1. JackDixon

    B Beta decay and the down quark.

    I was learning about beta decay, and how a down quark decays into an up quark by emitting a W- boson which then becomes an electron and an electron antineutrino. I have two main questions - Firstly, how can the down quark be considered a fundamental particle, when it can break down to produce...
  2. G

    I Are there quark "shells", just as electrons have shells?

    Historically, quantum mechanics, or wave mechanics, arose due to the anomaly that accelerating free charges ( electrons ) radiated EM waves. The quantisation theory provided a solution. Quarks also have electric charge, and are moving at relativistic speeds, and bound in the nucleon. As the...
  3. ohwilleke

    B Why is there still disagreement over the b quark's name?

    Some physics papers today describe the b quark as a beauty quark. For example: Others physics papers today refer to b quarks as bottom quarks. For example: The b quark is a particle that was theoretically predicted to exist in 1973 and first observed experimentally in 1977. But, here we...
  4. T

    I Higgs Boson decay to two Quarks Detected

  5. C

    I Does strong force increase or decrease with aligned spins?

    The deuterium exists only with the proton and neutron of aligned spin, which suggests that the residual strong force is greated with aligned spins, i.e. the binding energy is greater if the spins are aligned. On the other hand the mass of ##\Delta^{+}## is greater than the mass of proton ##p##...
  6. W

    I How to treat quark color pairs mathematically

    I am trying to work through a problem in the textbook "Particle Physics in a Nutshell." However, I am realizing how little I actually understand about working through problems involving quark color pairs. Given in the problem is the meson color singlet 1/\sqrt{3}(r\bar{r}+g\bar{g}+b\bar{b})...
  7. ohwilleke

    I Excited hadrons v. fundamental particles

    Mesons and baryons have both a ground state and excited states involving the same valence quarks but a higher mass (which can in principle be calculated from QCD). Fundamental fermions and bosons, however, do not appear to display this behavior. They have a ground state, and while there are...
  8. P


    I enjoy physics to a great degree. That is my personality
  9. P

    I Antimatter in proton

    Hi! I am asked to calculete the portion of antimatter present in protons. I am sayed that this portion is given by: r=(3R-1)/(3-R), where R is R=σ(antineutrino)/σ(neutrino). Another definition of r is r=∫x*Q'(x)dx/∫x*Q(x)dx, where Q(x) are partonic densities Q(x)=d(x)+u(x) (d is down quark and...
  10. Renu420

    I Quark and anti quark neutral particles question

    Hi there ppl! I have a question ! I learned that neutral miuon ( μ0) is made of a quark and his anti quark (can't remember which) which explains it's very little lifetime(around 10-24s if i'm not wrong). Now i wonder how two particles ,that are meant to destroy each other,form for a little time...
  11. referframe

    I How are protons, photons and quarks related electrically?

    When protons, due to their electric charge, interact with photons are the quarks somehow also involved in this same electric interaction? After all, the quarks do have fractional electric charges. Thanks in advance.
  12. Behrouz

    I Quark and lepton charges

    Hello everyone, I'm sorry if it's a dumb question, I'm very new in self studying particle physics. May I ask when we associate a charge (i.e. positive or negative) to quark and lepton, is it only because of their attraction or repulsion toward each other? in other words, is it just to name one...
  13. O

    I How bosons decay?

    Hey! I'm studying some particle physics. I ran into this example of a gluon decaying into a u - anti-u pair. (According to example 9: http://teachers.web.cern.ch/teachers/archiv/HST2002/feynman/examples.htm) How come this happens via strong force. Why isn't a Z0 boson doing this instead? Thanks!
  14. StanEvans

    I Beta radiation

    my understanding of beta radiation is that an up quark in a proton changes to a down quark, forming a neutron and emitting an electron as the result of the change in charge. My questions are, 1. Why does the quark change? 2. How does it change and how does it change charge?
  15. Stephanus

    Anti Proton vs Neutron annihilation

    Dear PF Forum, Just out of curiosity. What happens when an anti proton hits a 'normal' neutron? According to this: https://en.wikipedia.org/wiki/Proton https://en.wikipedia.org/wiki/Neutron A proton has 2 up quarks, 1 down quark A neutron has 1 up quark, 2 down quarks. 1. Does anti proton has 2...
  16. Ryan Reed

    Quark Overproduction in the Big Rip Theory

    In the big rip theory, the force of dark energy isn't constant and increases over time. This causes first galaxies to fly apart, then solar systems, then planets, then stars, then atoms, then the atom nuclei. If it keeps increasing, it would start pulling the quarks inside protons and neutrons...
  17. J

    What triggers beta decay?

    I am familiar with the proton:neutron ratio and stability but what about this instability actually causes a quark to emit a boson and change flavour? And what does this have to do with the weak nuclear force? Thanks
  18. M

    The pi-meson (π0)

    1. Homework Statement How does the pi-meson (π0) work without annihilating itself? 2. Homework Equations |π0 〉1/√2 〉- {|uu − |dd} u= anti-upquark d= anti-downquark 3. The Attempt at a Solution I do understand that it is a superposition, but why does it work when it is a partice with its...
  19. Ryan Reed

    How do quarks determine which quarks to pair with?

    Quarks join up with other quarks to form composite particles like protons and neutrons, but in the center of something like a nucleus, how do they know which quarks are in THEIR proton or neutron? When all the quarks are together and it becomes a "soup" of quarks, why doesn't it form things like...
  20. BiGyElLoWhAt

    On a scale of 1 to String, how speculative is this?

    http://arxiv.org/abs/1503.09158 Is this a legitimite thing? I've never heard of 4th color charge or quark-lepton unification.
  21. M

    Anti-lepton nomenclature?

    Is an electron anti neutrino and a positron neutrino the same thing?
  22. Ryan Reed

    Are there Quark-Antiquark Particles?

    There are exotic atoms such as the protonium (proton+antiproton) and positronium (electron+positron); I was wondering if quark-antiquark particles could appear even if they only exist for a fraction of a second.
  23. Stephanus

    Proton + Electron = Neutron?

    Dear PF Forum, I have a question to ask. Supernovae produce neutron star (or Black Hole). This is what I summarize from wikipedia. 1. Is P + e = N? Is it that simple? Judging by its mass, altough slightly off. 2. Is Up Quark + e = Down Quark? Thanks for any answer
  24. F

    What holds a quark together?

    What holds a quark together? Like the boundary force of this elementary particle? How do you create one? This thing is like minimum distance, it's never getting an answer.
  25. A

    Crippled Mesons?

    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...
  26. U

    Evidence for Quark Production

    1. Homework Statement (a) What are their vertex and propagator factors? (b) Find the value of R. (c) Explain the peaks at 3, 10 and 100 GeV. 2. Homework Equations 3. The Attempt at a Solution Part (a) They have the same propagator factor ##\frac{1}{P \cdot P}##. Vertex factor for muon...
  27. J

    Simplifying nuclear equations

    Hello all, I'm trying to answer a question about a meson and a proton interacting to form a neutron and an unknown meson- to be determined. The equation is : (Anti up and strange) + (uud) --> udd + (xy) I arrived at strange and anti down OR anti strange and down. Are both possibilities...
  28. Lobos

    What is the smallest thing discovered in our universe?

    I heard quarks could be the smallest things of the universe. How are they measured? What units of measure are associated with quarks?
  29. U

    Quick question on Baryon spin states

    Things I don't understand: What do they mean by "two spin-1/2 doublets and a spin-3/2 quadruplet"? Why do they use the two flavours "+2/3e and -1/3e" ?
  30. L

    Cross Section: Quark-Gluon vs. Quark-Photon

    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...