) All...

I am confused by eta meson and eta prime meson ?what is the difference between the two ones ? who can tell me what are they made up ? please help me ! thank you very much !

Homework Statement The decay D^{+} \rightarrow D^{0} \pi^{+} is not possible via a weak interaction which involves one virtual W+ meson. How many virtual W mesons are required? Homework Equations D0 has quark content c-ubar Pi+ has quark content u-dbar I'm not sure what D+ has...

Mesons are bosons, but are all bosons mesons e.g. intermediate vector bosons (w and z bosons in the weak interaction)?

I've been looking for a list of all the mesons there are, but cannot seem to find it online. Anyone know just how many mesons have been discovered? A link to a page that shows the names of each meson would also be appreciated.

what are mesons