Quark Definition and 250 Threads

Homework Statement I am given the following interaction, $$\pi^-+p\rightarrow \pi^++\pi^-+n,$$ and asked to draw the Feynman (quark flow diagram). Homework Equations None; just baryon number conservation, quark flavor conservation, etc. The Attempt at a Solution First, as baryon number and...

Personality wise which two are you and give a reason why/example: Up: Positive or upbeat Down: Realist or pessimist Strange: Goofy or comedian Charm: Social or life of party Top: Studious or intellectual Bottom: AthleticI would say I am Down Bottom. I play soccer a few times a week and overall...

If the top quark is heavier than the Higgs boson, then why was it discovered first? Does the top quark get all of its mass from the Higgs? Or does some of its mass come from somewhere else, perhaps a heavier Higgs boson, not yet discovered?

I'm not clear on whether the coupling constant for strange to antidown is modified in the same way as for strange to down, i.e. multiplied by ##\sin(\theta_C)##. And are the coupling constants of interactions mediated by Z also dependent on the Cabibbo angle? And what happens if you have say a...

the top quark is the heaviest quark. the current theory is its invariant mass is based solely on its interactions with the higgs field. in absence of the higgs field, fermions, quarks and leptons are massless, and in the presence of the higgs field, they acquire mass. the reason the top quark...

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...

from https://www.physicsforums.com/threads/world-made-up-of-2nd-3rd-gen-particles.883560/#post-5555878 quoting ohwilleke Have you come across this paper in peer reviewed Physical Review D... http://www.sciencedirect.com/science/article/pii/0370269379906671 or...

Gluons are spin 1 particles so the Strong Force can both attract and repulse. The constituent partons of a meson are a quark and an antiquark so they must carry a given color and its anticolor, respectively, in order that there is no net color carried by the parton. In that case, the force...

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.

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...

Why doesn't pdg baryons list show the quark compositions and electrical charges? For example, there is only one roper resonance entry, but there are two roper resonances with different quark compositions (although they have the same mass), why not list all the variations?

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!

Homework Statement Give 2 reasons which give support for the quark substructure of protons and neutrons Homework EquationsThe Attempt at a Solution My first reason was due to the fact that in deep elastic scattering of the electron from a proton, the analysis of the structure function...

Hi- Between the Planck particle and the Quark, these is a sizeable relative difference of about 10^15, or in other words and size unit, as if there were no objet whose size would stand between ours (about 1.70 m) and Antares... this is not only about vacuum (or void) in absolute term but also...

'In the SU(3) quark model there are two singlet vector states $$|\omega_8 \rangle = \frac{1}{\sqrt{6}} \left(|u \bar u \rangle + |d \bar d \rangle - 2 |s \bar s \rangle \right) $$ belonging to the octet and the pure singlet state $$|\omega_1 \rangle = \frac{1}{\sqrt{3}} \left(|u \bar u \rangle +...

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?

Do we know enough of string theory to say that because a quark is more complicated, in the sense that the quark experiences four forces verses three for the electron and two for a neutrino, that in terms of string vibrations quarks will have more complicated vibration patterns than electrons and...

Does it make sense to talk about the top mass at energies below mt, although in all processes the corresponding energy scale is above mt because of the rest mass energy of the top quark? Using an effective field theory approach, the top quark decouples at energies below the top quark mass and...

Homework Statement Hi, I need to get an estimate of the branching ratios of the processes [/B] t ---> b + W ---> b + c anti-s t ---> b + W ---> b + anti-tau nu(tau) without doing the calculations, just a qualitative estimation. I know I have to take into account the way W decays...

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...

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...

A couple of quotes from papers that have shown up recently: from: http://arxiv.org/pdf/1512.05327.pdf We consider several models for these fermions, including a single vector-like charge 2/3 T quark, a doublet of vector-like quarks (T, B), and a vectorlike generation including leptons that...

If a bubble of quark type matter formed near the core of a magnetized neutron star, what would happen to its shape? Would it elongate along the magnetic field lines? Could it burst out of the magnetic poles of the star?

I find that the quark mixing factor say for example ##V_{ub}## is the same for: u ##\Leftrightarrow## b ##u\Leftrightarrow\bar{b}## ##\bar{u}\Leftrightarrow## b ##\bar{u}\Leftrightarrow\bar{b}## Does this have something to do with weak interaction being unable to distinguish these from one...

In almost all direct detection articles (see for example Jungman, G., Kamionkowski, M. & Griest, K., 1996. Supersymmetric dark matter) I found the following parametrization for the matrix element of the quark axial-vector coupling: $$ \langle n|\bar...

Homework Statement The problem asks me to find \frac{d\sigma}{dz} for u\bar{u} \rightarrow t\bar{t} via the strong interaction and then to find the total cross section via QCD. I'm wondering what the difference is? I was just going to write the feynman rules for QCD to get the amplitude and...

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

Homework Statement How does the pi-meson (π0) work without annihilating itself? Homework Equations |π0 〉1/√2 〉- {|uu − |dd} u= anti-upquark d= anti-downquark 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 own...

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...

Why are charm quarks (+2/3e) heavier than strange quarks (-1/3 e) while up quarks (+2/3e) are lighter than down quarks (-1/3e)?

Hello, So, I know quarks are confined in baryons. In a proton, there are "3" quarks, but the sum of their masses is not the mass of the proton. This implies a major fraction of the proton mass comes from interactions. My question is, how then do they measure quark u and d masses? And...

Homework Statement A proton is composed of three quarks: two "up" quarks, each having charge +2e/3, and one "down" quark, having charge -e/3. Suppose that the three quarks are equidistant from one another. Take the distance to be 3×10-15 m and calculate the potential energy of the subsystem of...

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

this paper Do Black Holes End up as Quark Stars ? R.K.Thakur (Submitted on 25 Feb 2007) The possibility of the existence of quark stars has been discussed by several authors since 1970. Recently, it has been pointed out that two putative neutron stars, RXJ 1856.5 - 3754 in Corona Australis...

http://news.discovery.com/space/lhc-keeps-bruising-difficult-to-kill-supersymmetry-150727.htm LHC Keeps Bruising 'Difficult to Kill' Supersymmetry Previous attempts at measuring the beauty quark's rare transformation into a so-called "up quark" had yielded conflicting results. That prompted...

Is an electron anti neutrino and a positron neutrino the same thing?

Just started the study Exotic Hadrons (like mixing of Charmonium states with tetraquarks etc.) and got confused with quenched & unquenched quark model. What are the major differences between these two models? What key factors I should keep in mind doing calculations with these models...

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.

Hi all. I am curious as to why quark stars have not dominated by now, given their inability to decay as they are a mass of fundamental particles. What prevents this?

Hi there, so my question is as follows. I understand that only the weak interaction can change the flavour of a quark, but why? Idea 1: It's due to the change in flavour also meaning a change in mass, thus a massive exchange particle is needed (gravity is negligible so forget the massive...

Doing a bit of revision at the moment and I've been looking at the baryon spin-1/2 octet and the spin 3/2 decuplet. I've noticed that a lot of particles have the same quark composition. For instance the Δ0 particle from the 3/2 ducuplet has the same quark composition as a proton. Now I know that...

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

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.

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...

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. Homework EquationsThe Attempt at a Solution Part (a) They have the same propagator factor ##\frac{1}{P \cdot P}##. Vertex factor for muon production is...

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...

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

Hi! Does anyone know the most fundamental experiments that CERN did involving the discover of anything related to quarks? What is the most recent and important discover of CERN about quarks (heavy quarks)? Thank you.

Homework Statement (a) Find energy of incoming beam that creates highest cross section (b) What are the differences in the two reactions, using quark diagrams? (c) What would the peaks of the two reactions be like? Homework EquationsThe Attempt at a Solution Part(a) [/B] Cross section is...

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" ?