Quark Definition and 250 Threads

Hello, I'm a bit unclear on how the EM, weak, and strong forces can change the flavor of a quark. EM/Weak Force: Can you skip a generation (ie. u -> t or b -> d)? Also can you change quark generations with a W (ie, while also changing the quark charge, e.g. u -> s)? Strong force: Can...

Can anyone tell me, in detail, about Neutron - Proton interaction. Newbie here, so please use easy words(i know enough about quarks and gluons as well as strong interaction forces)

Dear Physics Forum, Is there any model where the electron and quark share a fundamental relationship, maybe in some string theory? I ask because it seems too much of a coincidence that two completely independent particles would have a simple charge relationship of 1/3:1 . Thanks, Mark

Does anyone know the magnetic moments of the up and down quarks? I am interested only in the best experimental data, not theoretical estimates.

What are flavor arguments that prevent a gluon from decaying into quark and photon, or anti-quark and photon, etc?

Can an up quark absorb a negative W particle and become a strange quark? I know s can turn into u via the opposite process (emission of positive W), but can the interaction go the other way? This arises when trying to draw the Feynman diagram for the rather unlikely decay B^+\to...

Hello! I have read that in the case of beta decay, a neutron becomes a proton neutron = proton + electron + antineutrino but the electron and antineutrino are ''materialized'' by the emission of an intermediate w- boson. What does ''materialize'' mean in this context? I have thought of the w...

Hello, I was looking at the quark masses and had this doubt regarding the muon decay: Why can't the muon decay into up and down quarks (plus neutrino). I know the explanation is because muon doesn't exhibit hadronic decays because its mass isn't big enough m_\mu=107MEV. But I just saw that...

From Ryder: "We can now see how a supermultiplet of ten baryons may arise. Baryons are made of three identical fermions, so the possible states may be classified according to their symmetry under interchange of quark labels. Altogether there are 27 states. One of these is totally...

There are four Delta particles made up of down and up quarks and having spin 3/2, but there are only two nucleons, the proton and the neutron. Why are there no particles made up of three up (or down) quarks and having spin 1/2??

I realize that because of the Pauli exclusion principle, two identical quarks (such as two up quarks in a proton) cannot occupy the same space, hence the variations in color provided by qluon interaction. I have two questions: Can "color" be thought of as a state, such a light switch can...

Hi everyone! Something has been bothering me lately. Consider the quark propagator: \langle 0|\psi_a(x)\psi_a(0) |0\rangle For a given color a. Now let's say we insert 1 = \sum |n \rangle \langle n| between the two quark fields, where the sum is over a complete set of energy...

Hi there! If an electron collides with a positron, they will annihilate producing a photon. But what about quarks? If an up quark collides with an antiup quark, do they produce a gluon or a photon? I ask that because I'm studying the reaction: \Pi^- + p \rightarrow \Lambda+K^0 where I suppose...

I've been looking at interactions between K mesons and "ordinary" matter such as protons and neutrons. Since I can't put a bar over a letter, I'll let a CAPITAL letter stand for an ANTI-quark. sD + duu ---> suu + uU (thru a resonance baryon suu ++) I know this one is possible, but what...

Consider a proton and antiproton collision. The goal is to produce a top quark and anti-top quark pair. If a top quark has a mass of 174 GeV/c2, how much energy is required in the center of mass frame to produce the combination? I'm somewhat utterly stumped. Obviously, the problem deals with...

Homework Statement Consider a proton and antiproton collision. The goal is to produce a top quark and anti-top quark pair. A top quark has a mass of 174 GeV/c2 How much energy is required in the center of mass frame to produce the combination? The Attempt at a Solution I'm somewhat utterly...

Article - http://news.bbc.co.uk/2/hi/science/nature/2502755.stm I wasn't real sure where to post this (mods move if necessary) Has anything come of this? Is it even relevant/accurate? The BBC doesn't seem to have a follow-up story or anything.

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...

I'm in trouble on answer to this question: "Wich is the (most probable) symmetry of the spatial part of the wavefunction for the lightest baryons? Why?" I know that the spatial and spin parts of a baryon wavefunction must be simmetric under an interchange of any two quarks (this is an...

Homework Statement I have a reaction \Omega^{-}(sss)\rightarrow\Lambda^{0}(uds)+K^{-}(\bar{u}s) I am supposed to analyse the reaction according to the quark content and I have connected u with \bar{u}, s with s, another s with s and I am left with s and d...how can I solve this? there can...

Note: I am not studying the topic in a class. I'm a complete layman when it comes to physics, so you may have to provide lots of detail in small words for me to really understand, heh. This was my stream of consciousness thought process: Radio wave > electromagnetic radiation > magnetism >...

Just wondering if anyone could tell me why the W boson cannot decay into the heavier top mass.

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.

Hi this isn't actually a homework question more my own curiosity/confusion. They have the same quark constituents and http://en.wikipedia.org/wiki/File:Baryon_octet.png" for both but mass and decay rate are different, please explain. (if the lambda is an excited state of the sigma why isn't it...

Are there any theories that suggest that there are smaller degenerate states than the state reached in a neutron star? For example, is there a degenerate state for quarks? For strings? (should they exist) For theories that suggest such possibilities, do they discuss what would happen to the...

Homework Statement At the Tevatron you observe the process u ̅u → τ+τ−. Draw the lowest order Feynman diagrams for the processes involved and state which interactions are responsible. Label all internal lines, external lines and vertices [u = up quark, τ = tau lepton] The Attempt at a...

Hello; My physics teacher asked me to name the combinations of quarks that could make up a proton and a neutron; uud = proton udd = neutron But is that all? Does it have to be 2 up quarks and 1 down quark to make the proton? Why not 2 charm quarks and 1 strange quark, for example? Or 2...

Some black holes may actually be "Quark Stars" http://www.usatoday.com/tech/science/space/2009-12-07-quarkstar07_ST_N.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+UsatodaycomScienceAndSpace-TopStories+%28Tech+-+Science+and+Space+-+Top+Stories%29": excerpts below: So how...

I am curious to know if there have been any experiments to measure change in nuclear disintegration rates/ gamma emissions with change of distance between quarks in nucleons? Thank you. Douglas

In the course of reading the "Quark and the Jaguar", http://www.osti.gov/accomplishments/gellmann.html" relates a moment of insight that applies not only to elementary particle physicists, but to artists, musicians and all creative people. In attempting to explain the behavior of new "strange...

I know that we (believe) we have found the mass of the 6 quarks. But, I have not been able to find anywhere if we have any idea of their various sizes. I would gesture that the heavier quarks would be larger. Does anyone know if there is any data on this?

I'm trying to understand quark color. Everyone seems to say that there are three quark colors, say Red, Blue, Green, that add up to uncolored. So why not just pick a basis, say Red and Blue, so that the color Green is equivalent to -1 Red plus -1 Blue?

Dear all! I am currently searching for experimental data on the sea and valence quark distribution of the proton together with the gluon distribution. You find plenty of F^p_2(x) structure functions but no consideration on how it splits in terms of sea and valence quarks. A big thanks for...

How can a down quark emit a W- when decaying if the boson is much heavier than the quark or even the whole neutron? Actually, the three quarks together make ~10 MeV, but the neutron is said to be ~939 MeV, so there is 929 MeV missing, i though that W- bosons made it up, but then i realized that...

Why in QCD chiral symmetry breaking study only the light quarks are taken into account? And why are their masses usually set to zero, Goldstone bosons are found, and then their masses are corrected by letting the quarks have non-zero mass? What happens if one study this symmetry breaking with...

First post, guys :) Hello all. My only degree is in Earth Sciences, and my physics and astronomy knowledge base is mostly from the pages of Scientific American...and since I'm like a first grader when math time comes...I haven't been able to expand that base by understanding the various...

Self-explaining question... Thanks.

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?

Question in title. Indeed, how are any particle masses determined? And especially quarks, since they have the added difficulty of being confined.

How masons can be massless while their composites quark (q) and antiquark (\bar{q}) are both massive? Is there any clear physical scenario to understand this?

Hi. I was wondering whether Quark technology is possible or not? You know, Quark reactors, etc ?

I've read conflicting definitions of what happens to the force between quarks as they're pulled apart. Do the gluon tubes form to maintain a constant force between them, or does the force actually increase as the distance between quarks increase? Is there an easily defined potential between the...

Where EXACTLY is the "Mass" of an Atom? Proton? Quark? Hadron? Gluon?? Just look at the simplest Hydrogen atom -- one Proton. The question is *where* exactly is the mass of this thing? Or *what* makes up the mass of this thing? Is it just Quarks? So where is the *mass* of those things? Where is...

im writing a physics simulator and now I decided to see about implementing the basic matter not just to atoms but down to the fundamental particles, so to start I am trying to figure out how exactly quarks are attracted, like I know an up and down quark are attracted through electromagnetism and...

during the big bang there was said to be at one time a giant soup of quarks for a split of a second before atoms were formed. But why is it quarks always link up in triplets to form protons and neutrons with up and down quarks. Why didnt five or six quarks join up together with the strong...

Here is a beta decay related question: Masses are from Particle Data Group (http://pdg.lbl.gov/2008/listings/contents_listings.html) Neutron has udd quarks. Mass is approximately 2.5, 5, 5 MeV. Total 12.5 MeV Products are: 1. Proton. uud quarks. Mass approx 2.5, 2.5, 5 MeV 2. Electron...

Homework Statement This is from Advanced Physics by Adams and Allday, section 9.11, question 2 c. What is the quark content of each of the following particles? [snip] c) Λ baryon, strangeness = -1, mass 1.12 GeV/c2? Homework Equations No equations. Table of masses at...

ive been reading a bit about this and its blowing my mind a bit lol. To think that the spin of a quark has something to do with whether or not something will hapen and the opposite reaction will co-exist in another universe sounds crazy. When it says spin does it mean rotational spin sort of...

Ive noticed when we are viewing the quark table in particular its charmness, and strangeness we know; c quark has a charmness of +1, but the strangeness of an s quark = -1. I would like to better understand why. Is it not thought that the s quark has a strangness of +1?

Hi: Quark gluon plasma is created at very high temperature, right?. Could you please explain me what happens to Quark gluon plasma after it is cooled?, is it possible to use quark gluon plasma to create nucleons? Thanks