Quark Definition and 250 Threads

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)...

What is the explicit 3x3 matrix operator which measures the colour of a quark? Essentially what I want to know is what is the analogue of ##S^z## for the measuring of spin.

I am puzzled by the mechanism that enables neutrinos to be able to pass though many light years of lead without interacting with anything. I understand that they do not feel the strong force and that the weak force is slow to respond, but to travel straight though a 100 light year thick slab of...

This isn't a homework problem. I am preparing for a particle physics exam and although I understand the theoretical side of field theory, I have little idea how to approach practical scattering questions like these. THE PROBLEM: Dark matter might be observed at the LHC with monojet and...

So I've been set a computational problem regarding applying the Shroedinger equation to quarkonium and I'm just trying to do some research around the subject because it's nothing like I've ever covered before and quite fascinating. There's quite a few questions that I can't find answers to...

Lets think we have a paticle system which consisting two quarks and they are combined.Then here I learned somehing strange.If we separate this two quarks the universe creates two quarks from universe so first we have 1 quark pairs now we have two. In this process virtual quarks (the matter ones)...

I read that the top quark is "the smallest quark, which means it is the most massive". How can it be the smallest and yet the most massive?

Homework Statement One of the following equations represent a possible decay of the K + kaon. K+ → π+ + π0 K+ → μ+ + νμ State, with a reason, which one of these decays is not possible.The Attempt at a Solution At first i thought the first decay was not possible, however, i recently learned...

How is the mass of hadrons calculated from constituent quarks? It seems classically it should come from three parts: (p2+m2)1/2 for each constituent quark with rest mass m, plus interactions between the quarks, which would be electromagnetic Coloumb 1/R potential between any two of the three...

I am planning to do some work on quark fragment into hadrons, and I have heard some models like Lund Model, feynman-field model and so on. Is there any good review articles on the topic of fragmentation model? (Recent years is better) Best Regards!

Hi, the "color" of quarks gives rise to the strong-force. I've read on some page (cannot remember where) that same-color repels and different color attracts. Additionally it was stated that the attractive force between color/anti-color is stronger than color/different color. But no ratios or...

I'm learning about particle physics at the moment, and have read that the J=3/2 multiplet contains baryons comprised of uuu, ddd, sss quarks. But the J=1/2 multiplet contains no baryons consisting of three quarks of the same flavour. Is there a reason for this? Is it something to do with quantum...

Homework Statement Write down the quark content of the following particles, made of (u; d; s) and their antiquarks: (a) A meson with strangeness S = 1, and isospin component I3 = 1/2 (b) An antibaryon with strangeness S = 0, and isospin I3 = -3/2 The Attempt at a Solution a) A meson...

I get the idea of confinement, and how it is impossible to separate a lone quark from a baryon: it needs more energy than creation of two more quarks, so the latter happens first, and you end up with having created a (color-neutral) meson. However, I don't see what prevents free quarks from...

Hello to all. I have a pretty general question. Hopefully it will require a somewhat technical answer. My question is this. Has there been any experiment where quarks have been smashed together? Perhaps at the lHC or Fermi. The other day I was told about such an experiment where two quarks were...

If I understand correctly, conservation of baryon and lepton numbers imply that quarks and leptons are "basic" i.e. non-interchangeable particles? What happens when one such particle is annihilated, can the energy produced be used to "generate" the other type, or do some additional particles...

Can anyone give an answer (or give a web reference) to the following question: How is a group assigned to a particle? I've seen groups assigned to shapes, polynomials, permutations, rotations and transformations. But how is a group assigned to a point particle?

Hi there, My homework problem is on particle physics and asks me to draw a feynman diagram for pp→\bar{t} t interaction, which is what I think the LHC is planning to do (or possibly is doing). For the more traditional interaction; \bar{p} p→\bar{t} t I have this diagram; In this...

I am having some difficulties in understanding something I found. Speaking about CKM matrix for N quark generations... I know that the Cabibbo Kobayashi Maskawa matrix is unitary, so it has N^2 free real parameters. Although I cannot understand how by an overall face they get (2N-1) less :/...

The quark content of the neutral pion is listed as \frac{u\overline{u}-d\overline{d}}{\sqrt{2}} What is the proper way to interpret this?

Nice posting by Bee Hossenfelder on her Blog !.. http://backreaction.blogspot.nl/2013/09/whatever-happened-to-adscft-and-quark.html A decade ago, the AdS/CFT correspondence was celebrated as a possible description of the quark gluon plasma. RHIC measurements of heavy ion collisions at that...

I'm a little confused about what is actually meant by the JP = 1/2 + octet. I'm pretty sure it means the particles must have spin 1/2 in the ground state (l=0) and an even parity but what I'm confused over is the absence of an sss, uuu or ddd state. I understand that this would give I3 = 3/2...

Hi, I'm currently doing a course in particle physics at masters level and I have this problem: I know that having an red:anti-red gluon isn't possible as this produces an non-zero trace for its representation, but if I have a red quark that emits a gluon and afterwards is still a red quark...

Good article about Quark stars: http://www.nanowerk.com/news2/space/newsid=31543.php of course, the title instantly makes me think, "Piccard would not approve!" :biggrin:

http://news.discovery.com/space/quirky-4-quark-quantum-monste-discovered-130618.htm Do you think this is legit? How exciting!

Dear Physics Forum, I was thinking about the properties of the combined electroweak force. Does it maintain the electromagnetic and weak force properties (in an additive fashion), or does it have new properties. If new properties, do we know what they are (well, you may, but I don't!)...

I'm currently reading about the parton model and deep inelastic scattering. As I've understood it was observed that when protons collided at high energy very little transverse momentum transfer was observed, while when electrons were collided with protons transverse momentum transfer was...

This isn't really a homework question but it's from a past paper for revision. It is a short question so it shouldn't require lengthy mathematics. It asks you to show that a quark and an anti-quark of the same colour will attract. The problem gives the 8 generator matrices of SU(3) and...

what happens to the gluon linking Quarks at time of formation of quark star? whether the quark star consists of only quarks or quark gluon plasma?

material made from up and down quark but we have four more quark what they are do??

Homework Statement why the isospin wave function was not considered in quark model? only the others (flavour, color, space, spin) are considered? Homework Equations The Attempt at a Solution

I was wondering that if positrons are antimatter and Down Quarks which are regular could be pushed together so that they break down into energy? The second question is whether this could be used for a form of fusion or fission reaction which ever is more accurate in this case by breaking a...

For quark anti-quark binding the potential takes the form: V(r) = -k/r + σr Where the first term comes from the Coulomb force and the second term comes from the strong nuclear force. My question is whether σ is the same for all quark anti-quark pairs or if it's different depending on...

In quark-level diagrams of decays, I often see, for instance, a baryon with one quark emitting a gluon and then the gluon goes on to decay into two new quarks. What I'm wondering is, if the gluon is color-neutral, can a photon play this same role in theory? Is this impossible due to some...

Homework Statement A proton has a diameter of about 1fm. Estimate the minimum momentum in units of MeV/C of a quark confined in a proton. Homework Equations The Attempt at a Solution I used the uncertainty relation \DeltaP\DeltaX ~ \frac{\hbar}{2} \DeltaP ~ \frac{\hbar}{2 x...

I'm studying chiral symmetry in QCD. I understand that in order for a spontaneous symmetry breaking to occur, there must be some state with a vacuum expectation value different from zero. My question is: can someone prove that is the chiral symmetry is an exact symmetry of the QCD then...

Homework Statement Basically I've been asked to draw a isospin vs. charge diagram - not a problem. But the question states that this is a sextet, but when I look at the combinations/look up baryons with charm quarks - there are many more than six! Am I missing some quark combination rules for...

Homework Statement (1) Indicate whether the following process (if possible) occurs due to the strong, weak or electromagnetic interation. \pi^{-} p → \pi^{-} \pi^{+} n (3) Sketch Quark flow diagrams for the following, stating whether it's due to EM, weak or strong interaction; K^{*+} →...

Okay, so I've just begun to have a grasp on the concepts of quantum chromodynamics. And what amazes me is that quarks never actually exist on their own as a single particle because of the strong interaction between them. I've read that when you try to pull apart a pair of quarks that is bonded...

You often see written that quarks cannot exist by themselves and only exist in mesons (2-quark combos) or baryons (3-quark combos). Yet you also see the top quark referred to as existing by itself. Which is right?

Hi, I am studying the soft neutrino spectrum from WIMP annihilation in Earth through the b-bbar channel as a part of my research. Can some one please tell me what is the decay tree for the b-bbar from neutralino WIMP or just the decay tree of the b quark. This seems like a simple...

Hi, I just remembered a question I have wondered about for countless of years without finding any answer to: Have (any of) the electric charges of quarks been empirically measured/tested/verified? (Yes, I know about the Standard Model and what the charges are supposed to be, that's not...

Hi, In the case of the gravitational collapse of a star where neither electron or neutron degeneracy pressure is sufficient to prevent further collapse, is there a possibility that the star will become a quark star rather than a black hole? From what I understand, quarks are perpetually...

Does anyone have any good introduction to theories of the quark and lepton mass matrices? Theories like textures and horizontal symmetry. My understanding of research into textures is that it often involves trying to make zero as many entries as possible in the mass matrices. Is that a fair...

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

i wasn't exactly sure what happens inside particle colliders but i recently learned that they actually take photographs of particles. i looked for a photo of the top quark and this is what i found: what exactly is going on in this image? how can one take photos of a top quark? what do...

I am studying A2 physics so don't know alot...my question is simple...is quark flavour conserved...I know quark number if conserved (because baryon number is consereved) but am not so sure about flavour...I have seen situations where it appears it is but then during beta-minus decay it appears...

Hi guys, I was reading about quark confinement and came up with a doubt i can't find the answer to: You have to use energy to try to 'pull away' one of the quarks in a meson, right? And when you give enough energy, a new quark/anti-quark pair is created and that's why you never find only one...

Hi. I am a bit confused by the fact that there are quantum numbers related to every flavour of quark except the up and down. A consequence of this is that the neutral pion is it's own anti-particle while the neutral kaon is not. Why is this so?